Purge and trap analysis

This is an alternative technique to headspace analysis for the identification and determination of volatile organic compounds in polymers. The sample is swept with an inert gas for a fixed period of time. Volatile compounds from the sample are collected on a solid sorbent trap - usually activated carbon. The trap is then rapidly heated and the compounds collected and transferred as a plug under a reversed flow of inert gas to an external GC. Chromatographic techniques are then used to quantify and identify sample components. 

OIC Analytical Instrument (Appendix 1) supplies the 4460 A purge and trap concentrator. This is a microprocessor-based instrument with capillary column capahility. It is supplied with an autosampler capable of handling 76 sample vials. Two automatic rinses of sample lines and vessel purge are carried out between sample analyses to minimise carry-over. 

CDS Analytical also supplies a microprocessor-controlled purge and trap concentrator which features cryogenic trapping and cryogenic refocusing and thermal desorption to a trap or directly to a GC. 

E Halmo, S. Surova, M. Balakova and A. Halmova in Proceedings of Technical Rubber Goods Part of our Everyday Life, Puchov, Slovakia, 1996, p.233. 

Perkins and G.E. Kanahan, Identification of Volatile Residues in Polymers by Headspace Gas Chromatography - Mass Spectroscopy, Hewlett Packard Gas Chromatography Application Brief, 1986. 

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Washall JW, Wampler TP. 1988. Purge and trap analysis of aqueous samples with cryofocusing. American Laboratory (July) 70-74. 

Corwen [140] used dynamic purge and trap analysis to determine ketones and aldehydes (acetone, butyaldehyde, and 2-butanone) in seawater. 

Tekmar are another supplier of purge and trap analysis equipment. Their LSC 2000 purge and trap concentrator features glass-lined stainless steel tubing, a menu-driven programming with four-method storage and a cyrofocusing accessory. 

For more volatile compounds in soils, such as aromatic hydrocarbons, alcohols, aldehydes, ketones, chloroaliphatic hydrocarbons, haloaromatic hydrocarbons, acetonitrile, acrylonitrile and mixtures of organic compounds a combination of gas chromatography with purge and trap analysis is extremely useful. Pyrolysis gas chromatography has also found several applications, heteroaromatic hydrocarbons, polyaromatic hydrocarbons, polymers and haloaromatic compounds and this technique has been coupled with mass spectrometry, (aliphatic and aromatic hydrocarbons and mixtures of organic compounds). 

Sinex et al. [71] have described a method for the determination of methyltin compounds based on reaction with sodium borohydride to form tin hydrides then purge and trap analysis followed by gas chromatography with mass spectrometric detection. Down to 3-5pg absolute (as tin) of methyltin compounds equivalent to the sub pg kg 1 range can be determined by this procedure. 

River sediment MeSn Purge and trap analysis 3-5 pg [89] ... 

Headspace analysis (EPA 3810, 5021) also works well for analyzing volatile petroleum constituents in soil. In the test method, the soil is placed in a headspace vial and heated to drive out the volatiles from the sample into the headspace of the sample container. Salts can be added for more efficient release of the volatile compounds into the headspace. Similar to water headspace analysis, the soil headspace technique is useful when heavy oils and high analyte concentrations are present, which can severely contaminate purge-and-trap instrumentation. Detection limits are generally higher for headspace analysis than for purge-and-trap analysis. 

One method (EPA 8020) that is suitable for volatile aromatic compounds is often referred to as benzene-toluene-ethylbenzene-xylene analysis, although the method includes other volatile aromatics. The method is similar to most volatile organic gas chromatographic methods. Sample preparation and introduction is typically by purge-and-trap analysis (EPA 5030). Some oxygenates, such as methyl-f-butyl ether (MTBE), are also detected by a photoionization detector, as well as olefins, branched alkanes, and cycloalkanes. 

Dreisch FA, Munson TO. 1983. Purge-and-trap analysis using fused silica capillary column GC/MS. J Chromatogr Sci 21 111-118. 

Page DB, Lacroix GM. 1995. On-line distillation/purge and trap analysis of halogenated, nonpolar, volatile contaminants in foods. J AOAC Int 78(6) 1416-1428. 

Headspace analysis, purge and trap analysis and gas chromatography coupled to mass spectrometry have all been employed in determinations of gasoline hydrocarbons in soil, yielding detection limits as low as 5 xg/g [24,25]. 

Characteristic Masses for Identification of Additional Organic Pollutants (Not Listed in the Text) by GC/MS Volatility of Some Additional Organic Substances (Not Listed in Text) for Purge and Trap Analysis Analysis of Elements by Atomic Spectroscopy ... 

Volatility of Some Additional Organic Substances (Not Listed in Text) for Purge and Trap Analysis... 

Two g soil was treated with 10 mL methanol. A lOO-pL aliquot of methanol extract was injected into 5 mL reagent grade water for purge and trap analysis of a volatile organic compound. The concentration of the compound was found to be 22 mg/L. Determine its concentration in the soil. 

APPENDIX F VOLATILITY OF SOME ADDITIONAL ORGANIC SUBSTANCES (NOT LISTED IN TEXT) FOR PURGE AND TRAP ANALYSIS... 

Purge and trap analysis of water and low level soil samples Equation 7 or 11, Appendix 22... 

Organosulphur compounds Purge and trap analysis GC- microwave induced atomic emission spectrometry ppt [348]... 

Chlorinated solvents Combination of purge and trap analysis with GC-MS... 

For purge-and-trap analysis, a portion of the extrudate was ground and 15 g were placed in a two-necked sample flask with 30 g of NaCl and 100 ml of distilled water. Headspace components were collected on activated Tenax TA by purging nitrogen gas through the sample suspension at a flow rate of 400 mL/min for 2 hours. 

Purge and Trap Analysis Using a Photoionization Detector Removal of Water Interference" Application Note B042281 Tekmar Company, Cincinnati, OH. 

The earliest traps specified in EPA s purge and trap methods contained equal amounts of Tenax, silica gel and coconut-based charcoal. Tenax absorbs compounds that are liquid, and silica gel substances that are gaseous, at room temperature. Charcoal is used to trap dichlorodifluoromethane (Freon 12), the boiling point of which is — 29°C. The superior adsorption and desorption efficiencies of these adsorbents for purge and trap analysis are supported through their continuous use today however, some alternative adsorbents have lately become popular for specific applications [47]. 

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