Static headspace injector

When using the static headspace injector the possible matrix effect should be studied and can be evaluated by a statistical method. ... 

The static headspace injector has been selected and flic method developed for water soluble products using water as dissolution medium or using N,N-dimethylformamide for water-insoluble products. IfN,N dimethylacetamide and/or N,N-dimethylformamide are suspected in the drug under investigation 1,3-dimethyl 2-imidazolinone (DMI) is used as dissolving medium. 

Fig. 1 Comparison of dynamic, static, and SPME headspace sampling, (a) Dynamic headspace sampling uses a sorbent or cold trap to concentrate volatile analytes before analysis by the GC. (b) Static headspace sampling uses direct transfer of a volume of gas from the headspace above the heated sample vial directly to the GC for analysis. Injection designs are illustrated in Fig. 2. (c) SPME headspace sampling uses a fiber support with solid-phase coating. The fiber is placed in the headspace and reaches equilibrium with the headspace volatile analytes. The SPME fiber is transferred by means of a syringe and thermally desorbed in the injector of the GC for analysis.

Fig. 5.9. Apparatus for the gas chromatography-olfactometry of static headspace samples. 1 Sample in ther-mostated glass vessel, 2 septum, 3 gastight syringe, 4 injector, 5 hydrophobed glass tube, 6 carrier gas, e. g, helium, 7 purge and trap system, 8 cold trap, 9 gas chromatograph with capillary column, 10 sniffing port, 11 flame ionization detector (according to Guth and Grosch, 1993)...

Static headspace gas chromatography (SHGC) was used to study the effects of saliva volume on the retention of the five aroma compounds by the emulsion. Emulsion to saliva ratios included 100 0, 80 20, 60 40, and 40 60. The 2mL of the samples was transferred to 10-mL headspace vials, which were then incubated at 37°C and agitated at 750 rpm for 6 min, using an automated headspace unit (Combipal-CTC Analytics JVA Analytical Ltd., Dublin, Ireland). One milliliter of the headspace was injected and analyzed by using a gas chromatograph (GC Varian CP-3800 JVA Analytical Ltd.) equipped with a flame ionization detector (FID). The injector and detector... 

Figure 20.4—Static mode of headspace sample analysis. The sampling phial is pressurised with the carrier gas of the chromatograph. After equilibrium, a small volume of the gas containing the volatile compounds is inserted into a sample loop. Rotation of the six-way valve allows introduction of the sample into the injector of the chromatograph. Consequently, this set-up combines sample preparation with sample introduction into the chromatographic column. (Reproduced by permission of Tekmar.)...

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. 

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