Extractability testing headspace analysis

Other SPME fibers have been demonstrated to give better performance than 100 /rm PDMS fibers. A porous layer activated charcoal (PLAC) coating showed detection limits between 1.5 and 2 pg/ml for headspace (HS)-SPME analysis of BTEX in water samples, while for PDMS fiber detection limits were in the range of 190 to 700 pg/ml. Polymeric fuUerene was also tested for the headspace analysis of BTEX where greater extraction recoveries compared to those obtained for PDMS fiber were observed. 

Chloropicrin is often analyzed by GC-MS and GC with ECD, as it is used as a component of plant protection agents and as a monitoring substance for testing filtration equipment. Analysis of PS in water by headspace analysis or extraction with n-heptane is often applied. 

SPME can also be used to extract target analytes from food and drug samples. Thus, it has been employed for the extraction of caffeine from coffee and tea [225], and for that of volatile impurities in drugs. Headspace SPME has also been tested for flavour analysis in foods. Thus, the SPME/GC/TOF-MS tandem was successfully used for the rapid analysis of volatile flavour compounds in apple fruit. The sample (300-450 g of apple) was subjected to static headspace sampling for 4 6 h in order to allow the volatiles... 

Electronic nose technology and analysis of volatiles has long been apphed in the food industry to control the quahty of food products and to determine shelf hves. For example, sensor arrays based on different Sn02 gas sensors can be used to distingiush milk products of different rancidity levels [41]. Standard microbial test prediction of shelf hfe of milk products has a low level of reliability due to relatively poor correlation between microbial counts and actual shelf hfe. Several alternative methods have therefore been developed. One method is based on dynamic headspace capillary gas chromatography analyses of volatiles in mUk followed by MDA analyses. [42]. Principals of this method were later used for development of a faster and simpler test, where the extraction was performed by the SPME technique, the extracts... 

HS-SPME is a very useful tool in polymer analysis and can be applied for absolute and semi-quantitative determination of the volatile content in polymers, for degradation studies, in the assessment of polymer durabihty, for screening tests and for quality control of recycled materials. For quantitative determination of volatiles in polymers, SPME can be combined with multiple headspace extraction to remove the matrix effects. If the hnearity of the MHS-SPME plot has been verified, the number of extractions can be reduced to two, which considerably reduces the total analysis time. Advantages of MHS-SPME compared to MAE are its higher sensitivity, the small sample amount required, solvent free nature and if an autosampler is used a low demand of labor time. In addition, if the matrix effects are absent, the recovery will always be 100%. This is valuable compared to other techniques for extracting volatiles in polymers in which the recovery should be calculated from the extraction of spiked samples, which are very difficult to produce in the case of polymeric materials. 

In a companion study, M. Palma et al. studied the extraction of grape seeds with pure SF CO2 and analyzed the derivatized extracts by GC-MS. These extracts were found to contain volatiles such as aliphatic aldehydes in addition to fatty acids and sterols. Even though we used similar conditions for our SF extraction and GC-MS analysis, we were unable to detect any similar volatile compounds. To further investigate the presence of volatiles in the cranberry seed extract, we adapted a solid phase microextraction (SPME) method from the work of Jelen et al. who had earlier developed it for the characterization of volatile compounds in different vegetable oils. SPME followed by gas chromatog[raphy was performed on the headspace of the cranberry seed extract to test for the presence of volatile compounds. The GC trace failed to show the elution of any components for either the SF or Soxhlet extract. 

DiNatale and coworkers have used a combined nose/tongue system to extract chemical information from liquid samples through the analysis of the solution and its headspace [70]. Both devices were based on the use of metalloporphyrins, which allowed uniformity of results. This system was tested for both food and clinical analyses, and there was an increase in the amount of information obtained compared with the individual devices. 

The method described herein for the analysis of volatile organics is a modified procedure of that described by Schuberth (28). Aliquots of 10-20 mL of blood are obtained from the test subjects with the use of a Vacutainer and collected into 10-mL tubes containing 15 mg of ethylenediaminotetraacetic acid (EDTA) and 100 mg of NaF as anticoagulant and preservative, respectively. The samples are then stored at 4°C. Aliquots of 1.5 mL of blood are then added to a headspace vial containing 1.8 g of NaCl. Headspace extraction is done at a bath temperature of 50°C and an equilibrium time of 30 min. 

To select the optimum fiber type for the analysis of flavor compounds, we used a test mixture containing a variety of functional groups, and performed extractions from both the aqueous phase and the headspace. A comparison of the adsorption capabilities of four different polar fiber types, using our test mixture, is... 

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