Application Of New Sample Preparation Technique To The Analysis Of Environmental And Biological Samples

Nowadays, more favour has been focused on miniaturated sample preparationtechnique, and some miniaturated, less solvent or solvent-free sample preparationtechnique, such as solid phase microextraction and liquid phase microextraction, havebeen developed rapidly, which conquers some shortcomings of labourious operation,time-consuming, high consumption of sample and reagent, etc. Being possessadvantages including simple, flexible, easily operational, environmental friendly, thetwo extraction techniques meet the development trend in practical application coulpedwith all kinds analytical instruments. With the unceasing development of new extractionmaterials, modes, high throughout, and automated devices in sample preparationtechnique, microextraction technique will play more important role in food,environmental, biological and medical analysis.In this dissertation, some applications were developed through two newmicroextrction techniques in environmental and biological analysis. These workinvolved are list below:1. The development of sample preparation was introduced, and foundation,extraction modes, influencing factors, the applications and developments of solid phasemicroextraction and liquid phase microextraction were reviewed comprehensively.2. A sensitive method has been established for the simultaneous analysis ofbenzimidazole multi-residues in egg, milk, chicken, and pork. This method is based onthe combination of polymer monolith microextraction (PMME) technique with liquidchromatography and electrospray ionization mass spectrometry (LC-ESI/MS). Theextraction was performed with a poly (methacrylic acid-co-ethylene glycoldimethacrylate)(MAA-co-EGDMA) monolithic capillary column. Under the optimizedextraction conditions, good extraction efficiencies for the targets were obtained, and nointerferences from the matrix were observed for the quantification of the analytes in thesubsequent detection. The method was later successfully applied for the determinationof primary and metabolite residues in eggs after oral administration of albendazole tohens. 3. A simple, rapid, and efficient method for simultaneous determination of tenbenzimidazole drugs in animal tissues samples was developed. This analyticalprocedure involved extracting samples with magnetic solid-phase extraction (MSPE)using magnetite/silica/poly (methacrylic acid-co-ethylene glycol dimethacrylate)(Fe3O4/SiO2/Poly (MAA-co-EGDMA)) magnetic microspheres, and determination bycapillary electrophoresis (CE) with field-amplified sample stacking technique (FASS).The results showed good linearities were obtained for the analytes, and the developedmethod has also good precision and accuracy. The combination of MSPE and CE willpovide new practical tool for veterinary drug multi-residues analysis.4. A novel molecular complex-based dispersive liquid-liquid microextraction(DLLME) method was established and applied to fast analysis of phenols in aqueoussolution. In this approach, tri-n-butylphosphate (TBP), a Lewis base, was directly used,instead of the traditional water-immiscible organic solvents, as the extractant forDLLME. The phenols, which are typical Lewis acids, were successfully extracted fromaqueous samples. In addition, extraction was accomplished in a disposable polyethylenepipet with the open and narrow tip upside, for an easy collection of the above extractantlayer, i.e. TBP. The developed approach provides a new way to facilitate DLLME oforganic polar compounds from aqueous solutions.5. A new method combined the solid-phase extraction (SPE) and the molecularcomplex-based dispersive liquid-liquid microextraction (MC-DLLME) has beendeveloped for the determination of several acidic phytohormones in natural coconutjuice. Indole-3-acetic acid (IAA), salicylic acid (SA), abscisic acid (ABA) andindolyl-3-butyricacid (IBA) were selected to assess the extraction procedure anddetermined by liquid chromatography with ultraviolet detection (LC-UV). Insolid-phase extraction-dispersive liquid-liquid microextraction (SPE-DLLME), analyteswere firstly adsorbed into C18sorbent from a large volume of coconut juice samples.The eluate containing the desired compounds was outflowed from the sorbent by usingmethanol, which was used as the dispersive solvent in MC-DLLME procedure. The newmethod provided a high enrichment factor (319.1-477.7) for several acidicphytohormones. Good linearities were obtained for the analytes, and the developed method has also good precision and accuracy.