Octanol-supported wooden tips as sustainable devices in microextraction: A closer view of the influence of wood matrix

Abstract

This article describes the use of wooden tips as substrates under a hybrid microextraction format. This format synergically combines the extraction capacities of wood (solid substrate) and an organic solvent (immobilized in the wooden structure). 1-octanol has been selected as solvent as its extraction ability is fully characterized. In fact, the octanol–water partition coefficient is well-reported for many compounds as it is used as a polarity index. In this article, the extraction capabilities of octanol-supported wooden tips have been studied using non-steroidal anti-inflammatory drugs as model analytes. Their extraction has been optimized considering the effect of three main variables: pH, ionic strength, and extraction time. The impact of the wood matrix compounds on determining the analytes by mass spectrometry has also been studied. Although the direct infusion-mass spectrometry analysis resulted in a rapid and efficient approach for determining the drugs at therapeutic levels, the ion suppression effect induced by the wood matrix reduces its potential. In this context, liquid chromatography allowed to improve the performance. Working under the optimal conditions (1.5 mL of 1:4 diluted sample, pH 3, 30 min of extraction), the proposed method permits the determination of the drugs with limits of quantification as low as 8–32 µg/L, precision (expressed as relative standard deviation) better than 21.3 %, and accuracy (defined as relative recoveries) in the range of 80 to 114 %.