A simple, cost-effective and rapid method for simultaneous determination of Strychnos nux-vomica alkaloids in blood and Ayurvedic medicines based on ultrasound-assisted dispersive liquid-liquid microextraction-thin-layer chromatography-image analysis.

A simple, rapid, cost-effective and green analytical method is developed based on ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) coupled to thin-layer chromatography (TLC)-image analysis for the simultaneous determination of two major alkaloids of Strychnos nux-vomica L i.e., strychnine and brucine. The method is composed of three steps, namely (i) US-DLLME by injecting a mixture of 100-µL chloroform (extraction solvent) and 1-mL methanol (disperser solvent) in 5 mL of aqueous sample, followed by ultrasonication and centrifugation, (ii) TLC of 20 µL of sedimented phase with methanol: ammonia (100:1.5, v/v) as the mobile phase and visualization under ultraviolet radiation (254 nm) and (iii) photography of TLC plate and quantification of spots by image analysis using freely available imageJ software (National Institute of Health, Bethesda, MD, USA). The limit of detection and limit of quantification for both alkaloids were found to be in the range of 0.12-0.15 and 0.36-0.48 µg/spot, respectively. The method was found to be linear in the range of 0.5-5 µg/spot with correlation coefficient (R2) of 0.995 and 0.997 for strychnine and brucine, respectively. The developed method was successfully applied for the determination of strychnine and brucine in Ayurvedic formulations and blood samples. The method does not require any sophisticated instrument and handling skills and can be adopted for rapid analysis of strychnine and brucine in forensic toxicological laboratories.

Rapid and sensitive analytical procedure for biomonitoring of organophosphate pesticide metabolites in human urine samples using a vortex-assisted salt-induced liquid-liquid microextraction technique coupled with ultra-high-performance liquid chromatography/tandem mass spectrometry.

RATIONALE: Organophosphate pesticides (OPPs) are the most commonly used insecticides around the world in various agricultural and domestic practices, and humans are frequently exposed to these hazardous insecticides that can lead to several chronic health effects. Therefore, a fast and sensitive analytical method is required for biomonitoring the markers of OPPs in humans for exposure estimation. In this study, a fast and sensitive analytical procedure was developed for the determination of the metabolites of OPPs in human urine samples. METHODS: Metabolites of OPPs were extracted from 2 mL of urine sample using a novel vortex-assisted salt-induced liquid-liquid microextraction (VA-SI-LLME) technique, and the preconcentrated metabolites were analyzed by ultra-high-performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS). Various factors affecting the efficiency of VA-SI-LLME were thoroughly investigated. RESULTS: The metabolites of OPPs exhibited very good linearity over the concentration range between 0.05 and 50 ng mL-1 with coefficient (r2 ) values ranging between 0.9986 and 0.9999. The method showed excellent sensitivity with detection limits ranging from 0.01 to 0.03 ng mL-1 and quantification limits from 0.03 to 0.05 ng mL-1 . The developed method was applied to the analysis of real samples and the recoveries ranged between 85.0 and 114.1% with related standard deviations <5%. CONCLUSIONS: The results showed the VA-SI-LLME/UHPLC/MS/MS method to be a simple, rapid, sensitive, and selective analytical procedure for the biomonitoring of the metabolites of OPPs in humans. This efficient and cost-effective analytical method could be a potential alternative method for the biomonitoring of the metabolites of pesticides in humans.

High throughput bar adsorptive microextraction: A novel cost-effective tool for monitoring benzodiazepines in large number of biological samples.

In this work, we propose an innovative high throughput (HT) apparatus using the bar adsorptive microextraction (BAµE) technique, which enables the simultaneous enrichment of up to 100 samples. This novel configuration was combined with microliquid desorption and high-performance liquid chromatography-diode array detection to monitor trace levels of eight benzodiazepines (diazepam, prazepam, bromazepam, oxazepam, lorazepam, alprazolam, temazepam and loflazepate) in biological samples. The proposed methodology was fully developed, optimized and validated, resulting in suitable intraday and interday precision (RSD ≤ 15%), with recovery yields ranging from 33.0% to 104.5%. The lower limits of quantification were between 20.0 and 100.0 µg L-1, using 1.0 mL of urine and 0.5 mL of plasma or serum samples. The application of the proposed methodology to real matrices resulted in average sample preparation time of around 2 min per sample, demonstrating that it is user-friendly, cost-effective and a rapid decision-making tool, whenever large number of samples are involved.

Emulsification microextraction of amphetamine and methamphetamine in complex matrices using an up-to-date generation of eco-friendly and relatively hydrophobic deep eutectic solvent.

In this study, a new extraction medium based on a quite bio-compatible and bio-degradable deep eutectic solvent comprising choline chloride and phenylethanol (ChCl: Ph-ETOH) was simply and cheaply synthesized at room temperature. At the next step, it was effectively utilized at the service of air agitated-emulsification microextraction (AA-EME) of two major amphetamine-type stimulants (ATSs) in human plasma and pharmaceutical wastewater pursued by high performance liquid chromatography-ultraviolet detection (HPLC-UV). This safe, effective, and rapid enrichment process based on the new low-density DES was easily practicable via a homemade extraction cell possessing a narrow neck and with no extra demand the emulsifier intermediates. Statistical study of main parameters effects using central composite design (CCD) combined with desirability function (DF) demonstrated that pH 12, 250 µL of extraction solvent, 8 air agitation cycles, and 5% of salt amount resulted in maximum extraction efficiencies (63-66%) with DF value close to 0.98. Under optimal conditions, wide linear dynamic ranges (LDRs) of 15.0-2000 and 8.0-3000 ng mL-1 with the determination coefficients (R2s) close to 0.99 were obtainable for amphetamine and methamphetamine, respectively. Low limits of detection (LODs) as well as relative standard deviations (%RSDs, n = 3) were found to be 2.0-5.0 ng mL-1 and 5.7-7.8%, respectively. Also, enrichment factors (EFs) were quantitative in the span of 47-50. On the other hand, satisfactory and accurate assessment at low levels close to therapeutic and toxic domains in human plasma sample and pharmaceutical wastewater was successfully obtained.

An effervescence-assisted switchable fatty acid-based microextraction with solidification of floating organic droplet for determination of fluoroquinolones and tetracyclines in seawater, sediment, and seafood.

This study developed a new effervescence-assisted switchable fatty acid-based microextraction combined with solidification of a floating organic-droplet (EA-SFAM-SFO) for simple and rapid determination of fluoroquinolones and tetracyclines in seawater, sediment, and seafood. Five medium-chain fatty acids (pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid) were tested as an extraction solvent, given their ability to change between hydrophobic and hydrophilic forms by pH adjustment. As nonanoic acid had the highest extraction recovery (>92%) for the six antibiotics and the ability to transform from liquid to a solidified floating state at low temperature, it was selected as the optimum extraction solvent. The prominent advantages of the newly developed method are: (1) reaction between the procedures salt and fatty acid changed extraction solvent from the hydrophobic to hydrophilic state; (2) bubbling with CO2 greatly increased the contact area between fatty acid and analytes resulting in improved extraction recovery; and (3) solidification of the fatty acid at a low temperature provided good separation and avoided the use of specialized equipment. Single-factor screening and optimization of the main factors were conducted using Plackett-Burman design and central composite design, respectively. The main parameters were optimized as follows: 258 µL fatty acid, 406 µL H2SO4 (98%), 3.9 min vortex time, and 354 µL Na2CO3 (2 mol L-1). Under optimized conditions, limits of detection were 0.007-0.113 µg L-1 or µg kg-1 and extraction recoveries were 82.2%-116.7% for six fluoroquinolone and tetracycline antibiotics in seawater, sediments, and seafood. The newly developed method combines the advantages of effervescence-assisted dispersion, hydrophobic/hydrophilic switchable solvent, and liquid/solid transition induced by low temperature. Overall, the new method is simple, quick, and environment-friendly with low detection limits and high recoveries. Thus, the newly developed method has excellent prospects for sample pretreatment and analysis of antibiotics in marine environmental and food samples. Graphical Abstract ᅟ.

Fast and easy extraction of antidepressants from whole blood using ionic liquids as extraction solvent.

This study aims to prove that ionic liquids (ILs) can be used as extraction solvents in a liquid-liquid microextraction, coupled to LC-MS/MS, for the quantification of a large group of antidepressants in whole blood samples. The sample preparation procedure consisted of adding 1.0mL aqueous buffer pH 3.0 and 60µL of IL (1-butyl-3-methylimidazolium hexafluorophosphate) to 1.0mL whole blood. Subsequently, a 5-min rotary mixing step was performed followed by centrifugation. The lower IL phase was collected, diluted 1:10 in methanol and 10µL was injected into the LC-MS/MS. The following analytes were included in the full-quantitative method: agomelatine, amitriptyline, bupropion, clomipramine, dosulepin, doxepin, duloxetine, escitalopram, fluoxetine, imipramine, maprotiline, mianserin, mirtazapine, nortriptyline, paroxetine, reboxetine, trazodone and venlafaxine. Selectivity was checked for 10 different whole blood matrices. Additionally, possible interferences of deuterated standards or other antidepressants were evaluated. Overall, no interferences were found. For each analyte a matrix-matched calibration curve was constructed (7 levels, n = 6), covering therapeutic and low toxic concentrations. Accuracy and precision were evaluated over eight days, at three concentration levels (n = 2). Bias, repeatability and intermediate precision results met with the proposed validation criteria, except for fluvoxamine, which was therefore only included in the semi-quantitative method. LOQs were set at the lowest calibrator concentration and LOD values were - for most analytes - within a range of 1-2ng/mL. Recoveries (RE) and matrix effects (ME) were evaluated for five types of donor whole blood, at two concentration levels. RE values were within a range of 53.11-132.98%. ME values were within a range of 61.92-123.24%. In conclusion, this study proves the applicability of ILs as extraction solvents for a large group of antidepressants in complex whole blood matrices.

Rapid and simple procedure for the determination of cathinones, amphetamine-like stimulants and other new psychoactive substances in blood and urine by GC-MS.

In the last few years an increasing number of new psychoactive substances (NPS), with different chemical structures (of which 37% are stimulants), have been released into the illicit drug market. Their detection and identification in biological samples is hence of great concern. The aim of this work was to develop a high-throughput and rapid method for the determination of different classes of stimulants (amphetamine-type stimulants, cathinones, phenethylamines and ketamine analogues) from blood and urine samples using GC-MS. The proposed method allows the almost simultaneous derivatization and extraction of analytes from biological samples in a very short time, by using hexyl chloroformate as derivatization agent. The extraction of analytes was performed by Dispersive Liquid Liquid Microextraction (DLLME), a very rapid, cheap and efficient extraction technique that employs microliter amounts of organic solvents. The chromatographic method allowed for the separation of 26 stimulants including positional isomers (3-MMC and 4-MMC). The method was validated on urine and blood samples with the ability to detect and quantify all analytes with satisfactory limits of detection (LODs) ranging between 1 and 10ng/mL, limits of quantification (LOQs) between 2 and 50ng/mL, selectivity and linearity (5-1000ng/mL). The method was then applied to real samples from forensic cases, demonstrating its suitability for the screening of a wide number of stimulants in biological specimens.

Rapid determination of some psychotropic drugs in complex matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

Simple and rapid determinations of some psychotropic drugs in some pharmaceutical wastewater and human plasma samples were successfully accomplished via the tandem dispersive liquid-liquid microextraction combined with high performance liquid chromatography-ultraviolet detection (TDLLME-HPLC-UV). TDLLME of the three psychotropic drugs clozapine, chlorpromazine, and thioridazine was easily performed through two consecutive dispersive liquid-liquid microextractions. By performing this convenient method, proper sample preconcentrations and clean-ups were achieved in just about 7min. In order to achieve the best extraction efficiency, the effective parameters involved were optimized. The optimal experimental conditions consisted of 100µL of CCl4 (as the extraction organic solvent), and the pH values of 13 and 2 for the donor and acceptor phases, respectively. Under these optimum experimental conditions, the proposed TDLLME-HPLC-UV technique provided a good linearity in the range of 5-3000ngmL-1 for the three psychotropic drugs with the correlation of determinations (R2s) higher than 0.996. The limits of quantification (LOQs) and limits of detection (LODs) obtained were 5.0ngmL-1 and 1.0-1.5ngmL-1, respectively. Also the proper enrichment factors (EFs) of 96, 99, and 88 for clozapine, chlorpromazine, and thioridazine, respectively, and good extraction repeatabilities (relative standard deviations below 9.3%, n=5) were obtained.

Determination of endocrine-disrupting chemicals in human milk by dispersive liquid-liquid microextraction.

AIM: Human populations are widely exposed to numerous so-called endocrine-disrupting chemicals, exogenous compounds able to interfere with the endocrine system. This exposure has been associated with several health disorders. New analytical procedures are needed for biomonitoring these xenobiotics in human matrices. A quick and inexpensive methodological procedure, based on sample treatment by dispersive liquid-liquid microextraction, is proposed for the determination of bisphenols, parabens and benzophenones in samples. RESULTS: LOQs ranged from 0.4 to 0.7 ng ml(-1) and RSDs from 4.3 to 14.8%. CONCLUSION: This methodology was satisfactorily applied in the simultaneous determination of a wide range of endocrine-disrupting chemicals in human milk samples and is suitable for application in biomonitoring studies.

Ultrasound-assisted dispersive liquid-liquid microextraction of tetracycline drugs from egg supplements before flow injection analysis coupled to a liquid waveguide capillary cell.

A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 µg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 µg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption.

Ultrasound assisted extraction combined with dispersive liquid-liquid microextraction (US-DLLME)-a fast new approach to measure phthalate metabolites in nails.

A new, fast, and environmentally friendly method based on ultrasound assisted extraction combined with dispersive liquid-liquid microextraction (US-DLLME) was developed and optimized for assessing the levels of seven phthalate metabolites (including the mono(ethyl hexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (5-OH-MEHP), mono(2-ethyl-5-oxohexyl) phthalate (5-oxo-MEHP), mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), monoethyl phthalate (MEP), and mono-benzyl phthalate (MBzP)) in human nails by UPLC-MS/MS. The optimization of the US-DLLME method was performed using a Taguchi combinatorial design (L9 array). Several parameters such as extraction solvent, solvent volume, extraction time, acid, acid concentration, and vortex time were studied. The optimal extraction conditions achieved were 180 µL of trichloroethylene (extraction solvent), 2 mL trifluoroacetic acid in methanol (2 M), 2 h extraction and 3 min vortex time. The optimized method had a good precision (6-17 %). The accuracy ranged from 79 to 108 % and the limit of method quantification (LOQm) was below 14 ng/g for all compounds. The developed US-DLLME method was applied to determine the target metabolites in 10 Belgian individuals. Levels of the analytes measured in nails ranged between <12 and 7982 ng/g. The MEHP, MBP isomers, and MEP were the major metabolites and detected in every sample. Miniaturization (low volumes of organic solvents used), low costs, speed, and simplicity are the main advantages of this US-DLLME based method. Graphical Abstract Extraction and phase separation of the US-DLLME procedure.

Development of continuous dispersive liquid-liquid microextraction performed in home-made device for extraction and preconcentration of aryloxyphenoxy-propionate herbicides from aqueous samples followed by gas chromatography-flame ionization detection.

In this study, a rapid, simple, and efficient sample preparation method based on continuous dispersive liquid-liquid microextraction has been developed for the extraction and preconcentration of aryloxyphenoxy-propionate herbicides from aqueous samples prior to their analysis by gas chromatography-flame ionization detection. In this method, two parallel glass tubes with different diameters are connected with a teflon stopcock and used as an extraction device. A mixture of disperser and extraction solvents is transferred into one side (narrow tube) of the extraction device and an aqueous phase containing the analytes is filled into the other side (wide tube). Then the stopcock is opened and the mixture of disperser and extraction solvents mixes with the aqueous phase. By this action, the extraction solvent is dispersed continuously as fine droplets into the aqueous sample and the target analytes are extracted into the fine droplets of the extraction solvent. The fine droplets move up through the aqueous phase due to its low density compared to aqueous phase and collect on the surface of the aqueous phase as an organic layer. Finally an aliquot of the organic phase is removed and injected into the separation system for analysis. Several parameters that can affect extraction efficiency including type and volume of extraction and disperser solvents, sample pH, and ionic strength were investigated and optimized. Under the optimum extraction conditions, the extraction recoveries and enrichment factors ranged from 49 to 74% and 1633 to 2466, respectively. Relative standard deviations were in the ranges of 3-6% (n = 6, C = 30 µg L(-1)) for intra-day and 4-7% (n = 4, C = 30 µg L(-1)) for inter-day precisions. The limits of detection were in the range of 0.20-0.86 µg L(-1). Finally the proposed method was successfully applied to determine the target herbicides in fruit juice and vegetable samples.

A highly efficient three-phase single drop microextraction technique for sample preconcentration.

A highly efficient three-phase single drop microextraction (SDME) method is presented by using an organic-aqueous compound droplet. A coupling microdevice is designed to produce compound droplets in different sizes conveniently. In this way, the volume ratio of organic phase to aqueous phase in a compound droplet can be significantly reduced. Good operability and droplet stability were observed during extraction under vigorous stirring conditions. Five statins were used as model compounds and spiked in river water and human serum samples to evaluate the analytical performance of the proposed method. By using a 1.2 µL toluene-aqueous compound droplet (volume ratio 0.2 : 1), a 350 to 1712 fold enrichment of statins was obtained within 4 minutes. The results indicate that the proposed method is a very rapid and efficient sample pretreatment method, and is promising for automated and high-throughput applications.

Rapid and sensitive analysis of nine fungicide residues in chrysanthemum by matrix extraction-vortex-assisted dispersive liquid-liquid microextraction.

A simple sample pretreatment for simultaneous determination of nine fungicides (triadimefon, picoxystrobin, kresoxim-methyl, diniconazole, epoxiconazole, trifloxystrobin, triticonazole, difenoconazole, and azoxystrobin) in chrysanthemum was developed using matrix extraction-vortex-assisted dispersive liquid-liquid microextraction (ME-VADLLME) prior to gas chromatography with electron capture detection. The target fungicides were firstly extracted with acetonitrile and cleaned with the mixture of primary secondary amine and graphite carbon black. The VADLLME procedure was performed by using toluene with lower density than water as the extraction solvent and the acetonitrile extract as the dispersive solvent, respectively. After vortexing and centrifugation, the fine droplet of toluene was collected on the upper of the mixed toluene/acetonitrile/water system using a 0.1-mL pipettor. Under the optimum conditions, the relative recoveries ranged from 73.9 to 95.1% with relative standard deviations of 3.5-9.7% for all of the analytes. The limits of detection were in the range of (0.005-0.05)×10(-3) mg kg(-1). In the proposed method, the ME step provides more effective cleanup for the chrysanthemum matrix, and VADLLME introduces higher sensitivity with the remarkable enrichment factors up to 88-fold compared with the conventional QuEChERS or SPE. The good performance has demonstrated that ME-VADLLME has a strong potential for application in the multi-residue analysis of complex matrices.

Molecularly imprinted polymer coupled with dispersive liquid-liquid microextraction and injector port silylation: a novel approach for the determination of 3-phenoxybenzoic acid in complex biological samples using gas chromatography-tandem mass spectrometry.

A novel analytical approach based on molecularly imprinted solid phase extraction (MISPE) coupled with dispersive liquid-liquid microextraction (DLLME), and injector port silylation (IPS) has been developed for the selective preconcentration, derivatization and analysis of 3-phenoxybenzoic acid (3-PBA) using gas chromatography-tandem mass spectrometry (GC-MS/MS) in complex biological samples such as rat blood and liver. Factors affecting the synthesis of MIP were evaluated and the best monomer and cross-linker were selected based on binding affinity studies. Various parameters of MISPE, DLLME and IPS were optimized for the selective preconcentration and derivatization of 3-PBA. The developed method offers a good linearity over the calibration range of 0.02-2.5ngmg(-1) and 7.5-2000ngmL(-1) for liver and blood respectively. Under optimized conditions, the recovery of 3-PBA in liver and blood samples were found to be in the range of 83-91%. The detection limit was found to be 0.0045ngmg(-1) and 1.82ngmL(-1) in liver and blood respectively. SRM transition of 271→227 and 271→197 has been selected as quantifier and qualifier transition for 3-PBA derivative. Intra and inter-day precision for five replicates in a day and for five, successive days was found to be less than 8%. The method developed was successfully applied to real samples, i.e. rat blood and tissue for quantitative evaluation of 3-PBA. The analytical approach developed is rapid, economic, simple, eco-friendly and possess immense utility for the analysis of analytes with polar functional groups in complex biological samples by GC-MS/MS.

Air-assisted liquid-liquid microextraction used for the rapid determination of organophosphorus pesticides in juice samples.

A novel and simple air-assisted liquid-liquid microextraction (AALLME) is introduced to analyze the organophosphorus pesticide (OPP) residues in fruit juice samples, using the gas chromatography-flame photometric detection (GC-FPD). In this method, fine extraction solvent drops are rapidly formed and dispersed into the aqueous samples, by using a syringe to withdraw and push-out the mixture of aqueous sample solution and extraction solvent several times. The parameters affecting the extraction efficiency were investigated including the type and volume of the extraction solvent, salt addition, extraction times, and pH. Under optimized conditions, the method showed good linearities with the correlation coefficients (γ) higher than 0.9988, and the sensitivity with the limits of detection (LODs) between 0.02µgL(-1) and 0.6µgL(-1). The method was applied to determine the OPP residues in juice samples and the recoveries were ranged from 79% to 113% with relative standard deviations (RSDs) of 0.4-9.9%. The feasibility of the method in real samples was proved.

Rapid analysis of aflatoxin M1 in milk using dispersive liquid-liquid microextraction coupled with ultrahigh pressure liquid chromatography tandem mass spectrometry.

A simple, rapid, and sensitive method based on simultaneous protein precipitation and extraction of aflatoxin M1 (AFM1) followed by dispersive liquid-liquid microextraction (DLLME) and ultrahigh pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis was developed for the determination of AFM1 in milk samples. In order to precipitate the proteins and extract AFM1 from milk, a sample pretreatment using acetonitrile and NaCl as the extraction/denaturant solvent and salting-out agent, respectively, was optimised. Subsequently, the acetonitrile (upper) phase, containing AFM1, was used as the disperser solvent in DLLME, and extractant (chloroform) and water were added in turn to the extract to perform the DLLME process. The main parameters affecting the extraction efficiency of the whole analytical procedure, such as acetonitrile volume, amount of salt, type and volume of extractant and water volume, were carefully optimised by experimental design. Under optimum conditions, the developed method provides an enrichment factor of 33 and detection and quantification limits (0.6 and 2.0 ng kg(-1), respectively) below the maximum levels imposed by current regulations for AFM1 in milk and infant milk formulae. Recoveries (61.3-75.3%) and repeatability (RSD < 10, n = 3), tested in different types of milk at four AFM1 levels, met the performance criteria required by EC Regulation No. 401/2006. Moreover, the matrix effect on the signal intensity of the analyte was negligible. The proposed method provides a rapid extraction and an accurate determination of AFM1 in milk and formula milk using a simple and inexpensive sample preparation procedure.

Development of an ionic liquid-based dispersive liquid-liquid microextraction method for the determination of nifurtimox and benznidazole in human plasma.

Dispersive ionic liquid-liquid microextraction combined with liquid chromatography and UV detection was used for the determination of two antichagasic drugs in human plasma: nifurtimox and benznidazole. The effects of experimental parameters on extraction efficiency-the type and volume of ionic liquid and disperser solvent, pH, nature and concentration of salt, and the time for centrifugation and extraction-were investigated and optimized. Matrix effects were detected and thus the standard addition method was used for quantification. This microextraction procedure yielded significant improvements over those previously reported in the literature and has several advantages, including high inter-day reproducibility (relative standard deviation=1.02% and 3.66% for nifurtimox and benznidazole, respectively), extremely low detection limits (15.7 ng mL(-1) and 26.5 ng mL(-1) for nifurtimox and benznidazole, respectively), and minimal amounts of sample and extraction solvent required. Recoveries were high (98.0% and 79.8% for nifurtimox and benznidazole, respectively). The proposed methodology offers the advantage of highly satisfactory performance in addition to being inexpensive, simple, and fast in the extraction and preconcentration of these antichagasic drugs from human-plasma samples, with these characteristics being consistent with the practicability requirements in current clinical research or within the context of therapeutic monitoring.

Rapid detection of haloarchaeal carotenoids via liquid-liquid microextraction enabled direct TLC MALDI-MS.

For the first time, we demonstrate the use of TiO2 nanoparticles (NPs) for enhancing the carotenoid production by the extremophilic haloarchea, Haloferax mediterranei. TiO2 NPs at optimal concentration of 375 mg/L results in a 95% increase in the production of carotenoid pigment compared to the control (no TiO2 NPs). The carotenoid pigments extracted from TiO2 NPs treated H. mediterranei cells, were separated using thin layer chromatography (TLC). The separated carotenoid spots were subjected directly for MALDI MS detection. To limit the sample diffusion during matrix addition on TLC plates, a simple bordering mode was exercised. Using this method we were able to detect the pigments successfully using MALDI-MS, directly from TLC plates after separation. In addition, we also applied the Pt NPs capped with ODT via Liquid-liquid microextraction (LLME) for extracting the pigment molecules from the halobacteria in MALDI-MS. These novel NP approaches possess numerous advantages such as; rapidity, ease in synthesis, high sensitivity and low cost.

Stereoselective quantitation of mecoprop and dichlorprop in natural waters by supramolecular solvent-based microextraction, chiral liquid chromatography and tandem mass spectrometry.

Liquid chromatography (LC)/tandem mass spectrometry (MS/MS) after supramolecular solvent-based microextraction (SUSME) was firstly used in this work for the enantioselective determination of chiral pesticides in natural waters. The method developed for the quantitation of the R- and S-enantiomers of mecoprop (MCPP) and dichlorprop (DCPP) involved the extraction of the herbicides in a supramolecular solvent (SUPRAS) made up of reverse aggregates of dodecanoic acid (DoA), analyte re-extraction in acetate buffer (pH = 5.0), separation of the target enantiomers on a chiral column of permethylated α-cyclodextrin under isocratic conditions, and detection of the daughter ions (m/z = 140.9 and 160.6 for MCPP and DCPP, respectively) using a hybrid triple quadrupole mass spectrometer equipped with an electrospray source operating in the negative ion mode. Similar recoveries (ca. 75%) and actual concentration factors (ca. 94) were obtained for both phenoxypropanoic acids (PPAs). The quantitation limits were 1 ng L(-1) for R- and S-MCPP, and 4 ng L(-1) for R- and S-DCPP, and the precision, expressed as relative standard deviation (n = 6) was in the ranges 2.4-2.7% ([R-MCPP] = [S-MCPP] = 5 ng L(-1) and [R-DCPP] = [S-DCPP] = 15 ng L(-1)) and 1.6-1.8% (100 ng L(-1) of each enantiomer). The SUSME-LC-MS/MS method was successfully applied to the determination of the enantiomers of MCPP and DCPP in river and underground waters, fortified at concentrations between 15 and 180 ng L(-1) at variable enantiomeric ratios (ER = 1-9).