Page:NIOSH Manual of Analytical Methods - 3503.pdf/2

 HYDRAZINE: METHOD 3503, Issue 2, dated 15 August 1994 - Page 2 of 3 EQUIPMENT:

REAGENTS: 1. 2. 3.

4.

5. 6.

Hydrochloric acid, 0.1 M. Dilute 8.6 mL conc. HCl to 1 L with distilled water. Methanol, reagent grade.* Calibration stock solution, 1.0 mg/mL. Dissolve 0.10 mL hydrazine* in methanol to make 100 mL solution. Solution of p-dimethylaminobenzaldehyde in methanol, 0.168 M. Dissolve 12.5 g p-dimethylaminobenzaldehyde in methanol to make 500 mL solution. Glacial acetic acid.* Sodium hydroxide solution, 1.8 M. Dissolve 7.2 g NaOH in distilled water to make 100 mL solution.

1. Sampler: midget bubbler, glass, with 15 mL 0.1 M HCl. 2. Glass tube, 5 cm x 6-mm ID, packed loosely with glass wool. 3. Personal sampling pump, 0.2 to 1 L/min, with flexible connecting tubing. 4. Vials, 20-mL, with PTFE-lined screw caps. 5. Spectrophotometer set at 480 nm, with matched cuvettes, glass, 1-cm path length. 6. Volumetric flasks, 25-, 50-, 100- and 500-mL and 1 L. 7. Pipets, 1-, 2-, 10- and 15-mL, with pipet bulb. 8. Syringe, 10-µL, readable to 0.1 µL. 9. Syringe, 50-µL, readable to 1 µL. 10. pH paper.

See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: Hydrazine is carcinogenic, toxic, and flammable, and can be absorbed through the skin [5]. Acetic acid and methanol are flammable. Wear gloves, handle compounds in a well-ventilated fume cabinet, avoid inhalation of vapors, and protect compounds from sparks and flames.

SAMPLING: 1. 2. 3. 4.

Connect the outlet of the sampler and the inlet of the pump to a tube packed with glass wool to protect the pump from splashover. Calibrate the personal sampling pump with sampler in line. Sample at 0.2 to 1.0 L/min for a sample size of 7 to 100 L. Transfer the solution from the bubbler to a glass vial, rinsing both the bubbler stem and body with 1-mL portions of 0.1 M HCl. Cap the vial securely for shipment.

SAMPLE PREPARATION: 5. 6. 7. 8. 9. 10. 11.

Transfer bubbler solution to a 50-mL volumetric flask. Rinse vial with 1 mL 0.1 M HCl, and add rinse to the flask. Add 1.8 M NaOH (ca. 1 mL) to make the solution neutral or slightly alkaline to pH paper. Immediately add 10 mL 0.168 M p-dimethylaminobenzaldehyde solution. Agitate the mixture and allow to stand 30 min. Bring volume of solution to 50 mL with glacial acetic acid. Dilute 2 mL of the solution to 25 mL with glacial acetic acid. Prepare field blanks and media blanks according to steps 4 through 10.

CALIBRATION AND QUALITY CONTROL: 12.

Calibrate daily with a blank and six working standards over the range 1 to 400 µg hydrazine per sample. a. Add aliquots of calibration stock solution to 15 mL 0.1 M HCl in 50-mL volumetric flasks and dilute to the mark. Designate one flask as a blank and do not add hydrazine to that flask. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94