Variations in headspace microextraction procedures and current applications in bioanalysis

In sample preparation, analytes are extracted from the sample and concentrated in a solvent compatible with analytical instrumentation. Some drawbacks are usually associated with the procedures traditionally used, namely the amounts of organic solvents that need to be properly discarded and the presence of several interferences which may impair analyte identification and quantitation. Headspace microextraction procedures have appeared as a promising solution to overcome these problems. On the one hand, being microextraction techniques, the amount of solvent and sample is reduced; on the other hand, since it is the headspace above the specimen which is sampled rather than the sample itself, analytical interferences are minimized, prolonging the lifetime of the devices and analytical instrumentation.

Biological sample preparation: attempts on productivity increasing in bioanalysis

Sample preparation is an important step of any biomedical analysis. Development and validation of fast, reproducible and reliable sample preparation methods would be very helpful in increasing productivity. Except for a few direct injection methods, almost all biological samples should at least be diluted before any analysis. Sometimes dilution is not possible because of the low concentration of the target analyte in the sample, and alternative pretreatments, such as filtration, precipitation and sample clean up using different extraction methods, are needed. This review focuses on the recent achievements in the pretreatment of biological samples and investigates them in six categories (i.e., dilution, filtration/dialysis, precipitation, extraction [solid-phase extraction, liquid–liquid extraction], novel techniques [turbulent flow chromatography, immunoaffinity method, electromembrane extraction] and combined methods). Each category will be discussed according to its productivity rate and suitability for routine analysis, and the discussed methods will be compared according to the mentioned indices.