Page:NIOSH Manual of Analytical Methods - 5602.pdf/2

 CHLORINATED AND ORGANONITROGEN HERBICIDES (AIR SAMPLING): METHOD 5602, Issue 1, dated 15 January 1998 - Page 2 of 14

REAGENTS:

EQUIPMENT:

1. 2. 3. 4.

Analytes listed in Table 1. Methanol, pesticide analytical grade. Methyl t-butyl ether, pesticide analytical grade. Extraction solvent. Add10 mL of methanol to a 100-mL volumetric flask. Dilute to volume with methyl t-butyl ether. D i a z a l d® ( N - m e t h y l - N - n i t r o s o p-toluenesulfonamide.)* Silicic Acid, 100-mesh. Diazomethane* derivatizing reagent. (See APPENDIX) Herbicide stock solutions. Prepare individual standard stock solutions of each herbicide of interest in extraction solvent. NOTE: All herbicides in Table 1 were found to be soluble to at least 1 mg/mL, except simazine, which is soluble to 0.5 mg/mL. Calibration stock solution. Dilute the appropriate volume of herbicide stock solution to a known volume with extraction solvent. NOTE: Spiking solutions may contain more than one analyte. Purified gases: helium, 5% methane in argon, or nitrogen.

1.


 * See SPECIAL PRECAUTIONS.

9.

5. 6. 7. 8.

9.

10.

2. 3. 4. 5. 6.

7. 8.

10.

Sampler: glass tube, 11-mm ID x 13-mm OD x 50 mm long, with the outlet end drawn to a 6-mm OD x 25 mm long tube (Figure 2). The enlarged part of the tube contains a 270-mg front section of 20/60 mesh XAD-2 sorbent held in place by a 11-mm quartz fiber filter and polytetrafluoroethylene (PTFE) retaining ring at inlet and a small plug of polyurethane foam at the back end. The back section consists of 140-mg XAD-2 sorbent held in place by a long plug of polyurethane foam. Tubes commercially available (SKC, Inc. Cat. No. 226-58). Personal sampling pump, 0.2 to 1 L/min with flexible connecting tubing. Gas chromatograph, electron capture detector, integrator, and column (Table 2). Vials, glass, 4-, 2-, and 0.1-mL limited-volume vials with PTFE-lined caps. Syringes, 1- and 5-mL; 10-, 50-, and 100-µL as needed. Volumetric flasks, 2-, 5-, 10-, 25-, 50-, and 100-mL for working standard preparation and solutions. Forceps. PTFE syringe filters, 0.45-µm pore size (Gelman Sciences or equivalent). Syringe, luer lock, 1-, 2.5-, or 5-mL, for sample filtering. Platform shaker

SPECIAL PRECAUTIONS: Diazomethane has been cited as a carcinogen. It is extremely toxic and highly irritating. Diazomethane may explode under some conditions. Do not heat above 90 °C. Avoid rough surfaces: fire-polish glass tubing, or use Teflon®. Do not expose solutions to strong light. Keep dilute solutions at 0 °C. Prepare in a hood [5]. Avoid skin contact withDiazald® and herbicides. Avoid skin contact and open flame with solvents. Wear appropriate protective clothing and work with these compounds in a well ventilated hood.

SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Connect the sampler to the personal sampling pump with flexible tubing. The sampler should be placed vertically with the large end down. 3. Sample at a known flow rate between 0.2 and 1 L/min for a total sample size of 12 to 480 L. 4. Cap both ends of the sampler with plastic caps and pack securely for shipment. SAMPLE PREPARATION: 5. Remove cap from large end of sampler and remove PTFE retainer ring; carefully transfer filter and front XAD-2 resin section to a 4-mL vial. Transfer the short polyurethane foam plug along with the back-up XAD-2 resin bed to a second 4-mL vial. Discard back-up plug. 6. Add 2 mL of diazomethane derivatizing reagent to each vial using a 5-mL syringe or 2-mL pipette; cap each vial. Mix by rotating at 5 to 10 RPM on a platform shaker for a minimum of one hour. 7. Add approximately 10 mg of silicic acid to the solution, mix, and allow to stand for one hour. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition