Preface

The miniaturization of the preliminary steps of the chemical measurement process is one of the challenges of Analytical Chemistry as it clearly facilitates the reduction of dimensions of the whole analytical process, being also favorable for the design of portable analyzers and opens up a door for on-site analysis. Among the substeps included in sample treatment, extraction techniques are unavoidable for the majority of the samples, either for analyte preconcentration, interference removal or conditioning prior to instrumental analysis. Therefore, their miniaturization must be systematically considered.

The new microextraction techniques, including the solid and liquid formats have emerged in this context. The advances and innovations in this field affect not only on the units designed for analytes isolation but also on the new materials that are used. They are characterized to be more efficient than classical ones, thus yielding better enrichment factors. This results in an enhanced sensitivity/selectivity of the whole analytical process.

The Anaytical Microextraction Techniques ebook is fully devoted to this subject matter of increasing interest in the last decades. It is divided into three parts. The first one, composed of four chapters, deals with the general aspects of microextraction techniques in the green chemistry context. It also affords the use of new phases, which results in more efficient devices, fully compatible with the green chemistry principles.

The second part of this ebook is fully devoted to micro solid phase extraction. It starts with the reference technique in this context: solid phase microextraction. Next, fully consolidated formats such as stir bar sorptive extraction and microextraction by packed sorbents are afforded. Dispersive solid phase extraction is usually employed for interference removal. However, its applicability for analytes isolation and preconcentration has been recently evaluated. In this ebook, it is considered in two chapters, one of them dealing with the use of magnetic nanoparticles. Their role is crucial to simplify the extraction process avoiding the need for centrifugation and/or filtration. This section concludes with a chapter devoted to thin film microextraction.

The liquid phase microextraction is compiled in section 3 where single drop and membrane-based ones are presented. Single drop microextraction was the first miniaturized technique developed in the liquid-liquid format, reducing the volume of solvent needed to the low microliter level. Since its proposal, several alternatives have been reported aimed at increasing the versatility of the initial approach. The use of porous materials (flat membranes or hollow fiber) as support of the liquid phase, allows the use of large volumes of solvent, which results in higher enrichment factors.

This ebook would serve as a useful reference to readers to provide the current state of the art of this research area as well as to stimulate the developments of innovative approaches on the topic.