Page:NIOSH Manual of Analytical Methods - 3515.pdf/2

 1,1-DIMETHYLHYDRAZINE: METHOD 3515, Issue 2, dated 15 August 1994 - Page 2 of 3 EQUIPMENT:

REAGENTS: 1. 2. 3.

4.

5. 6.

1,1-Dimethylhydrazine,* ACS reagent grade. Hydrochloric acid, ACS reagent grade. Collection medium, 0.1 M hydrochloric acid. To 300 mL of distilled water in a 1000-mL volumetric flask, add 8.6 mL of concentrated hydrochloric acid with caution. Mix and bring to volume with distilled water. Phosphomolybdic acid solution. Dissolve 15 g of phosphomolybdic acid in 500 mL distilled water, allow to stand one day, and filter through a fluted paper filter. Water, deionized and distilled. Calibration stock solution, 1 mg/mL. Weigh 500 mg of 1,1-dimethylhydrazine in a 100mL volumetric flask and fill to the mark with 0.1 M hydrochloric acid.



1. Sampler: 25-mL bubbler with 10 mL 0.1 M hydrochloric acid. 2. Personal sampling pump, 0.2 to 1.0 L/min, with flexible polyethylene or PTFE tubing. 3. Glass or non-reactive stopper for bubbler. 4. Glass tube, 5 cm long by 6-mm I.D., loosely packed with glass wool. 5. Spectrophotometer, set at 730 nm. 6. 1-cm spectrophotometer cells. 7. Test tube, large. 8. Volumetric flasks, 50-mL, 100-mL, 500-mL, 1000-mL. 9. Pipets, 10-, 15-, 25, and 50-µL; 10- and 15-mL glass, delivery, with pipet bulb. 10. Graduated cylinders, glass, 10-mL, 25-mL. 11. Water bath at 95 °C. 12. Stopwatch. 13. Thermometer, ca. 0-120 °C.

See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: 1,1-Dimethylhydrazine may be fatal if inhaled, swallowed or absorbed through the skin [5]. Contact may cause burns to skin and eyes. Vapor may be irritating to the eyes, skin, and mucous membranes. Handle with caution and use appropriate protective equipment.

SAMPLING: 1. 2. 3. 4. 5.

Calibrate each personal sampling pump with a representative sampler in line. Transfer 10 mL 0.1 M hydrochloric acid to a bubbler. Connect outlet arm of bubbler to the glass-wool-packed tube (to prevent splashover into the pump) and then to the sampling pump with the flexible tubing. Sample at an accurately known rate of 0.2 to 1.0 L/min for total sample size of 2 to 100 L. Remove bubbler stem and rinse with 2 mL of 0.1 M hydrochloric acid into bubbler body. Seal bubbler with an inert stopper for shipment in a suitable container in order to prevent damage during transit.

SAMPLE PREPARATION: 6. 7. 8.

Transfer the liquid from the bubbler, quantitatively, to a volumetric flask. Add 10 mL of phosphomolybdic acid solution and bring volume to 50 mL with 0.1 M hydrochloric acid. Transfer an aliquot of this solution to a large test tube and heat to 95 °C for 60 min. Place test tube under running tap water to cool before measurement.

CALIBRATION AND QUALITY CONTROL: 9.

Calibrate daily with at least six working standards to cover the range of 1 to 250 µg 1,1-dimethyl hydrazine per sample. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94