Sample extraction procedure

The sample extraction procedures are similar to those for the Multi-residue analysis method (see Section 3.3.1). 

What data are available concerning sampling, extraction procedures and the... 

Determination of DCB in Rat Urine. In this study a method for the determination of DCB in rat urine was developed. The sample extraction procedure employed was as follows ... 

One example of a miniaturized LC/MS strategy is the use of 96-well sample plates (Kaye et al., 1996) for extraction. This sample extraction procedure combines batch sample processing within a miniaturized format. Increased sensitivity and decreased volume advances have fostered a new wave of scale-down models. Experiments that were formerly performed at the bench are, instead, performed at the microliter scale in the batch mode. For example, synthetic process research was traditionally performed manually with apparatus at the milliliter level. This approach involves the testing of a range of synthetic conditions for optimum yield and minimum impurity production. Now, process research conditions are tested in microliter levels to produce information on purity and structure (Rourick et al., 1996). This strategy requires fewer reagents and accelerates the evaluation of a wider range of conditions in a shorter time. Another example includes the direct analysis of samples from cell culture experiments (Kerns et al., 1997). 

Most of these DNA isolation procedures are time-consuming or hazardous to the operators because toxic chemicals are used in the sample extraction procedure. They all require centrifugation, pipetting, votexing or thermal incubation steps which are almost impossible to integrate with current instrumentation. 

However, protein precipitation usually produces severe matrix effect [54-56], Therefore, in most LC-MS published methods, more extensive sample extraction procedures were used, being liquid-liquid (LLE) and SPE the most frequent techniques. 

Author, year [Ref] Compounds IS Sample Extraction procedure Stationary phase Mobile phase IM/analyzer (detection mode) Method validation... 

Sample Extraction procedure Stationary phase Mobile phase mode) Method validation... 

Both RIA and enzyme immunoassay methodologies have been applied to the determination of progesterone in saliva. Although sample extraction procedures are often necessary to eliminate protein influences/ direct methods are favored in routine laboratories and have been described.Rigorous standardization of sample collection and preparation is important for obtaining meaningful results for cHnical purposes... 

Biological matrices are not directly compatible with LC-MS analysis, since these samples tend to block LC columns and contaminate the ion source. Extraction of compounds of interest from biological fluids is required prior to LC-MS/MS analysis [20]. Sample extraction can be achieved off-line with protein precipitation (PP), liquid-liquid extraction (LLE), or solid-phase extraction (SPE) [21]. With the ease of use and sophistication of automated liquid-handling systems, sample extraction procedures in a 96-well format can handle microliter volumes with multiple sorbents per plate and can simplify and expedite SPE method development [22,23]. The technique can be used to routinely develop methods for multiple analytes and examine a set of eluent compositions for each analyte [16]. 

The detailed residue analysis method must be reported including the sample extraction procedure and clean-up. The method of detection must be simple and feasible, and the instrumentation and its operating conditions are to be acceptable for residue laboratories. Secondly, the recovery, RSD (relative standard deviation), and sensitivity (limit of detection and minimum concentration of detection) of the analytical method should meet the requirements of the Residues Experiment Guideline of Pesticide Registration. 

Sample extraction procedures are often perceived as bottlenecks in analytical methods, as they may be time consuming and require particular attention. In most developed analytical techniques, lipids extraction represents a crucial task and the first step of an efficient analytical method, since the validity of the results depends on proper sampling and sample handling preparation prior to analysis. The task of lipid sample extraction, preparation, and handling has been comprehensively discussed, recently [21],... 

Once a suitable sample extraction procedure has been established, the choice of LC parameters is important in terms of attaining the best sensitivity and selectivity to be obtained from the mass spectrometer. 

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