Strategies for the microextraction of polar organic contaminants in water samples

Abstract

In this paper the most recent developments in the microextraction of polar analytes from aqueous environmental samples are critically reviewed. The particularities of different microextraction approaches, mainly solid-phase microextraction (SPME), stir-bar-sorptive extraction (SBSE), and liquid-phase microextraction (LPME), and their suitability for use in combination with chromatographic or electrically driven separation techniques for determination of polar species are discussed. The compatibility of microextraction techniques, especially SPME, with different derivatisation strategies enabling GC determination of polar analytes and improving their extractability is revised. In addition to the use of derivatisation reactions, the possibility of enhancing the yield of solid-phase microextraction methods for polar analytes by using new coatings and/or larger amounts of sorbent is also considered. Finally, attention is also focussed on describing the versatility of LPME in its different possible formats and its ability to improve selectivity in the extraction of polar analytes with acid-base properties by using separation membranes and buffer solutions, instead of organic solvents, as the acceptor solution.

Analytical Methods for Polar Pollutants

“…In fact, the US-EPA has two methods available for their determination: one based on SPE [43] and the other based on LLE [44], where, however, the volume of extracting solvent has been minimized to 4 mL of MTBE. The alternatives to SPE are microextraction techniques, namely SPME and, more recently, LPME, as they consume less organic solvent or sample volume (or virtually none in the case of SPME) [45]. Both SPE and microextractions are discussed in more detail.…”

“…A step further was achieved by solid-phase microex-traction (SPME) and liquid-phase microextraction (LPME), where either no organic solvent is employed (SPME) or only a few microliters (LPME), and also the amount of sample is reduced to ca. 10-50 mL [45]. SPME was developed in 1989 [79] and became commercially available in 1993.…”

“…In the case of LC, automation can be achieved by so-called in-tube SPME, where the sample analytes are preconcentrated into a coated capillary that is connected on-line to the LC [82]. However, SPME hyphenation to LC is hampered by the slow desorption process, leading to band-broadening problems [45].…”

“…However, several options are available for combining SPME and derivatization, depending on the characteristics of the analytes and the derivatizating agent ( Fig. 1.5) [45,80,84].…”

Estudo de alcaloides harmânicos em sementes de Passiflora edulis Sims f. flavicarpa Degener (maracujá azedo) por SBSE/CLAE-Flu dual

“…Em amostras complexas, assim como as sementes de maracujá, com a possibilidade de ocorrer o efeito de matriz, a eficiência da extração por SBSE pode ser afetada; por isso, para a quantificação de harmana e de harmina em sementes de maracujá azedo, foi utilizado o método de adição de padrão por meio da construção de curvas analíticas, sendo este método o mais indicado por corrigir a influência dos componentes da matriz (efeito de matriz) na quantificação exata dos analitos (CUADROS-RODRÍGUEZ et al, 2003;RIBANI et al, 2004;QUINTANA;RODRIGUEZ, 2006;PINHO et al, 2009). *DP = desvio padrão.…”