Worldwide Solutions - February 2008 - (Page 11) GERSTEL Solutions Worldwide Application f you were to ask people in a shopping for this article. The EPA methodology was mall what the acronym PAH stands for, followed and the work was performed by a most might be forgiven for thinking it was reputable German contract laboratory. The lab had previously relied on HPLC some political movement. Far from it! As any chemist knows, PAH is the acronym with fluorescence detection. This approach for polycyclic aromatic hydrocarbon. As it often required large amounts of solvent. were, many political movements would love Clean-up steps for the sample extracts had to get the level of exposure and press cov- mainly been performed manually based erage that PAH has. No environmental lab- on solid phase extraction (SPE). Followoratory in the world can safely disregard ing sample clean-up, eluates were evaporated and the concentrate was taken up in PAH analysis. Around 100 different compounds are an HPLC-compatible solvent. In summaconsidered to be PAHs. The distinguishing ry, the original method was based on sevfeature of a PAH is the presence of at least eral labor intensive manual steps. The user had a strong wish to simtwo aromatic rings. Most attention, however, is focused on those PAHs that have four plify the procedure and to save time and money in the process. Oliver Lerch, Ph.D., to seven rings. The US Environmental Protection GERSTEL application scientist was responAgency (EPA) lists 16 PAH compounds sible for the project: “The request we received from the contract laboratoas particularly dangerous. EPA ry was to determine whether the Method 610, increasingly seen GERSTEL SPE system coupled with as the standard world-wide Large Volume Injection (LVI) and method, contains the following GC/MS could deliver equal or betleast wanted list: Naphthalene, ter quality of results compared with Acenaphthylene, Acenaphthene, the original procedure.” Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, The detection limit target was Benzo[a]pyrene, Benzo[a]anset at 0.01 µg/mL for each of the 16 thracene, Chrysene, Benzo[b] PAH compounds contained in the fluoranthene, Benzo[k]fluo- Oliver Lerch, Ph.D., standard EPA test mix. The pre-GC/ ranthene, Dibenz[a,h]anthra- GERSTEL application MS part was divided into two aucene, Benzo[g,h,i]perylene and scientist tomated parts: Sample preparation Indeno[1,2,3-c,d]pyrene. and sample introduction. Sample PAHs are of major concern, preparation: The roofing and tar exnone more so than Benzo[a]pyrene, due to tracts were diluted 20:1 or 100:1 with a 50:50 its endocrine disrupting, mutagenic and mixture of dichloromethane and hexane. highly carcinogenic properties. Once in- Clean-up of the diluted extracts was perside the human body, PAHs accumulate in formed using automated SPE. The method fatty tissue. Adsorbed onto soot and oth- was calibrated over the concentration er fine particulate matter, PAHs can pen- range from 0.5 to 1000 ng/mL. A soluetrate deep into the lungs. PAHs are not tion of d10-phenanthrene in methajust harmful, but persistent and ubiqui- nol was used as internal standard, 4 tous as well: Even in the permanent ice cap µL were added per 1 mL sample or of the Antarctica, anthropogenic PAHs are calibration standard. found. 100 µL of the cleaned extract was introduced to the GERSTEL Mineral Oil – a Blessing Cooled Injection System (CIS) and a Curse in the GC. The injection speed PAHs are found in coal, crude oil, and al- was almost equal to the evaporaso in varying amounts, in products that are tion speed of the solvent, which derived from these raw materials. Examples means the solvent was evaporatare tar and asphalt as well as gasoline and ed almost completely during the diesel fuel. PAHs are added to some poly- injection step. The solvent vapors mer based products as well (see box); this were vented from the system through the CIS split vent. is more often the case for prodThe analytes were retained ucts that are dyed black, but they can be added for a variin the CIS liner by keepety of reasons to get the proper product properties. PAHs also are formed during incomplete combustion of diesel, gasoline, heating oil, wood or tobacco. Combustion residues can therefore contain PAHs. Construction materials such as roofing and tar can contain large amounts of PAHs, these are the types of samples that were analyzed I High PAH concentrations in consumer products Even though PAHs are feared due to their toxicity, soot containing PAHs is routinely used as additive in lesser polymers thanks to its positive effect on product properties and product quality. In one recent case, a consumer watchdog in Germany found almost 1000 milligrams PAH per kilogram material in tubing used for bicycle pumps. The highly toxic Benzo[a]pyrene was present in the rubbery black tubing at a level of 51 milligrams per kilogram. The webpage of the organization reported that the toxic compounds could be transferred to the body of the user by simply touching the product. A previous example centered on high PAH levels in tool handles such as hammers, which are held firmly against the skin for extended periods of time during normal use. Such products provide ample opportunity for transfer of the highly toxic compounds to the body of the user. PAHs are found in coal, crude oil, and also, in varying amounts, in products that are derived from these raw materials. GERSTEL Solutions Worldwide – February 2008 11
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