Page:NIOSH Manual of Analytical Methods - 5011.pdf/2

 ETHYLENE THIOUREA: METHOD 5011, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS:

EQUIPMENT:

1. 2.

Bromine, Br 2, ACS reagent.* Disodium pentacyanonitrosyl ferrate dihydrate (sodium nitroferricyanide; sodium nitroprusside), Na 2Fe(CN) 5NO·2H 2O, ACS reagent. 3. Hydroxylamine hydrochloride, NH 2OH·HCl, ACS reagent. 4. Sodium bicarbonate, NaHCO 3, ACS reagent. 5. Hexane, spectrophotometric quality. 6. Methanol, spectrophotometric quality. 7. Water, distilled or deionized. 8. Complexing reagent (see APPENDIX). 9. Dilute complexing reagent. Mix 1 volume complexing reagent with 2 volumes water. Prepare fresh daily. 10. Ethylene thiourea (ETU) (see APPENDIX). 11. Calibration stock solution, 1000 µg/mL. Dilute 0.250 g recrystallized ETU to 250 mL with distilled water.



See Special Precautions

1. Sampler: PVC filters, 5-µm pore size, 37-mm diameter or mixed cellulose ester filters, 0.8-µm pore size, 37-mm diameter; plastic filter holders (cassettes). 2. Personal sampling pump, 1 to 3 L/min, with flexible connecting tubing. 3. Spectrophotometer to operate at 590 nm. 4. Matched glass cuvettes, 5-cm optical path length. 5. Analytical balance capable of weighing to the nearest 0.1 mg. 6. Mortar and pestle. 7. Waterbath thermostatically controlled to 60 ± 1 °C. 8. Glass vials, 20-mL capacity, with PTFE-lined screw caps. 9. Beakers, assortment of 50- to 250-mL. 10. Adjustable pipettes (5- to 50-µL, 50- to 250-µL, 0.5- to 5-mL) with disposable tips. 11. Volumetric pipettes, assortment of 1- to 25-mL, with pipet bulb. 12. Volumetric flasks, 25-, 100-, 200- and 250-mL capacity. 13. Miscellaneous: tweezers, microspatula, rubber suction bulb, wood applicator stick weighing paper, filter paper and filter funnel with stand.

SPECIAL PRECAUTIONS: Bromine is very SAMPLING: corrosive and causes severe burns; vapors are extremely irritating and toxic. Wear gloves and 1. Calibrate each personal sampling pump handle only in a hood. with a representative sampler in line. 2. Sample at an accurately known flow rate Ethylene thiourea is an animal teratogen and between 1 and 3 L/min for a total sample carcinogen [3,4]. Extra care must be taken to size of 200 to 800 L. Do not exceed 2 mg avoid inhalation, ingestion or skin contact. Keep dust loading on the filter. ETU in a bottle labelled "animal carcinogen" and 3. Collect a high-volume air sample or rafter place the bottle in a resealable thick-walled plastic dust sample. Ship in a glass vial in a bag in locked storage. separate container from the filters.

SAMPLE PREPARATION: 4.

Remove the top portion of the filter holder. Hold the bottom portion containing the filter and filter support over a piece of weighing paper. Remove the plug from the bottom of the filter holder and insert the applicator stick through the hole. Gently raise the filter and grasp the edge with tweezers. Very carefully transfer the filter to a 20-mL glass vial and push it gently to the bottom. Add to the vial any material remaining in the filter holder or collected on the weighing paper.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94