ABSTRACTThe experiment was conducted to identify unknown trace elements in Sample A and B by using the inductively coupled plasma (ICP) mass spectrometer. As for the preparation, 5 solutions of zinc chloride (ZnCl2) with different relative proportions of part per million (ppm) rating from zero to 100 ppm were prepared via dilution. Then, each of the samples were transferred into tubes and placed in the ICP mass spectroscope holder together with the Sample A and B. In a period of 15 minutes all the samples were analyzed thoroughly and subsequently all data was tabulated by the computer. The tabulated data includes ppm, units in counts per second (Cts/S), %RSD and the trace elements. In order to determine the amount of the unknown trace elements the data need to be graphed for the verification of the trace elements concentration. As for the result, Sample A contains cobalt contaminant and Sample B contains zinc contaminant.

INTRODUCTIONAlmost every metallic element can be determined quantitatively by using the absorption characteristics of atoms. The principles of atomic absorption spectroscopy are similar to those of UV-visible spectroscopy except that the absorbing species are free atoms or ions. Unlike molecules, atoms and ions do not have rotational or vibrational energy and the only transitions that occur are between electronic energy levels. Consequently, atomic absorption spectra consist of sharply defined lines rather than the broad bands typical in molecular spectroscopy. Almost every metallic element can be analysed by using atomic absorption spectroscopy, although not all with high sensitivity or usefully low detection limit. For example, the detection limit for cadmium in a flame ionizer is 1 part per billion (1ppb, 1 in 109) whereas that for mercury is only 500 ppb. Limits of detection using a graphite furnace can be as low as 1 part in 1015. Generally, to analyse for a particular element, a set of calibration standards is prepared in a similar matrix to the sample, and the standards and the sample are analysed under the same conditions.For this experiment, the instrument that has been used is the Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). It is an analytical technique used for the detection of trace metals. It is a type of emission spectroscopy that uses the inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element. The intensity of this emission is indicative of the concentration of the element within the sample.

Diagram of ICP-AES spectrometer

THEORYThe ICP-AES is composed of two parts: the ICP and the optical spectrometer. The ICP torch consists of 3 concentric quartz glass tube and a coil of the radio frequency (RF) generator which surrounds part of this torch. Argon gas is typically used to create the plasma.When the torch is turned on, an intense magnetic field from the RF generator is turned on. The argon gas flowing through is ignited with a Tesla unit (typically a copper strip on the outside of the tube). The argon gas is ionized in the field and flows in a particular rotationally symmetrical pattern towards the magnetic field of the RF coil. A stable, high temperature plasma of about 7000 K is then generated as the result of the inelastic collisions created between the neutral argon atoms and the charged particles.A peristaltic pump delivers an aqueous or organic sample into a nebulizer where it is atomized and introduced directly inside the plasma flame. The sample immediately collides with the electrons and other charged ions in the plasma and is broken down into charged ions. The various molecules break up into their respective atoms which then lose electrons and recombine repeatedly in the plasma, giving off the characteristic wavelengths of the elements involved.A shear gas, typically nitrogen or dry compressed air is used to cut the plasma flame at a specific spot. One or two transfer lenses are then used to focus the emitted light on a diffraction grating where it is separated into its component radiation in the optical spectrometer. The light intensity is then measured with a photomultiplier tube at the specific wavelength for each element line involved. The intensity of each line is then compared to previous measured intensities of known concentrations of the element and its concentration is then computed by extrapolation along the calibration line.

OBJECTIVE1. To analyse the compositions of the samples solutions.2. To determine the concentration of metallic element in the samples.3. To determine whether the samples are safe to drink or not.

APPARATUS ICP ZnCl2 Volumetric flask Beaker Titrate Spatula

PROCEDURES

1.2 set of 100ppm of Zinc Chloride was measured by using volumetric flask and added into 100ml of distilled water. [Note: 200ppm ZnCl2 in 100ml = 0.01g ZnCl2 solid]2.A 50ml of distilled water was measured and poured into a beaker. The sample bottle was labeled as blank sample (0ppm).3.20ppm of the ZnCl2 solution was measured and poured into a flask. Distilled water was filled into the flask until it reaches 50ml.4.The solution was poured into a beaker and labeled.5.Step 3-4 was repeated for 15, 10 and 5ppm.6.50ml of unknown solution, sample A and sample B were measured into a beaker and labeled.7.All the solution was added to the sample bottle. The sample bottle was inserted into the I.C.P sample slots according to this order; Blank, 5ppm, 10ppm, 15ppm, 20ppm, sample A and sample B.8.On the computer screen, Zinc element was selected from periodic table.9.All set of the sample was set by using standard name; Blank, 5ppm, 10ppm, 15ppm, 20ppm, sample A (0ppm) and sample B (0ppm).10.Then all the setting was set and saved.11.The I.C.P machine automatically tested the entire sample one by one.12.The result was printed.

RESULTTHE DILUTION OF SOLUTION PERFORMED SAMPLE (ppm)DISTILLED WATER (mL)STOCK SOLUTION (mL)

050.00

547.52.5

1045.05.0

1542.57.5

2040.010.0

AVERAGE COMPOSITION OF ZnSAMPLESAVERAGE COMPOSITION OF Zn, Cts/s

Blank-

5ppm-

10ppm6.24633

15ppm11.5191

20ppm16.1915

Sample A36.6498

Sample B0.359676

CONCENTRATION OF SAMPLE A AND SAMPLE BWater sampleAverage Compositon of ZnComposition of Znlevel of heavy metals allowed in drinking waterConclusion

A36.649841.005 mg/LNot Safe

B0.3596763.32Safe

CALCULATIONFor standard solution preparation,1ppm = 1mg/L

= 0.4796 ppmFor 100 ppm0.4796 ppm 1 mg/L100 ppm = 208.496 mg/L100 mL = 0.1 L208.496 mg/L X 0.1 L=20.85 mg=0.02085 g of ZnCl2 in 100mL of distilled water.For stock solution :For 5 ppmM1V1 = M2V2(100)(V1)=(5)(0.05) V1 = 2.5 mL

For 10 ppmM1V1 = M2V2(100)(V1)=(10)(0.05) V1 = 5.0 mL

For 15 ppmM1V1 = M2V2(100)(V1)=(15)(0.05) V1 = 7.5 mL

For 20 ppmM1V1 = M2V2(100)(V1)=(20)(0.05) V1 = 10.0 mL

From the graph,Y= mX + cY= 0.9631X 2.8413From the data, y- axis =Average composition of Zn, Cts/s and X-axis = ppm

For sample A:Y= 0.9631X 2.841336.6498= 0.9631X 2.8413 X= 41.00 ppm or mg/L

For sample B:0.359676= 0.9631X 2.8413 X=3.32 ppm or mg/L

DISCUSSIONIn this experiment, the Inductive Couple Plasma (ICP) was conducted to determine whether selections of water samples are safe to drink.

Graph 1

The graph shows that the concentration (ppm) is not accurate. The theoretical results is 0.997 but the actual results that we get is 0.9771 which is far enough to the theoretical one.

During doing this experiment, there were some systematic errors occurred during preparing the Zinc Chloride solution (). The exact amount for preparing 100ppm solution must be 0.02085g. Then the will be diluted to an amount of distilled water in a beaker. This process is called as dilution process. The same method will be used to prepare for the next 5ppm, 10ppm, 15ppm and 20ppm. The 100ppm solution that was prepared earlier will be transferred into 4 different beakers before diluted with distilled water. There is a lot errors during prepare this stock solutions, which are; The amount of that we used is 0.02810g. So, the stock solutions will be affected by this major error. When preparing the stock solutions, we added more distilled water into the conical flasks that contain 5ppm, 10ppm, 15ppm and 20ppm. The most of pipette suckers inside the preparation lab were broken and no accurate measurement can be retrieved. Different apparatus give out different measurement although the differences were small.Referring to the internet source, this type of diluted solution preparation had to be done in series or sequential dilutions. In order to get better proportions of solutions and lesser error percentage more solutions had to be prepared, for example it would take 10's to 100's of experiments (depending on how many solutions you make) to find out the errors and correct it. The advantages of using this sequential dilution are; It is quite trivial to account the systematic errors. It does not change the trend of data, just not the "correct" value. If you do it non-sequentially, it is quite easy to ruin any possible trend, because there might be errors in measurements in both directions.

CONCLUSION

In this experiment, the Inductive Couple Plasma (ICP) was conducted to determine whether selections of water samples are safe to drink.From the result, we can conclude that the experiment is not successful because of some systematic errors. The graph shows that the concentration (ppm) is not accurate. The theoretical results is 0.997 but the actual results that we get is 0.9771 .There were some errors occurred during preparing the Zinc Chloride solution () And the stock solutions.

RECOMMENDATION When titrated the ZnCl2 to the volumetric flask, make sure the amount is accurate. The amount of solute ZnCl2 is 0.02085 g. Not more or less. Filled the distilled water in the volumetric flask ( with ZnCl2 solution) until the line that provided on the flask.

REFERENCES1. Shriver, D.F., Atkins, P.W., Overton, T.L., Rourke, J.P., Weller, M.T. and Armstrong, F.A., 2006. Inorganic Chemistry. 4th ed. Oxford: Oxford University Press.2. A. Montaser and D.W. Golightly, eds. Inductively Coupled Plasmas in Analytical Atomic Spectrometry, VCH Publishers, Inc., New York, 1992.3. en.wikipedia.org/.../Inductively_coupled_plasma_atomic_emission_spectroscopy -4. www-odp.tamu.edu/publications/tnotes/tn29/technot2.htm5. Fair, G. M. & Geyer, J. C. (1965). Elements of water supply and waste-water disposal. New York: John Wiley & Sons.6. Smith, P. G. & Scott, J. G. (2005). Dictionary of waste water management. (2nd ed.). London: IWA Publishing.7. World Health Organization. (2006). Chemical fact sheets. Guidelines for drinking-water quality. (pp. 296 - 460). Geneva: World Health Organization. Retrieved March 4, 2009 from: http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/index.html.

APPENDIX

Flexible Report By SampleAuthor:Published: 4/15/2013 3:33:25PMMethod Name: EH220 4A gp6 (1) (1)0K40K80K120K160K200K0 4 8 12 16 20(S)IRElement Name: ZnElement Wavelength:Date of Calibration: 4/15/2013 3:28:36PMDate of Fit: 4/15/2013 3:28:36PMType of Fit: LinearCorrelation: 0.9771A0 (Offset): 461.8A1 (Gain): 9,779Concentration Units: ppmZn 213.856 nm1.0000.00001.0000.0000Reslope QC NormalizeSlope:Y Int:Slope factor:Offset:A2 (Curvature): 0.0000n (Exponent): 1.000ConcentrationStandard Name Stated Found Diff % Diff (S)IR Stddev EmphasisBlank 0.0000 0.000000 -0.002350 0.0000 438.9 4.315 1CalibStd-5PPM 5.000 8.170 3.166 63.31 80,310 281.9 1CalibStd-10PPM 10.00 10.20 0.2017 2.017 100,200 328.1 1CalibStd-15PPM 15.00 14.11 -0.8942 -5.961 138,400 1,014 1CalibStd-20PPM 20.00 17.53 -2.473 -12.37 171,900 1,207 1Sample Name Acquisition Date Correction FactorBlank 4/15/2013 3:19:42PM 1.00ConcentrationElement/Wavelength Zn2138Units: ppmAvg. of Repeats: z *****Std Dev: ----%RSD: ----Repeat: 1 z ----Repeat: 2 z ----Repeat: 3 z ----Sample Name Acquisition Date Correction FactorCalibStd-5PPM 4/15/2013 3:21:28PM 1.00ConcentrationElement/Wavelength Zn2138Units: ppmAvg. of Repeats: z *****Std Dev: ----%RSD: ----Repeat: 1 z ----Repeat: 2 z ----Repeat: 3 z ----Published: 4/15/2013 3:33:25PM Page 1 of 3Sample Name Acquisition Date Correction FactorCalibStd-10PPM 4/15/2013 3:23:16PM 1.00ConcentrationElement/Wavelength Zn2138Units: ppmAvg. of Repeats: 6.24633Std Dev: 0.0205362%RSD: 0.328772Repeat: 1 6.23561Repeat: 2 6.23337Repeat: 3 6.27001Sample Name Acquisition Date Correction FactorCalibStd-15PPM 4/15/2013 3:25:03PM 1.00ConcentrationElement/Wavelength Zn2138Units: ppmAvg. of Repeats: 11.5191Std Dev: 0.0846513%RSD: 0.734875Repeat: 1 11.609Repeat: 2 11.4408Repeat: 3 11.5076Sample Name Acquisition Date Correction FactorCalibStd-20PPM 4/15/2013 3:26:52PM 1.00ConcentrationElement/Wavelength Zn2138Units: ppmAvg. of Repeats: 16.1915Std Dev: 0.114062%RSD: 0.704458Repeat: 1 16.3175Repeat: 2 16.1616Repeat: 3 16.0953Sample Name Acquisition Date Correction FactorSample-1 4/15/2013 3:28:40PM 1.00ConcentrationElement/Wavelength Zn2138Units: ppmAvg. of Repeats: 36.6498Std Dev: 0.595116%RSD: 1.62379Repeat: 1 37.2757Repeat: 2 36.5825Repeat: 3 36.0912Sample Name Acquisition Date Correction FactorSample-2 4/15/2013 3:30:14PM 1.00Published: 4/15/2013 3:33:25PM Page 2 of 3ConcentrationElement/Wavelength Zn2138Units: ppmAvg. of Repeats: 0.359676Std Dev: 0.0594507%RSD: 16.529Repeat: 1 0.425356Repeat: 2 0.344126Repeat: 3 0.309545Published: 4/15/2013 3:33:25PM Page 3 of 3

List of National Secondary Drinking Water RegulationsContaminantSecondary Standard

Aluminum0.05 to 0.2 mg/L

Chloride250 mg/L

Color15 (color units)

Copper1.0 mg/L

Corrosivitynoncorrosive

Fluoride2.0 mg/L

Foaming Agents0.5 mg/L

Iron0.3 mg/L

Manganese0.05 mg/L

Odor3 threshold odor number

pH6.5-8.5

Silver0.10 mg/L

Sulfate250 mg/L

Total Dissolved Solids500 mg/L

Zinc5 mg/L