NICOTINE: METHOD 2544, Issue 2, dated 15 August 1994 - Page 3 of 4 9.
10.
Determine the Desorption Efficiency (DE) at least once for each batch of sorbent used for sampling in the calibration range (step 8). Prepare three tubes at each of five levels plus three media blanks. a. Remove and discard back sorbent section of the media blank sampler. b. Inject a known amount of calibration solution directly onto the front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight at ambient temperatures prior to analysis. d. Transfer to a sample vial and desorb (steps 5 through 7) and analyze together with the working standards (steps 11 through 13). e. Plot DE vs. mg of nicotine recovered. Analyze three quality control blind spikes and three analyst spikes to insure that the calibration graph and the DE graph are in control.
MEASUREMENT: 11. 12.
13.
Set the gas chromatograph to conditions given on page 2544-1. Follow manufacturer's directions for the air/fuel (H 2) mixture for the NPD. Inject a 2-µL sample aliquot, using the solvent-flush technique or with autosampler. Make duplicate injections of samples and standards. NOTE: If the peak area is above the linear range of working standards, dilute an aliquot of the sample solution with ethyl acetate, reanalyze and apply the appropriate dilution factor in calculations. Measure the peak area.
CALCULATIONS: 16.
17.
Determine the mass (mg) of nicotine (corrected for DE) 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 concentration of nicotine in the actual air volume V (L) at the sampling site:
EVALUATION OF METHOD: Method S293 [2] was issued 3/26/76. Synthetic atmospheres of the analyte in dry air were generated dynamically at 22.1 to 24.5 °C and 765.4 to 767.9 torr (102 to 102.4 kPa) over the range 0.3 to 1.2 mg/m 3. The analyte was metered into dry dilution air using a calibrated syringe pump; however, there was no independent measure of analyte concentration. Collected samples were stored five days prior to analysis. A 100-mg bed of the sorbent retained at least 0.2 mg of the analyte without breakthrough to the backup section, when 200 L of a challenge atmosphere containing 1.2 mg/m 3 of analyte in dry air was sampled at 1.1 L/min. There were no statistically significant differences at the 95% confidence level in the recoveries of samples that had been spiked with 0.03 to 0.13 mg of nicotine, and stored for 1 or 5-days prior to analysis. The method was originally validated using an alkali-flame ionization detector. Owing to the high variability in the response of this detector, it was necessary to use an internal standard - diphenylamine; this may not be necessary when using an NPD. The method has not been field tested.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
