Annual Meeting Abstract Open Access
Forensic Research 2015 : Application of solid-phase extraction tips for the analysis of drugs in human blood - Chika Hasegawa - Toho University School of Medicine
Solid-Phase Extraction (SPE) is a sample clean-up and pre-concentration technique that has been used widely to isolate target analytes from biological samples. Recent trends in SPE techniques focus on miniaturizing the process, reduction of sample and solvent consumption. In 2007, a new SPE device, the MonoTip C18 tip was jointly developed by our group and GL Sciences (Tokyo, Japan) for the extraction of drugs and poisons from human body fluids. In this device, octadecylsilane modified monolithic silica gel is directly attached to the inner surfaces of the pipette tips. The procedure for drug extraction with the SPE tip is essentially the same as that for the conventional SPE (conditioning, sample loading, washings, drying and elution) but differs in that all manipulations are carried out by aspirating and dispensing through a single pipette tip using a manual micropipettor. An advantage of using the SPE tips for sample preparation is that extraction is simpler and faster than with conventional SPE cartridges. Furthermore, the small bed volume and sorbent mass enables reduction of the sample and solvent volumes, cleaner extract and higher throughput. This unique SPE methodology is very useful in combination with gas chromatograpy/mass spectrometry (GC/MS) to provide high simplicity, recovery, reproducibility and sensitivity. Some successful data obtained by the SPE tips and GC/MS are presented for analyses of basic and acidic drugs in human blood samples. Strong stage extraction (SPE) is an inexorably helpful example readiness procedure. With SPE, huge numbers of the issues related with fluid/fluid extraction can be forestalled, for example, inadequate stage partitions, not exactly quantitative recuperations, utilization of costly, brittle strength dish sets, and removal of huge amounts of natural solvents. SPE is more effective than fluid/fluid extraction, yields quantitative extractions that are anything but difficult to perform, is quick, and can be robotized. Dissolvable use and lab time are diminished. SPE is utilized frequently to get ready fluid examples and concentrate semivolatile or nonvolatile analytes, yet in addition can be utilized with solids that are pre-separated into solvents. SPE items are brilliant for test extraction, fixation, and cleanup. They are accessible in a wide assortment of sciences, adsorbents, and sizes. Choosing the most reasonable item for every application and test is significant. The essential maintenance components for mixes on the SPE materials are portrayed previously. For the fortified silicas, it is conceivable that optional associations will happen. For turned around stage fortified silicas, the essential maintenance instrument includes nonpolar collaborations. Be that as it may, on account of the silica molecule spine, some polar auxiliary associations with remaining silanols —, for example, those portrayed for typical stage SPE – could happen. In the event that a nonpolar dissolvable doesn't productively elute a compound from a turned around stage SPE pressing, the expansion of a progressively polar dissolvable (for example methanol) might be important to upset any polar communications that hold the compound. In these cases, methanol can hydrogen-bond with the hydroxyl bunches on the silica surface, along these lines separating any hydrogen holding that the analyte might be acquiring. The silanol bunch at the outside of the silica, Si-OH, can likewise be acidic, and may exist as a Si-O- bunch above pH 4. Accordingly, the silica spine may likewise have cation trade optional collaborations, drawing in cationic or essential analytes of intrigue. In this case, a pH modification of the elution dissolvable might be important to disturb these communications for elution (acidic to kill the silanol gathering, or essential to kill the fundamental analyte). This can be done by utilizing acidic methanol (98% MeOH:2% concentrated HCl) or fundamental methanol (98% MeOH:2% concentrated NH4 Goodness), or by blends of these with an increasingly nonpolar, methanol-miscible dissolvable. Ordinary stage fortified silicas will show essential polar maintenance systems by means of the fortified utilitarian gathering, yet in addition can have some auxiliary nonpolar associations of the analyte with the little alkyl chain that bolsters the useful gathering. For this situation, an increasingly nonpolar dissolvable, or a blend of polar and nonpolar solvents, might be required for elution. Likewise with the switched stage silicas, auxiliary polar or cation trade collaborations of the adsorbed compound may happen with the silica spine. Particle trade fortified silicas can give optional nonpolar communications of analytes with the nonpolar bits of their utilitarian gatherings, just as polar and cation trade connections of the analyte with the silica spine. A fragile equalization of pH, ionic quality, and natural substance might be fundamental for elution of the analyte of enthusiasm from these packings. Arrangements utilized in SPE methods have an extremely wide pH go. Silica-based packings, for example, those utilized in HPLC segments, normally have a steady pH scope of 2 to 7.5. At pH levels above and underneath this range, thereinforced stage can be hydrolyzed and severed off the silica surface, or the silica itself can break up. In SPE, be that as it may, the arrangements for the most part are in contact with the sorbent for brief timeframes. The way that SPE cartridges are expendable, and are intended to be utilized just a single time, permits one to utilize any pH to advance maintenance or elution of analytes. On the off chance that solidness of the SPE cartridge at an outrageous pH is pivotal, polymeric or carbonbased SPE materials, for example, ENVI-Chrom P or ENVI-Carb may be utilized. These materials are steady over the pH scope of 1-14.
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