Validation of alpha-Methyl Styrene using SKC Passive Sampler 575-003

A sampling method for alpha-methyl styrene in air has been validated for concentration levels from 0.5 to 100 ppm and for exposure times from 1 through 8 hours. The 575-003 passive sampler used contains a sample medium of Anasorb 727. Desorption was with carbon disulfide and analysis by gas chromatography with flame ionization detection (GC-FID). The analytical recovery over the range of 0.5 to 100 ppm (13 to 2725 μg) was 101%. The sampling rate is 12.6 ml/min. Samples can be taken from 10° C to 40° C. Minimum recommended sampling time is 15 minutes. Maximum recommended sampling time is 8 hours. Samples were stable for up to 14 days when stored at room temperature or in a refrigerator (4° C). A full validation of styrene was done according to NIOSH Protocol and a partial NIOSH validation by the bi-level procedure was conducted for alpha-methyl styrene and other higher members of this homologous series. Two samples were validated simultaneously. The 575-002 sampler (containing Anasorb 747) has greater capacity, and can be used where more volatile compounds (e.g., acetone) are present. The 575-003 sampler has the better recovery and is, therefore, more useful at low concentrations or for measuring STELs. The 575-003 sampler should not be used to sample compounds with boiling points below that of styrene. Authors Daniel L. Fiorito Martin Harper Lloyd V. Guild Compiled by Martin Harper SKC Inc. 863 Valley View Road Eighty Four, PA 15330 USA 2 Publication No. 1373 Rev 0509 alpha-Methyl Styrene (575-003) Importance of Passive Sampler Validation There are distinct differences between a passive sampler and a sample tube. The most important difference is that a passive sampler does not have a foolproof back up section that guarantees that all of the chemical hazard has been collected and that there is a true and total measure of worker exposure. Secondly, the sorbent medium is exposed to the external environment and this poses problems not associated with a sample tube where the air sample passes into the sample tube directly contacting the sorbent medium. That is why it is critical to use a strong sorbent medium in passive samplers to assure complete capture and retention. Therefore, for compliance purposes a passive sampler must be laboratory tested and validated under worst case field conditions for all factors that affect sampling accuracy as well as interaction between affects. NIOSH has laid out a rigorous and complete validation protocol to assure that the sample collected is a complete and true measure of worker exposure. The following are the factors that the NIOSH protocol addresses: Factors That Affect Complete Sample Uptake & Retention Chemical hazard concentration Temperature Time of exposure Humidity Sorbent capacity Interfering chemicals Sorbent strength Reverse diffusion from sorbent surface Wind velocity Sampler orientation Interaction of any of the above factors Validation by NIOSH protocol assures that the sample results are a true and total measure of worker exposure. SKC validation follows the NIOSH Validation Protocol. Certain experiments may have been modified for practical reasons, or to provide more rigorous tests.