Packed-column supercritical fluid chromatography coupled with solid-phase extraction for the determination of organic microcontaminants in water

An automatic online solid-phase dehydrate extraction-ultra-high performance supercritical fluid chromatography-tandem mass spectrometry system using a dilution strategy for the screening of doping agents in human urine

An automatic online solid-phase dehydrate extraction (SPDE)-ultra-high performance supercritical fluid chromatography (UHPSFC)-MS/MS system was developed in this study, in which the automatic SPDE procedure was coupled with UHPSFC to allow UHPSFC to analyze aqueous samples directly. Moreover, a pre-column dilution strategy was employed, which focused the analytes in strong desorption solvent on the column head and helped to obtain narrow and symmetric peaks. The online SPDE-UHPSFC-MS/MS system was firstly applied to the screening of 45 prohibited substances in human urine for doping control, during which all the mechanisms and features of the online system were fully studied. The majority (91%) of the target compounds achieved weak matrix effects (80-120%), indicating that the online method was accurate and reliable thanks to the SPDE procedure and efficient UHPSFC separation. Owing to the reduction of the matrix effects, large volume injection and the pre-column dilution, the online system could achieve high sensitivity with the LODs ranging from 0.0380 ng L^-1 to 1.24 μg L^-1. Under the optimized conditions, the extraction recoveries of 66% target analytes were more than 50%. All the target compounds showed good linearity with linear correlation coefficients higher than 0.9928. The accuracy values of all the spiked prohibited substances were within 80.8-119.7%, while the RSDs% for the intra-/inter-day precision were within 10.8% and 15.4%. Compared with the dilute-and-shoot-ultra-high performance liquid chromatography-MS/MS method, in which the urine samples were simply diluted before analyzing, this online method was superior in sensitivity and reducing matrix effects, which demonstrated its utility in doping control. Compared with the previously reported online SPE-SFC system, the online SPDE-UHPSFC-MS/MS system showed advantages in automation, efficiency, sensitivity and chromatographic performance. In summary, the online SPDE-UHPSFC-MS/MS system is capable of analyzing complex aqueous samples.

Recent advances of online coupling of sample preparation techniques with ultra high performance liquid chromatography and supercritical fluid chromatography

Ultra high performance liquid chromatography and supercritical fluid chromatography techniques are favored because of their high efficiency and fast analysis speed. Although many sample preparation techniques have been coupled with common liquid chromatography online, the online coupling of sample preparation with the two popular chromatography techniques have gained increasing attention owing to the increasing requirements of efficiency and sensitivity. In this review, we have discussed and summarized the recent advances of the online coupling of sample preparation with ultra high performance liquid chromatography and supercritical fluid chromatography techniques. The main sample preparation techniques that have been coupled with ultra high performance liquid chromatography online are solid-phase extraction and in-tube solid-phase microextraction, while solid-phase extraction and supercritical fluid extraction are the main techniques that have been coupled with supercritical fluid chromatography online. Especially, the strategies for online coupling of sample preparation with chromatography techniques were summarized. Typical applications and growing trends of the online coupling techniques were also discussed in detail. With the increasing demands of improving the efficiency, throughput, and analytical capability toward complex samples of the analysis methods, online coupling of sample preparation with chromatography techniques will acquire further development.

Simple determination of the herbicide napropamide in water and soil samples by room temperature phosphorescence

A new, simple, rapid and selective phosphorimetric method for determining napropamide is proposed which demonstrates the applicability of heavy-atom-induced room-temperature phosphorescence for analyzing pesticides in real samples. The phosphorescence signals are a consequence of intermolecular protection and are found exclusively with analytes in the presence of heavy atom salts. Sodium sulfite was used as an oxygen scavenger to minimize room-temperature phosphorescence quenching. The determination was performed in 1 M potassium iodide and 6 mM sodium sulfite at 20 degrees C. The phosphorescence intensity was measured at 520 nm with excitation at 290 nm. Phosphorescence was easily developed, with a linear relation to concentration between 3.2 and 600.0 ng ml(-1) and a detection limit of 3.2 ng ml(-1). The method has been successfully applied to the analysis of napropamide in water and soil samples and an exhaustive interference study was also carried out to display the selectivity of the proposed method.

Preconcentration of contaminants in water analysis

Among the environmental areas, in this review attention will be focused on water matrices and both on organic (e.g., pesticides, herbicides, phenols, polycyclic aromatic hydrocarbons), inorganic species and anion pollutants, since these kinds of substances include a wide number of compounds with different physical and chemical properties and different effects on human health. Analytical methods for control of quality of waters are required to be highly specific and possibly highly sensitive for the determination of even low amounts of pollutants. The main problems encountered during the analysis are the separation of matrix components from the pollutants of interest and the achievement of low detection limits. Therefore an overview on different materials and techniques available for sample concentration and/or matrix removal will be provided and discussed according to the chemical characteristics of the pollutant that has to be enriched.

Solid-phase extraction of phenols

Sample preparation for phenol analysis using solid-phase extraction (SPE) is reviewed. The scope of the review has been restricted to the literature dealing with the analysis of phenols as the main objective. The use, advantages and disadvantages of silica sorbents, polymeric, functionalized, carbon-based and mixed available sorbents, when applied to the separation and preconcentration of phenols, as well as the available experimental devices, are discussed. Other aspects such as phenol derivatisation prior to SPE, solid-phase microextraction, matrix effects and the storage of phenols in SPE cartridges, have been also discussed.