Page:NIOSH Manual of Analytical Methods - 5600.pdf/3

 ORGANOPHOSPHORUS PESTICIDES: METHOD 5600, Issue 1, dated 15 August 1994 - Page 3 of 20 4.

Cap both ends of the sampler with plastic caps and pack securely for shipment.

SAMPLE PREPARATION: 5.

6. 7. 8.

Remove cap from large end and remove PTFE retainer ring; transfer filter and front XAD-2 section to a 4-mL vial. Transfer the short polyurethane foam plug along with back-up XAD-2 section to a second 4-mL vial. Add 2 mL of desorbing solvent to each vial using a 5-mL syringe or 2-mL pipette. Cap each vial. Allow to stand 30 minutes, immerse vials approximately 15 mm in an ultrasonic bath for 30 minutes. Alternatively, place the vials in a shaker or tumbler for 1 hour. Transfer 1 to 1.5 mL from each 4-mL vial to a clean 2-mL GC vial, cap and label.

CALIBRATION AND QUALITY CONTROL: 9.

10.

11.

Calibrate daily with at least six working standards covering the analytical range of the method for individual analytes. a. Add known amounts of calibration spiking solution (SS-1 or SS-2 according to schedule in Table 11) to desorbing solution in 2-mL volumetric flasks and dilute to the mark. NOTE: If an internal standard is included in the desorbing solution, then exactly 2 mL of desorbing solution in a volumetric flask must be concentrated slightly under a gentle stream of nitrogen in order to accommodate the specified volume of the spiking solutions. After adding the spiking solutions to the slightly concentrated desorbing solution, dilute to the 2-mL mark with toluene or 90/10 toluene/acetone. b. Include a calibration blank of unspiked desorbing solution. c. Analyze together with field samples, field blanks, and laboratory control samples (steps 12 and 13). d. Prepare calibration graph (peak area vs. µg analyte), or if internal standard (IS) is used (peak area of analyte/peak area of IS vs. µg analyte). Prepare Laboratory Control Samples (LCS) with each sample set, in duplicate. a. Remove cap from large end of sampler tube. Apply 30 µL of spiking solution SS-1 to face of quartz fiber filter. Cap and allow to stand for a minimum of 1 hour. Preferably, these should be prepared as soon as samples arrive and should be stored with the field samples until analyzed. b. Include an unspiked sampler as a media blank. c. Analyze along with field samples and blanks, and liquid calibration standards (steps 12 through 16). When extending application of this method to other organophosphorus compounds, the following minimal desorption efficiency (DE) test may be performed as follows: a. Determine the NIOSH REL, OSHA PEL, or ACGIH TLV in mg/m 3. b. Prepare spiking solution SS-1 (refer to Table 11, or use the following formulae, which are specific for the calculation of the weight of analyte to add to 10 mL toluene/acetone 90:10). For REL > 1 mg/m 3 (assuming 12-L collection vol.), let W = REL x 4 m 3 For REL ≤ 1 mg/m 3 (assuming 120-L collection vol.), let W = REL x 40 m 3 where W = weight (mg) of analyte to dissolve into 10 mL of desorbing solvent. Let [SS-1] = W/10 mL where [SS-1] = concentration of spiking solution SS-1 in mg/mL. Let [SS-2] = [SS-1] x 0.1 where [SS-2] = concentration of spiking solution SS-2. d. Prepare three tubes at each of five levels plus three media blanks. Concentration at each level may be calculated using formulae in entry 20, part II of Table 11. i. Remove plastic cap from large end of sampler, apply appropriate volume of spiking solution to face of quartz fiber filter following schedule in part I of Table 11. ii. Cap and allow sampler to stand overnight. e. Prepare tubes for analysis (Steps 5 through 8). f. Analyze with liquid standards (Steps 12 and 13). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94