National Institute for Occupational Safety and Health

“ Align the quartz cell in the optical path. Heat the quartz cell gradually to 800 °C using a variable transformer and thermocouple. Using a syringe, inject a sample aliquot ( ca. 2 to 3 mL) into the chromatograph, flushing the injection loop to avoid contamination from the previous injection. Rinse the syringe with deionized water and dry it between samples, or use disposable syringes. NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition, 8/15/94 ARSENIC, organo-: METHOD 5022, Issue 2, dated 15 August 1994 - Page 4 of 6 12. ”

“ If a signal is obtained at the approximate retention time of the latter two compounds, or if both compounds are known to be present in the sample, perform a second analysis using Eluent B (lower ionic strength) . If either of the two compounds is known not to be present, Eluent A will effectively determine the remaining compounds. With Eluent B the other species have very long retention times and will accumulate on the column, tying up active resin sites. Therefore, flush the column with Eluent A after each 10 to 15 samples and reequilibrate with Eluent B before further analysis. ”

“ Protect from light. d. Arsenic trioxide.* Dissolve 0.6602 g As 2O 3 in 5 mL 1 N NaOH. Dilute to 500 mL with deionized water. e. Arsenic pentoxide.* Dissolve 0.7669 g As 2O 5 in 5 mL 1 N NaOH. Dilute to 500 mL with deionized water. Calibration stock solution, 1 μg/mL mixed analyte. Dilute 0.1 mL of each stock standard (REAGENTS, 7.) with Eluent A in a 100-mL volumetric flask. Prepare fresh daily. ”