Page:NIOSH Manual of Analytical Methods - 8004.pdf/2

 APPLICABILITY: Since PCBs are rapidly absorbed from the lung, GI tract, and skin, this procedure is useful for estimating acute and chronic exposures to PCB, assuming (a) no metabolism of PCB, (b) all isomers of PCB are extracted with equal efficie ncy, and (c) similar ECD response for all PCBs. PCBs have high biological and chemical stability. They accumulate in adipose tissue and may present a serious latent health threat. Metabolism involves hydroxylation and conjugation with glucose and sulfa tes.

INTERFERENCES:Chlorinated hydrocarbons, phthalate based plasticizers, dibenzofurans, and chlorinated naphthalenes interfere.

OTHER METHODS: This replaces P&CAM 329 [1]. Other methods include a screening method for Aroclor 1254 in whole blood [2].

REAGENTS:

EQUIPMENT:

1. Methanol, hexane, ethyl ether, and acetone (pesticide grade). 2. Potassium hydroxide, KOH. 3. Calibration stock solutions, 0.1 mg/mL.* Dissolve 10 mg of the bulk sample or other suitable standard, e.g., Aroclor 1016, 1221, 1232, 1242, 1248, 1254, and 1260 in 100 mL n-hexane (standards available from EPA). 4. Silica gel, activity grade I. a. Heat to 130 °C for 24 h. b. Cool and add 3 g water per 100 g silica gel. Mix for 2 h in a sealed container. 5. Sodium sulfate (anhydrous). 6. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) solution, 50 ng/mL, in hexane. 7. Methanol KOH, 2% (w/v). Dissolve 2 g KOH in methanol to make 100 mL solution. 8. Methanol-water, 1:1 (v/v). 9. Hexane-ethyl ether, 1:1 (v/v). 10. Nitrogen, compressed, filtered.



See SPECIAL PRECAUTIONS.

1. Gas-liquid chromatograph equipped with an electron capture detector. 2. Syringes, glass, 30-mL.** 3. Culture tubes, 16- x 150-mm, organic-free, with PTFE-lined screw caps.** 4. Rotary mixer, variable speed. 5. Centrifuge. 6. Kuderna-Danish concentrator tubes, 25-mL.** 7. Micro-Synder Columns.** 8. Tube heater. 9. Chromatography column, 7-mm ID x 200 mm, with 50-mL reservoir and PTFE stopcock.** a. Put a small plug of glass wool in the bottom of the column. b. Pour a suspension of 3 g silica gel in 50 mL hexane into the column. c. Let the suspension settle and add 5 to 7 g sodium sulfate. 10. Syringes, 10-µL, glass. 11. Graduated cylinder, 25-mL.** 12. Pipet, Pasteur.

Clean all glassware, including that used in sampling as follows: Wash in detergent. Rinse with tap water. Soak in chromic acid. Rinse with, in order, tap water, distilled water, acetone and hexane.

SPECIAL PRECAUTIONS: Samples of blood collected from humans pose a real health risk to laboratory workers who collect and handle these samples. These risks are primarily due to personal contact with infective biological samples and can have serious health consequences, such as infectious hepatitis, and other diseases. There is also some risk from the chemical content of these samples, but this is much less. Those who handle blood specimens should wear protective gloves, and avoid aerosolization of the samples. Mouth pipetting, of course, must be avoided. PCBs have potential carcinogenicity in humans. They are microsomal enzyme inducers and liver toxins; therefore, use extreme caution when handling these substances [3].

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