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A pH-sensitive polymer based on the poly(styrene- alt -maleic anhydride) co-polymer serves as basis to develop a microextraction method (pH-HGME) in direct combination with high-performance liquid chromatography (HPLC) and fluorescence detection (FD) for the determination of seven organic com- pounds, including three polycyclic aromatic hydrocarbons (PAHs), three monohydroxylated PAHs and one alkylphenol, in urine. The method bases on the structural modification of the pH-sensitive polymer in the aqueous sample at a high pH value, followed by the formation and insolubilization of a hydrogel contain- ing the preconcentrated analytes by decreasing the pH, and the direct injection of the hydrogel-rich phase in the HPLC-FD system. The optimization of the main variables permitted the selection of low amounts of aqueous sample (10 mL), which was mixed with 10 mg of co-polymer also present in a low volume (150 μL) of concentrated NaOH. The method further requires the addition of 200 μL of concentrated HCl, 3 min of stirring, and 15 min of centrifugation. This pH-HGME-HPLC-FD method presented low limits of detection, ranging from 0.001 μg L −1 to 0.09 μg L −1 in ultrapure water, average relative recoveries of 96.9% for the concentration level of 0.60 μg L −1 , and enrichment factors between 1.50 and 17.7. The pro- posed method also exhibited high precision, with intermediate relative standard deviations lower than 16% for a concentration level of 0.60 μg L −1 . The developed pH-HGME-HPLC-FD method performed ade- quately when analyzing two human urine samples provided by a non-smoker male and a smoker female, respectively. One of the target analytes (2-hydroxynaphthalene) was quantified in both samples using the standard addition method, with a predicted concentration of 7.3 ±0.4 μg L −1 in the non-smoker male urine and 19.3 ±0.6 μg L −1 in the smoker female urine. Agencia Canaria de Investigación, Innovación y Sociedad de la Información University of Regensburg Ministerio de Ciencia, Innovación y Universidades Ministerio de Economía, Industria y Competitividad

A multiresidue method based on QuEChERS extraction followed liquid chromatography coupled with tandem mass spectrometry was developed and validated for the determination of 42 pesticides in marijuana. Less than 6 min is required for detection of all species. By using original QuEChERS, the sample preparation is also fast and simple. In the range from 1.0 to 50 μg kg−1, the coefficients of determination (r2) were greater than 0.980, and relative standard deviations for replicate injections were lower than 4.6%. The limit of detection (LOD) and limit of quantification (LOQ) were lower than 0.32 μg kg−1 and 1.07 μg kg−1, respectively. Precision and accuracy were verified through recovery of spiked samples at three distinct levels of concentration (1.0, 5.0, and 50.0 μg kg−1) in five replicates. Recovery values ranged from 82 to 119% with RSD lower than 6%. The method was applied to the detection of pesticide residues in six marijuana samples seized by the Police of Rio de Janeiro, Brazil, where imidacloprid, metazachlor, buprofezin, and metalaxyl were found in four of them.

The purpose of this article is to underline the miniaturized LC instrumental system and describe the evolution of commercially available systems by discussing their advantages and drawbacks. Nowadays, there are already many miniaturized LC systems available with a great variety of pump design, interface and detectors as well as efficient columns technologies and reduced connections devices. The solvent delivery systems are able to drive the mobile phase without flow splitters and promote gradient elution using either dual piston reciprocating or syringe-type pumps. The mass spectrometry as detection system is the most widely used detection system; among many alternative ionization sources direct-EI LC-MS is a promising alternative to APCI. In addition, capillary columns are now available showing many possibilities of stationary phases, inner diameters and hardware materials. This review provides a discussion about miniaturized LC demonstrating fundamentals and instrumentals' aspects of the commercially available miniaturized LC instrumental system mainly nano and micro LC formats. This review also covers the recent developments and trends in instrumentation, capillary and nano columns, and several applications of this very important and promising field.