Embed Size (px)
Citation preview
ENSAYO 01:
• En un tubo de ensayo colocar 1 ml de solución de dicromato de potasio, añadir 1 ml de acido sulfúrico 3M y luego 2 ml de solución de yoduro de potasio.
• Agitamos con cuidado y notamos sus cambios: color(amarillento), y luego al agregar KI da color oscuro.
K2Cr2O7 + H2SO4 + KI ??' I2 + Cr2(SO4)3 + K2SO4 + H2O
ENSAYO 02:
• En un tubo de ensayo introducimos un trocito de cobre metálico y añadimos 1 ml de acido nítrico concentrado y observamos burbujeos y desprendimiento de gases.
• Luego de que haya bajado la intensidad de la reacción agregamos agua 5 ml ; desprende gas y cambia de color a verde esmeralda.
Cu + HNO3 ??' Cu(NO3)2 + H2O + NO
Cu(NO3)2 + H2O ??'
ENSAYO 03:
• En un tubo de ensayo colocar 1 ml de solución de permanganato de potasio, agregamos 5 gotas de acido sulfúrico 3N, se mantiene el color del permanganato de potasio (violeta).
• Luego agregamos agua oxigenada gota a gota hasta observar la decoloración total de la solución.
KMnO4 + H2SO4 + H2O2 ??' MnSO4 +K2SO4 + O2 + H2O
ENSAYO 04:
• En un tubo de prueba se deposita 1 ml de solución de cromato de potasio; agregamos 5 gotas de acido sulfúrico 3N, observamos el cambio de coloración de amarillo a amarillento
• Luego agregamos 5 gotas de peroxido de hidrogeno, agitamos suavemente y observamos los cambios de coloración de azul a verde.
K2CrO4 + H2SO4 ??' K2Cr2O7 + K2SO2 + H2O
K2Cr2O7 + H2O2 ??' H3CrO8 + H2O
ENSAYO 05:
En un tubo de ensayo colocamos 1 ml de de solución de permanganato de potasio, acidificamos con 5 gotas de acido sulfúrico 3N y luego añadimos algunos cristales de acido oxálico, agitamos y observamos el cambio de la coloración de la solución; inicialmente tenia un color violeta, luego guinda, luego amarillo , hasta llegar a ser incoloro.
2KMnO4 + 3H2SO4 + 5H2C2O4 ??' 2MnSO4 + K2SO4 + 10CO2 + 8H2O
ENSAYO 06:
Cogemos un poco de acido oxálico, echamos agua y calentamos un poco ; luego agregamos gota a gota permanganato de potasio, observamos que desaparece el color violeta y seguimos agregando mas hasta que ya no desaparezca.
H2C2O4 + KMnO4 ??' ________
________ + KMnO4 ??' ________
ENSAYO 07:
Tomamos cristales de yodato de potasio, agregamos agua (solución); agregamos 5 gotas de acido sulfúrico 3N se aprecia el color naranja, ahora agregamos yoduro de potasio, agitamos y observamos el color azul, enseguida agregamos almidón para reconocer la presencia del yodo libre; entonces el color azul marino nos indica que hay yodo libre.
,,,,,,,,,,,, + H2SO4 + KI ??' ,,,,,,,,,,,,
,,,,,,,,,,,, + almidón ??' ,,,,,,,,,,,, + I + ,,,,,,,,
ENSAYO 08:
En un tubo seco colocamos cristales de urea aprox. 5g , acidificamos con 3 gotas de acido clorhídrico concentrado; luego añadimos aprox. 2 ml de solución de nitrito de sodio. Agitamos y observamos el desprendimiento de gases, burbujeos
CO(NH2)2 + HCl(c) + NaNO2 ??' …………
ENSAYO 09:
Tomamos en un tubo de ensayo 2 ml de solución de sulfito de sodio, añadimos 2 ml de acido sulfúrico, y 1 ml de solución de permanganato de potasio.
Na2SO3 + H2SO4 + KMnO4 ??' ………
ENSAYO 10:
Colocamos en un tubo de ensayo una porción de cristales de permanganato de potasio, añadimos 1 ml de acido clorhídrico concentrado. En la reacción observamos desprendimiento de gases y el cambio de color violeta a marrón; también sube la temperatura.
2KMnO4 + 16HCl ??' 2MnCl2 + 2KCl + 5Cl + 8H2O
4.2. Reacciones en medio básico
ENSAYO 11:
En un tubo de prueba colocamos 1 ml de solución de permanganato de potasio, agregamos 5 gotas de solución de hidróxido de sodio y luego añadimos 1 ml de peroxido de hidrógeno. Agitamos suavemente y observamos la formación de un precipitado.
KMnO4 +NaOH + H2O2 ??' …………
ENSAYO 12:
Colocamos en un tubo de prueba 1 ml de solución de nitrato de cobalto, agregamos 5 gotas de hidróxido de sodio; luego añadimos 10 gotas de peroxido de hidrogeno. Observamos la formación de un precipitado, hubo una reacción muy rápida desprendiendo gases y burbujeos; y la formación de dos colores (marrón y celeste) como se ve en la foto.
Co(NO3)2 + NaOH +H2O2 ??' Co(OH)NO3 + NaNO3 + H2O + O2
ENSAYO 17:
En un tubo de prueba colocamos 1 ml de solución de sulfato de cobre, añadimos 1 ml de solución de yoduro de potasio. Observamos la formación de un precipitado pardo, que es una mezcla de yoduro cuproso (Cu2I2). El yodo libre
se puede reconocer entonces por medio de la coloración de azul intenso que se produce con la solución de almidón.
2CuSO4 + 4KI ??' Cu2I2 + I2 + 2K2SO4
Cu2I2 + I2 + K2SO4 + almidon ??' azul intenso
ENSAYO 19:
Tomamos en un tubo de ensayo cloruro mercúrico, agregamos gota a gota solución de yoduro de potasio hasta observar la formación de un precipitado naranja lechoso; luego agregamos exceso de solución de yoduro de potasio, hasta que se llegue a observar un color color ámbar; finalmente agregamos 3 gotas de solución de nitrato de plata, y observamos un color amarillo mostaza.
HgCl2 + 2KI ??' HgI2 + 2KCl
HgI2 + 2KI ??' K2[HgI4]
K2[HgI4] + AgNO3 ??' K2NO3 + Ag[HgI4]
5. CONCLUSIONES
Este informe lo hicimos con la finalidad de conocer las reacciones químicas, comunes y redox como reacciones en medio ácido, reacciones en medio básico y reacciones en medio neutro como hemos visto anteriormente.
6. RECOMENDACIONES
Los alumnos deben tener mucho cuidado con los reactivos que se van a utilizar, también deben de mantener la cara alejada durante la reacción.
7. BIBLIOGRAFÍA:
SALCEDO COA y otros. Química Experimental 1995
GAST?"N. Química general.
http://es.wikipedia.org/
Biblioteca de consulta Encarta 2008
8. CUESTIONARIO
1.- Señalar el nombre, su formula, su peso molecular y la función química de cada uno de los reactivos químicos utilizados en los ensayos.
Su nombre, formula, peso molecular y la función química ya están mencionados en la parte experimental.
2.- la disolución de un sólido en un líquido es un fenómeno físco o químico?
La disolución de un sólido en un líquido no reactivo puede ser considerada como el fenómeno inverso a la cristalización. Desde el punto de vista macroscópico, la disolución de un sólido corresponde a la desintegración de la estructura cristalina bajo la acción del disolvente que la rodeé. Las partículas así liberadas, se distribuyen en la fase solvente mediante el proceso de difusión que tiene lugar a partir de la superficie del sólido, llegando a ocupar todo el seno de la solución.
3. Ejemplos de reacciones donde el peroxido de hidrógeno actua como agente oxidante, y otras como agente reductor.
OXIDANTES:
H2O2 + 2H+ + 2e- ??" 2H2O
2Fe+2 + H2O2 + 2H+ ??' 2Fe+3 + 2H2
Antihacterial Finishes on Textile Materials: Assessment of
Antibacterial Finishes on Textile Materials: Assessment of
1. Purpose and Scope
1.1 This test method provides al quantitative procedure for the evaluation of the degree of antibacterial activity. Assessment of antibacterial finishes on textile materials is determined by the degree of antibacterial activity intended in the use of such materials. If only bacteriostatic activity (inhibition of multiplication) is intended, a qualitative procedure which clearly demonstrates antibacterial activity as contrasted With lack of such activity by an untreated specimen may be acceptable. However, if bactericidal activity is intended or implied. quantitative evaluation is necessary. Quantitative evaluation also provides a clearer picture for possible uses of such treated textile materials.
2. Principle
2.1 Swatches of test and control textile materials are tested qualitatively for antibacterial activity by AATCC Method 147, Antibacterial Activity Assessment of Textile Materials: Parallel Streak Method.
Those showing activity are evaluated quantitatively. Test and control swatches are inoculated with the test organisms After incubation, the bacteria are eluted from the swatches by shaking in known amounts of neutralizing solution. The number of bacteria present in this liquid is determined, and the percentage reduction by the treated specimen is calculated.
3. Terminology
3.1 activity, n.-of an antibacterial agent, a measure of effectiveness of the agent.
3.2 antibacterial agent, n-in textiles, any chemical which kills bacteria (bactericide) or interferes With the multiplieation, growth or activity of bacteria (bacteriostat).
4. Safety Precautions
NOTE: These safety precautions are for information purposes only. The precautions are ancillary to the testing procedures and are not intended to be all inclusive. it is the user´s responsibility to use sale and proper techniques in handling materials in this test method. Manufacturers MUST be consulted for specific details such as material safety data sheets and other manufacturer´s recommendations. All OSHA Standards and rules must also he consulted and followed.
4.1 Both the qualitative and quantitative tests should be carried out by persons with training and experience in the use of bacteriological techniques. The U.S. Department of Health and Human Services publication, Biosafety in microbiological and biomedicaldical Laboratories, should be
consulted (sec 13,1).
4.2 CAUTION: Some of the bacteria used in this test are capable of infecting humans and producing disease. There fore, every necessary and reasonahle preecaution must be taken to eliminate this risk to the laboratory personnel and to personnel in the associated environment. Wear protective clothing and respiratory protection that prevents penetration by the bacteria.
4.3 Good laboratory practices should be followed. Wear safety glasses in all laboratory areas.
4.4 All chemicals should he handled With care,
4.5 An eyewash/safety shower should be located nearby for emergency use.
4.6 Sterilize all contaminated sample and test materials prior to disposal.
4.7 Exposure to chemicals used in this procedure must be controlled at or below levels set by government authorities (e.g., Oecupational Safety and Health Administration´s [OSHA] permissible exposure limits [PEL] as found in 29 CFR 1910.1000 of january 1, 1989). ln addition, the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) comprised of time Weighted averages (TLV-TWA), short term exposure limits (TLV›STEL) and ceiling limits (TLV-C) are recommended as a general guide for air contaminant exposure which should be met (see 13.2).
5. Limitations
5.1 Por a qualitative, relatively quick and easily executed method to determine residual antibacterial activity of textile materials, refer to AATCC Method 147.
6. Test organisms
6.1 Test bacteria.
6.1.1 Staphylococcus aureus American Type Culture Collection No. 6538. Gram positive organism (seel3.3).
6.1,2 Klebsiella pneumoniae, American Type Culture Collection No. 4352. Gram negative organism (see 13.3).
6.1.3 Other suitable species can also be used.
7. Culture Medium
7.1 Suitable broth/agar media are Nutrient, Trypticase Soy and Brain-heart lnfusion.
Nutrient Broth:
Peptone (Bacto-peptone) (see 13.4) 5 g
Beef extract (see 13.5) 3 g
Distilled water to 1000 ml
7.2 Heat to a boil to disperse ingredients. Adjust to pH1 6.8 ± 0.1 With 1/V sodium hydroxide (NaOH) solution. (This is not necessary if prepared, dehydrated medium is used.)
7.3
Dispense in 10 ml. amounts in conventional bacteriological culture tubes (i.e., 125 X 17 mm). Plug and sterilize at 103 kPa (15 psi) for 15 min.
7.4 Nutrient agar, Add 1.5% bacteriological agar to nutrient (or appropriate) broth (see 7.1). Heat to boiling. Check pH and adjust to 7.1 ± 0.1 using NaOH solution if necessary. Dispense in 15 ± 1 mL amounts in conventional bacteriological culture tubos. Plug and sterilize at 103 kPa (15 psi) for 15 min. (May be sterilized in 1000 mL borosilicate glass flasks and petri dishes poured from this.)
7.5 Slurry lnoculum Carrier (for hydrophobic fabrics) (see 7.2 and 7.3):
Sodium Chloride 8.5 g
Agar 3.0 g
Distilled Water 1000 mL
8. Maintenance of Culture in Test Organisms
8.1 Using a 4 mm inoculating loop, transfer the culture daily in nutrient (or appropriate medium) broth for not more than two weeks. At the conclusion of two Weeks. make a fresh transplant from stock culture. incubate cultures at 37 ± 2°C (99 ± 3°F) or other optimal temperature.
8.2 Maintain stock cultures on nutrient or appropriate agar slants. Store at 5 ± 1°C (41 ± 2°F) and transfer once a month to fresh agar (see 13.6).
9. Qualitative Test (Screening or Presumptive Test)
9.1 For detection of bacteriostatic activity use AATCC Method 147 on a test specimen and control specimen using the organisms referred to above. For demon stration of bacterieidal activity, proceed to the quantitative test described below.
10. Quantitative Test (reference or Confirmatory Test)
10.1 Preparation. The following description will be in terms of fabric swatches. Textile materials not in fabric form can likewise be tested with the appropriate modification.
10.1.1 Size and shape of treated swatches Cut circular swatches 4.8 ± 0.1cm (1.9 ± 0.03 in.) in diameter, from the test Fabric (preferably With a steel die). Stack the swatches in a 250 mL wide-mouth glass jar with screw cap.
The number of swatches to be used is dependent on the fiber type and fabric construction. Use that amount of fabric which Will absorb the 1.0 ± 0.1 mL of inoculum, and leave no free liquid in the jar. For example, 4 swatches of cotton print cloth will absorb 1 ml.. The number of swatches used per jar should be reported.
10.1.2 Controls. Swatches of the same fiber type and fabric construction as test sample but containing no antibacterial finish (negative control).
10.1.3 Sterilization ot samples. This is Optional. The method to be used depends on the type of fiber and finish. Cotton, acetate and many manmade fibers can be sterilized in the autoclave. Wool can be sterilized by ethylene oxide or by intermittent (fractional) sterilization in flowing steam. The latter is also least damaging to certain finishes. Report method of sterilization, if used.
101.4 Size of inoculum per sample. Apply 1.0 ± 0.1 mL of an appropriate dilution of a 24 h broth culture of the test organism so that recovery from (1) untreated control fabric swatches or (2) treated test fabric swatches at “0" contact time (plated as soon as possible after inoculation) will show counts of -2 X 105 organisms. The dilution of the test organism should be made in nutrient (or appropriate) broth (see 7.1, 7.5 and 13.7).
10.2 Procedure.
10.2.1 Inoculaiion of tabrics. When sing Smphylococcus aureus, shake a 24 h culture and let stand for 15-20 min before preparing the inoculum* Place the swatches separately in sterile petri dishesid use 11 microliter pipette to inoeulate them making sure that there is even distribution of the inoculum (see 13.8). Transfer these swatches aseptically to the jar. Screw the jar tops on tightly to prevent evaporation.
10.2.2 As soon as possible after inoculation (“0" contact time), add 100 ± 1 mL of neutralizing solution to each of the jars containing the inoculated untrcated control swatches, the inoculated treated test swatches and the uninoculated treated test swatches.
10.23 The neutralizing solution should include ingredients to neutralize the specific antibacterial fabric treatment and to take care of any pH requirements of the fabrics (from finishes, antibacterial agents, etc.). The neutralizing solution employed should be reported (see 13,9).
10.1.4 Shake the jars vigorously for one minute. Make serial dilutions with water and plate (in duplicate) on nutrient (or appropriate) agar. Dilutions of 10 0 10 1, 10 2 are usually suitable.
10.2.5 lncubation over contact periods. incubate additional jars containing inoculated untreated control swatches and jars containing inoculated treated test swatches at 37 1 2°C (99 ± 3°F) for 18-
24 h. Similar jars may be incubatecl over other periods (e.g., 1 or 6 h) to provide information about the bactericidal activity of the treatment over such periods.
10.2.6 Sampling of inoculated and incubated swatches. After incubation add 100 ± l ml. of neutralizing solution to jars containing untreated control swatches and to jars containing treated test swatches. Shake the jars vigorously for one minute. make serial dilutions and plato (in duplicate) on nutrient (or appropriate) agar, Dilutions of 10 0 101 - 102 are usually suitable for treated test fabrics.
Several different dilutions may be required for untreated control fabrics depending on the incubation period .
10.2.7 lncubate all platos for 48 h at 37 ± 2°C (99 ± 3°F) or other optimal temperature.
11. Evaluation
11.1 Report bacterial counts as the numeber of bacteria per sample (swatches in jar) not as the number of bacteria per mL of neutralizing solution, Report “0” counts at 10“ dilution as “less than 100.”
11.2 Calculate percent reduction of bacteria by the specimen treatments by one of the following formulas:
1) l00(B-A)/B=R
where:
R = % reduction
A = the number of bacteria recovered from the inoculated treated test specimen swatches in the jar incubated over the desired contact period
B = the number ol bacteria recovered from the inoculated treated test specimen swatches in the jar immediately aficr inoculation (at "0" contact time)
2) 100 (C-A)/C=R
where:
C = the number of bacteria recovered from the inoculated untreated control specimen swateltes in the
jar immediately after inoculation (at “0” contact time)
lf “B and C” are not similar, the larger number should be used. lf “B" and “C” are not significantly different, (B +C)/2 should be used as follows: 3) 100(D -A)/D = R
where:
D= (B + C)/2
11.3 lf an untreated control is not available, use the following calculation which allows for any background organisms that might intcrfere with the test.
Bg = 100 [(B-E)-(A-F)/B-E]
where:
A, B: (see ll.2)
E = the number of bacteria initially recovered from the uninoculated treated test sample (existing background organisms)
F = The number of bacteria recovered from the uninoculated, pre-Wet treated test sample after
incubation in the jar over the desired contact period (existing background organisms after
contact period)
Bg = background organisms
11.4 For a valid test there should be: (1) “0” colonies of test organism recovered from the uninoculated treated test specimen swatches and (2) a significant increase in the nurnbers of bacteria recovered from the inoculated untreated control specimen swatches incubated for the specified contact time over the numbers of bacteria recovered from the inoculated untreated speeimen swatches at “O” contact time (immediately after inoeulation). This applics only if dilution Was made in broth (see 10.1.4 and 13.7).
11.5 Report percent reduction of bacteria by the specimen treatment against each test organism.
11.6 The critcrion for passing the test must be determined by the interested parties.
11.7 Report the dilution medium used.
12. Precision and Blas
12.1 Studies (see 13.10) indicate the following within-laboratory precision of the Standard Plate Count (SPC) Test: (a) among-anulifsl variation of l8% and (b) within-analyst variation of 8%,
13. Notes and References
13.1 Publication available from U.S. De~
pal1memofHealtl1 and Human Services CDC/
NlH~HHS Publication No. (CDF) 84-S395;
web site: wWw.l1hs.gov.
13.2 Booklet available fi'om Publications
Office, ACGIH, Kemper Woods Cemei: 1330
Kemper Meadow Dr., Cincinnati OH 45240;
ìel: 5l3¡`742~2(ì2(J', web site: www,acgìh.org.
13.3 Available from American Type Cul-
ture Collectinn (ATCC). P.O. Box 1549,
Manassas VA 20108; tel: 703/365-2700; fax:
703/3652701; web site: wwW.zx1cc.0rg.
l3.4 Bacm4Pcp1one may be obtained from
Difco Laboratories¬ 920 Henry St., Detroit Ml
4SZOl.
13.5 Beef extract may bs obtained (rom
Ballimore Biological Laboramries, 250 Scliìll-
mg Cír.¬ Cockcysville MD 21030; Difco Labo-
ratorios (address above); or Oxoid (USA) Ltd.,
9017 Red Branch Rd., Columbia MD 21045.
13.6 Conslstent and accurate testing 1'e~
quitas maintenance oía pure_ uncontamìnatcd,
nonmutam test culture. Avoíd comamination
by use of good sterile leclinique in plating and
transferring. Avoid mutation by Strict adhcr›
cnce to monthly stock t\'ansl`crs. Check cullure
purity by making sireak plates periodically
and obssrving for single species-chnractcribtìc
type ofcolonics.
13.7 The dilulion of the test organism may
bc prepared in slerilc 0.85% salina solution or
suitable buffer if a steadystale culture is de~
sircd during the comact perm; '
in the slurry inoculum carnft « * _'
bio fahrics are being Lesïed.
13.8 A surfactant mn) ha ¿¿;;;
tien medium to enhance \\ en'ï¿ "
bic fabrica. The surfixctuni num ':; ~
cause es reduction in bacmrial n_:".?:
testing al the intended uso concatf,
the use and concemration uf >_¡ï';_
13.9 [f slexile distillcd uma? ;~
Nace of a ncutralìzing soluuut. *f
ways be the possibilm tha: §:f'±
cide will be carried o\ er.
13.10 Pecìer, J. T: Leslie. J. W. Replicate counting errors by and bacterial colony counters, _' E
tion,Vol.45,1982, pp 238-240.
Acabados antibacterianos de las materias textiles: evaluación de
1. Objeto y ámbito de aplicación
1,1 Este método de ensayo proporciona al procedimiento cuantitativo para la evaluación del grado de actividad antibacteriana. Evaluación de acabados antibacterianos en los materiales textiles se determina por el grado de actividad antibacteriana destinado en el uso de tales materiales. Si sólo actividad bacteriostática (inhibición de la multiplicación) se destina, un procedimiento cualitativo que demuestra claramente la actividad antibacteriana en contraste con la falta de actividad por parte de una muestra no tratada puede ser aceptable. Sin embargo, si la actividad bactericida está previsto ni implícito. Evaluación cuantitativa es necesario. La evaluación cuantitativa también proporciona una imagen más clara de los posibles usos de tales materiales textiles tratados.
2. principio
2.1 Muestras de materias textiles de prueba y control se analizan cualitativamente la actividad antibacteriana por el método AATCC 147, Evaluación de la actividad antibacteriana de los Materiales Textiles: Método Streak paralelo.
Aquellos que muestra la actividad se evaluó cuantitativamente. Las muestras de prueba y control se inoculan con los organismos de ensayo Después de la incubación, las bacterias se eluyen de las muestras por agitación en cantidades conocidas de solución de neutralización. El número de bacterias presentes en este líquido se determina, y el porcentaje de reducción de la muestra tratada se calcula.
3. terminología
3,1 actividad, n.-de un agente antibacteriano, una medida de la eficacia del agente.
3,2 agente antibacteriano, n-en el sector textil, cualquier producto químico que mata las bacterias (bactericidas) o interfiere con la multiplieation, el crecimiento o la actividad de las bacterias (bacteriostático).
4. Precauciones de seguridad
NOTA: Estas instrucciones de seguridad son para fines informativos únicamente. Las precauciones son accesorios a los procedimientos de prueba y no se pretende que sea definitiva. es responsabilidad del usuario utilizar la venta y las técnicas adecuadas en el manejo de materiales en este método de ensayo. Los fabricantes deben ser consultados para obtener detalles específicos, tales como hojas de datos de seguridad y recomendaciones de otros fabricantes. Todas las normas de OSHA y las normas que deben consultar y seguir.
4.1 Tanto las pruebas cualitativas y cuantitativas deben ser realizadas por personas con formación y experiencia en el uso de técnicas bacteriológicas. Los EE.UU. Departamento de Salud y Servicios Humanos de publicación, Bioseguridad en laboratorios microbiológicos y biomedicaldical, debe ser
consultada (s 13,1).
4,2 PRECAUCIÓN: Algunas de las bacterias utilizadas en este ensayo son capaces de infectar a los seres humanos y producir la enfermedad. Hay tanto, cada preecaution necesario y reasonahle deben tomar medidas para eliminar este riesgo para el personal de laboratorio y personal en el medio ambiente asociado. Usar ropa protectora y protección respiratoria que impide la penetración de la bacteria.
4.3 Buenas prácticas de laboratorio deben ser seguidas. Use gafas de seguridad en todas las áreas de laboratorio.
4.4 Todos los productos químicos en caso de que manejarse con cuidado,
4.5 Una ducha lavaojos / seguridad debe estar situada cerca en caso de emergencia.
4,6 Esterilizar todas las muestras contaminadas y los materiales de ensayo antes de su eliminación.
4.7 La exposición a los productos químicos utilizados en este procedimiento debe ser controlada en o por debajo de los niveles establecidos por las autoridades gubernamentales (por ejemplo, seguridad Ocupacional y Administración de Salud [OSHA] los límites permisibles de exposición [PEL] que se encuentran en el 29 CFR 1910.1000 1 de enero de 1989) . En adición, la Conferencia Americana de Higienistas Industriales Gubernamentales (ACGIH) Los valores umbral límite (TLV) compuestos por tiempo promedios ponderados (TLV-TWA), los límites de exposición a corto plazo (TLV> STEL) y los límites de techo (TLV-C) se recomiendan como una guía general para la exposición a contaminantes del aire que debe ser cumplido (ver 13.2).
5. Limitaciones
Por un 5,1 cualitativo, método relativamente rápido y ejecutado fácilmente para determinar la actividad antibacteriana residual de materiales textiles, se refieren a AATCC Método 147.
6. Los organismos de ensayo
6.1 bacteria de prueba.
6.1.1 Staphylococcus aureus American Type Culture Collection N º 6538. Gram positivo organismo (ver. 13.3).
6.1,2 Klebsiella pneumoniae, American Type Culture Collection N º 4352. Organismo Gram negativo (ver 13.3).
6.1.3 Otras especies adecuadas también se pueden utilizar.
7. Medio de cultivo
7,1 adecuadas caldo / agar nutriente medios de comunicación son la soja, tripticasa y lnfusion cerebro-corazón.
Caldo Nutriente:
Peptona (Bacto-peptona) (ver 13.4) 5 g
Extracto de carne (véase 13.5) 3 g
Agua destilada hasta 1000 ml
7,2 calor a ebullición para dispersar los ingredientes. Ajuste a pH 1 6,8 ± 0,1 con 1 / V hidróxido de sodio (NaOH). (Esto no es necesario si el medio preparado, deshidratado se utiliza.)
7,3
Dispensar en 10 ml. cantidades en tubos de cultivo bacteriológicos convencionales (es decir, 125 X 17 mm). Enchufe y esterilizar a 103 kPa (15 psi) durante 15 min.
7,4 agar nutriente, Añadir 1,5% de agar bacteriológico de nutrientes (o apropiado) caldo (ver 7.1). Calentar hasta que hierva. Verificar el pH y ajustar a 7,1 ± 0,1 con solución de NaOH si es necesario. Se distribuye en 15 ± 1 ml en cantidades convencionales de tubos de cultivo bacteriológicos. Enchufe y esterilizar a 103 kPa (15 psi) durante 15 min. (Puede ser esterilizado en 1000 ml frascos de vidrio de borosilicato y platos petri vertido de esto.)
7,5 Slurry inoculo Carrier (para tejidos hidrofóbicos) (ver 7.2 y 7.3):
Cloruro de Sodio 8,5 g Agar 3,0 g Agua destilada 1000 ml
8. Mantenimiento de la Cultura en organismos de prueba
8.1 Uso de 4 mm asa de inoculación, transfiera la cultura cotidiana en nutrientes (o medio apropiado) de caldo por no más de dos semanas. Al término de dos semanas. hacer un trasplante fresco de la cultura de valores. incubar los cultivos a 37 ± 2 ° C (99 ± 3 ° F) o una temperatura óptima otro.
8.2 Mantener en cultivos de agar inclinado de nutrientes o apropiado. Almacenar a 5 ± 1 ° C (41 ± 2 ° F) y transferir una vez al mes a agar fresco (ver 13,6).
9. Prueba cualitativa (examen o prueba presuntiva)
9,1 Para la detección de uso bacteriostático Método actividad AATCC 147 en una muestra de ensayo y la muestra de control utilizando los organismos mencionados anteriormente. Por de demostración de la actividad bactericida, continúe con la prueba cuantitativa se describe a continuación.
10. Prueba Cuantitativa (referencia o prueba de confirmación)
10,1 Preparación. La siguiente descripción se dará en términos de recortes de tela. Los materiales textiles no en forma de tela de la misma manera se pueden probar con la modificación apropiada.
10.1.1 Tamaño y forma de muestras tratadas Cortar muestras circulares de 4,8 ± 0,1 cm (1,9 ± 0,03 cm) de diámetro, a partir de la tela de ensayo (preferiblemente con un troquel de acero). Pila de las muestras en un frasco de 250 ml de vidrio de boca ancha con tapón de rosca.
El número de muestras para ser utilizados depende del tipo de fibra y estructura de tejido. Use la cantidad de tejido que absorbe el 1,0 ± 0,1 ml de inóculo, y no dejan libre del líquido en el frasco. Por ejemplo, 4 muestras de tela de algodón de impresión absorberá 1 ml .. El número de muestras utilizadas por cada frasco debe ser reportado.
10.1.2 Controles. Muestras del tipo de fibra y de la construcción misma tela como la muestra de ensayo pero que no contiene acabado antibacteriano (control negativo).
10,23 La solución neutralizante debe incluir ingredientes para neutralizar el tratamiento específico de tejido antibacteriano y cuidar de los requisitos de pH de los tejidos (de acabados, agentes antibacterianos, etc.) La solución neutralizante empleado debe ser informado (ver 13,9).
10.1.4 Agitar los frascos vigorosamente durante un minuto. Realizar diluciones seriadas con agua y la placa (por duplicado) en los nutrientes (o apropiado) agar. Las diluciones de 10 0 10 1 10 2, son generalmente adecuadas.
10.2.5 lncubation durante períodos de contacto. incubar frascos inoculados adicionales que contienen muestras de control sin tratar y frascos que contienen las muestras de prueba tratadas inoculadas a 37 1 2 ° C (99 ± 3 º F) durante 18 a 24 h. Frascos similar puede ser incubatecl sobre
otros períodos (por ejemplo, 1 o 6 h) para proporcionar información sobre la actividad bactericida del tratamiento durante esos períodos.
10.2.6 Muestreo de muestras inoculadas e incubadas. Después de la incubación se añaden 100 ml ± l. de solución neutralizante a tarros que contenían muestras de control sin tratar y a tarros que contenían muestras de prueba tratadas. Agitar los frascos vigorosamente durante un minuto. hacer diluciones seriadas y Platón (por duplicado) en nutrientes (o apropiado) agar, diluciones de 10 0 101 a 102 son generalmente adecuadas para tejidos de ensayo tratados.
Varias diluciones diferentes puede ser necesaria para los tejidos de control no tratados en función del período de incubación.
10.2.7 lncubate todas Platos durante 48 horas a 37 ± 2 ° C (99 ± 3 ° F) o temperatura óptima otro.
11. evaluación
11.1 Informe bacterianas cuenta como el Numeber de bacterias por muestra (muestras en frasco) no como el número de bacterias por ml de solución neutralizante, Informe "0" cuenta en 10 "dilución" menos de 100 ".
Cálculo de 11,2 por ciento de reducción de las bacterias por los tratamientos de muestras por una de las fórmulas siguientes:
1) 100 (B-A) / B = R
donde:
R =% de reducción
A = el número de bacterias recuperadas de las muestras de prueba tratadas inoculadas especimenes en el frasco se incubaron durante el período de contacto deseada
B = número de las bacterias recuperadas de las muestras de prueba tratadas inoculadas especimenes en el frasco inmediatamente inoculación aficr (tiempo de contacto en "0")
2) 100 (C-A) / C = R
donde:
C = el número de bacterias recuperadas de la muestra de control no tratados inoculados swateltes en la
frasco inmediatamente después de la inoculación (en el momento de contacto "0")
Si "B y C" no son similares, el mayor número se debe utilizar. Si "B" y "C" no son significativamente diferentes, (B + C) / 2 debe ser utilizado de la siguiente manera:
Fiber Analysis: Quantitative
1. Purpose and Scope
1.1 This method presents individual procedures for the quantitative determination of moisture content, nonfibrous content and fiber composition of textiles.
1.2 The procedures for the determination of fiber composition include mechanical, chemical and microscopical methods. They are applicable to blends of the following generic classes:
NaiuralFillers Man— Marle Fibers
Cotton Acetate
Hair Acrylic
Hemp Modaciyllc
Linen Nylon (see 17.1)
Flamie Olefin
Silk Polyester
Wool Rayon
Spandex
2. Uses and Limitations
2.1 The procedure given for the removal of nonfibrous materials will remove most, but not all, of these components. Each treatment is applicable only to certain categories of these subsmnces and no general scheme can be given that is all inclusive. Some of the newer finishes may present special problems and the analyst Will have to deal with these cases as they arise. Thermosetting resins and crosslinking latices are not only difficult to remove but in some cases cannot be wholly removed without destroying the fiber. When it is necessary to modify a procedure, or use a new one, one should make sure that the fibrous portion of the specimen under test is not attacked. Fiber composition is generally expressed either on the oven-dry weight of the textile as received or on the oven-dry weight of the clean fiber after nonfibrous materials are first removed from the textile before the fiber analysis is carried out, or if the treatments described in Section 9 are incapable of removing them, any such materials present will increase the percentage of the fiber constituent with which they are removed during the analysis.
2.2 The procedure for determining fiber composition by mechanical separation is applicable to those textiles whcrcin the different fibers making up its composition are segregated in separate yarns, or plies, in the textile product‘
2.3 The chemical procedures for fiber composition described herein are applicable to most of the current, commercial production fibers within each generic class listed‘ Known exceptions are noted in Table ll. However, there may be in stances in which a method may not be fully adequate for a newly developed fiber falling within one ofthe listed generic classes and for re-used and/or physically or chemically modified fibers. Caution should be exercised when applying these methods to such eases.
2.4 The microscopical procedures for fiber composition are applicable to all fibers and their accuracy depends to a considerable extent upon the ability of the analyst to identify the individual fibers present.
However, owing to the tedious nature of this technique, its use is generally limited to those mixtures which cannot be separated mechanically or chemically; e.g., mixtures of hair and wool and mixtures of hjnjcotton, linen, hemp and/or ramie.
3. Terminology
3.1 clean-fiber content, n.—the amount of fiber after removal of nonfibrous content.
3.2 fiber, n. in textiles, a generic term for any one ofthe various types of matter that form the basic elements of a textile and which are generally characterized by flexibility, fineness and high ratio of length to thickness‘
3.3 moisture content, n. - that part of the total mass of a material that is absorbed or adsorbed water, compared to the total mass.
3.4 nonfibrous content, n.—products such as fiber finishes, yarn lubricants, slasher sizing, fabric softeners, starches, china-clay, soaps, waxes, oils and resins which are applied to fiber, yam, fabric or apparel‘
3.5 Additional terms used in this test method can be found in standard chemical dictionaries, in dictionaries of coinmon terms or in A Glassaljv of /IAT CC Standard Terminology (located elsewhere in this TEcui\11cA1. MANUAL).
4. Safety Precautions
NOTE: These safety precautions are for information purposes only. The precautions are ancillary to the testing procedures and are not intended to be all inclusive. It is the user’s responsibility to Lise safe and proper techniques in handling materials in this test method. Manufacturers MUST be consulted for specific details such as material safety data sheets and other manufacturer’s recommendations. All OSHA standards and rules must also be consulted and followed.
4.l Good laboratory practices should be followed. Wear safety glasses in all laboratory areas.
4.2 All chemicals should be handled with care.
4.3 Perform the soxhlet extractions in Section 9, Nonfibrous Material - Cleari Fiber Content, using Fluorocarbon ll3 (such as Freon TF) or hydrochlorofluorocarbon (such as Genesolv 2000) and ethyl alcohol inside an adequately ventilated laboratory hood. CAUTION: Ethyl alcohol is highly flammable.
4.4 Perform Chemical Analysis Procedure N o. l (Table II, 100% acetone) inside a ventilated laboratory hood. CAUTION: Acetone is highly flammable.
4 .5 Ethyl alcohol and acetone are llammable liquids and should be stored in the laboratory only in small containers away from heat, open llamc and sparks.
4.6 In preparing, dispensing, and handling hydrochloric acid (20%), sulfuric acids (59.5% and 70%), and formic acid (90%) used in Chemical Analysis Procedure Methods No. 2, 3, 4, and 6 (Table H), use chemical goggles or face shield,
impervious gloves and an impervious apron. Concentrated acids should be handled only in an adequately ventilated laboratory hood. CAUTION: Always add acid to water
4.7 ln preparing ammonium hydroxide (8:92) for use in Chemical Analysis Procedure Method No. 4 (Table II, 70% sulfuric acid), use chemical goggles or face shield, impervious gloves and an impervious apron. Dispense, mix and handle ammonium hydroxide only in an adequately ventilated laboratory hood.
4.8 An cycwash/safety shower should be located nearby and a selficontained breathing apparatus should be readily available for emergency use.
4.9 Exposure to chemicals used in this procedure must be controlled at or below levels set by governmental authorities (e,g., Occupational Safety and Health Administration’s [OSHA] permissible exposure limits [PEL] as found in 29 CPR l910.lO00 of January 1, 1989). In addition, the American Conference of Governmental Industrial Hygienists (AC GIH) Threshold Limit Values (TLVS) comprised of time weighted averages (TLV-TWA), short term exposure limits (TLV-STEL) and ceiling limits (TLV-C)
are recommended as a general guide for air contaminant exposure which should be met (see 17,17).
5. Apparatus
5.1 Analytical balance, capable of weighing to 0.1 mg.
5.2 Oven, maintained at 105-110°C.
5.3 Desiccator, containing anhydrous silica gel, calcium sulfatc (such as Drieite) or its equivalent.
5,4 Soxhlet extractor, 200 mL capacity.
5.5 Constant temperature bath, adjustable, capable of controlling temperature to + - 1°C.
5.6 Weighing bottle, 100 inL capacity, glass, with ground glass cover. (Alternate: aluminum weighing can; same size, tight cover.)
5,7 Erlenmeyer flask, 250 mL capacity, ground glass stopper.
5.8 Beaker, borosilicate heat resistant glass. 250 inL capacity.
5.9 Filtering crucible, fritted glass, coarse porosity, 30 mL.
5,10 Suction flask, with adapter, to hold filtering crucible.
5,11 Weighing bottle, large enough to hold filtering crucible.
5.12 Microscope, equipped with a moveable stage and a cross-hair ocular, 200-ZSOX magnification.
5.13 Projection microscope, capable of 500X magnification (see 17.12).
5.14 Fiber cutter: A device comprised of two razor blades, a threaded pin and an assemblage that will hold the blades rigidly in position. The device is operated by applying pressure vertically downward. lt cuts fibers approximately 250 um in length (see 17.3).
5.15 Wedge scale: Strips of heavy paper or Bristol board imprinted with a wedge for use at SOOX magnification (see 17.4).
6. Reagents
6.1 Ethyl alcohol (95%), pure or denatured.
6.2 Fluorocarbon 113 (such as Freon TF) or hydrochlorofluorocarbon (such as Genesolve 2000).
6.3 Hydrochloric acid (HCI), O.1N.
6.4 Enzyme solubilizing preparation.
6,5 Acetone (CH3COCH3), reagent grade.
6.6 Hydrochloric acid (HCl) (20%). Dilute HCl, sp gr l.l9, with water until the specific gravity ofthe solution is 1.10 at 20°C.
6.7 Sulfuric acid (H2SO4) (59.5%). Add H2SO4, sp gr 1.84, slowly to water. After the solution has cooled to 20°C, adjust the density to a value between 1.4902 and 1.4956 g/mL.
6.8 Sulfuric acid (H2SO4) (70%). Add H2SO4, sp gr 1.84, slowly to water. After the solution has cooled to 20 + - 1 °C adjust the density to a value between 1.5989 and 1.6221 g/mL (see 17.18).
6.9 Sulfuric acid (H2SO4) (1:19).
Slowly stir 1 volume of HZSO4, sp gr
1.84, into 19 volumes ofwater.
6.10 Sodium hypochlorite (NaOCl).
Prepare a solution of NaOCl, 5.25%
available chlorine. Sodium hypochlorite
based household bleach (nominally 5.25%) has been found to be acceptable.
6.11 Sodium bisultite (NaHSO3) (1%).
Freshly prepared.
6.12 Formic acid (HCOOH) (90%), sp gr of l .202 at 20°C.
6.13 Ammonium hydroxide (NH4OH) (8:92). Mix 8 volumes of NH4OH, sp gr 0.90, with 92 volumes of Water.
6.14 herzberg stain. Add the previously prepared solution A to solution B; allow to stand overnight; decant the clear liquid into a dark colored glass bottle and add a leaf of iodine.
Solution A
Zinc Chloride 50 g
Water 25 mL Iodine 0.25 g
Water 12.5 mL
Solution B
Potassium iodide 5.5 g
Iodine 0.25 g
Water 12.5 mL
7. Sampling
7.1 lt is not possible to give specific instructions for taking 21 laboratory test sample from all types of textile materials to which these methods may be applicable; but a few general recommendations will be given.
7.1.1 The sample should be as representative as possible of the lot 01‘ material
from which it was taken.
7.1.2 Ifa reasonably large lot is available, and if it is possible to do so, samplings should be taken from different, widely separated areas or parts of the lot.
7.1.3 In the case of fabrics where there is a definite repetition in the pattern, the sample should include all yarns in a complete pattern (see 17.6).
7.1.4 In the case ofyarns, not less than a 2-meter length should be taken.
Test Methods
8. Moisture Content
8.1 Procedure. Place not less than l g of the textile to be tested in a previously tared weighing bottle and immediately replace the eover. Weigh to the nearest 0.1 mg using the analytical balance and record the weight. Place the uncovered weighing bottle containing the specimen in an oven maintained at 105-110°C for 1.5 h. At the end of the time period, remove the bottle from the oven, immediately replace the cover and put it in the desiccator. When the bottle and contents have cooled to room temperature, remove them from the desiccator and reweigh.
Repeat the heating and reweighing process for periods of 30 min until the weight is constant to within I 0.001 g and record the constant weight.
8.2 Calculations.
8.2.1 Calculate thc moisture content of the specimen as follows:
M =( A- B / A - T)X100
where:
M = moisture content, percent.
A = Weight of sample before drying + bottle.
B = weight of sample after drying + bottle.
T = tare weight ofweighing bottle.
9. Nunfihrnus Material—CIean Fiber Content
9.1 Procedure. Take a specimen of not less than 5 g, dry it to constant weight in an oven at 105-110°C (sec 8.1), record the oven-dry Weight to the nearest 0.1 mg using an analytical balance and then subject it to one, or more. of the following treatments, as appropriate. When specific type olnonfibrous content is known, only that specific treatment, or treatments, need be performed; otherwise, all treatments l1'tLlSl be applied.
9.1.1 Hydrochlorofluorocarbon Treatment (for removal of oils, fats, Waxes. certain thermoplastic resins, etc.). Extract the dried specimen with l1ydrochlorotluorocarbon in a soxhlet extractor, siphoning ovcr a minimum of six times. Air dry, and then dry at 105-110°C to constant weight. For an alternative to soxhlet extractor, see 17.19.
9.1.2 Alcohol Treatment (for removal of soaps, cationic finishes, etc.). Extract the dried specimen with ethyl alcohol in a soxhlet extractor, siphoning over a minimum of six times. Air dry. and then dry at 105-110°C to constant weight. For an alternative to soxhlet extractor, see 17.19.
9.1.3 Aqueous Treatment (for removal of water soluble materials). immerse the dried specimen for 30 min in Water at 50°C using a 100:1 liquid to fabric ratio.
Stir occasionally or use a mechanical shaker. Rinse 3 times in fresh portions of water and dry at 105-110°C to constant weight.
9.1.4 Enzyme Treatment (for removal of starch. etc.). Immerse the dried specimen in aqueous solution of the enzyme preparation following the manufacturer’s recommendations as to concentration, liquid to fabric ratio and temperature and time of immersion. Rinse thoroughly with hot water and dry at 105-110°C to constant weight.
9.1.5 Acid Treatment (for removal of amino resins). Immerse the dried speci111611111 100 times its weight of 0.lN HCl at 80°C for 25 min, stirring occasionally. Rinse thoroughly with hot water and dry at 105-110°C to constant weight.
9.2 Calculations.
re recommended as a general guide for air contaminant exposure which should be met (see 17,17).
942.1 Calculate the nonfibrous content of the specimen as follows:
C—D
Nzi 100
C ><
where:
N I nonfibrous materials, percent.
C : dry weight, specimen, before
treatment.
D I dry Weight, specimen, afier treat-
ment.
9.22 Calculate the clean fiber content of the specimen as follows:
~_2
1“_C><100
Where:
F = clean fiber content, percent; other terms as in 9.2.1
10. Mechanical Separation
10.1 Procedure. Remove the non[ibrous materials using the appropriate treatment (see 9.1). Separate the cornponent yams by mechanical dissection; combine those yarns, or p11CS, having the same fiber composition and determine the oven-dry weight of each generic type present.
10.2 Calculation. Calculate the content of each generic fiber as follows:
W
:4’ 10
X, E><0
where:
X, = content of liber 1', percent.
W, I oven-dry Weight of fiber 1', after separation.
E = weight of clean, oven-dry specimen taken for analysis.
11. Chemical Ana|ysis—Genera|
ll.1 Specimen Preparation. Before analyses arc undertaken, the laboratory test sample should be disintegrated, homogenized and a portion of the homogenate taken for the chemical treatrnent(s).
In the case of a fabric. one should unravel it into its individual yarns, cut the yarns into lengths not greater than 3 mm, thoroughly mix the cut pieces and then take a representative portion for the specific determination. An alternate procedure, suimble in many cases, is to grind the sample using a Wiley Mill, homogethe oven-dry weight of each generic type present. 10.2 Calculation. Calculate the content of each generic fiber as follows:
X1=( Wi / E) X 100
where:
X, = content of liber i, percent.
W, I oven-dry Weight of fiber i, after separation.
E = weight of clean, oven-dry specimen taken for analysis.
11. Chemical Analysis—Genera|
11.1 Specimen Preparation. Before analyses arc undertaken, the laboratory test sample should be disintegrated, homogenized and a portion of the homogenate taken for the chemical treatrnent(s). In the case of a fabric. one should unravel it into its individual yarns, cut the yarns into lengths not greater than 3 mm, thoroughly mix the cut pieces and then take a representative portion for the specific determination. An alternate procedure, suimble in many cases, is to grind the sample using a Wiley Mill, homogenize the ground fibers by slurrying them in a water suspension in a Waring Blender and taking the representative portion from the dried homegenate for the speeilic determination. Yarns are treated the same Way but omitting the una necessary steps‘
11.2 Method Application. A tabulation of appropriate chemical treatments for binary fiber mixtures is given in Table I. To use this table one enters at the left side on the line listing one of the eomponents of the binary mixture and moves to the box under the column listing the other component and the nurnber therein is the method, or methods, that are applicable for that specific combination. The una bracketed methods are those that dissolve the fiber at the left side of the diagram while the bracketed ones dissolve the fiber at the top of the diagram. Mixtures of more than two components may be aria» lyzed by proper application ofa sequence of the individual methods. Table II presents the relative solubilities of the various libers in all the reagents and, from this, one can select the proper methods and their sequence for the analysis of multifiber mixtures (see 17.7).
12. Chemical Analysis Procedures
12.1 Method No. 1, 100% Acetone: Weigh accurately a 0.5-1.5 g portion 01 the clean, dry, prepared specimen and record the weight to the nearest 0.1 mg. Transfer into a 250 m.L Erlenmeyer flask. Add 100 times its weight of acetone and agitate vigorously for 15 min keeping the temperature at 40-50°C. Decant the liquid from the undissolved residue, add a fresh portion of acetone and agitate for a few more minutes. Repeat the decanting and agitation process one more time and then filter the undissolved residue by suction through a dried weighed, frittedglass,
filtering crucible. Dry the crucible and residue in air and then in an oven at 105-110°C to constant weight. Record the weight of the dried residue to the nearest 0.1 mg.
12.2 Method No. 2, 20% Hydrochloric acid: Weigh accurately a 0.5-1.5 g portion ofthe clean, dry, prepared specimen and record the weight to the nearest 0.1 mg. Transfer into a 250 mL Erlenmeyer flask. Add 50-150 mL of 20% hydrochloric acid (l00 rnL reagent/g of sample); shake vigorously and let stand for 5 min at 15-25°C. Shake again and let stand for 15 min. Shake for a third time (see 17.8) and filter the mixture through a dried weighed fritted-glass crucible. Wash into the crucible any residue left in the flask using a little more 20% hydrochloric acid. Apply suction to drain the excess liquor from the filter residue. Wash the residue in the crucible with about 40 mL of 20% hydrochloric acid and then with water until the filtrate is neutral to litmus.
Disconnect the suction and add to the crucible about 25 mL of ammonium hydroxidc (8:92) allowing the fiber residue to soak for 10 min before applying suction to drain it. Wash the residue with about 250 mL of water, allowing it to soak in the water for about 15 min. After thc final washing, apply suction to remove rinse water, and dry the crucible and residue in an oven at lO5-ll0°C to constant Weight. Record the dry weight to the nearest 0.1 mg.
12.3 Method No. 3, 59.5% Sulfuric acid: Weigh accurately a 0.5-1.5 g portion of the clean, dry, prepared specimen and record the weight to the nearest 0.1 mg. Transfer into a 250 n1L Erlenmeyer flask. Add 50-150 mL of 59.5% sulfuric acid (100 mL reagent/g of sample) and shake vigorously for l min. Let stand for 15 min at a temperature of 15-25°C‘ Shake again and let stand for another 15 min, shake For a third time (see l7.8) and then filter the mixture through a dried weighed Fritted-glass crucible. Wash into the crucible any residue lell in the flask using three 10 mL aliquots of 59.5% sulfuric acid‘ Apply suction to drain the excess liquor from the fiber residue after the addition of each aliquot. Wash the residue in the crucible with 50 rnL of suluric acid (1:19), then with water until the filtrate is neutral to litmus. Disconnect the suction and add to the crucible about 25 mL of aininonium hydroxide (8:92), allowing the fiber residue to soak for 10 min before applying suction to drain it. Wash the residue with about 150 mL of water, allowing it to soak in the water for about l5 min. After the final washing, apply suction to remove the rinse water and dry the crucible and fiber residue in an oven at l05-l 10°C to constant weight. Record thc weight of the dried residue to the nearest 0.1 mg (see 17.9).
12.4 Method No. 4, 70% SUlfUl'1C acid: Weigh accurately a 0.5-1.5 g portion of the clean, dry, prepared specimen and record the weight to the nearest 0.1 mg. Transfer into a 250 mL Erlenmeyer flask. Add 50-150 mL of 70% sulfuric acid (100 mL reagent/g of sample) and shake vigorously for 1 min. Let stand for 15 min at a temperature of 15-25°C. Shake again and let stand for another 15 min; shake for a third time (see 17.8) and then filter the mixture through a fritted-glass crucible which has been oven-dried, cooled in a desiccator and weighed to 0.1 mg. Wash into the crucible any residue left in the flask using three 10 mL aliquots of 70% sulfuric acid. Apply suction to drain the excess liquor from the fiber residue after the addition of each aliquot. Wash the residue in the crucible with 50 mL of sulfuric acid (1:19), then with Water until the filtrate is neutral to litmus. Disconnect the suction and add to the crucible about Z5 mL of ammonium
hydroxide (8:9Z); allow the fiher residue to soak For 10 min before applying suction to drain it. Wash the residue with about 150 mL of water, allowing it to soak in the water for about 15 min. After the final washing, apply suction to remove excess Water and dry the crucible and fiber residue in an oven at 105-110°C to constant weight. Record the weight of the dry residue to the nearest 0.1 mg.
12.5 Method No. 5. Sodium hypochlorite: Weigh accurately a 0.5-1.5 g portion of the clean, dry, prepared specimen and record the weight to the nearest 0.1 mg. Transfer into a 250 mL Erlenmeyer flask. Add 50-150 n1L of sodium hypochlorite reagent (100 ml. reagent/g of sample).
Stir the specimen in this solution for 20 min making sure the temperature is maintained at 25 i 1°C (use constant temperature bath) (see 17.10) and then filter through a dried weighed, fritted-glass crucible. Wash thoroughly with sodium bisulfite (1%) followed by water and remove the excess water by suction. After the final washing, apply suction to remove excess water and dry in an oven at 105-110°C to constant weight. Record the Weight of the dried residue to the nearest 0.1 mg.
12.6 Method N0. 6, 90% Forrnic acid: Weigh accurately a 0.5-1.5 g portion of the clean, dry, prepared specimen and record the weight to the nearest 0.1 mg. Transfer into a 250 mL Erlenmeyer flask.
Add 50-150 mL oF90% fonnic acid (100 ml. reagent/g of sample) and shake frequently over a period of 15 min (see 17.11). Decant the supernatant liquid into a dried, weighed, fritted-glass crucible, add another equal ponion of 90% formic acid to the flask and agitate For an additional 15 min. Filter the contents of the flask through the cruciblel rinse with two 50 mL portions of 90% formic acid and drain with the aid of suction‘ Wash the residue with 50 mL of Water and then allow it to soak in 25 mL ofammonium hydroxide (8:92) for about 10 min. Wash thc residue thoroughly with water until the filtrate is neutral to litmus. Drain the residue with the aid of suction and dry in an oven at 105-110°C to constant weight. Record the weight of the dried residue to the nearest 0.1 mg.
12.7 Method No. 7, Dimethylformamide: Weigh accurately a 0.5-1.5 g portion of the clean, dried, prepared specimen and record the weight to thc nearest 0.1 mg. Transfer to a 250 ml. Erlenmeyer flask. Add 50-150 mL of dirnethylformamide reagent (100 mL reagent/g of sample). Agitate for 20 min keeping the temperature at 98 1 1°C. Decant the liquid fiom the undissolved residue, add a fresh portion of dimethylfoiniamide and agitate for a few more minutes. Repeat the decanting and agitation process one more time and then filter the undissolved residue by suction through a dried, weighed frittcd glass filtering crucible. Dry the crucible and residue in air and then in an oven at 105-110°C to constant weight. Record the weight of the dried residue to the nearest 0.1 mg.
12.8 Calculations: Calculate the content of each generic fiber type as determined by any one of the above applicable chemical methods using one of the following equations:
12.81 If the fiber is dissolved by the test reagent:
G—H
X : —' 100
1 G X
12.8.2 lf the fiber is insoluble in the
test reagent:
X:%><l00
where:
X, = content of fiber 1', percent.
G = weight of clean, dry, prepared specimen
H,-= weight of dried residue after treatment
13. Microscopical Analysis, General
13.1 The Following procedure may be used for the quantitative analysis of textiles containing two or more fiber types which cannot be separated readily by mechanical or chemical methods. The procedures rely on the ability of a technician to identify and count, by mcans of a microscope, the relative number of fibers of each type in a prepared specimen. Such a count will result in a percent blend by number of fibers. ln order to convert this result to a percent by weight, the size of the fibers being counted and tlleir respective densities rnust be included in the calculation.
13.2 Microscope slides may be prepared to scan longitudinal or cross-section views of a fiber sample. The fiber images may be viewed either through a microscope or as projected onto a horizontal plane. While either viewing method may be used for identification and counting of fibers. the projection method is specifically used for measuring fiber diameters using a wedge scale (see 14.3.2).
13.3 Methods which may be used to identify fibers during the fiber counting procedures are discussed in AATCC Test Method 20. They include the following: AATCC 20 Herzberg stain (zinc chlor0- Section 9.9.1 iodide)
Acid phlomglucinol reagent Section 9.9.2 Longitudinal appearance Tables I and ll Cross-section appearance Tables I and ll and Appendix I It is recommended that reference tests be made on known fibers rather than placing total reliance on photographic reproductions and word descriptions ofcolors.
14. Microscopical Analysis Procedures
14.1 Preparation of Slides.
14.1.1 Longitudinal Sections of Vegetable Fibers (cotton, flax, rarnie, etc.): A swatch of fabric measuring at least 5 >< 5 cm should be available. Count the number of yarns in both the Warp and filling and select from each direction at random a number of yarns that is proportional to the fabric count. The combined number of warp and filling yarns should total at least 20 (see 17.12). If the sample is in yarn form, take at least a two-meter length and, from it, cut not less than twenty 5-cm sections at random. Cut approximately 2.5 cm of each yarn, or yarn section, into lengths of 0.5-1 mm. The shorter the lengths the easier it is to prepare a homogeneous fiber suspension. Collect the cut fibers on a paper of contrasting color and transfer to a 125 mL
Erlenmeyer flask. Add sufficient water so that afier stoppering the flask and shaking the contents, a unifomi and fairly dense fiber suspension is obtained. Quick boiling or the addition of a few glass pellets facilitates the separation of the fibers. Using a glass-marking pencil, draw two parallel lines about l in. apart across a glass slide. With a wide-mouth pipette, draw 0.5-1 rnL of the well shaken suspension and place it between the two reference lines on the slide. The amount of liquid taken is dependent upon the density of the suspension. Just sufficient liquid should be placed on the slide so that—after evaporationfa thin, uniform film of fibers remains. After all of the moisturehas evaporated from the slide, stain the fibers with Ilerzberg stain and cover with a cover glass.
14.1.2 Longitudinal Sections of Wool, Hair and other round Fibers: Select a representative swatch, or yarn sections, as in 14.1.l. With a fabric swatch, remove the outermost yarns in both directions so that the warp and filling yarns are protruding approximately 1 cm‘ Lay the sample fiat on a table and, using a fiber cutter, force the blades vertically downward into the warp fringe. Repeat the operation with the filling fringe. Remove the device with the top plate up. release the tension on the cutting blades and remove them together by their ends between the thumb and forefinger. Carefiilly separate the blades so that the cut fiber sections will adhere to the edge of one or both blades. Place a few drops of mineral oil on a clean slide and, with a dissecting needle, scrape the fiber sections onto thc oil. Thoroughly disperse the fibers in the oil with the dissecting needle and cover with a cover glass. For yarn samples, align the sections side-by-side and perform the above operation starting With the use of the fiber cutter.
14.1 .3 Cross-Sections of Fibers: Select representative yarns, or yarn sections,from thc sample and render them to staple by removing twist and drawing out fibers. Align the fibers parallel to each other so as to form a well blended tuft. Prepare a slide following the instructions of AATCC Test Method 20, Section 9.3.
1442 Fiber Counting.
14.2.1 Fibers Viewed Through Microscope: Place the slide prepared as in 14.1
on the moveable stage on a microscope equipped with a crosshair ocular and having a magnification of Z00-ZSOX. Begin to count near either the upper or lower comer of the field and, as the slide is moved slowly across the field in the horizontal direction, identify and count all fibers passing through the center of the erosshairs. After each trip across the field, move the slide l-2 mm vertically and identify and count the fibers as the field is again traversed. Repeat this procedure
until the whole slide has been covered. The spacing between each traverse is dependent upon the number of fiber sections on the slide. lf a fiber passes the crosshair more than once, record each passing (see l7.l3). ln a similar manner, count the fibers by moving the slide vertically. The combined horizontal and vertieal counts should total at least 1000 fibers.
14.2.2 Projected Images of Fibers: Calibrate the mieroprojector so that it will give a magnification of 500X in the plane of the projected image. To do this, place a stage micrometer (having units of 0.01 mm) on the stage of the microprojector with its scale toward the objective and place a large sheet of white, nonglare paper in the projection plane. Lower or raise the microscope until an interval of 0.20 mm on the stage micrometer will measure 100 mm when sharply focused in the center of the paper. Place the slide prepared as in 14.1 on the stage ofthe inicroprojector with the cover glass toward the objective. Draw a ll)-cm diameter circle in the center of the white paper in the projection plane. All measurements and counts are tn be made within this circle. Begin to count near either the upper or lower corner of the field and proceed exactly as described in 14.2.1 (see 17.14).
14.2.3 Video Imaging of Fibers: Using a video monitor with a crosshair placed in the center of the screen coupled to a video camera attached to a correctly adjusted transmitted light microscope scan the slide as outlined in 14.2.1.
14.3 Fiber Measurement.
14.3.1 Fibers with Noncircular CrossSections:
14.3.1.1 Paper Tracing Method: Prepare a slide as described in
14.1.3. Place this slide on the stage of the microprojector and project the image onto a shect of graph paper having one millimeter squares. Trace the image of the fibers on the graph paper using a sharpened pencil, taking care not to retrace fibers previously traced. Ifthere are not sufficient tibers on the slide to provide 100 of each type, prepare another slide as described above using another tuft of fibers. Continue to trace and to count on the new slide until lO0 fibers of each type have been tallied. By counting squares, and parts of squares, determine the crosssectional area of each individual fiber of each typc. Calculate the mean crosssectional area for each fiber type present by summing the individual values recorded for that type and dividing the sum by the total number of fibers of that type measured. Final values should be in mm?
14.3.1.2 Digital Tracing Method: Prepare a slide as described in 14.1.3. Place this slide on the stage and adjust until a clear well formed image appears on the video monitor. Use of a 50X objective with C mount video camera coupling has been found acceptable for most fiber types. Using correctly calibrated image analysis software and a digital image capture board digitally capture the crosssectional image. Using a mouse or stylus trace around the captured cross-sectional images. Use the image analysis sottware to store the resultant cross-sectional areas. If there arc not sufficient fibers on the slide to provide 100 ofeach type. prepare another slide as described above using another tuft of fibers. Continue totrace and count on the new slide until 100 fibers ofcach
type have been tallied. Calculate the mean cross-sectional area automatically using the statistical functions of the digital image analysis software. Final values should be in um?
14.3.2 Fibers with Circular Cross Sections: Prepare a slide as described in 14.1.2. Be sure to make measurements on the same day that the slide was prepared. Position the slide in the microprojector or microscope so that all areas of the slide can be reached.
14.3.2.l Measurement with Wedge
Scale and Microproiector: Bring each individual fiber being measured into sharp focus on the wedge scale. Adjust the position of the scale until the fiber image is projected on the wedge with a line line and mark on the wedge the point that corresponds to the width of the fiber midway of its length. Traverse the slide and measure successive fibers of each type following a planned course. Measure fibers only when their midpoint falls within the 10 cm circle central located in the field‘ Exclude from measurement those fibers that cross another fiber at the point of measurement and those that are shorter than 150 um. A minimum of 100 fibers of each type present should be measured. Calculate the mean cross-sectional area of each fiber type. Final values should be in uml (see l7.l5). Considerable variation can occur in the average diameter of hair and wool fibers. Thus, for accurate results on
