Page:NIOSH Manual of Analytical Methods - 5504.pdf/3

 Organotin Compounds (as Sn): Method 5504, Issue 2 dated 15 August 1994 - Page 3 of 6 5. Open the cassette filter holder. With tweezers, carefully transfer the filter to a 125-mL beaker. 6. Place the front sorbent section and front glass wool plug into a second beaker. Place the back sorbent section and remaining glass wool plugs into a third beaker. 7. Pipet 10.0 mL acetonitrile and 10 µL acetic acid into each beaker. Cover with plastic film. 8. Agitate beakers in ultrasonic bath for 30 min. CALIBRATION AND QUALITY CONTROL: 9. Calibrate daily with at least six working standards. a. Add known amounts of calibration stock solution to 0.1% (v/v) acetic acid in acetonitrile in 10-mL volumetric flasks and dilute to the mark. Use serial dilutions as needed to obtain concentrations of each organotin compound in the range 0.1 to 5 µg/mL (as Sn). b. Analyze with samples and blanks (steps 12 through 15), alternating samples and standards with similar responses. c. Prepare calibration graphs (peak height vs. µg Sn) for each organotin compound. 10. Determine recovery (R) in the range of interest. Prepare three samplers at each of three levels plus three media blanks. a. Remove and discard back sorbent section of a media blank sampler. b. Inject a known amount (2 to 20 µL) of organotin standard solution directly onto front sorbent section and a separate aliquot onto the filter, with a microliter syringe. c. Cap the sampler. Allow to stand overnight. d. Desorb (steps 5 through 8) and analyze with working standards (steps 12 through 15). e. Prepare a graph of R vs. µg Sn recovered for each organotin compound. 11. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graphs and recovery graphs are in control.

MEASUREMENT: 12. Set the AAS and graphite furnace according to manufacturer's recommendations and to conditions on page 5504-1. Adjust the sample injection/dry/atomize cycle so that it occurs exactly once every 60 sec. 13. Operate the HPLC according to manufacturer's recommendations and the following conditions: a. For non-tetraorganotin compounds: (1) Column: strong cation exchange (EQUIPMENT, 4.a). (2) Flush column with 50 to 60 mL acetate buffer prior to sample injection. (3) Eluent: flowrate = 2 mL/min (4) Eluent Gradient: Time (min) 0 - 15 15 - 18 18 - 40

b.

% Acetate Buffer 100 100 - 0 0

% Citrate Buffer 0 0 - 100 100

(5) After the chromatogram is complete, re-equilibrate the HPLC system to initial conditions by pumping acetate buffer through the column for 15 min. (6) Inject 100-µL sample aliquot. For tetraorganotin compounds: (1) Column: C18. (2) Flush column with 50 to 60 mL of 100% acetonitrile prior to sample injection. (3) Eluent: flowrate = 2 mL/min, isocratic, 100% acetonitrile. (4) Inject a 100-µL aliquot of sample solution.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94