Simultaneous determination of selected endocrine disrupters (pesticides,phenols and phthalates) in water by in-field solid-phase extraction (SPE) using the prototype PROFEXS followed by on-line SPE (PROSPEKT) and analysis by liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry

In this study, a new procedure, based on on-line solid-phase extraction (SPE) and analysis by liquid-chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS), has been developed for the simultaneous, multianalyte determination of 21 selected pesticides, phenols and phthalates in water. SPE was carried out on polymeric PLRP-s cartridges by percolating 20 mL-samples. For sample preconcentration, the performance of a prototype programmable field extraction system (PROFEXS) was evaluated against the commercial laboratory bench Prospekt system used for method development. The Profexs is designed for the automated on-site sampling, SPE preconcentration, and storage of up to 16 samples in SPE cartridges. These cartridges are further eluted and on-line analyzed with the Prospekt coupled to the chromatographic system. In the optimized method, where completely on-line SPE-LC-MS analysis of the samples is carried out with the Prospekt in the laboratory, detection limits lower than 100 ng/L, and satisfactory precision (relative standard deviations <25%) and accuracies (recovery percentages >75%) were obtained for most investigated compounds from the analysis of spiked Milli-Q water. The extraction efficiency achieved with the Profexs was comparable to that of the Prospekt for most compounds and somewhat lower for the most apolar analytes, probably due to adsorption on the pump filters. The completely on-line optimized method was applied to the analysis of surface water, ground water and drinking water from a waterworks in Barcelona. Some pesticides and phenols were found in both surface water and groundwater at ng/L or µg/L levels, but not in the final drinking water. Di(2-ethylhexyl)phthalate (DEHP) was present in all samples investigated, including blanks. To the author's knowledge, this is the first work describing the application of a fully automated on-line SPE-LC-MS method for the simultaneous analysis of pesticides, phenols, and phthalates in water, and the second one that examines the possibilities of the prototype Profexs for automated on-site SPE preconcentration of organic pollutants from water samples.     

Simple field‐based automated dispersive liquid–liquid microextraction of trace level phthalate esters in natural waters with gas chromatography and mass spectrometric analysis

A small, simple, and field‐based automated dispersive liquid–liquid microextraction method followed by gas chromatography mass spectrometric analysis was developed for trace level phthalate esters analysis in natural waters. With a single syringe pump that is coupled with a multiposition valve, the whole extraction procedure including cleaning, sampling, mixing of extractant and disperser solvents, extraction, phase separation, and analytes collection was carried out in a totally automated way with a sample throughput of 21 h^?1. Key factors, such as type and ratio of the extractant and disperser solvent, aspiration flow rate, extraction time, and matrix effect, were thoroughly investigated. Under the optimum conditions, linearity was found in the range from 0.03 to 60 μg/L. Limits of detection ranged from 0.0015 to 0.003 μg/L. Enrichment factors were in a range of 106–141. Reproducibility and recoveries were assessed by testing a series of three natural water samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied in analysis of real surface waters. The developed system is inexpensive, light (2.6 kg), simple to use, applicable in the field, with high sample throughput, and sensitive enough for trace level phthalate esters analysis in natural waters.     

Automated high throughput analysis of antiretroviral drugs in dried blood spots

For therapeutic drug monitoring in remote settings, dried blood spots (DBS) are particularly advantageous, as blood sample collection and handling is uncomplicated. The aim of this study was to develop and validate an automated extraction method for the analysis of nevirapine, efavirenz and lopinavir in DBS samples. Automated extraction was performed with methanol : water (70 : 30 v /v ), using a DBS‐MS 500 autosampler coupled to a liquid chromatography tandem mass spectrometry system. The autosampler used digital images of each DBS to position the extraction head, sprayed 10 μl of internal standard onto each DBS and extracted a 4‐mm disc (Ø) from the centre of each spot by unilateral flow using 25‐μl extraction solvent. The analytes were baseline separated on a pentafluorophenyl column and analysed by using electrospray ionization with multiple reaction monitoring in positive polarity mode for nevirapine and lopinavir and in negative mode for efavirenz. The method was linear between 10 and 10 000 ng/ml for all analytes. Automated sample extraction resulted in consistent recoveries (nevirapine: 70 ± 6%, efavirenz: 63 ± 11% and lopinavir: 60 ± 10%) and matrix effects between different donors and concentration levels. Intra‐day and inter‐day accuracy and precision deviations were ≤15%. Manual and automated extractions of DBS samples collected within the framework of an adherence assessment study in rural Tanzania showed good agreements with deviations of less than 10%. Our study highlights that therapeutic drug monitoring samples obtained in the resource‐constrained setting of rural Africa can be reliably determined by automated extraction of DBS. Overall, automatization improved method sensitivity and facilitates analysis of large sample numbers. Copyright © 2017 John Wiley & Sons, Ltd.     

Concentration of chlorophenols in water to dialkyated catinonic surfactant-silica gel admicelles

Chlorophenols including monochlorophenol, dichlorophenol, trichlorophenol, tetrachlorophenol, and pentachlorophenol in water were extracted into dialkylated cationic surfactant-silica gel admicelles. The dialkylated cationic surfactants such as didecyldimethylammonium bromide (DC10) and didodedyldimethylammonium bromide (DC12) sorbed on silica gel surfaces to form admicelles at pH 9. Approximately 200mg of DC10 was quantitatively sorbed on 1g of silica gel. The sorption further increased by further addition of DC10. This is in contrast to the fact that the maximum sorption of mono-alkylated cetyltrimethyammonium chloride (CTAC) was only ca. 100mg. Based on the fluorescent spectra of a molecular probe, N-phenyl-1-naphthylamine, DC10- and DC12-silica gel admicelles were more hydrophobic than CTAC-silica gel admicelles. The extents of the extraction of chlorophenols into DC10-silica gel admicelles were greater than those into CTAC-silica gel admicelles. However, the extractions to DC12-silica gel admicelles were insufficient due to leakage of DC12 vesicles. Consequently, DC10-silica gel admicelles were the most adequate for concentrating chlorophenols in water. An admicelle column was prepared by passing aqueous buffer solution of DC10 through a Bond Elut Jr. silica gel solid-phase extraction cartridge. It was successfully applied to the 500-fold concentration of chlorophenols including hydrophilic mono-substituted chlorophenol in water samples prior to their HPLC analysis.     

Exploiting sequential injection analysis with lab-at-valve (LAV) approach for on-line liquid-liquid micro-extraction spectrophotometry

Sequential injection analysis (SIA) with lab-at-valve (LAV) approach for on-line liquid-liquid micro-extraction has been exploited. Sample, reagent and organic solvent were sequentially aspirated into a coil attached to a central port of a conventional multiposition selection valve, where the extraction process was performed. The aqueous and organic phases were separated in a conical separating chamber LAV unit attached at one port of the valve. The organic phase containing extracted product was then monitored spectrophotometrically. The system offers a novel alternative on-line automated extraction in a micro-scale and has been successfully demonstrated for the assays of diphenhydramine hydrochloride (DPHH) in pharmaceutical preparations and anionic surfactant in water samples.     

Analysis of benzene ethylamine derivatives in urine using the programmable dynamic liquid-phase microextraction (LPME) device

An automated LPME device for a dynamic LPME method was manufactured and its extraction efficiency was tested using spiked urine samples. The developed home-made LPME device was a programmable automated syringe dispenser to overcome deteriorating precision and difficulties in manually manipulating the plunger repeatedly. To establish the optimum parameters for benzene ethylamines, the effects of sampling volume, solvent volume, pH, salt-effect, choice of solvents, plunger speed, and number of samplings were investigated. Good repeatabilities for the extraction of mephentermine, ephedrine, methoxyphenamine, selegiline, and bupropion were obtained and the RSD values were 2.4, 1.9, 1.3, 1.6 and 1.5% at a concentration of 3 microg mL(-1) in spiked urine samples, respectively. The limit of detection was below 0.05 microg mL(-1) for the investigated drugs. This developed device for LPME analysis gave good validation results and improved convenience.     

In Memoriam of Ernő Pungor 1923–2007

This review aims to present recent accomplishments in flow injection analysis by the use of surfactants, micellar systems, and cloud point extractions. The analysis of metals, pharmaceuticals, environmental samples, and samples of biological interest, as well as, surfactants themselves is covered. General considerations of micellar systems and cloud point extractions are briefly reviewed along with references to works that cover these fundamentals in greater detail. Highlights of the current work in these areas are given to stress the advantages of employing surfactants as an analytical tool to facilitate the experimental uses of these reagents and their future possibilities in green chemistry and automated laboratory techniques.     

Hydrodistillation–liquid-phase microextraction for infrared analysis of food

A combination of hydrodistillation (HD) and liquid-phase microextraction (LPME) has been successfully developed to improve sensitivity and selectivity in attenuated total reflection (ATR) infrared determination of semivolatile organic compounds from high water content plant and food matrices contributing to solve extraction efficiency drawbacks. The HD sampling facilitates the extraction of the semivolatile analytes from the sample matrix compared to headspace sampling, while the liquid-phase microextraction using a water immiscible solvent allows analyte preconcentration prior to ATR analysis. Experimental conditions regarding temperature and time of extraction, water effect and number of consecutive extractions have been deeply studied. The qualitative and quantitative capability of the developed methodology has been evaluated through the identification of the main semivolatile substances in plant and food matrices like spices and citrus peels and the effect of different drying treatments on the volatile composition of rosemary samples was studied through the quantification of camphor and eucalyptol.     

Multiple solid-phase microextraction of drugs from human urine

Summary The applicability of multiple solid-phase microextraction to the analysis of biological samples has been shown by extraction of a variety of compounds from human urine. Multiple solid-phase microextraction, in which extraction and desorption are repeated and analytes are collected at the head of the separation system before starting the analysis, has been combined with gas chromatography. Amphetamine, lidocaine, procaine, and mepivacaine were extracted from buffered urine by direct immersion of a 100-μm polydimethylsiloxane-coated fiber, to demonstrate that multiple SPME can be used for analytes with different extraction behavior. Multiple solid-phase microextraction was optimized for high extraction yield or short extraction time. For example, the total sample-handling time (extraction plus desorption) for the extraction of mepivacaine from urine can be reduced from approximately 60 min (one extraction) to 33 min (three extractions) without reducing extraction yield. In addition, the extraction yield for mepivacaine can be increased from 14.6% (one extraction) to 27.0% (five extractions) within the same total sample handling time of approximately 60 min. A good match between theoretical and experimental values was obtained. Chromatograms are shown to illustrate the usefulness of the procedure.     

Application of a new focused microwave technology with species-specific isotope dilution analysis for the quantitative extraction of organometallic contaminants in solid environmental matrices

A new self-tuning single-mode-focused microwave technology has been evaluated in this work to perform the quantitative routine extraction of organometallic species from solid matrices of environmental interest. Species-specific isotope dilution analysis has been employed to better investigate the real influence of the microwave-assisted extractions on the final results. The advantages of such methodology in comparison with other established microwave units for the routine speciation analysis of organomercury and organotin compounds are discussed (such as the capability of using disposable glass vials, a self-tuning mode to provide an accurate control of the temperature and pressure inside of the vials, and the possibility of performing automated sequence of extractions with low sample size). The results obtained in this work demonstrated that such technology provides a fast and reliable quantitative extraction of the organometallic species in a wide range of extraction conditions even when the multi-elemental (Sn and Hg) species-specific determination is carried out.     

Automated thermochemolysis reactor for detection of Bacillus anthracis endospores by gas chromatography–mass spectrometry

An automated sample preparation system was developed and tested for the rapid detection of Bacillus anthracis endospores by gas chromatography–mass spectrometry (GC–MS) for eventual use in the field. This reactor is capable of automatically processing suspected bio-threat agents to release and derivatize unique chemical biomarkers by thermochemolysis (TCM). The system automatically controls the movement of sample vials from one position to another, crimping of septum caps onto the vials, precise delivery of reagents, and TCM reaction times and temperatures. The specific operations of introduction of sample vials, solid phase microextraction (SPME) sampling, injection into the GC–MS system, and ejection of used vials from the system were performed manually in this study, although they can be integrated into the automated system. Manual SPME sampling is performed by following visual and audible signal prompts for inserting the fiber into and retracting it from the sampling port. A rotating carousel design allows for simultaneous sample collection, reaction, biomarker extraction and analysis of sequential samples. Dipicolinic acid methyl ester (DPAME), 3-methyl-2-butenoic acid methyl ester (a fragment of anthrose) and two methylated sugars were used to compare the performance of the autoreactor with manual TCM. Statistical algorithms were used to construct reliable bacterial endospore signatures, and 24 out of 25 (96%) endospore-forming Bacillus species were correctly identified in a statistically designed test.     

Analysis of musk fragrances in environmental samples

The methods for the determination of polycyclic and nitro-aromatic musk compounds in comparison to other fragrances such as OTNE ([1,2,3,4,5,6,7,8-octahydro-2,3,8,8-tetramethylnaphthalen-2yl] ethan-1-one) as well as those for the respective metabolites are described in this contribution. It covers instrumental aspects, as well as procedures for extraction and clean-up. Protocols for the determination of musks in water, sludge, biota, and air are summarised and discussed. Extractions by means of solid phase extraction (SPE) and liquid-liquid extraction (LLE) in case of water samples are evaluated for the diverse applications, i.e., wastewater, surface water and seawater. While LLE is preferred for the analysis of bulk for transport studies and for special process studies SPE might be worth the effort. Considering sludge, sediment and biota samples, drying and successive accelerated solvent extraction. Soxhlet extractions as well as cold column extractions are being compared. ASE has proven to be the most exhaustive and quickest to adopt method. Clean-up by means of size exclusion chromatography and silica sorption chromatography with their respective merits and problems are demonstrated. Suggestions for routine and research analysis are also given. The diverse approaches for enantioselective separations are discussed in respect to HHCB, AHTN and the metabolite HHCB-lactone. The power of two-dimensional (GCxGC) approaches is demonstrated considering the various production impurities (isomers) of the two polycyclic musks with the highest usage rates. The usage of tandem mass spectrometry and high resolution mass spectrometry for the same purpose is also discussed. The identification of an isomer of the HHCB-transformation product HHCB-lactone from wastewater treatment that has not been described in the literature before, is presented as well. Additionally some ideas to make the REACh process more efficient are discussed considering the special experiences from the development of the analysis of musk fragrances in the environment.     

Pressurised fluid extraction (PFE) as an alternative general method for the determination of pesticide residues in rape seed

A pressurised fluid extraction (PFE) multi-method has been developed for the determination of pesticide residues in rape seed. The method was validated for 25 different pesticides and metabolites. The reliability and efficiency of PFE for extracting pesticide residues from rape seed was investigated. The traditional extraction solvent, hexane saturated with acetonitrile, was used at elevated temperature and pressure. With increased temperature, the extraction kinetics were improved but at the same time more co-extractives were obtained in the form of lipids. When 1 g of rape seed was extracted at temperatures from 60 degrees C to 150 degrees C, the lipid content extracted was found to be as high as 17-26%. An additional clean-up step was therefore required and lipid co-extractives were effectively removed by gel permeation chromatography. The interpretation of the chromatograms and the quantification of the results were satisfactorily improved by the removal of interfering lipids. The developed method was used to extract vinclozolin and iprodione from incurred samples, resulting in a concentration in accordance with the results using conventional liquid-liquid extraction (LLE) between hexane and acetonitrile and also supercritical fluid extraction (SFE) using carbon dioxide. The results of the present study suggest that PEE is a good alternative extraction technique for the determination of pesticide residues in oil seed. Despite the necessity for a lipid-removal clean-up step, the PFE technique facilitated the extraction process by faster extractions and the possibility of automated analysis.     

Dodecylsulfate-doped polypyrrole film prepared by electrochemical fiber coating technique for headspace solid-phase microextraction of polycyclic aromatic hydrocarbons

The electrochemical fiber coating (EFC) technique was used for the preparation of dodecylsulfate-doped polypyrrole (PPy-DS), and applied as a new fiber for solid-phase microextraction (SPME) procedures. PPy-DS film was directly electrodeposited on the surface of a platinum wire from an aqueous solution containing pyrrole and sodium dodecylsulfate, using cyclic voltammetry (CV). The effect of polymerization conditions and type of dopants on the thermal stability, adhesion and extraction characteristics of the fiber were investigated. The electron microscopy imaging of PPy-DS film suggested that the surface fiber coating was well-distributed with a porous structure. The fiber coating can be prepared easily in a reproducible manner, and it is inexpensive and has a stable performance at high temperatures (up to the 300 degrees C). The extraction properties of the fiber to eight polycyclic aromatic hydrocarbons (PAHs) were examined, using a headspace-SPME (HS-SPME) device coupled with gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The results revealed study shows that PPy-DS as a SPME fiber coating is suitable for the successful extraction of PAHs. The effects of the extraction parameters including exposure time, sampling temperature, salt concentration, and stirring rate on the extraction efficiency have been studied. A satisfactory reproducibility for extractions from spiked water samples at PPb-level with R.S.D. < 7.6% (n = 7) was obtained. The calibration graphs were linear in the range of 0.5-100ng ml(-1) and detection limits for the selected PAHs were between 0.05-0.16 ng ml(-1). Comparing the HS-SPME results for extraction and determination of PAHs using PPy-DS fiber with the corresponding literature data using PDMS fiber shows that the proposed fiber has a better detection limit for low molecular weight PAHs. The life span and stability of PPy-DS fiber is good and it can be used more than 50 times at 250 degrees C without any significant change in sorption properties.     

Lab in a syringe: fully automated dispersive liquid–liquid microextraction with integrated spectrophotometric detection

A new approach for the integration of various analytical steps inside a syringe (Lab in a Syringe) is presented. Fully automated dispersive liquid-liquid microextraction with integrated spectrophotometric detection is carried out in-syringe using a very simple instrumental setup. The lighter-than-water organic droplets released in the extraction step accumulate at the head of the syringe, where two optical fibers are placed on both sides of the syringe, facing each other and enabling the in situ quantification of the extracted compounds. By this, monitoring of the progressively accumulating droplet in the head of the syringe was further possible. In this first report, the developed instrumental setup has been applied to the determination of the dye rhodamine B in water samples and soft drinks. The main parameters influencing the extraction such as the selection of the extractant and disperser solvents, extractant/disperser and organic/water phase ratios, pH of the aqueous phase, extraction flow rates, and extraction time were investigated. Under the selected conditions, rhodamine B was quantified in a working range of 0.023-2 mg L(-1) with a limit of detection of 0.007 mg L(-1). Good repeatability values of up to 3.2% (RSD) were obtained for ten consecutive extractions. The enrichment factor for a 1 mg L(-1) rhodamine B standard was 23, and up to 51 extractions were accomplished in 1 h.     

Screening and determination of drugs in human saliva utilizing microextraction by packed sorbent and liquid chromatography–tandem mass spectrometry

This study presents a new method for collecting and handling saliva samples using an automated analytical microsyringe and microextraction by packed syringe (MEPS). The screening and determination of lidocaine in human saliva samples utilizing MEPS and liquid chromatography–tandem mass spectrometry (LC‐MS/MS) were carried out. An exact volume of saliva could be collected. The MEPS C₈‐cartridge could be used for 50 extractions before it was discarded. The extraction recovery was about 60%. The pharmacokinetic curve of lidocaine in saliva using MEPS‐LC‐MS/MS is reported. Copyright © 2013 John Wiley & Sons, Ltd.     

Rapid analysis of ultraviolet filters using dispersive liquid–liquid microextraction coupled to headspace gas chromatography and mass spectrometry

An ionic‐liquid‐based in situ dispersive liquid–liquid microextraction method coupled to headspace gas chromatography and mass spectrometry was developed for the rapid analysis of ultraviolet filters. The chemical structures of five ionic liquids were specifically designed to incorporate various functional groups for the favorable extraction of the target analytes. Extraction parameters including ionic liquid mass, molar ratio of ionic liquid to metathesis reagent, vortex time, ionic strength, pH, and total sample volume were studied and optimized. The effect of the headspace temperature and volume during the headspace sampling step was also evaluated to increase the sensitivity of the method. The optimized procedure is fast as it only required ∼7–10 min per extraction and allowed for multiple extractions to be performed simultaneously. In addition, the method exhibited high precision, good linearity, and low limits of detection for six ultraviolet filters in aqueous samples. The developed method was applied to both pool and lake water samples attaining acceptable relative recovery values.     

Polydimethylsiloxane/polypyrrole stir bar sorptive extraction and liquid chromatography (SBSE/LC-UV) analysis of antidepressants in plasma samples

A new polymeric coating consisting of a dual-phase, polydimethylsiloxane (PDMS) and polypyrrole (PPY) was developed for the stir bar sorptive extraction (SBSE) of antidepressants (mirtazapine, citalopram, paroxetine, duloxetine, fluoxetine and sertraline) from plasma samples, followed by liquid chromatography analysis (SBSE/LC-UV). The extractions were based on both adsorption (PPY) and sorption (PDMS) mechanisms. SBSE variables, such as extraction time, temperature, pH of the matrix, and desorption time were optimized, in order to achieve suitable analytical sensitivity in a short time period. The PDMS/PPY coated stir bar showed high extraction efficiency (sensitivity and selectivity) toward the target analytes. The quantification limits (LOQ) of the SBSE/LC-UV method ranged from 20 ng mL⁻¹ to 50 ng mL⁻¹, and the linear range was from LOQ to 500 ng mL⁻¹, with a determination coefficient higher than 0.99. The inter-day precision of the SBSE/LC-UV method presented a variation coefficient lower than 15%. The efficiency of the SBSE/LC-UV method was proved by analysis of plasma samples from elderly depressed patients.     

Influence of extraction methodologies on the analysis of five major volatile aromatic compounds of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) grown in Thailand

This paper deals with the systematic comparison of extraction of major volatile aromatic compounds (VACs) of citronella grass and lemongrass by classical microhydrodistillation (MHD), as well as modern accelerated solvent extraction (ASE). Sixteen VACs were identified by GC/MS. GC-flame ionization detection was used for the quantification of five VACs (citronellal, citronellol, geraniol, citral, and eugenol) to compare the extraction efficiency of the two different methods. Linear range, LOD, and LOQ were calculated for the five VACs. Intraday and interday precisions for the analysis of VACs were determined for each sample. The extraction recovery, as calculated by a spiking experiment with known standards of VACs, by ASE and MHD ranged from 64.9 to 91.2% and 74.3 to 95.2%, respectively. The extraction efficiency of the VACs was compared for three solvents of varying polarities (hexane, dichloromethane, and methanol), seven different temperatures (ranging from 40 to 160 degrees C, with a gradual increment of 20 degrees C), five time periods (from 1 to 10 min), and three cycles (1, 2, and 3 repeated extractions). Optimum extraction yields of VACs were obtained when extractions were carried out for 7 min with dichloromethane and two extraction cycles at 120 degrees C. The results showed that the ASE technique is more efficient than MHD, as it results in improved yields and significant reduction in extraction time with automated extraction capabilities.