National Institute for Occupational Safety and Health

Name: NIOSH Manual of Analytical Methods — Chromium, Hexavalent, by Field-Portable Spectrophotometry (7703)
Author: National Institute for Occupational Safety and Health

NIOSH Manual of Analytical Methods… (1994)

Summary

“NIOSH Manual of Analytical Methods — Chromium, Hexavalent, by Field-Portable Spectrophotometry (7703)”, published in 1994, is a work by National Institute for Occupational Safety and Health. It explores elements such as filter, mL and elution.

Quotes from NIOSH Manual of Analytical Methods… (National Institute for Occupational Safety and Health)

National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)

“ Reduction of Cr [VI] can occur over time on any filter type, and is especially problematic on MCE filters [7] . However, the use of MCE and PTFE filters has been found to be acceptable for field use, where performance has been found to be equivalent to that of PVC filters [3] . During ultrasonic extraction, oxidation of Cr [III] in solution to Cr [VI] is prevented by the use of an ammonium buffer [8] . OTHER METHODS: This method is designed to be used in the field, but can also be utilized in the fixed-site laboratory. ”

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Source: Wikisource

National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)

“ Condition the cuvette by filling with the solution to be analyzed, and discard the solution. b. Refill the cuvette with the sample solution to be analyzed. c. Place the cuvette in the spectroph otom eter. NOTE: W ipe any extra moisture or liquid off the sides of the cuvette with a dry laboratory wipe, and take care to handle the cuvette only by the frosted sides. 20. Analyze samples, standards, and blanks. Record the absorbance. NOTE: If the absorbance value is greater than 2 absorbance units, dilute the solution to be analyzed with elution solution (strong buffer) and reanalyze. ”

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Source: Wikisource

National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)

“ SAMPLE PREPARATION: 5. Add 10 mL of extraction solution (weak buffer) to each 15-mL centrifuge tube containing the filter sample. Ensure that the filter is covered by the extraction solution. If necessary, push the filter down with a clean glass or plastic rod to imm erse the entire filter. Cap and label the tubes. 6. Place sample tubes in the ultrasonic bath (sonicator) . The water level in the bath should be higher than the liquid level in the centrifuge tube. ”

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Source: Wikisource

National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)

“ Set up the solid phase extraction manifold. a. Pla ce disposable solid phase extractio n (S PE ) cartridges in each port, and place scintillation vials beneath the cartridges. Label the cartridges. b. Attach the vacuum pum p to the SPE m anifold. c. To condition SPE cartridges, pipet 3 mL of methanol into each cartridge, and evacuate. Then pipet 3 m L of e xtrac tion so lution into eac h ca rtridge, and evacua te. Re pea t. 8. Extract Cr [VI] from sam ple solution. a. Pipet 3 to 5 mL of each ultrasonicated sample solution from the centrifuge tubes into the disposa ble SPE cartridge. ”

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Source: Wikisource

National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)

“ Centrifuge tubes, plastic, 15-mL, with screw caps. 11. Scintillation vials, 20-mL, glass, with PTFE-lined screw caps. 12. Assorted beakers (and possibly Erlenmeyer flasks) , various volumes. 13. Volumetric flasks, 25-, 100-, 250-, and 1000-mL. 14. Forceps, PTFE-coated. 15. Glass or plastic rods. 16. Disposable gloves, plastic or latex. 17. Laboratory wipes. 18. Portable power ge nerator (if necessary) . NOTE: If no power supply is available at the field site, electric power can be provided by means of a portable, gasoline (or othe r) genera tor. ”

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Source: Wikisource

National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)

“ Extraction solution (extraction buffer) : 0.05 M (NH 4) 2SO 4 / 0.05 M NH4OH, 1 L, aqueous in distilled or deionized water. NOTE: Modification of method by using carbonate buffer (e.g., sodium carbonate) is required for extraction of insoluble Cr [VI] . 9. Elution solution (elution buffer) : 0.5 M (NH 4) 2SO 4 / 0.1 M NH 4OH, 250 m L, in distilled or deionized water. 10. Cr (VI) stand ard (as p otas sium chro m ate) ,* 1000 μg/mL. 11. Ca libration s tock solution, 100 μg /m L: Dilute 100 0 μg /m L Cr (VI) s tand ard 1 :10 w ith extraction buffer. (Solution is stable for a m onth .) 12. ”

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Source: Wikisource

National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods… (1994)

“ Also analyze at least three of the calibration solutions in triplicate. 14. Prepare a calibration graph of absorbance vs, Cr [VI] concentration. NO TE : As a n altern ative to steps 12 to 14, the stand ard a ddition app roac h ca n be use d [11] . ”

National Institute for Occupational Safety and Health

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Quotes from NIOSH Manual of Analytical Methods… (National Institute for Occupational Safety and Health)

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