The in vitro metabolic stability of potential drug candidates is routinely examined at an early stage of drug discovery. Metabolic stability is a simple, well-established screening technique used to predict the in vivo hepatic clearance of a drug based on due to metabolism. With the ever-increasing chemical libraries, today’s drug metabolism and pharmacokinetic (DMPK) laboratories are constantly being asked to increase the number of molecules that can be assayed to decrease the time needed to identify lead drug candidates.
Direct thermal extraction (DTE) is a thermal desorption technique in which a small amount of sample, typically 10-50 mg, is placed in an empty fritted thermal desorption tube or into a small vial (μ-vial) within an empty thermal desorption tube. The sample is then heated in a thermal desorption unit under a fl ow of inert gas, in order to release volatile and semi-volatile compounds. The analytes are trapped and fi nally determined by GC/MS. DTE requires little sample preparation and can be used for trace analysis of volatile and semivolatile organic compounds in solid or liquid samples.
Food products are routinely monitored for quality, authenticity, and safety. Analysis of food products may also be necessary due to off flavor or odor complaints. The aroma and flavor profiles of each product are unique and made up from a variety of semi-volatile and volatile compounds including aldehydes, ketones, acids, alcohols, terpenes, esters and other trace level components. The wide range of concentrations, polarities, and functional groups used in the composition of a flavor/aroma profile can make the analysis of the sample difficult. Techniques which are simple, use little or no solvent and encompass a wide range of analytes are desirable.
A new fully automated thermal desorption (TD)-GC/MS method was developed for determination of formaldehyde and other airborne carbonyls as well as VOCs for material emission testing. The method includes an automated in-situ derivatization agent loading step prior to every sampling step, thus blank values are avoided. Pentafl uorophenylhydrazine (PFPH) was used as derivatization agent and was automatically loaded onto Tenax TA adsorbent using a dynamic headspace (DHS) technique.
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