ORGANONITROGEN PESTICIDES: METHOD 5601, Issue 1, dated 15 January 1998 - Page 3 of 21 EQUIPMENT (contd) REAGENTS (contd) 16. Pipettes, glass, disposable. solution. [10-12]. See APPENDIX. 12. Quality control spiking solutions: Add analyte stock solutions to acetonitrile at concentrations in the analytical range of the samples. Store in the freezer at –12 ± 1 °C until immediately before spiking. NOTE: Spiking solutions must not contain internal standard. 13. Mobile phase A. Combine 20 mL of 1-propanol and 2.8 mL of TEA in a 1-L volumetric flask and bring to volume with deionized water. Adjust pH to 7.0 (± 0.1) with phosphoric acid using a pH meter. Final concentrations: 2% 1-Propanol, 0.02 M TEA-PO4. Degas prior to use. 14. Mobile phase B. Add 20 mL of 1-propanol to acetonitrile in a 1-L volumetric flask and bring to volume. Degas prior to use.
- Low dead volumes will give lower dwell
volumes [13,14] and better resolution [15].
- See SPECIAL PRECAUTIONS
SPECIAL PRECAUTIONS: Pesticides: Avoid inhaling vapors or dust; avoid skin contact. Wear gloves and suitable clothing when handling pure material. Solvents: Avoid skin contact and open flame. Use in a hood. Phosphoric acid: Avoid skin contact. n-Butyl isocyanate may act as a sensitizer. Avoid skin contact.
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. Place sampler vertically, with the large end down, in the worker’s breathing zone. 3. Sample at an accurately known flow rate between 0.1 and 1 L/min for a total sampling volume up to 480 L. Record volume, and document presence of any known or potential interferences. 4. Cap both ends of the sampler with plastic caps and pack securely for shipment. SAMPLE PREPARATION: 5. Remove cap from large end. Transfer filter, PTFE retainer ring, and front XAD-2 resin section to a 4-mL vial. Transfer the polyurethane foam divider plug along with the back-up XAD-2 resin bed to a second 4-mL vial. 6. Add 2.0 mL of desorbing solvent with internal standards to each vial using a 2.5- or 5-mL syringe or 2-mL pipette; cap each vial. 7. Mix by rotating the vials end-over-end at 5 to 10 RPM for approximately 45 minutes. 8. Filter an aliquot into a 2-mL autosampler vial through a 0.45-µm PTFE filter. CALIBRATION AND QUALITY CONTROL: 9. Determine retention times for the analytes of interest using the column and chromatographic conditions of choice for the analysis. 10. Calibrate daily with at least six working standards covering the analytical range for individual analytes. a. Prepare working standards by diluting aliquots of the high-level calibration standard with desorbing solution containing internal standard in a volumetric flask. Include an unspiked desorption solution NIOSH Manual of Analytical Methods, Fourth Edition
