A review of new adsorbents for separation of BTEX biomarkers

The biomarker analysis of benzene, toluene, ethylbenzene and xylene (BTEXs) in biological samples is the primary technique for evaluating these compounds in occupational and environmental exposures. The BTEX biomarkers are widely used to study the BTEX distribution in the environment and workplaces. Liquid-liquid extraction and solid-phase liquid extraction are among the most commonly used conventional methods to analyze biological indices of BTEXs. New methods have been proposed to analyze BTEX biomarkers using novel adsorbents such as sol-gel composite nanotubes, molecularly imprinted polymers and metal-organic frameworks, which are based on the application of needle trap devices, microextraction by packed sorbent, and solid-phase microextraction techniques. This paper provides an overview of new methods since 2015 regarding applying microextraction methods based on new adsorbents and analyzing BTEX biomarker compounds for occupational and environmental exposures. The results were compared with the liquid-phase microextraction methods recommended for urinary BTEX biomarkers.

Two-phase agarose gel-electromembrane extraction: Effect of organic solvent as an acceptor phase in electroendosmosis flow phenomenon

In this study, a new mode of gel electromembrane extraction (G-EME) namely as "Two-phase G-EME", is suggested for the sensitive quantification of five basic drugs (desipramine, clomipramine, trimipramine, citalopram and clozapine) in biological samples. Compared to classical G-EME which is based on aqueous-gel-aqueous layout, herein, the aqueous acceptor phase (AP) was replaced with organic solvent. Briefly, negative electrode was immersed into the organic AP (with low conductivity) and positive electrode into the aqueous donor phase (DP). Based on our results, this simple adjustment significantly reduced electroendosmosis (EEO) flow phenomenon which is considered as the main issue in G-EME. In the workflow, target analytes were extracted from the 7.0 mL sample, across the fabricated agarose gel membrane, to the 100 μL of the AP under the optimized extraction conditions (organic solvent type: acetonitrile; pH of gel membrane: 5.0, pH of sample solution: 4.0, voltage: 45 V and extraction time: 22 min). Then, the organic AP with analytes was analyzed by gas chromatography (GC) instrument with flame-ionization detector (FID). The methodology offered limits of detection (LODs) and recoveries in the range of 1.0-1.5 ng mL^-1 and 48.5-89.0 %, respectively. Finally, we note that two-phase G-EME assembly was able to extract analytes-of-interest in the convenient and safe manner from the hazardous and difficult-to-process biological specimens such as human serum and urine.