An analytical method was developed for the determination of airborne concentrations of 2,4-dichlorophenoxyacetic-acid (94757). The method consisted of collection of the sample on a glass fiber filter, extraction with methanol, and analysis by high pressure liquid chromatography. Validation was performed by analysis of 18 spiked samples containing 50, 100, and 200 percent of the OSHA standard of 10 milligrams per cubic meter (mg/m3), and 18 samples from dynamically generated test atmospheres. The collection efficiency of the glass fiber filter, storage stability of the samples, and precision and accuracy of the method were assessed. The range of concentration was 5.1 to 20.3mg/m3. Collection efficiency of the filter was 0.99. Samples collected and analyzed immediately and after 7 days of storage contained a mean of 10.10 and 10.02mg/m3, respectively. The total coefficient of variation was 0.051. The authors conclude that the advantages of the method are that the collection is simple and involves no liquids, and analysis quick. The precision of the method is limited by the reproducibility of the pressure drop across the filter. Esters of the chemical are not measured.
Ten NIOSH Analytical Methods, Set 6, Division of Physical Sciences and Engineering, NIOSH, Cincinnati, Ohio, NTIS PB288-629, 22 pages, 8 references