(1) BENZIDINE and (2) 3,3'-DICHLOROBENZIDINE: METHOD 5509, Issue 2, dated 15 August 1994 - Page 3 of 4
11.
d. Prepare (steps 5 through 8) and analyze (steps 12 through 14) with working standards. e. Prepare a graph of R for each filter vs. µg analyte recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration and R graphs are in control.
MEASUREMENT: 12.
13. 14.
Set the liquid chromatograph to conditions given on page 5509-1 for analyte of interest. NOTE 1: If aniline is present, use a Waters Radial Pak A (C 18) column, or equivalent, and follow the procedures found in reference [2]. NOTE 2: The following compounds were found not to interfere with the determination of either compound: o-, p- and m-chloroaniline; 4,4'-methylenedianiline and ß-naphthylamine. 2-Chloro-4-methylaniline; 3,3'-dichlorobenzidine; 4,4'-methylenebis(2-chloroaniline); hydrazobenzene; and 1,2- and 1,4-naphthoquinone do not interfere in the determination of benzidine. Benzidine, aniline, N-methylaniline, 2-toluidine and 3,3'-dimethylbenzidine will not interfere in the determination of 3,3'-dichlorobenzidine [1]. Inject an aliquot (see page 5509-1 for appropriate size). Measure peak area.
CALCULATIONS: 15. 16.
Read the mass, µg (corrected for R), of analyte found on the sample filter (W) and on the media blank filter (B) from the calibration graph. Calculate concentration, C, of analyte in the air volume sampled, V (L):
EVALUATION OF METHOD: This method was evaluated over the range 21 to 63 µg/m 3 for benzidine and the range 20 to 130 µg/m 3 for 3,3'-dichlorobenzidine. The generated atmospheres for both compounds were at 30 °C and 80% relative humidity. The sampling rate was 0.8 L/min. The pooled overall precision ( SˆrT) was 0.07 for 29 benzidine samples and 0.07 for 28 3,3'-dichlorobenzidine samples. The sampling methods were evaluated for effects of temperature (25, 30, and 35 °C) and relative humidity (20 and 80%). No detectable quantities of either benzidine or 3,3'-dichlorobenzidine were found on backup silica gel tubes [1]. At 180 °C, vapors of these carried by a stream of dry nitrogen at 0.3 L/min did not break through the backup silica gel in 3 h [1]. The average recovery of benzidine from filters was determined to be 97% over the range 0.2 to 2.0 µg when stored at -15 °C for 11 days. Recoveries dropped to 89% and 75% after 15 days and 21 days, respectively. Recoveries of benzidine and benzidinium sulfate from filters and silica gel indicated that the compounds were unstable in these matrices at ambient temperature. Recoveries over the range of 0.5 to 5 µg 3,3'-dichlorobenzidine and its dihydrochloride were 96% after 21 days from both filters silica gel and stored at -15 °C and at ambient temperature [1].
REFERENCES: [1]
Morales, R., S. M. Rappaport, R. W. Weeks, Jr., E. E. Campbell, and H. J. Ettinger. Development of Sampling and Analytical Methods for Carcinogens, January 1 - September 30, 1976, Los Alamos Scientific Laboratory, Los Alamos, NM (1977) available as NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
