Page:NIOSH Manual of Analytical Methods - 2015.pdf/2

 CHLOROACETALDEHYDE: METHOD 2015, Issue 1, dated 15 August 1994 - Page 2 of 4 EQUIPMENT:

REAGENTS: 1. Chloroacetaldehyde*, ~50% (w/w) solution in water. 2. Water, deionized, distilled. 3. 50% Aqueous methanol. 4. 5% Hydrazine sulfate solution. Dissolve 12.5 g hydrazine sulfate in 250 mL deionized distilled water. 5. Ferric ammonium sulfate solution, saturated, in 1 M HNO 3. 6. Ammonium thiocyanate, 0.100 N. Accurately weigh 7.6139 ammonium thiocyanate and dilute to 1 L with deionized distilled water. 7. Silver nitrate solution, 0.100 N. Accurately weigh 16.987g silver nitrate and dilute to 1 L with deionized distilled water. 8. Nitric acid solution. Add 25 mL conc. nitric acid to 25 mL water. Boil until colorless to remove nitrous acid. 9. Nitrobenzene. 10. 5% Argon/methane. 11. Calibration stock solution. Dilute 1 mL 50 % chloroacetaldehyde solution to 250 mL with deionized distilled water. See APPENDIX for standardization method.

2. 3. 4.

2. 3. 4. 5. 6. 7. 8.

Sampler: glass, 8 cm long, 6-mm ID, containing two sections of 20/40 mesh silica gel (front = 520 mg; back = 260 mg), separated by 2 mm of urethane foam. Pressure drop across the tube at 1 L/min airflow must be less than 3.4 kPa. Tubes are commercially available. Personal sampling pump, 0.05 to 0.2 L/min with flexible connecting tubing. Gas chromatograph, 63Ni electron-capture detector, integrator and column (page 2015-1). Volumetric flasks, 25-mL, 1-L and other convenient sizes for preparing standards. Erlenmeyer flasks, 50-mL, 250-mL. Buret, 10-mL. Pipets, glass, 25-mL and other convenient sizes for making dilutions. Syringes, 10-, 50-, and 100-µL.

See SPECIAL PRECAUTIONS. SPECIAL PRECAUTIONS: Chloroacetaldehyde is corrosive to the skin and an eye irritant in low vapor concentrations. In storage, chloroacetaldehyde forms a water-insoluble polymer [4].

SAMPLING: 1.

1.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.05 and 0.2 L/min for a total sample size of 3 to 16 L. Cap the samplers with plastic (not rubber) caps and pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Transfer the glass wool plug and front section of silica gel to a 50-mL Erlenmeyer flask. Transfer the backup sorbent section to another flask. Pipet 25 mL 50% aqueous methanol into each flask. Shake each flask occasionally over a 30-min period. Analyze samples within 1 day.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards over the range 0.1 to 19 µg chloroacetaldehyde per sample. a. Add known amounts of calibration stock solution to 25-mL volumetric flasks and dilute to the marks with 50% aqueous methanol. Use serial dilution as necessary to prepare lower NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94