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8/10/2019 6-Chemical Parameter 3-revised.pptx
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DR. ATIKAHPOSTGRADUATE CHEMISTRY PROGRAMME
MATHEMATICAL AND NATURAL SCIENCES FACULTYBRAWIJAYA UNIVERSITY
2012
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Scope and Application
1. This method is applicable to the analysis of drinking,surface and saline waters, domestic and industrialwastes.
2. The method is capable of measuring phenolicmaterials at the 5 m g/L level when the colored endproduct is extracted and concentrated in a solventphase using phenol as a standard.
3. The method is capable of measuring phenolic
materials that contain more than 50 m g/L in theaqueous phase (without solvent extraction) usingphenol as a standard.
4. It is not possible to use this method to differentiatebetween different kinds of phenols.
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Phenolic materials react with 4-
aminoantipyrine in the presence of
potassium ferricyanide at a pH of 10 to form
a stable reddish-brown colored antipyrinedye.
The amount of color produced is a function
of the concentration of phenolic material.
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OH N
H3C-N C = O
H3C - C C- NH2
N
H3C-N C = O
H3C - C C- N=
+
K3Fe(CN)6
pH 10
Phenol
4-Aminoantipyrin
Yellowis red
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1. For most samples a preliminary distillation isrequired to remove interfering materials.
2. Color response of phenolic materials with 4-aminoantipyrine is not the same for all compounds.
3. Because phenolic type wastes usually contain avariety of phenols, it is not possible to duplicate amixture of phenols to be used as a standard.
4. For this reason phenol has been selected as astandard and any color produced by the reaction of
other phenolic compounds is reported as phenol.5. This value will represent the minimum
concentration of phenolic compounds present inthe sample.
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Biological degradation is inhibited by the
addition of 1 g/L of copper sulfate to the
sample and acidification to a pH of less than
4 with phosphoric acid. The sample should be kept at 4C and
analyzed within 24 hours after collection.
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1. Interferences from sulfur compounds areeliminated by acidifying the sample to a pH ofless than 4 with H3PO4and aerating briefly bystirring and adding CuSO4
2. Oxidizing agents such as chlorine, detected bythe liberation of iodine upon acidification inthe presence of potassium iodide, areremoved immediately after sampling by theaddition of an excess of ferrous ammonium
sulfate3. If chlorine is not removed, the phenolic
compounds may be partially oxidized and theresults may be low.
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1. Measure 500 mL sample into a beaker. Lower
the pH to approximately 4 with 1 + 9 H3PO4
(7.1), add 5 mL CuSO4solution (7.2) and
transfer to the distillation apparatus. Omit
adding H PO and CuSO4if sample waspreserved as described.
2. Distill 450 mL of sample, stop the distillation,
and when boiling ceases add 50 mL of warm
distilled water to the flask and resumedistillation until 500 mL have been collected.
3. If the distillate is turbid, filter through a
prewashed membrane filter.
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Prepare the following standards in 100 mL
volumetric flasks.
mL of working solution
A
Conc. F g/L
0 0.0
0.5 50.0
1.0 100.0
2.0 200.0
5.0 500.0
8.0 800.0
10.0 1000.0
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To 100 mL of distillate or an aliquot diluted
to 100 mL and/or standards, add 2 mL of
buffer solution (7.3) and mix. The pH of the
sample and standards should be 10 0.2. Add 2.0 mL aminoantipyrine solution (7.4)
and mix.
Add 2.0 mL potassium ferricyanide solution
(7.5) and mix. After 15 minutes read absorbance at 510 nm.
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Using working solution B (7.8), prepare the
following standards.
Standards may be prepared by pipetting the
required volumes into the separatory funnelsand diluting to 500 mL with distilled water.
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mL of working solution B Conc. F g/L
0.0 0.0
3.0 6.0
5.0 10.0
10.0 20.0
20.0 40.0
25.0 50.0
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Place 500 mL of distillate or an aliquot diluted to 500 mLin a separatory funnel. The sample should not containmore than 25 F g phenol.
To sample and standards add 10 mL of buffer solution (7.3)and mix. The pH should be 10.2.
Add 3.0 mL aminoantipyrine solution (7.4) and mix. Add 3.0 mL potassium ferricyanide solution (7.5) and mix.
After three minutes, extract with 25 mL of chloroform(7.9). Shake the separatory funnel at least 10 times, letCHCl settle, shake again 10 3 times and let chloroformsettle again. Vent chloroform fumes into hood.
Filter chloroform extracts through filter paper. Do not addmore chloroform. Carry out filtration in a hood. Dispose ofchloroform in environmentally acceptable manner.
Read the absorbance of the samples and standards againstthe blank at 460 nm.
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10.1 Using the extraction procedure for
concentration of color, six laboratories
analyzed samples at concentrations of 9.6,
48.3, and 93.5 F g/L. Standard deviations
were O.99, 3.1 and 4.2 F g/L, respectively.
Using the direct photometric procedure, six
laboratories analyzed samples at
concentrations of 4.7, 48.2 and 97.0 mg/L.Standard deviations were 0.18, 0.48 and 1.58
mg/L, respectively.
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Scope and Application
This method is applicable to the determination of
cyanides amenable to chlorination in drinking,
surface and saline waters, domestic and
industrial wastes.
The titration procedure is used for measuring
concentrations of cyanide exceeding 1 mg/L after
removal of the cyanides amenable to
chlorination.
Below this level the colorimetric determination is
used.
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A portion of the sample is chlorinated at a pH
> 11 to decompose the cyanide.
Cyanide levels in the chlorinated sample are
then determined by the method for Cyanide,Total, in this manual.
Cyanides amenable to chlorination are then
calculated by difference.
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1. Two sample aliquots are required to
determine cyanides amenable to
chlorination. To one 500 mL aliquot or a
volume diluted to 500 ml, add calcium
hypochlorite solution (3.1) dropwise while
agitating and maintaining the pH between
11 and 12 with sodium hydroxide (3.2).
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The initial reaction product of alkaline
chlorination is the very toxic gas cyanogen
chloride; therefore, it is recommended that
this reaction be performed in a hood.
For convenience, the sample may be agitated
in a 1 liter beaker by means of a magnetic
stirring device.
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2. Test for residual chlorine with KI-starch paper
(3.4) and maintain this excess for one hour,
continuing agitation. A distinct blue color on the
test paper indicates a sufficient chlorine level. If
necessary, add additional hypochlorite solution.
3. After one hour, add 0.5 g portions of ascorbic
acid (3.3) until KI-starch paper shows no residual
chlorine. Add an additional 0.5 g of ascorbic acid
to insure the presence of excess reducing agent.4. Test for total cyanide in both the chlorinated
and unchlorinated aliquots as in the method
Cyanide, Total, in this manual.
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Scope and Application
1.1 This method is applicable to the determination
of cyanide in drinking, surface and saline waters,
domestic and industrial wastes.
1.2 The titration procedure using silver nitrate
with p-dimethylamino-benzal-rhodanine
indicator is used for measuring concentrations of
cyanide exceeding 1 mg/L (0.25 mg/250 mL of
absorbing liquid).
1.3 The colorimetric procedure is used for
concentrations below 1 mg/L of cyanide and is
sensitive to about 0.02 mg/L.
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1. The cyanide as hydrocyanic acid (HCN) is released from cyanidecomplexes by means of, a reflux-distillation operation andabsorbed in a scrubber containing sodium hydroxide solution. Thecyanide ion in the absorbing solution is then determined byvolumetric titration or colorimetrically.
2. In the colorimetric measurement the cyanide is converted to
cyanogen chloride, CNCl, by reaction with chloramine-T at a pHless than 8 without hydrolyzing to the cyanate. After the reactionis complete, color is formed on the addition of pyridine-pyrazolone or pyridine-barbituric acid reagent. The absorbance isread at 620 nm when using pyridine-pyrazolone or 578 nm forpyridine-barbituric acid. To obtain colors of comparable intensity,it is essential to have the same salt content in both the sampleand the standards.
3. The titrimetric measurement uses standard solution of silvernitrate to titrate cyanide in the presence of a silver sensitiveindicator.
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1. Cyanide is defined as cyanide ion and complexcyanides converted to hydrocyanic acid (HCN) by
reaction in a reflux system of a mineral acid in thepresence of magnesium ion.
2. Oxidizing agents such as chlorine decompose most ofthe cyanides. Test a drop of the sample with potassiumiodide-starch test paper (KI-starch paper); a blue color
indicates the need for treatment. Add ascorbic acid, afew crystals at a time, until a drop of sample producesno color on the indicator paper. Then add an additional0.06 g of ascorbic acid for each liter of sample volume.
3. Samples must be preserved with 2 mL of 10 N sodiumhydroxide per liter of sample (pH 2 > or = 12) at the
time of collection.4. Samples should be analyzed as rapidly as possible after
collection. If storage is required, the samples should bestored in a refrigerator or in an ice chest filled withwater and ice to maintain temperature at 4C.
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1. Interferences are eliminated or reduced byusing the distillation procedure described inProcedure 8.1, 8.2 and 8.3.
2. Sulfides adversely affect the colorimetric andtitration procedures. Samples that containhydrogen sulfide, metal sulfides or othercompounds that may produce hydrogen sulfideduring the distillation should be distilled by theoptional procedure described in Procedure 8.2.The apparatus for this procedure is shown in
Figure 3.3. Fatty acids will distill and form soaps under the
alkaline titration conditions, making the endpoint almost impossible to detect.
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4. High results may be obtained for samples
that contain nitrate and/or nitrite.
During the distillation nitrate and nitrite will
form nitrous acid which will react with someorganic compounds to form oximes.
These compounds formed will decompose
under test conditions to generate HCN.
The interference of nitrate and nitrite iseliminated by pretreatment with sulfamic
acid.
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Acidify the sample with acetic acid (1 + 9) to pH 6.0 to7.0.
Caution: This operation must be performed in the hoodand the sample left there until it can be made alkalineagain after the extraction has been performed.
Extract with iso-octane, hexane, or chloroform(preference in order named) with a solvent volumeequal to 20% of the sample volume.
One extraction is usually adequate to reduce the fattyacids below the interference level.
Avoid multiple extractions or a long contact time at low
pH in order to keep the loss of HCN at a minimum.When the extraction is completed, immediately raisethe pH of the sample to above 12 with NaOH solution.
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In a single laboratory (EMSL), using mixed
industrial and domestic waste samples at
concentrations of 0.06, 0.13, 0.28 and 0.62
mg/L CN, the standard deviations were
0.005, 0.007, 0.031 and 0.094, respectively.
In a single laboratory (EMSL), using mixed
industrial and domestic waste samples at
concentrations of 0.28 and 0.62 mg/L CN,recoveries were 85% and 102%, respectively.
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Scope and Application1.1 This method is applicable to the
measurement of total and dissolved sulfides
in drinking, surface and saline waters,
domestic and industrial wastes.1.2 Acid insoluble sulfides are not measured by
this method. Copper sulfide is the only
common sulfide in this class.
1.3 The method is suitable for themeasurement of sulfide in concentrations up
to 20 mg/L.
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Sulfide reacts with dimethyl-p-phenylenediamine(p-aminodimethyl aniline) in the presence offerric chloride to produce methylene blue, a dyewhich is measured at a wavelength maximum of
625 nm.Comments
Samples must be taken with a minimum ofaeration.
Sulfide may be volatilized by aeration and anyoxygen inadvertently added to the sample mayconvert the sulfide to an unmeasurable form.
Dissolved oxygen should not be present in anywater used to dilute standards.
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Color development
Transfer 7.5 mL of sample to each of twomatched test tubes using a special widetipped pipet or filling to a mark on the testtubes.
To tube A add 0.5 mL amine-sulfuric acidreagent (5.2) and 0.15 mL (3 drops) FeClsolution (5.3).
Mix immediately by inverting the tube only
once. To tube B add 0.5 mL 1 + 1 H2SO4(5.4) and
0.15 mL (3 drops) FeCl2solution (5.3) andmix.
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Color will develop in tube A in the presence
of sulfide. Color development is usually
complete in about 1 minute, but a longer
time is often required for the fading of the
initial pink color.
Wait 3 to 5 minutes.
Add 1.6 mL (NH ) HPO solution (5.5) to each
tube.Wait 3 to 5 minutes and make color
comparisons. If zinc acetate was used wait at
least 10 minutes before making comparison.
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Visual
Add methylene blue solution 1 (5.6) and/or II
(5.7) (depending on sulfide concentration
and accuracy desired) dropwise to tube B(6.1.4) until the color matches that
developed in the first tube.
If the concentration exceeds 20 mg/L, repeat
6.2.1.1 using a portion of the sample dilutedto one tenth.
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Why Determine Fluoride in Water?
removal of excess fluoride in water supply;
addition of fluoride to optimum levels (1.0
mg/L) in drinking water supplies for dentalhealth;
for assessing contamination levels in
aluminum processing plants
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Immigration information on high levels ofdisfiguration of the teeth or mottled enamel(dental fluorosis) found among certainimmigrants from areas of Europe lead to the
suspicion that the problem must be local; Information about high incidence of mottled
enamel among USA natives largely from cities inthe Great Plains and Rocky Mountains Statesconfirms that the problem is local;
In 1930, the mystery was solved when highlevels of fluoride (> 1.0 mg/L) were correlatedwith high incidence of mottled enamel amongUSA natives
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1938 information was presented which
demonstrated that dental caries is less
prevalent among mottled enamel patients;
for and many other studies, it was established
that approximately 1 mg/L of fluoride ion is
desirable in public waters for optimal dental
health;
at decreasing levels, dental caries becomes a
serious problem and at increasing levels dentalfluorosis become problematic.
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One of the major industrial uses involve the
compound cryolite (Na3AlF6) as a molten solventfor Al2O3in the electrolytic production ofaluminum;
At the operating temperature, the moltencryolite develops considerable vapor pressure
which escapes to the atmosphere through theexhaust system; the gaseous fluoride condenses to form smoke and
much of the particulate matter settles on vegetationand the soil in the area;
can result in considerable bone and dental damage tolivestock and humans e.g. has occurred in certainareas of USA.
problem can be minimized by the use of electrostaticprecipitation units in the exhaust system.
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Fluorides in drinking water are supplemented
the the forms of: NaF, CaF2, HF, Na2SiF, H2SiF6
or (NH4)2SiF6
all these forms of fluoride can be determinedby any method that is sensitive to the
fluoride ion e.g.
SiF62-+ 3H2O 6F
-+ 6H++ SiO32-
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Summary of Method
Following distillation to remove
interferences, the sample is treated with the
SPADNS reagent. The loss of color resulting from the reaction
of fluoride with the zirconyl- SPADNS dye is a
function of the fluoride concentration.
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This method is applicable to the
measurement of fluoride in drinking, surface,
and saline waters, domestic and industrial
wastes.
The method covers the range from 0.1 to
about 1.4 mg/L F. This range may be
extended to 1000 mg/L using the Fluoride Ion
Selective Electrode Method (EPA 340.2) afterdistillation.
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SPADNS = sodium 2-(parasulfophenylazo)-1,8-
dihydroxy-3,6-naphthalene disulfonate
Formation of pre-formed color:
Zr2+
+ SPADNS Zr-SPADNS complexcolorless
Zr-SPADNS complex + 6F- ZrF62-+ SPADNS
bright color
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The SPADNS reagent is more tolerant of
interfering materials than other accepted
fluoride reagents.
Reference to Table 414:1, p 388, StandardMethods for the Examination of Waters and
Wastewaters, 14th Edition, will help the
analyst decide if distillation is required.
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The addition of the highly colored SPADNS
reagent must be done with utmost accuracy
because the fluoride concentration is
measured as a difference of absorbance in
the blank and the sample.
A small error in reagent addition is the most
prominent source of error in this test.
Care must be taken to avoid overheating theflask above the level of the solution.
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On a sample containing 0.83 mg/L F with nointerferences, 53 analysts using the Bellackdistillation and the SPADNS reagent obtained a meanof 0.81 mg/L F with a standard deviation of 0.089mg/L.
On a sample containing 0.57 mg/L F (with 200 mg/L
SO and 10 mg/L Al as 4 interferences) 53 analystsusing the Bellack distillation obtained a mean of 0.60mg/L F with a standard deviation of 0.103 mg/L.
On a sample containing 0.68 mg/L F (with 200 mg/LSO , 2 mg/L Al and 2.5 4 mg/L [Na(PO ) ] as
interferences), 53 analysts using the Bellackdistillation 3 6 obtained a mean of 0.72 mg/L F with astandard deviation of 0.092 mg/L. (AnalyticalReference Service, Sample 11 I-B water, Fluoride,August, 1961.)
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Uses fluoride sensitive membrane electrodesmade from lanthanum (III) fluoride singlecrystal doped with trace amounts ofeuropium (II) fluoride o serve as the
electrical barrier between the inside of theelectrode and the sample.
The supporting electrode inside theelectrode is NaCl/NaF at O.1M.
Potential is developed across the crystal(junction) when a solution of differentconcentration of fluoride is in contact withthe outside of the crystal.
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Interferences include OH-, Cl-, etc;Total ion
strength buffer(TISB) is added to standards
and samples to cancel out the ionic effects;
and expanded scale pH Meter.
Once the electrode is standardized,
measurement is very simple.
Improved sensitivity over the SPADNS Method
especially whencyclohyxlenediaminetetraacetic acid (CDTA)
is often added to TISB to free complexd
fluoride ions for improved method accuracy.
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Alizarin
Formation of pre-formed color:
Zr2++ Alizarin Zr- Alizarin complex
Yellow reddish color
Zr- Alizarin complex + 6F ZrF62-+ Alizarin
reddish color Yellow
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Monitoring supplementation of fluoride ion in
drinking water sources for adequate dental
health;
Monitoring fluorides for removal in areaswhere natural abundance exceeds US EPA
MCL of4mg/L.
Monitoring compliance in industrial sites.
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Sources of Chloride in the Environment
Solvolysis of minerals containing chlorides by water;most chlorides salts are soluble in water;
Salt crystals blown in-landform seas and oceans by
wind; Undercurrent flow of salt water into fresh water
reservoirs e.g. estimated that salt water flows up to 80km inland at Hudson river in New York, has limited theCitys used of the river as a drinking water source.
Human waste containing about 6g/person/day resultsin increase in chloride in waste by about 1 mg/L);
Industrial waste especially where brine waste from oilprocessing is allowed. e.g. Ohio river valley)
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Chlorides as used as tracers by environmental engineersfor the following reasons:
presence is not visually detectable
normal and non-toxic constituent of water
concentration used do not significantly altered or
changed the back ground to toxic levels not altered by biological activities
it is easily measured
where applicable, chloride has been replaced witorganic dyes which can be easily detected at trace
levels; however, for areas where soil-to-water ratio is high,
halides (especially bromide or chloride) is still in usebecause they are not retarded by adsorption to soilparticles.
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At reasonable concentration, chloride is not
harmful to humans;
at > 250 mg/L in drinking water it imparts
objectionable salty taste,hence limit of 250mg/L
is set for public drinking water supply;
limited to 250mg/L where where high
concentration of salts at irrigation root zones of
makes it difficult for crops to assimilate water
due to osmosis
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1. Volumetric
Argentiometric or Mohrs Method
Chloride (Titrimetric, Mercuric Nitrate)
Inorganic, Non-Metallics: Chlorine, TotalResidual, Titrimetric, Amperometric
2. Instrumental Methods
A. Spectrophotometric
Chloride (Colorimetric, Automated
Ferricyanide AAI)
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Chloride (Colorimetric, Automated
Ferricyanide AAII)
Inorganic, Non-Metallics: Chloride,
Colorimetric, Automated Ferricyanide, AA I
: Inorganic, Non-Metallics: Chloride,
Colorimetric, Automated Ferricyanide, AA II
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Chlorine, Total Residual, Titrimetric, Back,
Iodometric
Chlorine, Total Residual, Titrimetric,
Iodometric
Chlorine, Total Residual, Titrimetric, DPD-FAS
Chlorine, Total Residual,Spectrophotometric,
DPD
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Summary of Method
Water adjusted to pH 8.3 is titrated with
silver nitrate solution in the presence of
potassium chromate indicator.
The end point is indicated by persistence of
the orange-silver chromate color.
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This method is intended primarily for oxygen
bomb combustates or other waters where the
chloride content is 5 mg/L or more and
where interferences such as color or high
concentrations of heavy metal ions render
Method impracticable.
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Cl + AgNO3 AgCl(s) + NO3 +K2CrO4
0.0141N ksp= 3 x 1010
2Ag++ CrO42- Ag2CrO4
reddish-brown ppt
Calibration: use high purity NaCl
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titrate blank to correct for or indicator error
use uniform sample size;
keep pH 7 - 8;
pH8, AgOH precipitates use same quantity if indicator to avoid "too-
soon" or "not-soon-enough" color changes leadingto inadequate blank correction;typical value =0.2-0.4mL
Cl-(mg/L) = (mL AgNO3 - blank) x 0.5x1000
mL sample
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Bromide, iodide, and sulfide are titrated along
with the chloride.
Orthophosphate and polyphosphate interfere if
present in concentrations greater than 250 and
25 mg/L, respectively.
Sulfite and objectionable color or turbidity must
be eliminated.
Compounds that precipitate at pH 8.3 (certain
hydroxides) may cause error by occlusion.Residual sodium carbonate from the bomb
combustion may react with silver nitrate to
produce the precipitate, silver carbonate.
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This competitive reaction may interfere with
the visual detection of the end point.
To remove carbonate from the test solution,
add small quantities of sulfuric acid followed
by agitation.
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Average value
(g/g)
Repeatability
(g/g)
Reproducibility
(g/g)
500 180 355
1,000
360
710
1,500 540 1,065
2,000 720 1,420
2,500 900 1,775
3,000 1,080 2,130
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Amount
Expected (g/g)Amount
Found
(g/g)
Bias; (g/g) Percentbias
320 645 325 +102
480 665 185 +39
920 855 -65 -7
1,498 1,515 17 +1
1,527 1,369 -158 -10
3,029 2,570 -460 -15
3,045 2,683 -362 -12
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For determining the best selection of water
source for public or industrial use.
To determine the type of desalting
technique most suitable for the water supply.
For monitoring industrial disposal to
safeguard receiving waters such as rivers and
lakes.
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THANK [email protected]