Page:NIOSH Manual of Analytical Methods - 5016.pdf/2

 STRYCHNINE: METHOD 5016, Issue 2, dated 15 August 1994 - Page 2 of 3 EQUIPMENT:

REAGENTS: 1. 2. 3. 4. 5. 6. 7. 8.

9.

Strychnine, 98%.* Acetonitrile, chromatographic quality. Water, chromatographic quality. Acetonitrile:water, 1:1 (v/v). Mix equal volumes of acetonitrile and distilled water. Acetic acid, glacial.* Acetic acid, 0.01 N. Dilute 0.6 mL glacial acetic acid to 1 L with distilled water. 1-Heptanesulfonic acid sodium salt, 95%. Calibration stock solution, 1 mg/mL strychnine in 0.01 N acetic acid. Use an ultrasonic bath to aid dissolution. Mobile phase: Dissolve 1.1014 g 1heptanesulfonic acid sodium salt in 980 mL. 1:1 acetonitrile:water. Adjust pH to 3.5 with glacial acetic acid. Dilute to 1 L with 1:1 acetonitrile:water. Filter through 0.45-µm PTFE filter and refrigerate. Prepare fresh weekly and if cloudiness appears.

1. Sampler: glass fiber filter, 37-mm diameter, in cassette filter holder. 2. Personal sampling pump, 1 to 3 L/min, with flexible connecting tubing. 3. HPLC, UV absorption detector at 254 nm, recorder, integrator and column (page 5016-1). 4. Syringe filter, polypropylene housing, nylon membrane, 0.2-µm pore size. 5. Syringe, 20-µL. 6. Micropipets or syringes, 10- to 100-µL. 7. Jars, glass, squat-form ointment, with PTFE-lined screw caps. 8. Volumetric flasks, glass, 10-mL. 9. Pipet, 5-mL delivery, with pipet bulb. 10. Tweezers. 11. Ultrasonic bath.

See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: Strychnine is a potent convulsant. Use impervious clothing, gloves and face shields when handling it [3,4]. Avoid skin contact with acetic acid as it may cause severe burns.

SAMPLING: 1. 2.

Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 1 and 3 L/min for a total sample size of 70 to 1000 L.

SAMPLE PREPARATION: 3. 4. 5.

Transfer the filter carefully using tweezers to an ointment jar. Add 5.0 mL mobile phase. Seal and gently swirl the jar to wet the filter. Filter the sample solution through a syringe filter.

CALIBRATION AND QUALITY CONTROL: 6.

7.

Calibrate daily with at least six working standards over the range 1 to 70 µg strychnine per sample (0.2 to 14 µg/mL). a. Add known amounts of calibration stock solution to mobile phase in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with the samples and blanks (steps 9, 10, and 11). c. Prepare calibration graph (peak area vs. µg strychnine). Determine recovery (R) at least once for each lot of filters used for sampling in the calibration range. Prepare three filters at each of five levels plus three media blanks. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94