Static head-space

Piet, G.J., Luijten, W.C.M.M. van Noort, P.C.M. (1985b) Static head-space determination of volatile organic halogen compounds in water. In Fishbein, L. O Neill, I.K., eds. Environmental Carcinogens. Selected Methods of Analysis, Vol. l.Some Volatile Halogenated Hydrocarbons (lARC Scientific Publications No. 68), Lyon, lARC, pp. 321-330... 

For the analysis of trace quantities of analytes, or where an exhaustive extraction of the analytes is required, purge and trap, or dynamic headspace extraction, is preferred over static headspace extraction. Like static head-space sampling, purge and trap relies on the volatility of the analytes to achieve extraction from the matrix. However, the volatile analytes do not equilibrate between the gas phase and matrix. Instead, they are removed from the sample continuously by a flowing gas. This provides a concentration gradient, which aids in the exhaustive extraction of the analytes. 

Fenton, Z. Determination of residual solvent in pharmaceutical preparations by static head-space GC. J. High Resol. Chromatogr. 15, 329-331 (1992)... 

Headspace sampling is usually employed to identify the volatile constituents of a complex matrix without actually taking a sample of the material itself. There are three variations of the technique (a) static head-space sampling, (b) dynamic headspace sampling, and (c) purge and trapping. 

Chai XS, Hou QX, Schork FJ (2004) J Chromatogr A 1040 163 ASTM, F 2013 - Determination of Residual Acetaldehyde in Polyethylene Terephta-late Using an Automated Static Head-Space Sampling Device and a Capillary GC with a Flame Ionization Detector (2001)... 

Blood Thermally decarboxylated subjected to static head-space analysis GC/ECD (for metabolite TCA) 2 ppb 101-109 Ziglio etal. 1984... 

Food Undigested or H2S04-digested samples at 90°C subjected to static head-space analysis HRGC/ECD GC/MS 0.23 ppb 90-100 Entz and Hollifield 1982... 

Solid-phase microextraction (SPME) is a static head-space method similar to the carbon strip method however, it does not require a solvent desorption stage. Volatiles are extracted from the headspace by absorption into an absorbent polymer such as poly-dimethylsiloxane (ASTM method E2154). The absorbent polymer is coated onto a quartz fiber that is housed within a needle similar to a syringe needle. The coated fiber is exposed beyond the tip of the needle in the headspace above the fire debris. As with the carbon strip method, the fiber debris sample can be heated to increase the concentration of volatiles in the headspace. Volatiles are absorbed within the polymer with exposure times for routine screening being within the range 5-15 min. The fiber is retracted within the needle and can then be directly inserted into the injector of a gas chromatograph where the volatiles are thermally desorbed from the polymer onto the column. SPME fibers can be reused but appropriate blanks need to be run to ensure that the fiber is clean. 

Hgure 1 Comparison of purge and trap with static headspace extraction. (A) Static head space and (B) purge and trap. 

Head-space analysis. As previously mentioned, polymers often contain substances of medium volatility such as monomers and polymerisation solvents. In addition, when heated polymers release volatiles as a result of the thermal degradation of the polymer itself or of the formulation additives used. Characterisation of such volatiles is now becoming increasingly important for regulatory requirements. Head-space gas chromatography as a technique offers considerable potential in this area. Head-space analysis can be carried out in either the static or the dynamic mode and can be readily automated. In static head-space analysis, the substance to be analysed is placed in a sealed vessel, where the material under examination comes into equilibrium with its vapours at a predetermined temperature. When equilibrium has been reached, an... 

Table IH Determination of Volatile Compounds in Tomato Paste and Tomato Flakes by Static Head-Space-Gas Chromatography...

Volatile compounds of coconut oil were determined by GC-MS. Volatile compoimds can be identified and quantified by analysis of the headspace using methods such as static head space, dynamic headspace (purge-and-trap), direct thermal desorption,and solid phase microextraction (SPME) techniques (Santos et al., 2011). 

Validation of a SPME method for target analytes should be performed using standard reference materials with similar matrix, when available. Another possible and frequently used way is validation of a SPME method against well-accepted extraction techniques, such as purge-and trap [13,25,46] or static head-space [46]. Several interlaboratory studies demonstrated that SPME is a reliable technique for the quantitative analysis of volatile organic compounds [46] and pesticides in water samples [47 48]. We have validated our SPME-GC-MS method for the determination of nitrous oxide in urine by means of the comparison with static headspace [33]. 

Analyses at fairly low temperatures also limit the usefulness of static head-space for analytes with higher boiling points. Many materials that may be extracted and solvent injected onto a GC column and that may elute well at higher... 

B. Girard and S. Nakai, Grade classification of canned pink salmon with static head-space patterns, J. Food Sci. 59 507 (1994). 

The effects of dentifrice components on flavor release in vitro using static head-space had previously been studied (36-37). Recently consumer emphasis on long-lasting flavor has led to extensive work in understanding the release of flavor in the oral cavity (38). Atmospheric pressure chemical ionization techniques have... 

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