Page:NIOSH Manual of Analytical Methods - 8305.pdf/2

 PHENOL and p-CRESOL in urine: METHOD 8305, Issue 2, dated 15 August 1994 - Page 2 of 4 EQUIPMENT:

REAGENTS: 1. Phenol calibration stock solution, 2 mg/mL. Accurately weigh 200 mg phenol* and dissolve in distilled water. Dilute to 100 mL. Stable 14 days at 25 °C. 2. p-Cresol calibration stock solution, 5 mg/mL. Accurately weigh 500 mg p-cresol* and dissolve in methanol.* Dilute to 100 mL. Stable 14 days at 25 °C. 3. Diethyl ether.* 4. HCl, concentrated, or perchloric acid, 70%.* 5. Sodium sulfate, granular, anhydrous. 6. Thymol, USP. 7. Internal standard, 0.6 mg/mL. Dissolve 30 mg nitrobenzene* in 50 mL methanol. 8. Methanol.* 9. Nitrogen, purified. 10. Hydrogen, purified. 11. Air, filtered. 12. Dry ice.

1. Bottles, polyethylene, screw-top, 125-mL. 2. Gas chromatograph with FID, integrator and column (page 8305-1). 3. Centrifuge tubes, 15-mL, graduated, glassstopper. 4. Syringe, 10-µL, readable to 0.1 µL. 5. Volumetric flasks, 100-mL. 6. Pipets, Pasteur. 7. Pipets, 1-, 2- and 5-mL. 8. Mixer, vibration. 9. Culture tubes, disposable, 10 x 75-mm. 10. Water bath, 95 °C. 11. Ice bath or freezer.

See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: Samples of urine 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 urine specimens should wear protective gloves, and avoid aerosolization of the samples. Mouth pipetting, of course, must be avoided. Diethyl ether and methanol are fire risks. Phenol, p-cresol, methanol and nitrobenzene are toxic and can be absorbed through the skin. Hydrochloric acid and perchloric acid can damage the skin. Wear gloves and eye protection. Work in a fume hood. Handle perchloric acid only in a perchloric acid hood.

SAMPLING: 1. Collect 50 to 100 mL urine in a 125-mL polyethylene bottle containing a few crystals of thymol. NOTE: Collect two urine samples for each worker, one prior to exposure and one after exposure. Also, collect and pool control urine samples from unexposed workers. 2. Close the bottle immediately after sample collection and swirl gently to mix. 3. Freeze the urine and ship in dry ice in an insulated container.

SAMPLE PREPARATION: 4. 5. 6. 7. 8. 9.

Thaw urine sample. Determine creatinine (g/L urine) in an aliquot of the urine [5]. Pipet 5.0 mL urine into a 15-mL centrifuge tube. Add 1 mL conc. HCl or 5 drops 70% perchloric acid. Mix well. Stopper loosely. Heat in a water bath at 95 °C for 1.5 h. Remove from water bath. Add 10 µL internal standard. Adjust volume in the centrifuge tube to 10 mL with distilled water. 10. Pipet 2 mL diethyl ether into the tube. Stopper and shake vigorously for 1 min. Cool the tube to 0 °C and allow the phases to separate. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94