EQUIPMENT

1. Perkin-Elmer Model 3300 Atomic Absorption Spectrophotometer
2. Perkin-Elmer FIAS 400 flow injection unit
3. Perkin-Elmer AS 90 Autosampler
4. Arsenic electrodeless discharge lamp
5. Perkin-Elmer System 2 EDL Power Supply
6. 16 x 100 mm. disposable glass tubes.

GAS

1. Argon 99.99%

REAGENTS

1. Sodium Borohydride: NaBH₄
2. Sodium Hydroxide: NaOH
3. Potassium Iodide: KI
4. Hydrochloric Acid: HCl
5. Ascorbic Acid:

STANDARDS

1. Stock Solutions:
   1. 1000 ppm Arsenic - Use certified, NIST traceable standard.
   2. 10 ppm Arsenic - Pipet 10 mL of 1000 ppm arsenic standard into a 1 liter volumetric flask. Dilute to volume with deionized water and mix well.
   3. 50 ng/mL arsenic solution - Pipet 5 mL of 10 ppm arsenic solution into a 1 liter volumetric flask. Dilute to volume with deionized water and mix well.
2. Instrument Calibration Standards
   1. Pipet the designated mL of 50 ng/mL arsenic standard into 50 mL volumetric flasks containing 30 mL deionized water. Add 5 mL of potassium iodide/acsorbic acid solution and 5 mL hydrochloric acid and let stand for 45 minutes. Dilute to volume with deionized water and mix well.

      Standard	mL 50 ng/mL Arsenic	Final Arsenic Concentration (ng/mL)
      blank	0	0
      1	1	1
      3	3	3
      5	5	5

3. Spiking Solution
   1. 10 ng/mL Arsenic - Pipet 20 mL of 50 ng/mL arsenic standard into a 100 mL volumetric flask. Dilute to volume with deionized water and mix well.

SOLUTIONS

1. 0.2% sodium borohydride, 0.05% sodium hydroxide.
   1. Weigh 0.50 g sodium hydroxide into a 1 liter volumetric flask containing 600 mL deionized water. Dissolve and mix well.
   2. Add 2 g sodium borohydride. Dissolve, dilute to volume with deionized water and mix well.
2. 10% potassium iodide, 5% ascorbic acid.
   1. Weigh 50 g potassium iodide into a 500 mL volumetric flask containing 300 mL of deionized water. Dissolve and mix well.
   2. Add 25 g ascorbic acid. Dissolve, dilute to volume with deionized water and mix well.
3. 10 % HCl carrier solution.
   1. Add 100 mL hydrochloric acid to a 1 liter volumetric flask containing 600 mL deionized water. Dilute to volume with deionized water and mix well.

SAMPLE PREPARATION

1. Liquid Samples
   1. Pipet 1 to 5 mL of sample solution into a 16 x 100 mm. glass tube.
   2. Add 1 mL potassium iodide/ascorbic acid solution.
   3. Add 1 mL hydrochloric acid
   4. Add enough deionized water to make the final volume 10 mL
   5. Mix by gentle inversion and let stand for 45 minutes.
2. Solid Samples
   1. Weigh 1 g sample into a 150 mL beaker.
   2. Add 10 mL nitric acid.
   3. Add 5 mL perchloric acid.
   4. Cover with a watch glass.
   5. Heat on a hot plate until dense white fumes are observed.
   6. Allow to cool and add 10 mL 25% hydrochloric acid.
   7. Transfer to a 100 mL volumetric flask.
   8. Dilute to volume with deionized water and mix well.
   9. Proceed as in steps 1a through 1e for liquid samples.

ANALYSIS PROTOCOL

1. Analyze client samples in groups of 10 of less.
2. Analyze one quality control sample before and after each group of client samples.
3. For acid digested samples, prepare a reagent blank, a digest blank, and a spiked digest blank to be analyzed with the first group of client samples analyzed during the day.
4. For liquid samples, prepare only a reagent blank to be analyzed with the first client sample group during the day.
5. Prepare a client sample spike for each group of client samples analyzed.
6. Print a copy of the ID/WT file before beginning analysis.

SPIKE PROCEDURE

1. Client sample spike
   1. Pipet the same amount of sample solution that was used in analysis for arsenic into a 16 x 100 mm. glass tube.
   2. Add 1 mL 10 ng/mL arsenic solution.
   3. Add 1 mL potassium iodide/ascorbic acid solution.
   4. Add 1 mL hydrochloric acid.
   5. Add enough deionized water to bring the final volume to 10 mL
   6. Mix by gentle inversion and let stand for 45 minutes.
2. Blank Digestion Spike
   1. Add 10 mL nitric acid to a 150 mL glass beaker.
   2. Add 5 mL perchloric acid
   3. Add 5 mL of 50 ng/mL arsenic solution and cover with a watch glass.
   4. Heat on a hot plate until dense white fumes are observed.
   5. Allow the sample to cool and add 10 mL 25% hydrochloric acid.
   6. Transfer to a 100 mL volumetric flask.
   7. Dilute to volume with deionized water and mix well.
   8. Pipet 5 mL of spiked blank digest into a 16 x 100 mm. glass tube.
   9. Add 1 mL Potassium iodide/ascorbic acid solution.
   10. Add 1 mL of hydrochloric acid.
   11. Add 3 mL deionized water
   12. Mix by gentle inversion and let stand for 45 minutes.

PROCEDURE

1. Install Arsenic electrodeless lamp.
2. Turn on the System 2 EDL power supply. With the "MOD" button switched off (green light off), set the output level to 400 milliamps.
3. Turn the 3300 spectrophotometer, FIAS 400 unit, computer, monitor, printer, and gas supply.
4. Double click on " AA_INST.EXE". Three icons will appear at the bottom of the screen.
5. Click on "MHS-FIAS", double click on "ROUTINE", click on "ELEMENT FILE", click on "AS001.MEL", then click on "OK".
6. Press the "MOD" button (green light on) on the System 2 EDL power supply and adjust the output to 300 milliamps.
7. From the Windows menu at the top of the screen, click on "ALIGN LAMPS"
8. Allow the lamp to warm up until an energy reading of 50-54 is reached and then close the window.
9. From the Windows menu, click on "AS-90", double click on "DATA FILE", then click on "AS.DAT"
10. Click on "ID/WT"
11. Click on 1 or the following:
12. "AS_DIG" for digested sample analysis.
13. "AS_WATER" for liquid samples.
14. Beginning at position 9, enter sample identification and dilutions and then close the window.
15. From the Windows menu, click on "FIAS CONTROL", then click "ON" in the ON/OFF box by the word "cell". The "Hot" icon will highlight when the temperature of the quartz cell reaches 900 degrees C.
16. Place the reagent supply line in the sodium borohydride/sodium hydroxide solution.
17. Place the carrier line in the 10 % hydrochloric acid solution.
18. Engage the PUMP 2 platen.
19. Turn on PUMP 2 by clicking on the "ON/OFF" box by "PUMP 2".
20. Adjust the gas flow rate using the flowmeter/rotameter to 100 mL/min.
21. Load the autosampler in the following manner:

    Position 1	blank
    Position 2	1 ng/mL arsenic standard
    Position 3	3 ng/mL arsenic standard
    Position 4	5 ng/mL arsenic standard
    Position 8	quality control sample
    Positions 9-40	client samples

22. Engage the PUMP 1 platen.
23. Turn on PUMP 1 by clicking on the "ON/OFF" box by "PUMP 1" and close the window
24. From the Windows menu, click on "AS-90".
25. Click on the "YES" box by "Pumps off at end".
26. Click on "RUN ALL", and analysis will begin.

QUALITY CONTROL

1. Values on the quality control sample must be within the limits established by the supplier.
2. Recovery of arsenic from the spiked samples and spiked digest blank must be between 75% and 125%.
3. The r value for the calibration curve must be greater than 0.990.

REFERENCES

1. Perkin-Elmer Corp, Recommended Analytical Conditions and General Information for Flow Injection Mercury/Hydride Analyses Using the Perkin- Elmer FIAS-100/400, p 8, Order No. TSAA-10C.
2. Arsenic and Selenium by Hydride Generation Atomic Absorption Spectrometry, Method 3114 B, in Standard Methods for the Examination of Water and Wastewater, 19th Edition, 1995. chapter 3, p 28-31.