Phase Extraction Liquid Chromatography-tandem Mass Research Articles

Determination of Phenylethanolamine A Residues in Milk by Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry

A method was established for the determination of phenethanolamine A residue in milk by solid phase extraction, liquid chromatography-tandem mass spectrometry. The samples were extracted with ammonium acetate buffer solution under the condition of enzymatic hydrolysis and purified by MCX solid phase extraction column. The eluent was blown dry with nitrogen at 45℃ and dissolved with 1.0 mL 0.1% formic acid solution. The samples were isolated by Poroshell 120EC-C18, 100 mm ×3.0 mm (i.d.), 2.7 μm column, and then determined by mass spectrometry in multiple reaction monitoring mode, and quantified by internal standard method. The results showed that phenethanolamine A had good linear relationship in the concentration range of 0.5-50.0 μg/L, the correlation coefficient r=0.9984, the limit of detection was 0.17 μg/kg, and the limit of quantitation was 0.57 μg/kg. The average recovery was 98.3-108.7% and the precision was 2.4-3.7% at different supplemental levels. The established method can purify the samples effectively, improve the detection efficiency, and is suitable for the detection of phenethanolamine A residue in milk.

Rapid determination of perfluorinated compounds in pork samples using a molecularly imprinted phenolic resin adsorbent in dispersive solid phase extraction-liquid chromatography tandem mass spectrometry

Perfluorinated compounds (PFCs) that bioaccumulate enter the food chain through animals-derived foods and ultimately harm human health. However, these compounds are extensively used, and consequently, it is important to focus on the residual PFCs content in various animal-derived foods. In this work, a molecularly imprinted polymer with surface grooves and rapid mass transfer ability was prepared hydrothermally, applied as an adsorbent to a needle filter device, and combined with LC-MS/MS for the rapid extraction and determination of trace PFCs in pork. This method requires simple equipment (syringe filter), small amount of adsorbent (2 mg), and short operation time (6–8 min) and has a low detection limit (0.011–0.08 ng g−1), good recovery (89.3–116.3%), and satisfactory intra-day (≤4.0%) and inter-day (≤8.6%) precision. This study provides a new method for assessing the exposure risk of PFCs in complex samples.

Development, validation, and application of a new method for the quantitative determination of monohydrogen-substituted perfluoroalkyl carboxylic acids (H–PFCAs) in surface water

Per- and polyfluoroalkyl substances (PFASs) are a large and diverse class of chemicals. While some have been phased out internationally due to concerns over their human and environmental health risks, novel alternative PFASs continue to be manufactured and detected in environmental samples. The occurrence and fate of these alternatives remain poorly understood. The present study investigated the occurrence of an emerging class of PFAS alternative, the monohydrogen-substituted perfluoroalkyl carboxylic acids (H–PFCAs), in conjunction with the more well-known PFCAs. A weak anion exchange solid phase extraction-liquid chromatography tandem mass spectrometry method for quantitative determination of H–PFCAs in surface water was developed, validated, and applied on samples collected from the Netherlands. To improve chromatography, especially for short-chain (H-)PFCAs, an ion-pairing agent, tetrabutylammonium hydrogen sulphate, was used. The method was validated for linearity (R2 > 0.99), instrumental detection limits (0.01–0.09 ng/mL), method detection limits (0.03–0.75 ng/mL), matrix effects (<20%), percent absolute- and relative recovery (57–121%), trueness (130-80%), repeatability (<20%), and within-lab reproducibility (<20%). Eleven out of fourteen PFASs showed acceptable results. Application of the newly validated method to surface water throughout the Netherlands revealed trace levels of H–PFCAs (including two new H–PFCAs) and high concentrations of PFCAs.

An Online Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry Method for the Analysis of Parabens in Urban Waters

In this work, we report a method to quantify methylparaben, ethylparaben, propylparaben and butylparaben in urban waters of São Carlos (São Paulo State, Brazil) by online solid phase extraction-liquid chromatography tandem mass spectrometry (SPE-LC-MS/MS) system. The method achieved ng L-1 limits with good accuracy and precision (internal standards for each paraben were used). The total run cycle time takes 9.5 min per sample including the extraction, cleanup and columns conditioning cycles, lower collection volumes of urban water and solvent usage. The SPE cartridge applied showed robustness allowing over 500 sample injections (800 μL each) with good chromatographic performance. This study findings included the detection of parabens in samples in São Carlos.

Per- and polyfluoroalkyl substances and fluorinated alternatives in urine and serum by on-line solid phase extraction–liquid chromatography–tandem mass spectrometry

Per- and polyfluoroalkyl substances (PFAS), man-made chemicals with variable length carbon chains containing the perfluoroalkyl moiety (CnF2n+1–), are used in many commercial applications. Since 1999–2000, several long-chain PFAS, including perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), have been detected at trace levels in the blood of most participants of the National Health and Nutrition Examination Survey (NHANES)—representative samples of the U.S. general population—while short-chain PFAS have not. Lower detection frequencies and concentration ranges may reflect lower exposure to short-chain PFAS than to PFOS or PFOA or that, in humans, short-chain PFAS efficiently eliminate in urine. We developed on-line solid phase extraction–HPLC–isotope dilution–MS/MS methods for the quantification in 50 μL of urine or serum of 15 C3-C11 PFAS (C3 only in urine), and three fluorinated alternatives used as PFOA or PFOS replacements: GenX (ammonium salt of 2,3,3,3,-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoate, also known as HFPO-DA), ADONA (ammonium salt of 4,8-dioxa-3H-perfluorononanoate), and 9Cl-PF3ONS (9-chlorohexadecafluoro-3-oxanonane-1-sulfonate), main component of F53-B. Limit of detection for all analytes was 0.1 ng/mL. To validate the method, we analyzed 50 commercial urine/serum paired samples collected in 2016 from U.S. volunteers with no known exposure to the chemicals. In serum, detection frequency and concentration patterns agreed well with those from NHANES. By contrast, except for perfluorobutanoate, we did not detect long-chain or short-chain PFAS in urine. Also, we did not detect fluorinated alternatives in either urine or serum. Together, these results suggest limited exposure to both short-chain PFAS and select fluorinated alternatives in this convenience population.

Multiresidue analysis of 24 Water Framework Directive priority substances by on-line solid phase extraction-liquid chromatography tandem mass spectrometry in environmental waters

This paper reports the development of a fully multiresidue and automated on-line solid phase extraction (SPE) – liquid chromatography tandem mass spectrometry (LC–MS/MS) method for the determination of 24 priority substances (PS) belonging to different classes (pesticides, hormones or pharmaceuticals) included in the Directive 2013/39/UE and the recent Watch List (Decision 2015/495) in water samples (drinking water, surface water, and effluent wastewaters). LC–MS/MS conditions and on-line SPE parameters such as sorbent type, sample and wash volumes were optimized. The developed method is highly sensitive (limits of detection between 0.1 and 1.4ngL−1) and precise (relative standard deviations lower than 8%). As part of the method validation studies, linearity, accuracy and matrix effects were assessed. The main advantage of this method over traditional off-line procedures is the minimization of tedious sample preparation increasing productivity and sample throughput.The optimized method was applied to the analysis of water samples and the results revealed the presence of 16 PS in river water and effluent water of wastewater treatment plants.

Study of spatial and temporal distribution of antimicrobial in water and sediments from caging fish farms by on-line SPE-LC-MS/MS

ABSTRACTAn on-line solid phase extraction liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) method for the determination of 12 antimicrobials in sediment and surface water was developed and validated. Furthermore, the spatial and temporal antimicrobials distributions in the sediment and in the water of four fish farms located in the hydroelectric dam of Ilha Solteira Reservoir in Brazil were investigated over four seasons in three sampling sites: at the fish cages, 100 and 1,000 m downstream far from the cages. The method was performed using an Agilent Zorbax 80 SB-C8 column (9.4 × 15 mm, 5 µm) as the loading column, and the Agilent Zorbax Eclipse Plus C18 column (3.0 × 100 mm, 3.5 µm) as a separation column within a run time of 13 min. The limits of quantification were less than 9 ng·L−1 for the antibiotics in water and 16 µg·kg−1 in sediment; the recovery ranged from 80 to 119%, with a variation coefficient less than 11%, and the repeatability was lower than 15%. Oxytetracycline was found in the water in all sample seasons. However, florfenicol was identified in April and October 2013 and January 2014, and tetracycline was present in July 2013. Regarding the sediment, oxytetracycline and tetracycline were found in all sampling periods, but chlortetracycline was only identified in January 2014. The spatial distribution of antimicrobials showed that the main pollution source came from the fish farms. This study demonstrated that the proposed method is reliable for the monitoring of antimicrobials in water and sediments and it showed contamination in both matrices from Ilha Solteira Reservoir.

Development and validation of a fully automated online-SPE–ESI–LC–MS/MS multi-residue method for the determination of different classes of pesticides in drinking, ground and surface water

ABSTRACTThe present work describes a fully automated method based on online solid phase extraction–liquid chromatography–tandem mass spectrometry for the determination of different classes of pesticides, including acidic and polar pesticides and six thiamethoxam metabolites. Sample preconcentration was performed by extracting 4 mL of the sample with a single styrene-divinylbenzene polymer. Elution of the compounds was done within the high performance liquid chromatography gradient and tandem mass spectrometry determination was performed in the selected reaction monitoring mode, by recording 1–3 transitions per compound. The overall pretreatment and analysis time per sample was less than 15 min. Method validation was performed in drinking, ground and surface water. For nearly all compounds a recovery between 70% and 120% could be achieved. The limit of detection ranges from 1.2 to 18 ng/L in drinking water and 3.0 to 23 ng/L in ground and surface water. The correlation coefficients for a calibration range of 0.05–2 µg/L are between 0.9915 and 0.9999. The limit of quantification (LOQ) for all compounds lies below the required limit of 0.1 µg/L, to fulfil the Council Directive 98/83/EC. Most of the compounds easily reach an LOQ below 0.05 µg/L.

An on-line solid phase extraction–liquid chromatography tandem mass spectrometry method for the determination of perfluoroalkyl substances in the Antarctic ice core samples

An on-line solid phase extraction–high performance liquid chromatography–tandem mass spectrometry method for the analysis of perfluoroalkyl substances (PFASs) in water samples was developed. The optimal analytical conditions were obtained through the optimization of the extraction efficiency of on-line solid phase extraction column, sample loading rate and loading volume, and the concentration of ammonium acetate in mobile phase. Under the optimal condition, the analytical method displayed good linearity (r2 > 0.99) for 12 PFASs (C5–C14 perfluoroalkyl carboxylic acids and C6/C8 perfluoroalkyl sulfonic acids) over a concentration range of 0.5–100 ng/L. The limits of quantitation for samples were between 0.025 ng/L and 0.5 ng/L and the relative standard deviations (RSD) of five consecutive analyses were less than 10% for 1 ng/L standard solution. Satisfactory results were obtained using this analytical method for the analysis of perfluoroalkyl substances in Antarctic ice core samples. The recoveries of all perfluoroalkyl substances were in a range of 73%–117% when the samples were spiked with standards at the concentrations of 2.5 ng/L and 25 ng/L.

Detection of human exposure to saxitoxin and neosaxitoxin in urine by online-solid phase extraction-liquid chromatography-tandem mass spectrometry.

Saxitoxin (STX) and neosaxitoxin (NEO) are potent neurotoxins that cause paralytic shellfish poisoning (PSP). PSP typically occurs through the ingestion of bivalve shellfish that have consumed toxin producing dinoflagellates. Due to initial presentation of symptoms being nonspecific, a clinical measurement is needed to confirm exposure to these toxins. Our group has developed an online solid phase extraction hydrophilic interaction liquid chromatography (HILIC) method for the analysis of STX and NEO in human urine with tandem mass spectrometry. A unique feature of this online method is the incorporation of a new synthetic (15)N4-STX labeled internal standard used for quantitation. Manual sample preparation time was reduced by approximately 70% for 98 urine samples as compared to a previously reported method. The lowest reportable limit for STX was improved from 5.0ng/mL to 1.01ng/mL and from 10.0ng/mL to 2.62ng/mL for NEO. Three analysts validated the method with 20 calibration curves total over 30 days with precision and accuracy within ±15% for all QCs. This new online method rapidly identifies STX and NEO exposure with improved sensitivity, which can facilitate the work of public health authorities to confirm the cases of PSP, complementing the many shellfish monitoring programs worldwide.

A novel method for the measurement of plasma metanephrines using online solid phase extraction-liquid chromatography tandem mass spectrometry.

Measurement of plasma metanephrine, normetanephrine and 3-methoxytyramine is useful in the diagnosis of phaeochromocytomas, but many assays require a large volume of plasma due to poor assay sensitivity, and often require lengthy sample preparation. Our aim was to develop a method for measurement of plasma metanephrines using a small sample volume with minimal hands-on preparation. Samples were deproteinised using 10 K spin filters prior to online solid phase extraction using a Waters Acquity UPLC Online SPE Manager (Waters, Manchester, UK) coupled to a Waters Xevo TQ-S mass spectrometer (Waters, Manchester, UK). The assay was validated and results compared to a previously published method. We achieved a limit of quantification of 37.5 pmol/L for metanephrine and 3-methoxytyramine and 75 pmol/L for normetanephrine using only 150 µL of sample. The assay was linear up to 30,000 pmol/L for all analytes and in a method comparison study results showed good agreement with a previously published LC-MS/MS assay. We have developed a simple method for measurement of plasma metanephrine, normetanephrine and 3-methoxytyramine using only 150 µL of sample. There is minimal hands-on sample preparation required and the assay is suitable for routine use in a clinical laboratory.

Development of a SPE-LC/MS/MS method for simultaneous quantification of baicalein, wogonin, oroxylin A and their glucuronides baicalin, wogonoside and oroxyloside in rats and its application to brain uptake and plasma pharmacokinetic studies

This study aims to identify and quantify the six major bioactive flavones of the traditional Chinese medicine Scutellariae Radix (RS), including baicalein, baicalin, wogonin, wogonoside, oroxylin A and oroxyloside in rat after oral administration of a standardized RS extract. A novel, sensitive and selective method for simultaneous determination of these six analytes in rat brain and plasma using solid phase extraction-liquid chromatography–tandem mass spectrometry (SPE-LC/MS/MS) was developed and fully validated. The lower limits of quantification (LLOQs) for the six RS flavones in brain tissue were 0.02nmol/g. The LLOQs in plasma were 0.005nmol/ml for B, W and OA, 0.025nmol/ml for WG and OAG, and 0.1875nmol/ml for BG. The current study provides novel evidence of the presence of all the tested RS flavones and an isoform of BG (BG′, probably baicalein-6-O-glucuronide) in the rat brain after oral administration of RS extract, suggesting their ability to permeate through the blood–brain barrier. The method was also successfully applied to the pharmacokinetic study of all these analytes in plasma after oral administration of RS extract (300mg/kg) to Sprague-Dawley rats. The developed assay method provides a useful tool for both preclinical and clinical investigations on the disposition of RS flavones in brain and plasma.

Short term variability in urinary bisphenol A in Australian children

Used frequently in food contact materials, bisphenol A (BPA) has been studied extensively in recent years, and ubiquitous exposure in the general population has been demonstrated worldwide. Characterizing within- and between-individual variability of BPA concentrations is important for characterizing exposure in biomonitoring studies, and this has been investigated previously in adults, but not in children. The aim of this study was to characterize the short-term variability of BPA in spot urine samples in young children. Children aged ≥2–<4years (n=25) were recruited from an existing cohort in Queensland, Australia, and donated four spot urine samples each over a two day period. Samples were analysed for total BPA using isotope dilution online solid phase extraction–liquid chromatography–tandem mass spectrometry, and concentrations ranged from 0.53 to 74.5ng/ml, with geometric mean and standard deviation of 2.70ng/ml and 2.94ng/ml, respectively. Sex and time of sample collection were not significant predictors of BPA concentration. The between-individual variability was approximately equal to the within-individual variability (ICC=0.51), and this ICC is somewhat higher than previously reported literature values. This may be the result of physiological or behavioural differences between children and adults or of the relatively short exposure window assessed. Using a bootstrapping methodology, a single sample resulted in correct tertile classification approximately 70% of the time. This study suggests that single spot samples obtained from young children provide a reliable characterization of absolute and relative exposure over the short time window studied, but this may not hold true over longer timeframes.

Development and Validation of a Dispersive Solid Phase Extraction Liquid Chromatography Mass Spectrometry Method with Electrospray Ionization for the Determination of Multiclass Pesticides and Metabolites in Meat and Milk

A dispersive solid phase extraction–liquid chromatography tandem mass spectrometry method with electrospray ionization was validated in food of animal origin for the determination of multiclass pesticide residues and their metabolites. A simple and low-cost sample preparation procedure using freezing as the clean-up step was used to identify and quantify analytes belonging to 39 different chemical classes in meat and milk matrices. Mean recoveries in the range of 70–120% with relative standard deviations <10% were obtained for the majority of the analytes. The limit of quantification of the method was 10 µg/kg. The matrix effects were statistically evaluated and the quantification of the analytes was conducted using calibration curves constructed with matrix matched calibration standards covering concentrations from 5 to 200 µg/kg. The proposed method was applied in 86 samples of animal origin taken from the Greek market, two of which were found positive for pesticides.

Determination of Ethiprole Enantiomers Residue in Rices Using Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry

Determination of Ethiprole Enantiomers Residue in Rices Using Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry

Fast and Selective Determination of Pesticides in Water by Automated On-Line Solid Phase Extraction Liquid Chromatography Tandem Mass Spectrometry

An automated on line-solid phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 17 polar pesticides in water. Minimizing sample pretreatment and using a fast chromatographic separation, the method allowed a sample to be processed in 15 minutes. The MS analysis was performed by Data Dependent Acquisition, using the triggered Multiple Reaction Mode function that provided analyte confirmation, thus enhancing selectivity without compromising sensitivity. In fact, the optimized method enabled the determination of the considered pesticides at the ultratrace level, with detection limits in the range 0.07–1.65 ng/L (propazine and atrazine-desisopropyl, respectively); the only exception was linuron that showed a slightly higher detection limit (12.2 ng/L). The optimized method was then applied to real water samples; five pesticides were determined in river water, in the range 1.17–14.2 ng/L, while four were measured in drinking water, in the range 0.91–2.25 ng/L.

Occurrence and behavior of pesticides in wastewater treatment plants and their environmental impact

Reports on pesticides elimination during wastewater treatment are rare since these substances are typically considered of agricultural rather than of urban origin. In this context, the aim of this work was to evaluate the presence, removal and environmental relevance of 22 selected pesticides in three different wastewater treatment plants (WWTPs), paying attention not only to their occurrence and elimination but also to the toxicity of each pesticide against three aquatic micro organisms (algae, daphnia and fish) through the calculation of the so-named Environmental Relevance of Pesticides from Wastewater treatment plants Index (ERPWI). For this purpose, an analytical method based on isotope dilution on-line solid phase extraction–liquid chromatography–tandem mass spectrometry (SPE–LC–MS/MS) was optimized, allowing the determination of the 22 target pesticides in wastewater with satisfactory sensitivity (limits of detection below 30ng/L), accuracy and precision. Concerning the results, total pesticide levels were in most instances below 1μg/L but removal in the WWTPs was variable and often poor, with concentrations in the effluent sometimes higher than in the corresponding influent. Possible explanations for these poor or negative removal rates are, among many others considered (e.g. sampling, sample preservation, method biases, atmospheric deposition), deconjugation of metabolites and/or transformation products of the pesticides, hydrolysis, and desorption from particulate matter during wastewater treatment. The most significant pesticides in terms of concentration and frequency of detection were diazinon and diuron. These two pesticides, followed by atrazine, simazine and malathion, were also the most relevant from the environmental point of view, according to the calculated ERPWI.

Fully automated determination of nine ultraviolet filters and transformation products in natural waters and wastewaters by on-line solid phase extraction–liquid chromatography–tandem mass spectrometry

This paper describes the development and validation of the first fully automated method, based on on-line solid phase extraction–liquid chromatography–tandem mass spectrometry (on line-SPE–LC–MS/MS), for the determination of UV filters (UV F) and transformation products, with a wide range of physicochemical properties. The developed method was validated and applied to the analysis of the selected compounds in river water (RW), groundwater (GW), influent and effluent wastewater (IWW and EWW). Comparing with the off-line methodologies published so far the presented method provides several advantages including a shorter extraction time, lower sample volume and minimum manipulation. Low limits of detection were achieved for all the studied matrices, <3ng/L (GW), <3.5ng/L (RW), <4ng/L (EWW) and <10ng/L (IWW), allowing a reliable and accurate quantification of the analytes at trace level. SPE optimization and critical aspects associated with the trace level determination of the target compounds (e.g. matrix effects) have been also considered and discussed. The method was successfully applied to the analysis of the UV F in five real water samples of each considered matrix, being the first time that these compounds were determined in GW.

Evaluation of a Novel Commercial Assay for the Determination of Cyclosporine A, Tacrolimus, Sirolimus, and Everolimus by Liquid Chromatography–Tandem Mass Spectrometric Assay

The aim of this study was the evaluation of the first commercially available in-vitro diagnostic (IVD)- mass spectrometric immunosuppressant assay from Chromsystems (MassTox Immunosuppressants ONEMINUTE Test) and the comparison to a routinely used online solid phase extraction liquid chromatography-tandem mass spectrometric assay method for the measurement of cyclosporine A, everolimus, sirolimus, and tacrolimus in patient whole blood samples. An API 4000 [tandem mass spectrometer (AB SCIEX)] combined with a CTC Pal autosampler (CTC Analytics AG) and a Shimadzu ultra-fast liquid chromatography (UFLC) system were applied for the direct liquid chromatography-tandem mass spectrometric assay analysis using electrospray ionization in positive ion mode. Isotope-labeled internal standards were used for the commercial assay. Within- and between-day variation, accuracy, and limits of quantification were determined. Samples from external international proficiency testing schemes were measured to assess the accuracy of the commercial assay. About 100 patient samples were reanalyzed with the commercial test kit, and the results were compared with our in-house results. The limit of quantification for the commercial assay was 0.5 ng/mL for everolimus, sirolimus, and tacrolimus and 5 ng/mL for cyclosporine A. The coefficient of variation for all immunosuppressants was lower than 7% (within day) and 12% (between days) for all 5 concentration levels. Accuracy ranged between 82% and 111% for quality control samples and between 89% and 112% for samples from the external quality assurance program. Both methods showed a very good agreement (r > 0.91) in patient samples over the whole concentration range for all immunosuppressants. The commercial immunosuppressant assay from Chromsystems represents a standardized IVD-certified alternative to our in-house developed assay.

On-line solid phase extraction–liquid chromatography–tandem mass spectrometry for the determination of 17 cytostatics and metabolites in waste, surface and ground water samples

A fully automated on-line solid-phase extraction–liquid chromatography–tandem mass spectrometry (SPE–LC–MS/MS) method has been developed for the determination of 13 cytostatics and 4 metabolites in aqueous matrices, including groundwater, surface water, and raw and treated wastewater. On-line SPE is performed by loading 5mL of water sample at pH 2 through a PLRP-s cartridge. MS/MS is performed with an electrospray (ESI) interface operating in the positive ion mode and registering two selected reaction monitoring (SRM) transitions per compound. Quantification is carried out by the isotope dilution method using 15 different isotope-labelled compounds, specific for the target analytes, as internal standards (IS). The main advantages of the method are high sensitivity, with limits of determination in groundwater, surface water, and raw and treated wastewater below 5ngL−1 for all compounds except for gemcitabine (6.9–9.3ngL−1), temozolomide (26–50ngL−1), imatinib (80–180ngL−1) and etoposide (38–65ngL−1), repeatability, with relative standard deviations (RSDs) in most cases below 15%, and selectivity and reliability of results. The method is also fairly simple and fast, with an analysis time per sample (excluding the manual steps, i.e., sample filtration, pH adjustment, and addition of IS) of 40min. Application of the method to influent wastewater samples collected daily during eight consecutive days from a wastewater treatment plant (WWTP) from Catalonia showed the presence of methotrexate, ifosfamide, capecitabine, tamoxifen and 6(α)-hydroxypaclitaxel but at fairly low concentrations (up to 43ngL−1).