Microextraction Techniques as a Sample Preparation Step for Metal Analysis

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Analytical methods consist of several steps including; sampling, sample preparation, analysis, calculations and statistical evaluation of the results. Each step has a direct impact on accuracy, precision and sensitivity of the method. Among theses steps, sample preparation is the most time consuming step. Result of studies showed that more than 60% of analysis time is spent for sample preparation. Sample preparation follows two main aims; sample clean-up and concentration. Sample Clean-up is carried out for isolating the target analytes from matrix components which interfere on determination and concentration is done for enrichment of the analytes in sample because despite advances in analytical instrumentation, sensitivities are limited. Characteristics of an ideal sample preparation technique are listed as below: Minimum loss of the sample and maximum recovery of the analyte Elimination of accompanying compounds with high yield Simple, fast and cheap method Capable with analytical instruments In agreement with green chemistry In the case of atomic absorption spectrometry (AAS) which is the subject of this book, there are two priciple systems which are familiar with readers of this book, flame and electrothermal AAS. In continue of our discussions about microextraction techniques for metal analysis by AAS, we will emphasis on reduced volumes of extracting phases in the microlitre scale. It is clear that due to consumption of large volumes (in the mililitre scale) of the sample in flame AAS, coupling of microextraction techniques with flame AAS is difficult. But in the case of electrothermal AAS, this is so easy. Because volume of the samples introduced to graphite furnaces are very low and in microlitre scale. So a review on literature show that most of the microextraction methods are capable with electrothermal AAS not with flame AAS.