Purge and trap sampling

For example, if gasoline is suspected to be the sole contaminant, the method will use purge-and-trap sample introduction. If higher-boiling petroleum fractions (diesel, middle distillates, motor oil) are the contaminants, the analysis will use direct injection and hotter oven temperatures. Mixtures or unknown contamination may require both volatile range and extractable range analyses. Alternatively, a single injection can be used to analyze the entire sample, but the extraction method must not use a solvent evaporation step. 

Why is splitless injection used with purge and trap sample preparation ... 

Aqueous samples extracted by purge and trap sample purged with helium or nitrogen analyte thermally desorbed out of the trap and swept onto a GC column for separation detected by HECD, ECD, PID or a mass spectrometer. 

All fuel methods analyze GRO with a purge and trap sample introduction technique, whereas semi volatile diesel fuel and heavy, non-volatile motor oil (DRO and RRO) are first extracted from soil or water samples, and the extracts are injected into the analytical instrument. This distinction in sample preparation gave rise to the terms of total purgeable petroleum hydrocarbons (TPPH) or total volatile petroleum hydrocarbons (TVPH) and total extractable petroleum hydrocarbons (TEPH). A group of petroleum fuels with the carbon range of C7 to Cig may be analyzed with either technique. Common petroleum fuels and other petroleum products fall into these three categories as shown in Table 2.3. 

Another configuration of MAP gas-phase extraction relates to dynamic headspace sampling, often referred to as purge and trap sampling. The container can be fitted with an aperture enclosing a trap, or a sorbent, cooled by some common means. This allows the application of a prolonged, low-power irradiation, or of a multi-pulse irradiation of the sample, thus providing a means to extract all of the volatile analytes from the matrix. The contents of the trap can then be transferred (by elution for a chemical or sorbent trap, or by thermal desorption for a cold trap) to an analytical instrument, such as a... 

Jackson, J.-A.A., W.R. Blair, F.E. Brinckman, and W.P. Iverson. 1982. Gas-chromatographic speciation of methylstannanes in the Chesapeake Bay using purge and trap sampling with a tin-selective detector. Environ. Sci. Technol. 16 110-119. 

Water, soil, and solid waste Purge-and-trap sample thermally desorb GC/MS low ppb level (water, solid waste) low ppm level (soil) NR... 

Split injection, splitless injection, SPME, headspace SPME, gas valve injection, tenax trapping with thermal desorption, purge and trap sampling... 

VOC analysis by headspace sampling technique Purge-and-trap sampling technique... 

Purge-and-Trap Sampling Purge and trap sampling is a family of methods that are used to capture the headspace above a condensed phase for subsequent analysis, most often for complex mixtures, environmental samples, etc. The headspace is the vapor space that develops above any condensed (solid or liquid) phase. Thermodynamics assures us that the concentration of a particular analyte found in the headspace will be different than that found in the condensed phase, but often the relationship is predictable. The value in the method comes from the simplicity sample preparation is usually far simpler than the cleanup that is typically required for many complex mixtures. Purge and trap methods fall into two general categories ... 

The following table provides fluids (in some cases mixtures) that can be used to chill trapping sorbents (or any cold trap) for the purge and trap sampling of solutes (Refs. 1-4). In each case the ratio is mass/mass. Practical use of these methods can require optimization and proper insulation. 

Analytical (2010) Proper Trap Selection for the OI Analytical Model 4560 and 4660 Purge-and-Trap Sample Concentrators. Application Note 12861111, OI Analytical, College Station, TX. 

Purge-and-trap sampling, dynamic headspace procedure, a concentration technique for volatile solutes. The sample is purged with an inert gas that entrains volatile components onto an adsorptive trap. The trap is then heated to desorb trapped components into a GC column. 

Pelusio et al. (2) studied volatiles, including organic sulfur compounds, in black and white truffles, comparing results with SPME extraction to a purge-and-trap sample preparation technique using Tenax as the adsorbent. 

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