Dynamic headspace analysis

Other workers have discussed the application of dynamic headspace analysis to the determination of aliphatic hydrocarbons in seawater [14-18]. 

Direct methods of analysis such as distillation [158,167,168], liquid-liquid extraction [ 159,169], headspace analysis [ 170-172], dynamic headspace analysis [157,173-178], and direct injection [179] have been used mainly for specific volatile components. 

In this method volatile organic matter in seawater is concentrated on a Tenax GC solid adsorbent trap and dry-ice trap in series. The trapped organic material is then desorbed and oxidised to carbon dioxide, which is measured with a non-dispersive infrared analyser. A dynamic headspace method was used for the extraction with the assistance of nitrogen purging. Dynamic headspace analysis [184] is an efficient extraction procedure. The efficiency of extraction... 

Table III. Amounts of volatile compounds (ng/kg) detected in white bread by dynamic headspace analysis CX)NTROL is without and SOYA is with 30 g soya flour addition (see recipe 15)...

The key advantage of this headspace method, compared to static headspace analysis, is the sensitivity obtained. While static headspace shows the status at equilibrium and can measure thermodynamic constants, purge-and-trap or dynamic headspace can measure the kinetics of... 

Theirry, A., Maillard, M. B., and Le Quere, J. L. (1999). Dynamic headspace analysis of Emmental aqueous phase as a method to quantify changes in volatile flavor compounds during ripening. Int. Dairy. 9, 453-463. 

We have previously carried out studies on fresh black truffle aroma by strip and trap / dynamic headspace analysis. Experiments were carried out with truffle flesh (1,2), entire truffles ( Talou,... 

Headspace Sampling Technique. The method used a new gas chromatographic desorption - concentration - GC introduction device (D.C.I.) based on dynamic headspace analysis and available from Delsi Instruments (Paris, France). This apparatus made it possible to isolate volatiles from both solid and liquid samples (4). 

Kim, Y.D., Morr, C.V. 1996. Dynamic headspace analysis of light activated flavor in milk. Int. Dairy J. 6, 185-193. 

Hammers WE, Bosnian HFPM. 1986. Quantitative evaluation of a simple dynamic headspace analysis technique for non-polar pollutants in aqueous samples at the ng/kg level. J Chromatogr 360 425-432. 

Roberts, J. "Semiautomated Dynamic Headspace Analysis of Vegetable Oil Volatiles" presented at the 74th Meeting of the American Oil Chemists Society Chicago, IL May, 1983. 

There are few studies reporting on the effect of ethanol on the release of aroma compounds using dynamic methodologies. In one study (dynamic headspace analysis and APCI-MS), Tsachaki et al. (2005) observed that in aqueous systems (no ethanol) there was a rapid decrease in MS signal intensity until the rate of replenishment equalled the rate of loss from headspace purging. However, above ethanolic solutions, there was a similar initial rapid decrease followed by a steady state loss at much higher levels (at 50-90%) of the initial relative intensity depending on the volatile compound (Fig. 8F.2). In contrast to the aroma release effects noted under... 

Tsachaki, M., Linforth, R.S.T., Taylor A.J. (2005). Dynamic headspace analysis of the release of volatile organic compounds from ethanolic systems by direct APCI-MS. J. Agric. Food Chem, 53, 8328-8333. 

Thompson JA, Ho B, Mastovich SL. 1985. Dynamic headspace analysis of volatile metabolites from the reductive dehalogenation of trichloro - and tetrachloroethanes by hepatic microsomes. Anal Biochem 145 376-384. 

Trussell AR, Moncur JG, Lieu FY, et al. 1983. New developments in dynamic headspace analysis of halogenated organics. Water Chlorination Environmental Impact Health Effects 4 583-592,... 

The basic set-up for headspace analysis comprises an HS element — the characteristics of which depend on the particular mode used for pretreatment and a gas chromatograph or, less often, an alternative detector for measurement. Static and dynamic headspace (purge and trap included) differ in the type of equipment required multiple headspace uses the same automated device as static headspace. 

Soil spiked with trichloroethylene and toluene was analysed using a gas chromatograph equipped with a PT concentrator that was found to be replaceable by a headspace unit in order to simplify the overall assembly. The headspace analysis of soil samples was found to be restricted by incomplete desorption of the contaminants in soil-water mixtures this shortcoming, however, was effectively overcome by the addition of methanol. Henry s law constants for volatile organics in methanol must previously be determined if the method is to be applied to soils [142]. A comparison of the performance of static and dynamic (PT) headspace modes in the determination of nine VOCs in five different soils revealed poor PT recoveries in relation to those of static headspace (which ranged from 68 to 88%) the latter, however, required longer development times [143],... 

Rosillo, L., Rosario Salinas, M., Garijo, J., and Alonso, G.L. (1999). Study of volatiles in grapes by dynamic headspace analysis. Application to the differentiation of some Vitis vinifera varieties, /. Chromatogr. A, 847, 155-159. 

CHAPTER 33 - PURGE AND TRAP AND DYNAMIC HEADSPACE ANALYSIS... 

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