National Institute for Occupational Safety and Health

“ CALIBRATION AND QUALITY CONTROL: 8. Calibrate daily with at least six working standards to cover the analytical range of the method. If necessary, additional standards may be added to extend the calibration curve. a. Add known amounts of calibration stock to methanol 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 (peak area vs μg analyte) . 9. Determine desorption efficiency (DE) at least once for each lot of silica gel used for sampling in the calibration ranges (step 8) . ”

“ Avoid inhalation. Nitrobenzene and m-nitrotoluene are absorbed through contact with skin and can cause methemoglobinemia [5,6] . 4-Chloronitrobenzene is a carcinogen. Methanol is highly flammable.
SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. 3. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for nitrotoluene isomers. Use a flow rate of 1 L/min or less for nitrobenzene and 4-chloronitrobenzene. ”

“ During sampling, high humidity may greatly decrease breakthrough volume. OTHER METHODS:This method is an update of NMAM 2005, Nitrobenzenes, issued 15 August 1994, which combined and replaced methods S217, S218, and S223 [2,3] .
NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition NITROAROMATIC COMPOUNDS: METHOD 2005, Issue 3, dated 15 January 1998 - Page 2 of 5 EQUIPMENT:
REAGENTS:
1. Sampler: glass tube, 7 cm long, 6-mm OD, Methanol, HPLC chromatographic grade. 4-mm ID, flame-sealed ends with plastic Nitrobenzene*, reagent grade. ”