Page:NIOSH Manual of Analytical Methods - 5519.pdf/3

ENDRIN: METHOD 5519, Issue 2, dated 15 August 1994 - Page 3 of 4 10.

Wash the filter cassette parts as follows: Pipet 10.0 mL hexane into a clean vial and mark the level. Remove the hexane and allow to dry. Place the bottom part-cassette on the open, marked vial. Invert the top part-cassette and place it on the bottom part-cassette. Hold the metal screen over the set-up with clean tweezers. Rinse the screen with 10.0 mL hexane, allowing the rinse to drain from top cassette through bottom cassette to the marked vial. Remove any remaining rinse from the cassette parts with clean disposable pipet and transfer to the marked vial. Dilute with hexane to the marked levels. Cap immediately. NOTE: Analysis should be done within 24 hours of desorption.

CALIBRATION AND QUALITY CONTROL: 11.

12.

13.

Calibrate daily with at least six working standards covering the range of samples. a. Add known amounts of calibration stock solution to toluene in 10-mL volumetric flasks and dilute to the mark. Use serial dilution as needed to obtain endrin concentrations in the range 0.004 to 7 µg/mL. b. Analyze (steps 14 through 16) the working standards and blank in duplicate. c. Prepare a calibration graph (peak area vs. µg endrin); analyze two additional check standards for each ten sample injections. Determine the analytical method recovery at least once for each lot of filter and Chromosorb 102 used. Prepare four samplers at each of five levels plus three media blanks. a. Place a MCEF filter and 100 mg of Chromosorb 102 in a vial. b. Inject calibration stock solution onto the combined filter and Chromosorb 102 in the container with a microliter syringe. Include blank samples. c. Cap the vial and let stand overnight. d. Analyze in duplicate; prepare graph of recovery vs. µg endrin. Check recovery at two levels for each sample set in duplicate. Repeat recovery graph determination if checks do not agree to within 5% of recovery graph.

MEASUREMENT: 14. 15.

16.

Set gas chromatograph to conditions given on page 5519-1. Inject 5 µL sample aliquot using solvent flush technique. Make duplicate injections of sample and standards. NOTE: Under these conditions, t r for endrin is ca. 5 min. Measure peak areas.

CALCULATIONS: 17.

18.

Determine the mass, µg (corrected for recovery) of endrin found on the sampler (filter plus front section of Chromosorb 102), W 1, back of section, W 2, and the rinse from screen and cassette, F, and in the average media blank (filter plus front tube section, B 1, and back tube section, B 2. NOTE: If W 2 > W 1 + F/10, report breakthrough and possible sample loss. Calculate the concentration of endrin, C (mg/m 3), in the air volume sampled, V (L):

EVALUATION OF METHOD: Method S284 was validated on July 8, 1979 [1,2,4]. The substance used to dynamically generate test atmospheres at 25 °C and 760 mm Hg was: 1.6 EC, Velsicol Chemical Corporation. Collection efficiencies were close to 1.00 in the range 28 to 33 µg per sample. The analytical recoveries from NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94