The separation and identification of synthetic cathinones by portable low microflow liquid chromatography with dual capillary columns in series and dual wavelength ultraviolet detection

A modified micro-solid phase extraction device for in-port elution and injection into portable liquid chromatography: A proof-of-concept study

A micro-solid phase extraction (micro-SPE) device packed with a C18 sorbent (10 mg) has been developed for the enrichment and purification of organic water pollutants prior to their analysis using a portable liquid chromatograph with a dual UV detector. To this end, the sorbent was immobilized at the inlet of a 4 mm syringe filter (0.20 µm), which was modified to reduce its internal volume. The filter was coupled to the needle of the chromatograph. After loading the sample and cleaning the sorbent for analyte purification, the device was installed into the injection port of the chromatograph, and the target compounds were desorbed and transferred directly to the chromatographic column with a small volume of organic solvent. Under optimized conditions, sample volumes as large as 50 mL could be processed with the micro-SPE device, while the analytes were desorbed with only 60 µL of methanol. As a result, efficient preconcentration could be reached, as demonstrated for different water contaminants, namely aclonifen, bifenox, tritosulfuron, triflusulfuron-methyl and caffeine. The proposed micro-SPE device was applied to the analysis of different types of water (river, well, sea, ditch and wastewater). The recoveries of the target compounds in samples ranged from 76 % to 109 %, which allowed their detection at low to sub µg/L levels. All operations were carried out manually, and thus, no additional laboratory instruments such as centrifuges, stirrers or evaporators were required. This proof-of-concept study shows that the proposed micro-SPE approach can be considered a reliable and effective option for the on-site analysis of pollutants in environmental water samples by portable liquid chromatography.

Use of micro, capillary, and nano liquid chromatography for forensic analysis

The use of micro, capillary, and nano liquid chromatography systems for forensic analysis has excellent potential. In a field where sample size is often limited, several studies have presented the viability of capillary columns with microflow and nanoflow, and when using mass spectrometric analysis limits of detection can be improved. Reduction in flow rates result in significant reduction in operating costs. Recent advances in miniaturized liquid chromatography systems also aim at in-laboratory and on-site detection, which have already been applied to forensic drug cases. This critical review will discuss the advantages, disadvantages, and applicability of microflow and nano liquid chromatography. In this regard, included in this article is a discussion of some promising areas not yet applied to forensic research.

Recent forensic applications of enhanced chromatographic separation methods

This study reviews the recent applications of enhanced separation methods employed in forensic analysis utilizing gas chromatography, liquid chromatography, and supercritical fluid chromatography published between 2015 to 2020, except papers previously covered in relevant review articles. Applications of enhanced chromatographic separation methods to arson investigations, environmental forensics, sexual assault investigations, drug analysis, and toxicology are discussed. Future directions for enhanced chromatographic separation methods in forensic science are also explored.