Page:NIOSH Manual of Analytical Methods - 7600.pdf/4

 CHROMIUM, HEXAVALENT: METHOD 7600, Issue 2, dated 15 August 1994 - Page 4 of 4 NOTE 2:

If the absorbance values for the samples are higher than the standards, dilute using 0.5 N H2SO 4, repeat this step, and multiply the resulting absorbance by the appropriate dilution factor.

CALCULATIONS: 12. 13.

From the calibration graph, determine the mass of Cr(VI) in each sample, W (µg), and in the average blank, B (µg). Calculate the concentration, C (mg/m 3), of Cr(VI) in the air volume sampled, V (L):

EVALUATION OF METHOD: P&CAM 169 and S317 are essentially the same method and are suitable for soluble chromate and chromic acid. Method S317 was validated with generated samples of chromic acid mist [2,6], and P&CAM 169 was tested with field samples [1,7]. P&CAM 319 was developed because a method was needed to analyze for insoluble chromates [3]. This method was tested with insoluble chromates in matrices such as paints, primer and ceramic powders [3]. Precision, analytical range, recovery data, etc., for the three methods pooled are as follows: Total SˆrT: Measurement Sr [1-3]: Range [3]: Collection Efficiency [5]: Sampling Rate [1,3]: Stability (two weeks) [1]: Acceptable Filters [3]:

0.084 0.02 to 0.04 0.5 to 10 µg/m 3 94.5% 1.5 to 2.5 L/min 96% recovery FWSB (MSA); VM-1 (Gelman).

REFERENCES: [1] NIOSH Manual of Analytical Methods, 2nd. ed., V. 1, P&CAM 169, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-A (1977). [2] Ibid, V. 3, S317, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-C (1977). [3] Ibid, V. 6, P&CAM 319, U.S. Department of Health and Human Services, Publ. (NIOSH) 80-125 (1980). [4] NIOSH (1975) Criteria for a Recommended Standard: Occupational Exposure to Chromium (VI). Cincinnati, OH: U.S. Department of Health, Education, and Welfare, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 76-129. [5] NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards. Occupational Health Guidelines for Chromic Acid and Chromates. U.S. Department of Health and Human Services (NIOSH) Publication No. 81-123 (1981). [6] Documentation of the NIOSH Validation Tests, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-185 (1977). [7] Abell, M. T. and J. R. Carlberg. A Simple Reliable Method for the Determination of Airborne Hexavalent Chromium, Am. Ind. Hyg. Assoc. J., 35, 229 (1974).

METHOD REVISED BY: Martin T. Abell, NIOSH/DPSE; Method S317 validated under NIOSH Contract CDC-99-74-45.

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