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A fully automated integrated analytical platform that included continuous water sampling, sample preparation (extraction), and analysis for the determination of nine glucocorticoids was developed. A peristaltic pump was employed to deliver the water sample automatically. The subsequent sample preparation and analytical processes were also fully automated with the use of a commercial autosampler unit coupled to an ultrahigh performance liquid chromatography-tandem mass spectrometric system. The sample preparation step involved membrane bag liquid-phase microextraction in which a synergistic mixture of n-octanol enhanced with surfactant sodium dodecyl sulfate (SDS) (0.10% in n-octanol) was applied as the extractant phase. Addition of SDS helped to improve the extraction, increasing enrichment factors (EFs) by severalfold compared with the use of n-octanol only as extractant solvent. Various parameters to improve extraction efficiency were evaluated. They included percentage of surfactant used, sample pH, agitation rate, extraction duration, salting out effect, extraction temperature, and flow rate for sample introduction. Under the most favorable conditions, enrichment factors of between 32 and 189 were attained with relative standard deviations of

Sorptive extraction techniques have experienced increased popularity, but they face limitations in dynamic range and sensitivity. In this study, a new method combining stir bar sorptive extraction (SBSE) and thin-film solid-phase microextraction (TFSPME) was developed, and optimization for extraction temperature (70 °C) and time (120 min) was carried out. Polydimethylsiloxane (PDMS)-coated SBSE and PDMS/carboxen (PDMS/CAR)-coated TFSPME were used, and both headspace and direct immersion extraction modes were also studied. Using 40 selected volatile compounds, the combined method generally gave a wider linearity range with lower minimum limits (2 to 3 orders), satisfactory coefficient of determination (R2>0.980), and improved sensitivity when compared to SBSE-only or TFSPME-only techniques. Furthermore, despite the combined use of two extraction devices, the repeatability (

An automated bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) methodology in combination with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed for the determination of perfluorinated compounds (PFCs) in environmental aqueous matrices. Eight PFCs were considered, including perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid. Experimental parameters influencing extraction efficiency, such as number of hollow fibers in the BHF extraction device, type of extraction and desorption solvent, extraction conditions (stirring rate, temperature and duration), elution conditions and the salting out effect were examined. Under the most favourable conditions, enrichment factors of between 9 and 40 were achieved for the target compounds when extracting from 10 mL of sample. Good intra and inter-day precision were obtained with relative standard deviations of less than 12%. The linearity range investigated was between 5 and 10,000 ng L−1, with coefficients of determination (r2) ≥ 0.991. The developed method was applied for the UHPLC-MS/MS determination of environmental PFCs in industrial water discharge samples. The automation of BHF-LPME together with UHPLC-MS/MS rendered the method efficient, rapid and sensitive to determine PFCs, with the possibility of on-site real-time monitoring of contaminants in environmental waters.

A membrane-based solid phase extraction (SPE)-ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the determination of nine glucocorticoids in water. This new hybrid SPE approach involved the deposition of sodium dodecyl sulfate (SDS)-multi-walled carbon nanotubes (MWCNTs) on a piece of polypropylene membrane that served as the extraction device. Hitherto, such a sample preparation procedure has not been applied to the analysis of water contaminants before. The use of the surfactant helped to disperse the MWCNTs effectively so that they were coated uniformly onto the polypropylene membrane. This increased the overall extraction efficiency of the procedure. Characterisation of the SDS-MWCNTs material was performed using transmission electron microscopy and scanning electron microscopy. The membrane device did not require a pre-conditioning step. The most favourable extraction parameters such as type of surfactant, percentage of surfactant, type of desorption solvent, stirring rate, desorption time, extraction time, temperature, salting-out effect, pH and diameter of MWCNTs were obtained. The method showed linearity ranges from 0.2 to 100 ng mL−1 for hydrocortisone, dexamethasone, cortisone acetate and beclomethasone dipropionate, and 0.5–100 ng mL−1 for the rest of the analytes. Limits of detection ranging from 0.019 to 0.098 ng mL−1, and limits of quantification ranging from 0.065 to 0.326 ng mL−1, were obtained for the analytes. The intra-day repeatability was between 1.77 and 3.56% while the inter-day reproducibility was between 2.69 and 9.53%, respectively. The method was used to analyse glucocorticoids as contaminants in the canal water samples.

The present work describes the development of a novel fully automated online solid phase extraction (SPE) coupled with high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) using negative electrospray ionisation (ESI) for the simultaneous determination of six estrogens and six glucocorticoids in water. Filtered water samples (5mL) were preconcentrated on a HyperSep™ Retain PEP SPE cartridge, eluted in back-flush mode, and separated on an LC column before analysis by tandem mass spectrometry. The total analysis time for each sample was 17min. Different experimental parameters such as the type of online SPE cartridge, loading flow rate, and composition of methanol in the loading phase were optimised. The intra-day repeatability of method ranged from 1.48 to 9.68% for all analytes, and the inter-day reproducibility ranged from 2.03 to 8.63% for all analytes, except for dexamethasone at 11.95%. These were calculated based on the peak area responses of the targeted analytes spiked at 50ng/L in ultrapure water. The method also showed good linearity from 1 to 100ng/L, with the limits of detection (LODs) ranging from 0.16 to 2.14ng/L. The proposed method was applied to the analysis of municipal wastewater. This fully automated online SPE extraction coupled with LC-MS/MS method is effective and reliable to measure estrogens and glucocorticoids simultaneously due to its high throughput, relatively low solvent consumption, reusability of the online SPE cartridge, and reduction of manual labor.

A novel fully automated liquid-phase microextraction (LPME) procedure making use of a conical polypropylene membrane bag to hold the solvent, coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) with positive electrospray ionisation was developed to determine glucocorticoids (including cortisol, cortisone, dexamethasone, prednisone and prednisolone) in water. The solvent was a synergistic mixture of 10% v/v of ionic liquid, 1-butyl-3-methylimidazolium methylsulfate in n-octanol. The use of ionic liquid as an additive enhanced the extraction performance due to the favourable ionic and hydrogen bonding interactions with the analytes. Different experimental parameters such as the types of organic solvent as supported liquid membrane and ionic liquid, various composition of ionic liquid, volume of extractant phase, agitation time and speed, temperature of extraction were investigated. Under the most favourable extraction conditions, enrichment factors of 49.4-83.1 were obtained for the target compounds with relative standard deviations of10%. The intra-day repeatability of the method ranged from 4.23 to 6.42% and the inter-day reproducibility ranged from 6.87 to 9.20%. Good linearity 0.05-50 ng mL

A bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) approach has been developed for the ultra-high performance liquid chromatography tandem mass spectrometric determination of estrone, 17β-estradiol, estriol, and 17α-ethinylestradiol. The BHF was dipped in n-octanol to impregnate only the wall pores of the hollow fibers without deliberate loading of extractant solvent in the lumens, before placing it in the sample for extraction. Parameters influencing extraction efficiency, such as number of bundled hollow fibers, type of extraction and desorption solvent, agitation mode, extraction temperature and duration, and the salting out effect were examined. Under the most favourable experimental conditions, the enrichment factors were between 77 and 137-fold for the target compounds. The developed method offered high sensitivity and reproducibility. Low limits of detection and limits of quantification were achieved, i.e., between 0.251 and 0.440ng/L, and 0.995 and 1.82ng/L, respectively. Good intra and inter-day precision were obtained with relative standard deviations (RSDs) of less than 9%. BHF-LPME provided a new perspective on using membrane solvent-supported hollow fiber-mediated LPME. Raman spectroscopy was also introduced in this study to reaffirm that the polypropylene BHF did not play any role in the extraction; only the solvent was responsible.