Pretreatment techniques biological

In the separation of biomolecules, sample preparation almost always involves the use of one or more pretreatment techniques. With high-performance liquid chromatography (HPLC), no one sample preparation technique can be appHed to all biological samples. Several techiques may be used to prepare the sample for injection. For example, complex samples require some form of preffactionation before analysis, samples that are too dilute for detection require concentration before analysis, samples in an inappropriate or incompatible solvent require buffer exchange before analysis, and samples that contain particulates require filtration before injection into the analytical instrument. 

The potential of the SFE-SFC couple has been assessed by a number of authors as this combined technique solves one of the major problems encountered in using SFC for bio-analysis. In fact, many pretreatments for biological samples use polar solvents, which are highly detrimental to the phase systems employed in this technique. This problem is readily solved by the SFE-SFC combination, proper performance of which, however, relies on the following conditions ... 

Satake, K. and Uehiro, T. (1985). Carbonisation technique for pretreatment of biological materials in x-ray fluorescence spectrometry. Analyst 110,1165-1168 Schauenburg, H. and Weigert, P. (1992). Determination of element concentrations in biological reference materials by solid sampling and other analytical methods, Fres. Z. Anal. Chem. 342, 950-956... 

When coupled with heightened mass transport and cavitational cleaning, this previously unreported type of ion liberation resulting from insonation removes the necessity for complex and degradative sample pretreatments in biological samples. The result is a facile and inexpensive technique that can provide an accurate measure of copper status from an appropriate volume of blood without incurring undue time or cost. 

In the following sections, the sample pretreatment techniques and the UHPLC-MS/MS conditions for determining procyanidins and alkaloids in cocoa samples and their metabolites in biological samples are reported. 

The reported LODs and LOQs for procyanidins (catechin, epicatechin, dimer, and trimer) in plasma samples that were lower than 4 and 10 nM, except for the trimers, which were 800 and 980 nM, respectively, using the off-line SPE-UHPLC-MS/MS [31], Similar results were obtained when the off-line iSPE-UHPLC-MS/ MS was used to analyze these procyanidin compounds in the biological sample [33]. This demonstrated the high capacity of the pSPE sample pretreatment technique, where the LODs and LOQs were similar in comparison with SPE. In contrast, the preconcentration factor obtained in SPE was 10, in comparison with obtained in pSPE, which was 3.5. 

Narayanaswamy, N., Dheeran, P, Verma, S., Kumar, S. Biological pretreatment of lignocel-lulosic biomass for enzymatic saccharification. In Pretreatment Techniques for Biofuels and Biorefineries, Fang, Z. (Ed.), Springer New York, 2013, pp. 3-34. 

Detection and determination of unknown drugs of abuse in biological matrices represent a challenge for the analytical laboratory due to the high amount of substances possibly present and the different potential matrix effects. Sample pretreatment of biological matrices can reduce the effects of the interfering species, preconcentrate the analytes of interest, and reduce, when LC-MS techniques are used, possible effects of signal suppression or enhancement. 

Standard analytical techniques for sampling and pretreatment and analytical requirements for sediment studies are less available than for water and soil studies. To obtain meaningful results from laboratory experiments, the sediment samples should be kept in the original aqueous matrix, and analyses should be carried out immediately to minimize changes to the sample matrix due to chemical and biological processes that could occur during storage. 

It is not possible to prescribe specific pretreatment procedures here because these can only be decided upon when the system and the purpose of the experiments has been properly defined. However, a wealth of information exist in various biochemical reference books on how to isolate various biological compounds. The recommended techniques and methods could be used as part of the trace element speciation protocol often after slight modification, taking into consideration the following points First, the trace element blank levels have to be low, less than 10% of the total concentration in the sample. Second, the regents used should not interfere with subsequent analytical determinations. Third, the experimental conditions should not deviate markedly from those found in vivo, especially the pH and ionic strength of the medium. 

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