Microextraction By Packed Sorbent Research Articles

Determination of lamotrigine in human plasma and saliva using microextraction by packed sorbent and high performance liquid chromatography–diode array detection: An innovative bioanalytical tool for therapeutic drug monitoring

A ground-breaking high-performance liquid chromatography-diode array detection method based on microextraction by packed sorbent (MEPS) as sample preparation approach is described herein for determination of lamotrigine (LTG), a narrow therapeutic index drug, in human plasma and saliva. MEPS variables and chromatographic conditions were optimized to achieve appropriate selectivity and sensitivity using small sample volumes (100μL). The chromatographic separation of LTG and chloramphenicol [internal standard (IS)] was accomplished in <5min on a C18-column, at 35°C, using a mobile phase composed by acetonitrile/methanol/water-triethylamine 0.3% at pH6.0 (13:13:74, v/v/v) pumped isocratically at 1mL/min. LTG and IS were detected at 215nm. A good linearity was obtained for LTG (r2≥0.9936) in the range of 0.1–20μg/mL in plasma and saliva, with the limit of quantification of 0.1μg/mL. The method was shown to be precise (RSD ≤14.5%) and accurate (bias±13.4%), and the absolute recovery ranged from 64.9% to 73.6%. The stability of LTG was demonstrated in plasma and saliva samples in all studied conditions. The proposed assay was applied to the analysis of real human plasma and saliva samples from epilepsy patients under LTG therapy and the results support its usefulness for therapeutic drug monitoring.

Sensitive determination of THC and main metabolites in human plasma by means of microextraction in packed sorbent and gas chromatography-tandem mass spectrometry.

Cannabis is one of the most available and consumed illicit drug in the world and its identification and quantification in biological specimens can be a challenge given its low concentrations in body fluids. The present work describes a fast and fully validated procedure for the simultaneous detection and quantification of ▵9-tetrahydrocannabinol (▵9_THC) and its two main metabolites 11-hydroxy ▵9_tetrahydrocannabinol (11-OH-THC) and 11-nor-9-carboxy-▵9- tetrahydrocannbinol (THC-COOH) in plasma samples using microextraction by packed sorbent (MEPS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). A small plasma volume (0.25mL) pre-diluted (1:20), was extracted with MEPS M1 sorbent as follows: conditioning (4 cycles of 250μL methanol and 4 cycles of 250μL 0.1% formic acid in water); sample load (26 cycles of 250μL); wash (100μL of 3% acetic acid in water followed by 100μL 5% methanol in water); and elution (6 cycles of 100μL of 10% ammonium hydroxide in methanol). The procedure allowed the quantification of all analytes in the range of 0.1-30ng/mL. Recoveries ranged from 53 to 78% (THC), 57 to 66% (11-OH-THC) and 62 to 65% (THC-COOH), allowing the limits of detection and quantification to be set at 0.1ng/mL for all compounds. Intra-day precision and accuracy revealed coefficients of variation (CVs) lower than 10% at the studied concentrations, with a mean relative error within±9%, while inter-day precision and accuracy showed CVs lower than 15% for all analytes at the tested concentrations, with an inaccuracy within±8%.

Use of microextraction by packed sorbent directly coupled to an electron ionization single quadrupole mass spectrometer as an alternative for non-separative determinations.

Sometimes it is not necessary to separate the individual compounds of a sample to resolve an analytical problem, it is enough to obtain a signal profile of the sample formed by all the components integrating it. Within this strategy, electronic noses based on the direct coupling of a headspace sampler with a mass spectrometer (HS-MS) have been proposed. Nevertheless, this coupling is not suitable for the analysis of non-volatile compounds. In order to propose an alternative to HS-MS determinations for non-volatile compounds, here we present the first 'proof of concept' use of the direct coupling of microextraction by packed sorbents (MEPS) to a mass spectrometer device using an electron ionization (EI) and a single quadrupole as ionization source and analyzer, respectively. As target compounds, a set of analytes with different physic-chemical properties were evaluated (2-ethyl-1-hexanol, styrene, 2-heptanone, among others). The use of MEPS extraction present many advantages, such as it is fast, simple, easy to automate and requires small volumes of sample and organic solvents. Moreover, MEPS cartridges are re-usable as samples can be extracted more than 100 times using the same syringe. In order to introduce into the system all the elution volume from the MEPS extraction, a programmable temperature vaporizer (PTV) is proposed as the injector device. Results obtained with the proposed methodology (MEPS-PTV/MS) were compared with the ones obtained based on the separative scheme, i.e. using gas chromatography separation (MEPS-PTV-GC/MS), and both methods provided similar results. Limits of detection were found to be between 3.26 and 146.6μgL-1 in the non-separative scheme and between 0.02 and 1.72μgL-1 when the separative methodology was used. Repeatability and reproducibility were evaluated with values below 17% in all cases.

Development and validation of a MEPS-UHPLC-PDA method for determination of ulifloxacin in human plasma and urine of patients with peripheral arterial disease

A novel sensitive analytical method based on the use of a semi-automatic microextraction by packed sorbents (MEPS) techniques combined with ultra high-performance liquid chromatography (UHPLC) with PDA detection has been developed and validate for the analysis of ulifloxacin, the active metabolite of prulifloxacin using danofloxacin as internal standard in human plasma and urine. Different experimental parameters were optimized and validated according to international guidelines. Complete separation of the analytes was achieved with a Waters BEH C18 (50×2.1mm I.D., 1.7μm particle size) analytical column, a mixture of 10mM ammonium acetate (pH 3.0) (A) with and acetonitrile (B) both containing 1% triethylamine were used as mobile phase, at a flow rate of 0.6mL/min in gradient elution, and detection wavelength of 272nm. This method is linear in concentration range of 0.02–10.0μg/mL for plasma and urine, respectively. The limit of quantitation was 20ng/mL for the two fluids. The recoveries of the method were 95% for ulifloxacin in human plasma and urine and 95.5% for the internal standard. Intra- and inter- assay precision and accuracy for ulifloxacin were lower than 10% at all tested concentrations. The proposed method was successfully applied to measure plasma and urine concentrations of ulifloxacin in patients suffering from Peripheral Arterial Disease and for pharmacokinetics study.

Optimisation by response surface methodology of microextraction by packed sorbent of non steroidal anti-inflammatory drugs and ultra-high performance liquid chromatography analysis of dialyzed samples

A procedure based on microextraction by packed sorbent (MEPS) followed by ultra-high performance liquid chromatography (UHPLC) with photodiode array (PDA) detection has been developed for the analysis of seven selected non steroidal anti-inflammatory drugs (NSAIDs) in human dialysates. The influence on MEPS efficiency of pH of the sample, pH of the washing solvent and methanol content in the hydro-alcoholic elution mixture has been investigated by response surface methodology based on a Box-Behnken design of experiments. Among the above factors, pH of sample is the variable that mostly influences MEPS recovery. UHPLC separation of the NSAIDs was completed within less than 4min under isocratic elution conditions on a Fortis SpeedCore C18 column (150×4.6mm I.D., 2.6μm) using acetonitrile-phosphate buffer as the mobile phase. Calibration curves of the NSAIDs were linear over the concentration range 0.025–15μg/mL, with correlation coefficients≥0.998. Intra- and inter-assay relative standard deviations were <8% and recovery values ranged from 94% to 100% for the quality control samples. The results reveal that the developed MEPS/PDA-UHPLC method exhibits a good accuracy and precision and is well suited for the rapid analysis of human dialysate from patients treated with the selected NSAIDs.

Microextraction by packed sorbent (MEPS)-UHPLC-UV: A simple and efficient method for the determination of five benzodiazepines in an alcoholic beverage

This article describes a nano-scale method for the determination and quantification of five benzodiazepines (BDZ) in an alcoholic grappa drink (chlordiazepoxide; lorazepam; diazepam; oxazepam; medazepam). BDZ are typically used in drug-facilitated crimes (DFC) for their accessibility and synergistic effects with alcohol. Specimens collected on the crime scene must be rapidly analyzed to prove the crime, though, in most cases, a very small amount is available. Off-line MEPS extraction of diluted grappa samples proved to be an efficient and reliable method for the recovery of the selected compounds. Requiring a very small amount of extraction solvents, MEPS is an environment-friendly technique. LC separation with UV detection was used as the analytical technique because it is simple, robust, relatively economic and easy-to-find in most laboratories. The method was validated in terms of precision, accuracy and recovery. Limits of detection and quantitation were in the range of 0.5–2ng/μL. Linearity (R2) spanned from 0.9994 and 1.0000. Intra- and inter-day repeatabilities were lower than 12% at any concentration. Recovery percentages of an equivalent-to-real sample at three different concentrations were between 70.7 and 74.1%.

Determination of metoprolol enantiomers in human plasma and saliva samples utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry.

A sensitive, accurate and reliable bioanalytical method for the enantioselective determination of metoprolol in plasma and saliva samples utilizing liquid chromatography-electrospray ionization tandem mass spectrometry was developed and validated. Human plasma and saliva samples were pretreated by microextraction by packed sorbent (MEPS) prior to analysis. A new MEPS syringe form with two inputs was used. Metoprolol enantiomers and internal standard pentycaine (IS) were eluted from MEPS sorbent using isopropanol after removal of matrix interferences using aliquots of 5% methanol in water. Complete separation of metoprolol enantiomers was achieved on a Cellulose-SB column (150 × 4.6 mm, 5 μm) using isocratic elution with mobile phase 0.1% ammonium hydroxide in hexane-isopropanol (80:20, v/v) with a flow rate of 0.8 mL/min. A post-column solvent-assisted ionization was applied to enhance metoprolol ionization signal in positive mode monitoring (+ES) using 0.5% formic acid in isopropanol at a flow rate of 0.2 mL/min. The total chromatographic run time was 10 min for each injection. The detection of metoprolol in plasma and saliva samples was performed using triple quadrupole tandem mass spectrometer in +ES under the following mass transitions: m/z 268.08 → 72.09 for metoprolol and m/z 303.3 → 154.3 for IS. The linearity range was 2.5-500 ng/mL for both R- and S-metoprolol in plasma and saliva. The limits of detection and quantitation for both enantiomers were 0.5 and 2.5 ng/mL respectively, in both matrices (plasma and saliva). The intra- and inter-day precisions were presented in terms of RSD values for replicate analysis of quality control samples and were <5%; the accuracy of determinations varied from 96 to 99%. The method was able to determine the therapeutic levels of metoprolol enantiomers in both human plasma and saliva samples successfully, which can aid in therapeutic drug monitoring in clinical laboratories. Copyright © 2016 John Wiley & Sons, Ltd.

Use of functionalized nanoporous silica for the microextraction by packed sorbent of ellagic acid from fruit juice

A semi-automated microextraction by packed sorbent (MEPS) method was developed for the HPLC determination of ellagic acid (EA) in juice samples. The procedure includes enrichment of the analyte on a nanoporous silica sorbent by the MEPS method using a laboratory-made programmable apparatus. Three functionalized SBA-15 nanoporous sorbents were evaluated for this purpose and 3-[bis(2-hydroxyethyl)amino]propyl-triethoxysilane (HPTES)-SBA-15 showed superior efficiency. Only 2 mg of the adsorbent packed in a syringe’s hub was sufficient for a quantitative recovery of EA. Different factors influencing the performance of the MEPS method such as the nature of desorption solvent, elution volume, pH, number of extraction cycles (draw–eject) and sample volume were carefully studied and optimized. Under the optimized conditions, a detection limit of 0.8 mg/L and a linear calibration curve with an R2 of 0.9995 were obtained for EA. The average recovery of the analyte for juice samples was 97.6% with a relative standard deviation of 4.4% for six replicates. The method was successfully applied to the HPLC determination of EA in pomegranate and grape juice samples.

Fractionation of Cuticular Waxes from the Leaves of Solanaceae Plant Species Using Microextraction by Packed Sorbent

The microextraction by packed sorbent (MEPS) was applied to a fractionation of cuticular wax extracts from several solanaceous plant species. A procedure developed requires only 0.6 mL of organic solvents and may be completed in less than 10 min. Hydrocarbons, which are frequently used in chemotaxonomy of Solanaceae, were almost exclusively eluted in one fraction. The amounts of most commonly detected polar wax components (alcohols, sterols, triterpenes) in the same fraction were reduced to ca. 34–46% of the total amounts in the whole extract. Despite the contamination of the hydrocarbon fraction with other wax components, the results obtained using MEPS and standard column chromatography on silica gel were similar when compared using cluster analysis based on the hydrocarbon profiles. However, the method was far less successful in removing the sucrose esters from extracts of Nicotiana rustica leaves. Thus, MEPS fractionation of plant cuticular waxes may be a fast and reliable alternative for the standard...

Application of graphitic sorbent for online microextraction of drugs in human plasma samples

In the present work a new sorbent based on graphitized carbon (CarbonX® COA) was evaluated in microextraction by packed sorbent (MEPS) for extraction of lidocaine and ropivacaine from human plasma samples. The new graphitic sorbent showed high recoveries of lidocaine and ropivacaine compared to C18 sorbent. In the present study the G-MEPS (syringe packed with graphitic sorbent) was connect online with liquid chromatography tandem mass spectrometry (LC–MS/MS). In order to obtain a fast and reliable method different factors affecting MEPS performance were investigated. The extraction efficiency of the graphitic sorbent was compared with silica-based sorbents used in MEPS. The G-MEPS was also evaluated for reuse (50–100 times). The recoveries of lidocaine and ropivacaine from plasma samples were 79% and 82%; respectively. The method was validated according to FDA (Food and Drug Administration) guideline for bioanalytical method validation. Linearity was assessed in the range 5–2000nmol/L, with coefficient of determination r2>0,995 (n=3) for lidocaine and r2>0.997 (n=3) for ropivacaine. The lower limit of quantification (LLOQ) was 5nmol/L and the limit of detection (LOD) was 1nmol/L for studied analytes in plasma samples. For both analytes considered in this study the accuracy values in plasma samples were ranged from 86% to 113%. The Inter-day precisions, expressed as relative standard deviation (%RSD), at three different concentrations (QC-samples) ranged from 8% to 9% for lidocaine, and from 4% to 11% for ropivacaine.

Analytical Profiling of Bioactive Phenolic Compounds in Argan (Argania spinosa) Leaves by Combined Microextraction by Packed Sorbent (MEPS) and LC-DAD-MS/MS.

The argan tree (Argania spinosa) is an endemic species from south-western Morocco. Argan-based preparations have been widely used in Moroccan traditional medicine for their biological properties, as well as for several cosmetic purposes. Whereas kernel, pulp of fruit and trunk have been extensively studied for their nutritional and pharmacological effects, relatively little is known about argan tree leaves. The main purpose of the present study is to investigate and characterise the bioactive phenolic fractions in both crude and aqueous extracts derived from argan tree leaves. A qualitative profile of the antioxidant phenolic compounds in argan leaves was obtained by means of structural hypothesis based on UV spectra and mass spectrometric fragmentation patterns. Moreover, selected phenolics were quantified in argan leaves by using a fully validated method based on liquid chromatography coupled to diode array detection and tandem mass spectrometry (LC-DAD-MS/MS). All the extracts were purified by a fast and reliable microextraction by packed sorbent (MEPS) procedure, before analysing them by LC-MS/MS. Based on retention times, mass spectrometric fragmentation and UV spectra, 13 phenolic compounds were identified or tentatively elucidated from crude and aqueous extracts derived from Argania spinosa leaves, while seven compounds were quantified in both extracts. The obtained results could represent a first step towards a complete characterisation of the argan plant, its bioactive profiling and the valorisation of its by-products as a source of potentially beneficial bioactive molecules.

Microextraction by packed sorbent.

Microextraction by packed sorbent (MEPS) is a miniaturized form of SPE. MEPS can handle small sample volumes and be connected on-line with LC or GC without any modifications. In addition, the MEPS sorbent bed is integrated into an injection syringe and can be used for more than 100 extractions. The key aspect of MEPS is that the solvent volume used for the elution of the analytes is of a suitable order of magnitude to be injected directly into GC or LC systems. MEPS has been used in many research fields such as environmental, biological and food analysis. This article gives an overview of the MEPS technique, including fields of application and common formats.

Determination of urinary levels of leukotriene B4 using ad highly specific and sensitive methodology based on automatic MEPS combined with UHPLC-PDA analysis

Leukotriene B4 (LTB4) is a potent mediator of inflammation and plays a key function in the pathophysiology of chronic asthma. Detectable urinary levels of LTB4, arises from the activation of leukotriene pathways. In this study an ultra-fast, selective and sensitive analytical method based on semi-automatic microextraction by packed sorbents (MEPS) technique, using a new digitally controlled syringe (eVol®) combined with ultra-high pressure liquid chromatography (UHPLC), is proposed for the measurement of urinary LTB4 (U-LTB4) levels in a group of asthmatic patients (APs) and healthy controls (CTRL). Important parameters affecting MEPS performance, namely sorbent type, number of extraction cycles (extract–discard) and elution volume, were evaluated. The optimal experimental conditions among those investigated for the quantification of U-LTB4 in urine samples were as follows: porous graphitic carbon sorbent (PGC), 10 extractions cycle (10×250μL of sample) and LTB4 elution with 100μL of acetonitrile. The UHPLC optimum conditions resulted in a mobile phase consisting of 95% (v/v) of acid aqueous solution (v/v), and acetonitrile 5% (v/v); flow rate of 500µL/min, and a column temperature of 37±0.1°C.Under optimized conditions the proposed method exhibit good selectivity and sensitivity LOD (0.37ng/mL) and LOQ (1.22ng/mL). The recovery ranging from 86.4 to 101.1% for LTB4, with relative standard deviations (% RSD) no larger than 5%. In addition, the method also afforded good results in terms of linearity (r2>0.995) within the established concentration range, with a residual deviation for each calibration point below 6%, and intra- and inter-day repeatability in urine samples with RSD values lower than 4 and 5%, respectively. The application of the method to urine samples revealed a tendency towards the increased urinary LTB4 levels in APs (5.42±0.17ng/mL) when compared to those of CTRL group (from ND to 1.9ng/mL). Urinary measurement of LTB4 may be an interesting and non-invasive option to assess control of asthma.

Development of MEPS–UHPLC/PDA methodology for the quantification of clozapine, risperidone and their major active metabolites in human urine

A new, fast and reliable methodology using a digitally controlled microextraction by packed sorbent (MEPS), followed by ultrahigh pressure liquid chromatography (UHPLC) separation combined with a photodiode array (PDA) detection, has been developed and validated for the simultaneous determination of clozapine and risperidone, and their active metabolites, in urine samples. Important parameters affecting MEPS performance, including type of sorbent material (C2, C8, C18, SIL, M1, R-AX, R-CX, PGC, PEP, HLB-DVB and H-DVB), elution solvent system, number of extraction cycles, sample volume, elution volume, and sample pH, were evaluated. The optimal experimental conditions involved the loading of 500μl of sample through a C18 sorbent in a five extraction cycles and in a short time period (5min for the entire sample preparation step). The obtained extract was analyzed by UHPLC, using a binary mobile phase, composed of aqueous 0.1% formic acid and methanol in the gradient elution mode (10min total analysis). Good results were obtained under the optimized conditions, in terms of linearity with correlation coefficients (r2) values higher than 0.9986. Low detection limits, ranging between 0.052 and 0.055μg ml−1 were achieved, whereas the lowest quantification limit was 0.1μg ml−1, corresponding to the lowest concentration of the standard curve. Satisfactory results were found with accuracy values ranging from 83% to 116%, and with precision results from 2.65% to 18%. Recoveries ranged between 76% and 96%, which was in agreement with results reported by other studies.

On-line coupling of Micro-Extraction by Packed Sorbent with Sequential Injection Chromatography system for direct extraction and determination of betaxolol in human urine

A novel approach for automation of Micro-Extraction by Packed Sorbent (MEPS), a solid phase extraction technique, is presented, enabling precise and repeatable liquid handling due to the employment of sequential injection technique. The developed system was used for human urine sample clean-up and pre-concentration of betaxolol before its separation and determination. A commercial MEPS C-18 cartridge was integrated into an SIChrom™ system. The chromatographic separation was performed on a monolithic High Resolution C18 (50×4.6mm) column which was coupled on-line in the system with Micro-Extraction using an additional selection valve. A mixture of acetonitrile and aqueous solution of 0.5% triethylamine with acetic acid, pH adjusted to 4.5 in ratio 30:70 was used as a mobile phase for elution of betaxolol from MEPS directly onto the monolithic column where the separation took place. Betaxolol was quantified by a fluorescence detector at wavelengths λex=220nm and λem=305nm. The linear calibration range of 5–400ngmL−1, with limit of detection 1.5ngmL−1 and limit of quantification 5ngmL−1 and correlation r=0.9998 for both the standard and urine matrix calibration were achieved. The system recovery was 105±5%; 100±4%; 108±1% for three concentration levels of betaxolol in 10 times diluted urine – 5, 20 and 200ng mL−1, respectively.

Graphite-based microextraction by packed sorbent for online extraction of β-blockers from human plasma samples.

In the present work a new graphitic material (Carbon-XCOS) was used as a sorbent for microextraction by packed sorbent (MEPS). The β-blockers metoprolol and acebutolol in plasma samples were extracted and detected online using Carbon-MEPS syringe and liquid chromatography and tandem mass spectrometry (LC-MS/MS). Factors affecting the MEPS performance such as conditioning, washing and elution solutions were investigated. The validation of the bioanalytical method was performed using human plasma. The standard curve ranged from 10 to 2000nM and the lower limit of quantification (LLOQ) was set to 10nM. The method validation showed good accuracy and precision for the quality control (QC) samples at three concentration levels (30, 800 and 1600nM). The accuracy values of the QC samples were in the range of 86-108% (n=18). The precision values of intra- and inter-day for QC samples ranged from 4.4% to 14.4% (RSD) for the both studied analytes. The coefficient of determination (R(2)) values were ≥0.999 (n=3).

Hybrid silica monolith for microextraction by packed sorbent to determine drugs from plasma samples by liquid chromatography–tandem mass spectrometry

The present study (1) reports on the synthesis of two hybrid silica monoliths functionalized with aminopropyl or cyanopropyl groups by the sol–gel process; (2) evaluates these monoliths as selective stationary phase for microextraction by packed sorbent (MEPS) to determine drugs in plasma samples via liquid chromatography–tandem mass spectrometry (LC–MS/MS) in the multiple reactions monitoring (MRM) mode; and (3) discusses important factors related to the optimization of MEPS efficiency as well as the carryover effect. The prepared hybrid silica monoliths consisted of a uniform, porous, and continuous silica monolithic network. The structure of the aminopropyl hybrid silica monolith was more compact than the structure of the cyanopropyl hybrid silica monolith. The Fourier-transform infrared spectroscopy (FTIR) spectra of the hybrid silica monoliths displayed readily identifiable peaks, characteristic of the cyanopropyl and aminopropyl groups. Compared with the aminopropyl hybrid silica phase, the cyanopropyl hybrid silica phase exhibited higher binding capacity for most of the target drugs. The developed method afforded adequate linearity at concentrations ranging from the lower limit of quantification (0.05–1.00ngmL−1) to the upper limit of quantification (40–10,500ngmL−1); the coefficients of determination (r2) were higher than 0.9955. The precision of the method presented coefficients of variation (CV) lower than 14%; the relative standard error (RSE) of the accuracy ranged from −12% to 14%. The developed method allowed for simultaneous analysis of five antipsychotics (olanzapine, quetiapine, clozapine, haloperidol, and chlorpromazine) in combination with seven antidepressants (mirtazapine, paroxetine, citalopram, sertraline, imipramine, clomipramine, fluoxetine), two anticonvulsants (carbamazepine and lamotrigine), and two anxiolytics (diazepam and clonazepam) in plasma samples from schizophrenic patients, which should be valuable for therapeutic drug monitoring purposes.

Determination of illicit drugs and metabolites in oral fluid by microextraction on packed sorbent coupled with LC-MS/MS.

Oral fluid (OF) has become a valuable biologic specimen for toxicological analysis, especially in driving under the influence of drugs (DUID) investigations, because of easy and non-invasive collection procedures. In OF testing, being the sample volume is limited, multi-analyte procedures are particularly advantageous since they save time and resources. In this work, a procedure for the simultaneous analysis of 20 illicit drugs, belonging to the classes of cocaine, amphetamines, natural and synthetic opioids and hallucinogens, is presented. The sample preparation is based on microextraction by packed sorbent (MEPS), a novel technique which is based on the miniaturization of solid-phase extraction (SPE). The presented method, which includes all the most diffused illicit drugs and their metabolites, has been fully validated according to the Scientific Working Group for Forensic Toxicology (SWGTOX) guidelines. LLOQs ranged from 0.5 to 30ngmL(-1) (diacetylmorphine); the presented method allows the detection of all the selected drugs quite below the cutoff values recommended by Substance Abuse and Mental Health Services Administration (SAMHSA) for abuse identification.

Quantification of furanic derivatives in fortified wines by a highly sensitive and ultrafast analytical strategy based on digitally controlled microextraction by packed sorbent combined with ultrahigh pressure liquid chromatography

An improved, reliable and powerful analytical strategy based on digitally controlled microextraction by packed sorbent (MEPS) combined with ultrahigh pressure liquid chromatography (UHPLC) was validated for the simultaneous identification and quantification of major furanic derivatives, namely 5-hydroxymethyl-2-furaldehyde (5HMF), 5-methyl-2-furaldehyde (5MF), 2-furaldehyde (2F) and 2-furyl methyl ketone (2FMK), in fortified wines. To enhance the extraction efficiency of the target furanic derivates, several influencing extraction parameters, such as number of loading cycles, nature of elution solvent and elution volume, were evaluated and optimized. In addition the ability of different MEPS sorbent materials, namely C2, C8, C18, SIL, M1, R-AX, R-CX and PGC, were also tested. The optimal analytical conditions involved loading 3×200μL of wine samples through a C8 sorbent in a MEPS syringe placed in the semi-automatic eVolH syringe followed by elution using 200μL MeOH:H2O (95:5, v/v). The furanic derivates separation was achieved using a CORTECS UPLC® C18 analytical column in an ultrafast chromatographic run (within 4min). The method performance was assessed for dry/medium dry (D/MD) and sweet/medium sweet (S/MS) model wines in terms of selectivity, linearity, limit of detection (LOD), limit of quantitation (LOQ), accuracy, precision and matrix effect, using model wine matrix-matched calibration. Good linearity was obtained with a regression coefficient (r2) higher than 0.992. A good precision was attained (RSD<5%) and low LODs were achieved for D/MD (4.5–129.3ngL−1) and S/MS (6.9–285.2ngL−1) model wines. The quantification limits (LOQ) for D/MD model wines ranged from 14.9 to 431.0ngL−1, whereas for S/MS model wines range from 23.1 to 950.5ngL−1. The method also afforded satisfactory results in terms of accuracy, ranging from 74 to 97% for D/MD wines and between 84 and 99% for S/MS wines.The MEPSC8/UHPLC–PDA analytical strategy was successfully applied to analyze furanic derivates in 26 fortified Madeira wines from different types (D/MD, S/MS) and ages. The obtained results revealed the analytical strategy as a suitable tool which combines sensitivity, effectiveness, reduced analysis time and simple analytical procedure. Principal component analysis (PCA) suggested that fortified wines can be organized based on their age on PC1, which are mainly characterized by 5HMF.

Microextraction by packed sorbent (MEPS) to analyze catecholamines in innovative biological samples

A new microextraction by packed sorbent (MEPS) procedure coupled to a high-performance liquid chromatographic method has been developed for quantitation of catecholamines (i.e. norepinephrine, epinephrine and dopamine) in innovative biological samples, namely dried plasma and urine spots. Analyses were carried out on a C18 reversed-phase column using a mobile phase composed of 2.5% methanol and 97.5% aqueous citrate buffer, containing octanesulfonic acid. Coulometric detection was used, setting the first analytical cell at −0.350V and the second analytical cell at +0.400V. Dried matrices were purified by means of a fast and feasible MEPS procedure, optimized on C18 sorbent and requiring only a small amount of biological sample. The availability of miniaturized procedures allowed satisfying specific requirements that ought to be considered during pre-treatment intended for catecholamine analysis. The extraction yield values were always higher than 85% and sensitivity was good, with a limit of quantitation of 100pgmL−1 for all the analytes. Satisfactory results were also obtained in terms of linearity, precision and accuracy. The method was successfully applied to dried plasma and urine spots derived from two socially diversified groups, namely psychiatric patients and poly-drug abusers, in comparison to healthy volunteers.