Hach DR2400 - Page 94

Arsenic
© Hach Company, 2003. All rights reserved. Printed in the U.S.A. 3/04 1ed
Page 6 of 6 Arsenic_None_Other_SDC_Eng_Ody.fm
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Summary of Method
Arsenic is reduced to arsine gas by a mixture of zinc, stannous chloride,
potassium iodide, and hydrochloric acid in a specially equipped distillation
apparatus. The arsine is passed through a scrubber containing cotton saturated
with lead acetate and then into an absorber tube containing silver
diethyldithiocarbamate in pyridine. The arsenic reacts to form a red complex
which is read colorimetrically. This procedure requires a manual calibration. Test
results are measured at 520 nm.
Required Reagents
Quantity Required
Description per test Unit Cat. No.
Arsenic Standard Solution, 1000-mg/L As...........................................varies .............. 100 mL...............14571-42
Hydrochloric Acid, ACS..........................................................................25 mL .............. 500 mL...................134-49
Lead Acetate Solution, 10%.....................................................................1 mL ................ 100 mL...............14580-42
Potassium Iodide Solution, 20%.............................................................3 mL ................ 100 mL...............14568-42
Pyridine, ACS............................................................................................50 mL .............. 500 mL...............14469-49
Silver Diethyldithiocarbamate................................................................1 g.................... 25 g.....................14476-24
Stannous Chloride Solution ....................................................................1 mL ................ 100 mL...............14569-42
Water, deionized ................................................................................................................. 4 liters ....................272-56
Zinc, 20-mesh, ACS ..................................................................................6 g.................... 454 g.......................795-01
Required Apparatus
Balance, analytical, SA-120, 115 VAC.....................................................1 ....................... each....................26103-00
Balance, analytical, SA-120, 220 VAC ....................................................1 ....................... each....................26103-01
Balls, cotton ...............................................................................................1 ....................... 100/pkg...............2572-01
Boat, weighing, 8.9-cm square................................................................2 ....................... 500/pkg.............21790-00
Bottle, amber, 237-mL, glass....................................................................1 ....................... 6/pkg...................7144-41
Cap, polypropylene, for amber bottle ...................................................1 ....................... 6/pkg.................21667-06
Cylinder, graduated, 25-mL ....................................................................2 ....................... each........................508-40
Cylinder, graduated, 250-mL ..................................................................1 ....................... each........................508-46
Distillation Apparatus, Arsenic Accessories ........................................1 ....................... set .......................22654-00
Distillation Apparatus, General Purpose Accessories ........................1 ....................... set.......................22653-00
Flask, volumetric, Class A, 1000-mL, with glass stopper ...................1 ....................... each....................14574-53
Flask, volumetric, Class A, 200-mL........................................................1 ....................... each....................14574-45
Flask, volumetric, Class A, 500-mL........................................................6 ....................... each....................14574-49
Pipet Filler, safety bulb ............................................................................1 ....................... each....................14651-00
Pipet, serological, 5-mL............................................................................2 ....................... each........................532-37
Pipet, volumetric, Class A, 1.00-mL.......................................................2 ....................... each....................14515-35
Pipet, volumetric, Class A, 2.00-mL.......................................................1 ....................... each....................14515-36
Pipet, volumetric, Class A, 4.00-mL.......................................................1 ....................... each....................14515-04
Pipet, volumetric, Class A, 6.00-mL.......................................................1 ....................... each....................14515-06
Pipet, volumetric, Class A, 8.00-mL.......................................................1 ....................... each....................14515-08
Pipet, volumetric, Class A, 10.00-mL.....................................................1....................... each....................14515-38
Sample Cells, 10-20-25 mL, w/cap.........................................................2....................... 6/pkg.................24019-06
Stopper, hollow, poly., No. 1 ...................................................................2 ....................... 6/pkg.................14480-00
Select one based on available voltage:
Distillation Apparatus Heater, 115 VAC, 60 Hz....................................................... each....................22744-00
Distillation Apparatus Heater, 230 VAC, 50 Hz ...................................................... each....................22744-02