Phase Extraction-ultra High Performance Liquid Research Articles

Determination of oxylipins and their precursors in breast milk by solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry

Oxylipins and their precursors (long-chain polyunsaturated fatty acids, LCPUFAs) are key intercellular signaling molecules influencing the inflammatory response. Each oxylipin has pro- and/or anti-inflammatory effects, and the relative abundance of different oxylipins can alter the inflammatory balance, making it important to clarify the oxylipin profile of breast milk for optimal infant health. The extraction, identification, and simultaneous quantification of oxylipins in breast milk are challenging due to the structural similarity, limited stability, and the low endogenous concentration of oxylipins and the complex matrix of breast milk. This study aimed to develop a solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry (SPE-UPLC-MS/MS) method for the comprehensive and specific quantification of oxylipins and their precursors in breast milk. The LC conditions (including column, mobile phase, and gradient conditions) and SPE procedure (including SPE cartridges, elution solvent, and elution volume) were optimized to achieve accurate quantification and better analyte recovery. A single 18-minute chromatographic run allows for the quantification of 20 oxylipins and 5 PUFAs. The results showed good linearity (R2 > 0.99) over the concentration range of 2 to 100 ng/mL, with the instrument detection limits ranging from 0.01 to 0.90 ng/mL for oxylipins and 0.02 to 0.59 ng/mL for PUFAs. The method is rapid, sensitive, and reproducible (RSD ≤ 10%) and is suitable for the quantitative analysis of oxylipins and their precursors in infant formula samples.

A "dilute-and-shoot" column-switching UHPLC-MS/MS procedure for the rapid determination of branched nonylphenol in human urine: method optimisation and some fundamental aspects of nonylphenol analysis.

Technical grade branched nonylphenol (NP) was determined in human urine by online solid phase extraction-ultra high-performance liquid chromatography-tandem mass spectrometry (SPE-UHPLC-MS/MS). Prior to analysis, urine specimens were simply diluted and enzymatically deconjugated. The run time of the chromatography, including SPE and re-equilibration, was 9min per injection. The enzymatic cleavage of NP conjugates was optimised with incurred sample material from a human metabolism study: the highest recoveries were obtained with β-glucuronidase from E. coli K 12 in 0.1M ammonium acetate at pH 6.5, within a minimal hydrolysis time of 30 to 60min. Using sodium acetate instead of ammonium acetate led to systematically decreased recovery rates. The analytical method was validated regarding its precision (coefficients of variation: 2.9-7.4%), accuracy (relative recovery rates: 93-105%), robustness (relative recovery rates in individual urine matrices: 92-117%), selectivity, and limit of quantification (1.0μgL-1). Fundamental aspects in the analysis of technical product mixtures such as NP, comprising various isomers and homologues, were considered. Validation results, an exposure scenario and the application of the procedure to real samples, show that it enables a rugged monitoring of NP exposures above, at, and significantly below health-based guidance values, corresponding to daily NP intakes in the low μg kg-1 d-1 range. On the other hand, background levels in non-specifically exposed populations cannot be detected with this method. Hence, while alternative approaches should be pursued for NP analysis at environmental trace level, the speed and simplicity of our method are ideal for high-throughput human biomonitoring in occupational medicine.

Determination of four fungicides in water by magnetic solid phase extraction-ultrahigh performance liquid chromatography-tandem mass spectrometry using covalent organic framework material

Fungicides can lead to soil and plant diseases after long-term enrichment in the environment; they can also penetrate deeper into the soil and groundwater by rainwater or irrigation, threatening the water environment and human health. Therefore, it is crucial to develop a simple, rapid, efficient, and sensitive analytical method for the detection of fungicides in the water environment. Sample pretreatment is important for the extraction and enrichment of pollutants from environmental water. Magnetic solid phase extraction (MSPE) is a new sample pretreatment method, which uses magnetic materials as adsorbents dispersed in solution, and rapid separation can be achieved by the aid of external magnets. Because of its advantages of short analytical time, less organic solvent consumption, and easy separation of adsorbents, MSPE has attracted much attention. The key to MSPE is the preparation of highly selective magnetic adsorbents. Covalent organic frameworks have the advantages of large surface area, good chemical and thermal stability, tunable porous structure, low density, and easy functionalization, all of which are ideal for adsorbing fungicides. The concentration of fungicides in environmental water is low. Ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has high sensitivity and high selectivity, which is suitable for the analysis of fungicides. In this work, a magnetic covalent organic framework Fe3O4@TpBD was prepared by an in situ method, as the MSPE sorbent material to enrich of benzimidazole fungicides (thiabendazole, carbendazim, fuberidazole) and organic sulfur fungicide (isoprothiolane) in environmental water. An extraction method based on π-π conjugation, hydrogen bonding, and electrostatic interaction between Fe3O4@TpBD and the fungicides, in combination with UHPLC-MS/MS, was developed for the determination of four trace fungicides in water. Transmission electron microscopy (TEM), X-ray diffractometry (XRD), and Fourier transform-infrared spectroscopy (FT-IR) were performed to confirm the successful synthesis of Fe3O4@TpBD and to characterize this material. A series of experiments were carried out to decide the optimal extraction conditions, i. e., the magnetic ratio and dosage of Fe3O4@TpBD, pH of the water sample, adsorption time, type and volume of the eluent, elution time, and salinity. Gradient elution was carried out with methanol-water as the mobile phase. The target analytes were separated on an ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm), and multiple reaction monitoring (MRM) was conducted in the positive electrospray ionization mode. The ion source temperature and ion source voltage were set to 500 ℃ and 5 kV, respectively. The analytical method was established under the optimized extraction conditions. The four fungicides showed good linearity in the range of 3-1200 ng/L, with linear correlation coefficients greater than 0.998. The limits of detection (LODs) and limits of quantification (LOQs) of this developed method were 0.06-0.28 ng/L and 0.20-0.92 ng/L, respectively. Recovery tests were performed at three spiked levels of 15, 150, and 600 ng/L, with relative standard deviations of 2.8% to 10.0% (intra-day) and 4.4% to 15.7% (inter-day). The accuracy of the established analytical method was investigated by using it to test real water samples, and satisfactory recoveries for the four analytes were achieved within 77.1% to 119.1%. Trace amounts of carbendazim were detected in the reservoir water at 27.5 ng/L. The method has good sensitivity, accuracy, and precision, and the operation process is convenient.

On-line solid phase extraction–ultra high performance liquid chromatography–quadrupole/Orbitrap high resolution mass spectrometry determination of per- and polyfluoroalkyl substances in human serum

A rapid, high-performance, and accurate on-line TurboFlow ultra high performance liquid chromatography–quadrupole/Orbitrap high resolution mass spectrometry method was developed for the analysis of 46 per- and polyfluoroalkyl substances (PFAS), including 17 perfluoroalkylcarboxylic acids, 15 perfluoroalkylsulfonates, 3 fluorinated telomer sulfonates, 2 perfluoroalkyl unsaturated carboxylates, 2 perfluorooctanesulfonamidoacetic acid, 3 perfluorooctanesulfonamides, hexafluoropropylene oxide-dimer acid, ammonium 4,8-dioxa-3H-perfluorononanoate, 6:2 chlorinated polyfluorinated ether sulfonate (Cl-PFESA), and 8:2 Cl-PFESA, in human serum. The TurboFlow column, mobile phase, sample injection volume, loading flow rate, and elution time were optimized. The linearities of matrix calibration curves, method limits of quantification, accuracy and precision were investigated for method validation. Serum samples (50 μL) were precipitated with acetonitrile and directly injected into the system. The method showed good linearity (R2 > 0.99), satisfactory recoveries (matrix-spiked recoveries range: 68.9%–115.7%), good precision (relative standard deviation ranges: 1.2%–12.1%) and a low method limit of quantification (0.1–1 ng mL−1). The developed method is rapid, accurate and convenient for large-scale biomonitoring of PFAS in humans. Fifty real serum samples from China were analyzed and the results showed that br-perfluorooctanesulfonate (PFOS) accounted for approximately 30% of the ∑PFOS in serum, which suggested there was high exposure to 6:2 Cl-PFESA.

Determination of disulfoton and its metabolites in agricultural products by dispersive soild phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

基于超高效液相色谱-串联质谱(UHPLC-MS/MS)建立定量分析乙拌磷及其5个代谢物(乙拌磷砜、乙拌磷亚砜、内吸磷-S、内吸磷-S-砜、内吸磷-S-亚砜)的方法,应用该方法分析其在农产品(豌豆、芦笋、小麦、咖啡豆和花生)中的残留量。对样品前处理及色谱条件进行优化,样品经过乙腈涡旋提取(小麦、咖啡豆和花生先加水润湿),经盐析分层,取上清液经50 mg C18、50 mg PSA和50 mg NH2混合分散固相萃取净化后,经Thermo Syncronis C18色谱柱(150 mm×2.1 mm, 5 μm)分离,柱温40 ℃,进样量2 μL,以水和乙腈为流动相梯度洗脱后,采用ESI源,在正离子扫描和多反应监测(MRM)模式下检测,外标法定量。结果表明,乙拌磷及其代谢物在2.0~200.0 μg/L范围内线性关系良好,相关系数(R2)≥0.9981。方法的检出限(LOD)为0.02~2.0 μg/kg,并以最小添加水平5 μg/kg为定量限(LOQ)。乙拌磷及其代谢物在豌豆、芦笋、小麦、咖啡豆和花生中5、100、1000 μg/kg 3个添加水平下的平均回收率为75.0%~110.0%,相对标准偏差(RSD)为0.7%~14.9%,方法的准确度和精密度符合农药残留测定。应用建立的方法对市售的40份小麦样品和40份花生样品进行检测,均低于方法的检出限。该方法具有操作简单、快速、灵敏、准确的特点,适用于谷物、油料、蔬菜等多种农产品中乙拌磷及其代谢物的残留检测。

An On-Line Solid Phase Extraction-Ultra High Performance Liquid Chromatography-Quadrupole/Orbitrap High Resolution Mass Spectrometry Method for the Determination of Per- and Polyfluoroalkyl Substances in Human Serum

An On-Line Solid Phase Extraction-Ultra High Performance Liquid Chromatography-Quadrupole/Orbitrap High Resolution Mass Spectrometry Method for the Determination of Per- and Polyfluoroalkyl Substances in Human Serum

Determination of Urinary Mycotoxin Biomarkers Using a Sensitive Online Solid Phase Extraction-UHPLC-MS/MS Method.

In the course of assessing the human exposure to mycotoxins, biomarker-based approaches have proven to be important tools. Low concentration levels, complex matrix compositions, structurally diverse analytes, and the large size of sample cohorts are the main challenges of analytical procedures. For that reason, an online solid phase extraction-ultra high-performance liquid chromatography-tandem mass spectrometry (online SPE-UHPLC-MS/MS) method was developed, allowing for the sensitive, robust, and rapid analysis of 11 relevant mycotoxins and mycotoxin metabolites in human urine. The included spectrum of analytes comprises aflatoxin M1 (AFM1), altenuene (ALT), alternariol monomethyl ether (AME), alternariol (AOH), citrinin (CIT) and its metabolite dihydrocitrinone (DH-CIT), fumonisin B1 (FB1), ochratoxin A (OTA), and zearalenone (ZEN) as well as α- and β-zearalenol (α- and β-ZEL). Reliable quantitation was achieved by means of stable isotope dilution, except for ALT, AME and AOH using matrix calibrations. The evaluation of method performance displayed low limits of detection in the range of pg/mL urine, satisfactory apparent recovery rates as well as high accuracy and precision during intra- and interday repeatability. Within the analysis of Zimbabwean urine samples (n = 50), the applicability of the newly developed method was shown. In addition to FB1 being quantifiable in all analyzed samples, six other mycotoxin biomarkers were detected. Compared to the occurrence rates obtained after analyzing the same sample set using an established dilute and shoot (DaS) approach, a considerably higher number of positive samples was observed when applying the online SPE method. Owing to the increased sensitivity, less need of sample handling, and low time effort, the herein presented online SPE approach provides a valuable contribution to human biomonitoring of mycotoxin exposure.

Determination of 11 perfluorinated compounds in drinking water by solid phase extraction-ultra high performance liquid chromatography tandem mass spectrometry

To develop a method for the determination of 11 perfluorinated compounds(PFCs) in drinking water by solid phase extraction-ultra performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS). The target analytes in water samples were concentrated and purified by Oasis WAX SPE column and eluted with 5 mL methanol and 7 mL 0. 1% ammonia-methanol solution. The eluent was blown to near dryness under a nitrogen gas, diluting with methanol water solution(3∶7, V/V) to 1 mL for analysis by UPLC-MS/MS. There were good liner relationship in the range of 0. 5-50 μg/L. The detection limit and the limit of quantitation were 0. 03-0. 7 ng/L and 0. 5-3. 0 ng/L, respectively. The recoveries of 11 PFCs at three different spiked concentrations were 90. 0%-122. 3%, 87. 1%-130. 0% and 80. 0%-113. 7%, respectively, and the relative standard deviation were 1. 95%-8. 59%, 1. 27%-9. 08% and 2. 17%-10. 51%(n=6), respectively. This method has wide linear range, low detection limit and limit of quantitation, applicable for simultaneous analysis and monitorting of 11 PFCs in drinking water.

Prevalence of Antibiotic Resistance Genes and Their Association with Antibiotics in a Wastewater Treatment Plant: Process Distribution and Analysis

Effluents from wastewater treatment plants has been identified as a main point-source of antibiotics and antibiotic resistance genes in natural water environments. In this study, a typical municipal sewage treatment system in south China was taken as the research object to investigate the effects of each treatment unit on eight target antibiotics (sulfamethoxazole, sulfamethazine, tetracycline hydrochloride, oxytetracycline dihydrate, norfloxacin, ofloxacin, clarithromycin, roxithromycin), 17 antibiotic resistance genes (ARGs) and class 1 integron genes in the system using Accelerated Solvent Extraction-Solid phase extraction-Ultra high Performance Liquid Chromatography-Tandem mass spectrometry (ASE-SPE-UPLC-MS/MS) and real-time fluorescent quantitative PCR (qPCR) and the correlation between them. Seven antibiotics (mainly sulfonamides and tetracyclines, 4.19–141.97 ng·L−1) were detected in the influent, while only sulfamethoxazole, sulfamethazine, ofloxacin, and clarithromycin were detected in the effluent (3.11–16.61 ng·L−1). The tetracycline antibiotics in the wastewater treatment plant (WWTP) were transferred to the sludge phase by adsorption, in which tetracycline hydrochloride and oxytetracycline dihydrate were mostly removed in the aerobic and anaerobic stages, while sulfamethoxazole was mainly removed through biological transformation. Sul I was the most abundant resistance gene, but the WWTP had no obvious effect on its removal. Anaerobic treatment was found to play an important role in tetA, tetQ, and tetX removal. Moreover, correlation analysis revealed that the relative abundance of tetX was significantly correlated with clarithromycin (p = 0.039) and ofloxacin (p = 0.028), while that of tetQ was significantly correlated with sulfamethazine (p = 0.007) and sulfamethoxazole (p = 0.001), and that of tetC was significantly correlated with the class 1 integron gene (p = 0.014). Overall, the results presented herein provide a reference for improving the antibiotics and ARGs removal efficiency of WWTPs in south China.

Fluoroquinolones in Hospital Wastewater: Analytical Method, Occurrence, Treatment with Ozone and Residual Antimicrobial Activity Evaluation

Fluoroquinolones antimicrobials are partially excreted in natura after administration. Their occurrence was investigated in hospital raw sewage (HRS) and treated wastewater (TW) using an online solid phase extraction-ultra high-performance liquid chromatography-tandem mass spectrometry method (SPE-UHPLC-MS/MS). The analytical curves ranged from 0.25 to 46 ng mL-1 and the matrix effect, assessed for marbofloxacin and lomefloxacin, ranged from –63 to +1%. All HRS samples contained ciprofloxacin (1-34 ng mL-1) and ofloxacin (0.9-27 ng mL-1), while norfloxacin was detected in 17% of the samples (0.8-4.4 ng mL-1). Only ciprofloxacin (0.5-5.6 ng mL-1) was detected in TW samples. The antimicrobial activity of the HRS samples for E. coli was higher than a ciprofloxacin solution of 1 mg L-1, due to the presence of other antimicrobial agents. Ozonation (10 mg O3 L-1 min-1 ; 10 min) degraded up to 84% of the fluoroquinolones and removed the antimicrobial activity of HRS samples.

Dried blood spots for reliable biomonitoring of poly- and perfluoroalkyl substances (PFASs)

Dried blood spot (DBS) sampling has gained attention in several scientific areas because of the low sampling burden. The study aimed to develop a method for the determination of poly- and perfluoroalkyl substances (PFASs) in DBS using a standardized blood volume. The DBS method using a simple methanol extraction followed by online solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry quantification was validated. Only 30 μL of blood is required. Based on the measurements of DBS dispersed areas from known blood volumes (20–70 μL), the blood volume on a 3 mm diameter DBS subsample was calculated to be 3.3 μL (median, n = 708 measurements, 59 adults). Strong correlations of PFAS concentrations between finger prick DBSs and venous whole blood samples (n = 57) were found (rho 0.72–0.97, p < 0.0001). Also, Passing-Bablok regressions and Bland-Altman plots demonstrated good agreements of PFAS concentrations in finger prick DBSs and venous whole blood samples. This finding indicates that the DBS method was satisfactory, and allows straightforward analysis of PFASs in DBS without hematocrit correction. This DBS method is reliable for accurate determination of PFASs and has a high potential for use of self-collected DBS in large-scale biomonitoring studies as well as for archived DBS samples.

Determination of 42 glucocorticoids in infant eczema products by auto-solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of 42 glucocorticoids in infant eczema products by auto-solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (ASPE-UHPLC-MS/MS).The analytes were extracted by acetonitrile after dispersing in saturated sodium chloride solution.Macromolecules matrix were precipitated by adding potassium and zinc acetate, and then purified by HLB SPE column.The chromatographic separations were performed on a DIKMA EndeavorsilTM C18 column (100 mm×2.1 mm, 1.7 μm).Acetonitrile and 0.1%(v/v) formic acid aqueous solution were used as the mobile phases.Electrospray ionization (ESI) source was operated in the positive mode using multiple reaction monitoring (MRM) scanning mode.The results were quantified by external standard method.The correlation coefficients of linear calibration curves were greater than 0.998 in the corresponding mass concentration ranges.The average recoveries at three spiked levels ranged from 78.7% to 101.5%, and the relative standard deviations (RSDs) were 2.0%-8.8%(n=6).The LODs (S/N ≥ 3) and LOQs were 0.002-0.031 mg/kg and 0.0007-0.103 mg/kg, respectively.The method is simple, rapid, sensitive, and reliable, and can be used for the detection of glucocorticoids in infant eczema products.

High throughput online solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry method for polyfluoroalkyl phosphate esters, perfluoroalkyl phosphonates, and other perfluoroalkyl substances in human serum, plasma, and whole blood

A rapid, sensitive and reliable method was developed for the determination of a broad range of poly- and perfluoroalkyl substances (PFASs) in various blood matrices (serum, plasma, and whole blood), and uses only 50 μL of sample material. The method consists of a rapid protein precipitation by methanol followed by high throughput online solid phase extraction (SPE), ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), and negative electrospray ionization detection. The method was developed for simultaneous determination of twenty-five PFASs, including polyfluoroalkyl phosphate esters (PAPs; 6:2, 8:2, 6:2/6:2, and 8:2/8:2), perfluoroalkyl phosphonates (PFPAs; C6, C8, and C10), perfluoroalkyl sulfonates (PFSAs; C4, C6, C7, C8, and C10), perfluoroalkyl carboxylates (PFCAs; C5C14), and perfluoroalkyl sulfonamides (FOSAs; C8, N-methyl, and N-ethyl). High linearity of matrix-matched calibration standards (correlation coefficients, R = 0.99–0.999) were obtained in the range of 0.006–45 ng mL−1 blood. Excellent sensitivity was achieved with method detection limits (MDLs) between 0.0018 and 0.09 ng mL−1, depending on the compound and matrix. The method was validated for serum, plasma, and whole blood (n = 5 + 5) at six levels in the range 0.0180–30 ng mL−1. The accuracy (n = 5) was on average 102± 12%. The intermediate precision (n = 10) ranged from 2 to 40% with an average between-batch of analyses difference of 10± 10%. Two human serum samples from a former interlaboratory comparison were analyzed and the differences between the applied method and the consensus values were below ≤22% (n = 5). The method was also successfully applied to samples of human plasma and whole blood with coefficients of variation in the range 0.8–15.2% (n = 5).

On-line solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry as a powerful technique for the determination of sulfonamide residues in soils

Sulfonamides are antimicrobials used widely as veterinary drugs, and their residues have been detected in environmental matrices. An analytical method for determining sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline residues in soils employing a solid phase extraction on-line technique coupled with ultra-high performance liquid chromatography and tandem mass spectrometry (SPE-UHPLC–MS/MS) was developed and validated in this study. SPE and chromatographic separation were performed using an Oasis HLB column and an Acquity UPLC BEH C18 analytical column, respectively, at 40°C. Samples were prepared by extracting sulfonamides from soil using a solid-liquid extraction method with water:acetonitrile, 1:1v/v (recovery of 70.2–99.9%). The following parameters were evaluated to optimize the on-line SPE process: sorbent type (Oasis and C8), sample volume (100–400μL), loading solvent (water and different proportions of water:methanol) and washing volume (0.19–0.66mL). The method produced linear results for all sulfonamides from 0.5 to 12.5ngg−1 with a linearity greater than 0.99. The precision of the method was less than 15%, and the matrix effect was −27% to −87%. The accuracy was in the range of 77–112% for all sulfonamides. The limit of quantitation in the two soils (clay and sand) was 0.5ngg−1. The SPE column allowed for the analysis of many (more than 2000) samples without decreasing the efficiency.

A fast and sensitive method for the simultaneous analysis of a wide range of per- and polyfluoroalkyl substances in indoor dust using on-line solid phase extraction-ultrahigh performance liquid chromatography-time-of-flight-mass spectrometry

A fast and sensitive method for simultaneous determination of 18 traditional and 6 alternative per- and polyfluoroalkyl substances (PFASs) using solid-liquid extraction (SLE), off-line clean-up using activated carbon and on-line solid phase extraction-ultrahigh performance liquid chromatography-time-of-flight-mass spectrometry (on-line SPE-UHPLC-TOF-MS) was developed. The extraction efficiency was studied and recoveries in range the 58–114% were obtained. Extraction and injection volumes were also optimized to 2mL and 400μL, respectively. The method was validated by spiking dust from a vacuum cleaner bag that had been found to contain low levels of the PFASs in focus. Low method detection limits (MDLs) and method quantification limits (MQLs) in the range 0.008–0.846ngg−1 and 0.027–2.820ngg−1 were obtained, respectively. For most of the PFASs, the accuracies were between 70 and 125% in the range from 2 to100ngg−1 dust. Intra-day and inter-day precisions were in general well below 30%. Analysis of a Standard Reference Material (SRM 2585) showed high accordance with results obtained by other laboratories. Finally, the method was applied to seven indoor dust samples, and PFAS concentrations in the range 0.02–132ngg−1 were found. The highest median concentrations were observed for some of the alternative PFASs, such as 6:2-diPAP (25ngg−1), 8:2-diPAP (49ngg−1), and PFOPA (23ngg−1), illustrating the importance of inclusion of new PFASs in the analytical methods.

Sensitive profiling of phenols, bile acids, sterols, and eicosanoids in mammalian urine by large volume direct injection-online solid phase extraction-ultra high performance liquid chromatography-polarity switching tandem mass spectrometry

A new sensitive LVDI-online SPE-UHPLC-psMS/MS method was developed and applied for simultaneous and direct determination of 28 constituents, including 10 BAs, 5 sterols, 8 eicosanoids and 8 phenolic compounds in mammalian urinary samples.

Determination of amantadine and rimantadine residues in egg and chicken samples by dispersive solid phase extraction purification-ultra high performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of residual amantadine and rimantadine in eggs and chickens by dispersive solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry. Egg and chicken samples were extracted with ammonia water-acetonitrile (2:98, v/v). The extraction solution was dried to 1 mL under nitrogen, and then purified by dispersive solid phase extraction method with C18 and NH2 sorbents. After purification, the extraction solution was filtered through a filter. The target compounds were analyzed by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) on a ZORBAX C18 column using a mixture of 1 mmol/L ammonium acetate solution (containing 0.1% (v/v) formic acid) and methanol as mobile phases with gradient elution. The mass spectrometer was operated under multiple reaction monitoring (MRM) mode in positive mode. The good linearities were obtained for amantadine and rimantadine at a concentration range of 0.15-10.0 μg/L. The limits of detection for amantadine and rimantadine were all 0.05 μg/kg, and the limits of quantification were 0.20 μg/kg. The recoveries of amantadine and rimantadine in eggs and chickens at three spiked levels (0.2, 1.0 and 2.0 μg/kg) age of 89%-108% with the relative standard deviations of 5.0%-8.6%. The results demonstrated that the method is suitable for the determination of amantadine and rimantadine in eggs and chickens.

Determination of six amide pesticide residues in vegetables and fruits by solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

A solid phase extraction coupled with ultra high performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) method was developed for simultaneous determination of six amide pesticides, cyantraniliprole, mandipropamid, boscalid, fluopicolide, thifluzamide and flubendiamide, in vegetables and fruits. After extraction with acetonitrile, purification with Florisil SPE cartridges and dissolution with methanol, the targets in the sample solutions were analyzed by UPLC-MS/MS on an Agilent Proshell 120 EC-C18 column with a mixture of 0.1% formic acid solution and methanol as the mobile phases under gradient elution conditions. The mass spectrometer operated in multiple reaction monitoring (MRM) mode with the negative and positive modes. Good linearity was obtained for the six amide pesticides at the mass concentrations of 0.000 5 - 1.00 mg/L with the correlation coefficients more than 0.999. The fortified recoveries were in the range of 72.4% - 119.4% with the concentration levels at 0.01, 0.1 and 1.0 mg/kg for cyantraniliprole, mandipropamid, boscalid, fluopicolide, thifluzamide, and 0.001, 0.01 and 0.1 mg/kg for flubendiamide. The relative standard deviations (RSDs) were less than 15% and the limits of quantification were 0.01 mg/kg for cyantraniliprole, mandipropamid, boscalid, fluopicolide, thifluzamide, and 0.001 mg/kg for flubendiamide. All the above observations indicate that the established analytical method is simple, efficient and sensitive, and suitable for the determination of the six amide pesticides in vegetables and fruits.

Determination of choline chloride in milk powder and jelly by solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

Determination of choline chloride in milk powder and jelly by solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

Rapid and sensitive on-line solid phase extraction-ultra high performance liquid chromatography–electrospray-tandem mass spectrometry analysis of pesticides in surface waters

A simple, fast and sensitive method has been developed for the determination of 37 LC-amenable pesticides in surface water samples. On-line solid phase extraction (SPE) coupled to ultra high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS. was employed for pre-concentration and analysis of all compounds in 16min. SPE parameters were evaluated in order to increase sample throughput and detectability. Thus, injected sample volume, sample loading flow, carryover effects and reusability of the cartridges employed were studied, observing that 70 extractions can be performed with the same cartridge. Validation parameters were performed and good linearity (R2>0.99 in all cases) and precision (interday relative standard deviation values were lower than 14%) were obtained. Limits of detection (LOD) and limits of quantification (LOQ) were lower than 6.0 and 18.0ngL−1 applying an injection sample volume of 1.5mL, respectively, with exception of thifensulfuron methyl, whose limits were 10.0 and 33.0ngL−1, respectively. On-line SPE recoveries were evaluated for three concentration levels (0.01, 0.03, 0.10 and 0.20μgL−1) and acceptable values were found. The on-line SPE method was also compared with off-line SPE. Matrix effects were observed for majority of compounds and standard addition method was selected for analysis of real water samples. Finally, surface water samples were analyzed and, in all cases, the pesticide concentrations were below than the allowable limit in water for human consumption.