Page:NIOSH Manual of Analytical Methods - 5503.pdf/3

 POLYCHLOROBIPHENYLS: METHOD 5503, Issue 2, dated 15 August 1994 - Page 3 of 5 CALIBRATION AND QUALITY CONTROL: 8.

9.

10.

Calibrate daily with at least six working standards over the range 10 to 500 ng/mL PCB. a. Add known amounts of stock standard solution to hexane in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (sum of areas of selected peaks vs. ng PCB per sample). Determine desorption efficiency (DE) at least once for each lot of glass fiber filters and Florisil used for sampling in the calibration range (step 8). Prepare three tubes at each of five levels plus three media blanks. a. Remove and discard back sorbent section of a media blank Florisil tube. b. Inject known amounts of stock standard solution directly onto front sorbent section and onto a media blank filter with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 5 through 7) and analyze together with working standards (steps 11 and 12). e. Prepare a graph of DE vs. µg PCB recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and DE graph are in control.

MEASUREMENT: 11.

12.

Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 5503-1. Inject sample aliquot manually using solvent flush technique or with autosampler. NOTE 1: Where individual identification of PCB is needed, a procedure using a capillary column may be used [12]. NOTE 2: If peak area is above the linear range of the working standards, dilute with hexane, reanalyze and apply the appropriate dilution factor in calculations. Sum the areas for five or more selected peaks.

CALCULATIONS: 13.

14.

Determine the mass, µg (corrected for DE) of PCB found on the glass fiber filter (W) and in the Florisil front (W f) and back (W b) sorbent sections, and in the average media blank filter (B) and front (B f) and back (B b) sorbent sections. NOTE: If W b > W f/10, report breakthrough and possible sample loss. Calculate concentration, C, of PCB in the air volume sampled, V (L):

EVALUATION OF METHOD: This method uses 13-mm glass fiber filters which have not been evaluated for collecting PCB. In Method S120, however, Aroclor 1242 was completely recovered from 37-mm glass fiber filters using 15 mL isooctane [8,13,14]. With 5 mL of hexane, Aroclor 1016 was also completely recovered from 100mg Florisil beds after one-day storage [1]. Thus, with no adsorption effect likely on glass fiber filters for PCB, 5 mL hexane should be adequate to completely extract PCB from combined filters and front sorbent sections. Sample stability on glass fiber filters has not been investigated. Breakthrough volume was >48 L for the Florisil tube at 75% RH in an atmosphere containing 10 mg/m 3 Aroclor 1016 [1].

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