Page:NIOSH Manual of Analytical Methods - 2514.pdf/3

 ANISIDINE: METHOD 2514, Issue 2, dated 15 August 1994 - Page 3 of 4 a. b.

10.

Remove and discard the back sorbent section of a media blank sampler. Inject a known amount (e.g., 1 to 20 µL) of calibration stock solution, or a dilution thereof in methanol, directly onto the front section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 5 through 7) and analyze with working standards (steps 11 and 12). e. Prepare graphs of DE vs. µg isomer recovered. Analyze three quality control blind spikes and three analyst spikes with each subsequent set from the same lot to ensure that the calibration graph and DE graph are in control.

MEASUREMENT: 11.

12.

Set HPLC to conditions given on page 2514-1. Inject sample aliquot. NOTE: Sensitivity is ca. 0.083 absorbance unit/mg of either isomer in a 10-mL injection volume with a 1-cm flow cell. Approximate retention times are 7.5 min for p-anisidine and 12 min for o-anisidine. Measure peak area.

CALCULATIONS: 13.

14.

Determine the quantities (sum of quantities of the o- and the p-isomers corrected for DE), mg of analytes found in the sample front (W f) and back (W b) sorbent sections, and in the average media blank front (B f) and back (B b) sorbent sections. NOTE: If W b > W f/10, report breakthrough and possible sample loss. Calculate the sum of the concentrations, C, of the isomers in the air volume sampled, V (L):

EVALUATION OF METHOD: Method S163 was issued on February 16, 1979 [2], and was validated over the range 0.13 to 0.58 mg/m 3 for the o-isomer and 0.12 to 0.58 mg/m 3 for the p-isomer using 225-L air samples [1,5]. The generation system was constructed so that samples were generated for both isomers at the same time. Concentrations were verified by an independent method using bubblers containing methanol and HPLC analysis [1]. The overall precision, SˆrT, for the combined sampling and measurement of both isomers was 0.068 with an average recovery of 100.7% for the o-isomer and 99.7% for the p-isomer [1], which represent non-significant biases for the isomers. A separate breakthrough test was conducted for each isomer with XAD-2. Samples were taken at ca. 1.0 L/min. o-Anisidine was generated at 1.03 mg/m 3 with a relative humidity of 81% at 21 °C. Breakthrough (3%) from 150 mg XAD-2 occurred after 236 min, but did not increase above this amount up to 479 min. p-Anisidine was generated at 1.04 mg/m 3 with a relative humidity of 82% at 20 °C. Breakthrough did not occur during the 361-min test. Samples containing both isomers were stored for one week at room temperature and found to be stable. Desorption efficiencies averaged 0.95 and 0.91 for o- and p-anisidine, respectively, in the range 30 to 240 µg per sample.

REFERENCES: [1] [2] [3]

NIOSH Backup Data Report S163 (unpublished, February, 1979). NIOSH Manual of Analytical Methods, 2nd ed., Vol. 5, S163, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 79-141 (1979). Ibid., Vol. 1, P&CAM 168, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-A (1977). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94