Solid-phase Extraction Liquid Chromatography Research Articles

Quantitative analysis of free glycerol in biodiesel using solid-phase extraction and high-performance liquid chromatography

This study developed a method for separating and quantifying free glycerol in biodiesel. The free glycerol in biodiesel samples was separated using solid-phase extraction (SPE) and subsequently quantified by high-performance liquid chromatography (HPLC) using an ion-exchange stationary phase and refractive index detector (IR). The proposed method (SPE-HPLC-IR) was validated for high- and low-concentration samples (coefficient of determination, R2≥0.99): limit of detection (0.00029% m/m, high; 0.00018% m/m, low); limit of quantification (0.00089% m/m, high; 0.00054% m/m, low); precision (standard deviation < 5.0%), and accuracy (recovery of 98.93% to 106.71%). The proposed method was compared with the reference method (ASTM D6584) using the paired t-test, and no statistical differences were found between them (95% confidence). As such, the proposed method offers a simple, quick, effective method for determining free glycerol in biodiesel and a viable alternative to the reference method.

Simple and efficient preparation of high-purity trehalulose from the waste syrup of isomaltulose production using solid-phase extraction followed by hydrophilic interaction chromatography.

A simple and efficient method was developed for the preparation of high-purity trehalulose from the waste syrup of isomaltulose production. The waste syrup was pre-treated with C18 solid-phase extraction, where 98% decolorization and 97% reducing sugar recovery were obtained, followed by hydrophilic interaction liquid chromatography separation on a cysteine-bonded zwitterionic column. Under optimized conditions, trehalulose was separated from isomaltulose isomer and prepared on a semi-preparative scale with >99% purity. The structure of the prepared trehalulose was subsequently confirmed by nuclear magnetic resonance, and three tautomers of trehalulose (α-D-glucosylpyranosyl-1,1-β-D-fructopyranose, α-D-glucosylpyranosyl-1,1-β-D-fructofuranose, and α-D-glucosylpyranosyl-1,1-α-D-fructofuranose) were detected and completely characterized by 13 C NMR spectroscopy for the first time in this study. The tautomerization of α-D and β-D type transition was observed by hydrophilic interaction liquid chromatography on an AdvanceBio Glycan Mapping column, with smaller particle size (2.7 μm). Furthermore, the prepared trehalulose was applied as a standard for trehalulose quantification during the sucrose conversion by Klebsiella sp. LX3. The combination of solid-phase extraction and hydrophilic interaction liquid chromatography offers a new avenue for the preparation of sugar isomers from complex natural or fermentation products.

Simultaneous determination of notoginsenoside R1 and ginsenosides Rg1, Re, Rb1 in dietary supplements by HPLC-DAD

A method using solid phase extraction (SPE) and high performance liquid chromatography with diode array detector (HPLC-DAD) has been optimized for the&amp;nbsp;simultaneous&amp;nbsp;determination&amp;nbsp;of notoginsenoside R1 and three ginsenosides Rg1, Re, Rb1 in solid, oil, and liquid dietary&amp;nbsp;supplements. The substances were separated by an InertSustain C18 column (250 mm &amp;times; 4.6 mm&amp;nbsp;i.d.; particle size 5 &amp;mu;m) with a gradient program composed of acetonitrile and water. Linearities&amp;nbsp;were in the range of 4.0 - 400 &amp;mu;g/mL with the coefficients of determination were more than&amp;nbsp;0.999. The limits of detection and limits of quantitation were 2.13 - 6.89 &amp;mu;g/g and 7.11 - 22.98&amp;nbsp;&amp;mu;g/g, respectively. The recovery values of the compounds were in the range of 87.2 - 103.5%.&amp;nbsp;The precision study showed the intra-day relative standard deviation (RSD) of 1.41 - 2.91%, and&amp;nbsp;inter-day RSD of 1.87 - 4.85%, which meet the AOAC International requirements. The method&amp;nbsp;was applied to determine the content of notoginsenoside R1, ginsenoside Rg1, ginsenoside Re,&amp;nbsp;and ginsenoside Rb1 in 20 dietary supplement samples containing Ginseng and&amp;nbsp;Pseudoginseng.

Determination and risk assessment of acrylamide in thermally processed Atractylodis Macrocephalae Rhizoma

As one of the medicine homologous foods in China, Atractylodis Macrocephalae Rhizoma (AMR) is usually distributed after thermal processing, which raised the possibility of acrylamide pollution and a potential carcinogenic risk. In this study, a method was developed for the determination of the acrylamide in AMR using graphited multiwalled carbon nanotubes as the dispersive solid phase extraction sorbent and liquid chromatography tandem mass spectrometry. The concentration of acrylamide was investigated at processing conditions of 80℃-210℃ and 5 min–100 min. Method validation results demonstrated the reliability of the method with good linearity, accuracy and precision. Significant increment of acrylamide was found in AMR after thermal processing with the highest concentration at 9826 μg/kg, which led to a margin of exposure at 90.83–181.7 according to the BMDL10 of carcinogenicity at 0.17 mg/kg, indicating a high health risk of taking thermally processed AMR, and monitoring and controlling should be considered.

Occurrence Characteristics and Health Risk Assessment of Endocrine Disrupting Chemicals in Groundwater in Wuxi-Changzhou

The concentrations of 22 endocrine disrupting chemicals, including 4 categories of sex hormones, progesterones, glucocorticoids, and phenolic hormones, in groundwater of Wuxi-Changzhou were analyzed using solid-phase extraction and ultra-performance liquid chromatography tandem mass spectrometry. The results indicated that 20 EDCs were detected, among which bisphenol A (BPA), estrone (E1), estradiol (E2), and 17α-ethinyl estradiol (EE2) were the main components with detection ratios greater than 90%, followed by estriol (E3) and methyl-prednisolonel (Meprednl), which had detection rates 67.7% and 48.4%, respectively. The average concentration of BPA was the highest (4.95 ng·L-1), followed by that of Meprednl, E2, prednisolone (Prednl), testosterone propionate (TES-pro), and megestrol-acetate (MA; 2.84, 0.71, 0.64, 0.58, and 0.53 ng·L-1, respectively). The total concentration in each site ranged from 0.38 to 147.35 ng·L-1. The sites with higher concentration were mainly distributed in the Xinbei District, Liyang City, and the Zhonglou District of Changzhou City. The potential sources were analyzed by a principal component analysis (PCA) combining the point sources near sample sites. The results showed that domestic sewage, aquaculture, and industrial wastewater were the main sources, following by medical wastewater. A non-carcinogenic risk assessment showed a low risk of EDCs in the groundwater of the study area, and the risk of drinking water was greater than that of skin exposure. EE2 had the highest non-carcinogenic risk and is suggested to be monitored in priority.

Development of a pH-paralleling approach of quantifying six-category pharmaceuticals in surface water using SPE-HPLC-MS/MS

An analytical protocol was developed to quantify six-category pharmaceuticals in surface water under paralleling pHs using a combination of solid phase extraction (SPE) and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Of 121 compound standards commercially, 94 compounds were reliably quantified using a paralleling pH combination at 3 and 9 with a sound recovery-rate of 50-150%. The quantified compounds covered 6 categories as 37 antibiotics, 16 central nervous system drugs (CNs), 14 cardiovascular drugs (CVs), 12 endocrine and family planning drugs (EFs), 8 antiparasitic drugs (APs), and 7 non-steroidal anti-inflammatory drugs (NSAIDs). The protocol achieved limits of detection and quantitation in ranges of 0.001–11.9 ng L–1 and 0.003–39.7 ng L–1, respectively. Serial field surface water samples from Jiulong River in Fujian, China were testified using the protocol with 41 quantified compounds of the above-mentioned 6 categories from < LODs to 1,389 ng L−1 (caffeine). The key procedure prior to the SPE is to split filtrate of each surface water sample into two portions, adjusted to pH 3 and 9 separately and both spiked with 0.2 g Na2EDTA.

On-line separation/analysis of Rhodamine B dye based on a solid-phase extraction high performance liquid chromatography self-designed device.

A special self-designed device based on poly-1-vinyl-3-pentylimidazole hexafluorophosphate (PILs-C5) solid-phase extraction and high performance liquid chromatography (HPLC) is proposed as a novel method for the on-line separation and analysis of Rhodamine B (RhB) dye. Single factor experiment design and orthogonal experiment design were used to optimize the experimental parameters, such as pH, the amount of PILs-C5, sample volume, flow rate, eluent type, eluent concentration, eluent volume, and the flow rate of eluent. Under the optimized conditions, the linear range was 0.02–2.4 μg mL−1, with the correlation coefficients (R2) of 0.997. The limit of detection (LOD) and limit of quantification (LOQ) were 0.004 μg mL−1 and 0.02 μg mL−1, respectively. The extraction capacity was 6.22 mg g−1, and enrichment ratio was 15. The extraction mechanism and the post-treatment method of PILs-C5 were also studied. This method was applied to analyze RhB in a wide variety of real samples with satisfactory results.

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.

Lung deposition and systemic bioavailability of dose delivered to smoker compared with non-smoker COPD subjects.

Inhaled drugs are the most commonly used class of medications for COPD subjects. No studies have been performed to assess the influence of smoking on lung deposition of aerosolized medication, especially for the exacerbated COPD subject. The present study aimed to assess the influence of smoking on the lung deposition of the aerosol delivered to exacerbated COPD subjects. Twenty-four exacerbated COPD subjects using automatic continuous positive airway pressure (Auto-CPAP), 12 smokers (six females) and 12 non-smokers (six females) were recruited in the study. The subjects participated in the study received four salbutamol study doses; 1200µg (12 puffs 100µg/puff) of salbutamol emitted from pMDI canister connected to AeroChamber MV spacer; 1200µg of salbutamol emitted from pMDI canister connected to Combihaler spacer; 1mL of salbutamol respirable solution (5000µg/mL) nebulized by Aerogen Solo connected to its T-piece; and 1mL of salbutamol respirable solution nebulized by Aerogen Solo connected to Combihaler spacer with 2 puffs salbutamol MDI (200µg salbutamol) before nebulisation. The subjects were randomised to receive the four selected dose-adaptor combination in a sealed envelope design on days 1, 3, 5 and 7. A washout period of 24hours was provided between each salbutamol dosing. Auto-CPAP was adjusted at non-invasive ventilation mode with the integrated heated humidifier, as a source of humidity. Urine samples were provided by subjects, 30minutes and cumulatively 24hours post inhalation, as an index of the relative and systemic bioavailability, respectively, and aliquots were retained for salbutamol analysis using solid-phase extraction and high-performance liquid chromatography (HPLC). On day 2 of the study, a collecting filter was placed between the aerosol generator and the subject's mask so that the subjects would not inhale the salbutamol delivered. The same study doses and/or adapters were delivered to each subject, with filters changed with each dose-adapter combination. Salbutamol entrained on the filter was desorbed to be analysed by the HPLC. Significantly higher lung deposition (30minutes urinary salbutamol) was detected with the non-smoker compared with smokers (P<.05). Significantly higher systemic bioavailability (pooled 24-hour urinary salbutamol) for smokers compared with non-smokers was found with Aerogen Solo connected to its T-piece and CombiHaler spacer with pMDI (P<.05) only. Significantly higher amount desorbed from the ex-vivo filter were found from pMDI with both spacers in non-smokers (P<.05) compared with the smokers. The study demonstrated that smoking reduced the lung deposition of inhaled salbutamol delivered by nebulizer or pMDI. However, the smoking effect on cytochrome p450 was observed to increase systemic absorption of the ingested portion of the inhaled dose. The lower lung deposition and possible higher systemic absorption should be taken into consideration while prescribing inhaled medication to COPD smokers especially exacerbated patients that need ventilation. Further studies are needed.

Simultaneous determination of 16 flavonoids and ferulic acid in honey by solid phase extraction and high performance liquid chromatography-tandem mass spectrometry

Flavonoids are polyphenol compounds that are widely distributed in honey; they play an important role in its antioxidant activity and aid in distinguishing various species of honey. An analytical method based on solid phase extraction and high performance liquid chromatography with tandem mass spectrometry (SPE-HPLC-MS/MS) for the simultaneous determination of rutin, myricetin, morin, quercetin, naringenin, hesperetin, luteolin, genistein, kaempferol, isorhamnetin, apigenin, pinocembrin, wogonin, chrysin, galangin, genkwanin, and ferulic acid in honey was developed and validated. The honey samples were diluted with HCl solution (pH 2) and cleaned up on a C18 column by solid phase extraction; the methanol eluent was filtered through a nylon membrane and analyzed by LC-MS/MS on an ODS-3 column (150 mm×4.6 mm, 3 μm). Quantitative detection was performed by LC-MS/MS in the multiple reaction monitoring (MRM) mode under negative electrospray ionization (ESI-) conditions. The external standard method was used for quantitation. The method validation data were obtained. The calibration standard curve solutions were prepared by honey matrix-matching; the linear range was 0-200 μg/kg, with correlation coefficients of the calibration standard curves greater than 0.997. The limits of quantification (LOQs) of this method were 20 μg/kg. The recoveries were in the range of 64.5%-113%, and the relative standard deviations were 1.4%-14.5% at three spiked levels (20, 40, and 100 μg/kg). The developed method is convenient, rapid, and effective, and it is suitable for the determination and confirmation of flavonoids in honey samples.

Determination of perfluorinated and polyfluorinated alkyl substances in drinking water samples using automated solid phase extraction and liquid chromatography–tandem mass spectrometry

AbstractA new analytical method was developed to extract and determine 25 perfluorinated and polyfluorinated alkyl substances from aqueous samples using an automated solid phase extraction system and liquid chromatography–tandem mass spectrometry. Full method validation including assessment of background signal, lowest concentration minimum reporting level, calibration, limit of quantitation, precision, and accuracy was performed. The analysis of drinking water samples was performed for all target analytes. This method also incorporates the use of isotope dilution in which isotopically labeled analogs of the target analytes are added to the sample prior to extraction in a known amount to correct for sample matrix interference and improve data quality. We demonstrated that the automated solid‐phase extraction system provided reliable extraction of the target perfluorinated and polyfluorinated alkyl substances analytes from large‐ of use, reduced human errors, avoidance of massive lab contaminations and saving up to 50% operational time to manual operation while ensuring high reproducibility and productivity for analytical testing laboratories.

Distribution Characteristics and Risk Assessment of PPCPs in Surface Water and Aquatic Organisms in Chaoshan Coastal Area along the South China Sea

To investigate the occurrence, distribution, and potential risks of pharmaceuticals and personal care products (PPCPs) in the South costal area of China, a total of 20 PPCPs in water and aquatic organisms (fish, crab, and shellfish), obtained from 7 coastal rivers of the Chaoshan area, were determined using solid-phase extraction (SPE) and high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The results showed that up to 16 to 18 kinds of PPCPs could be detected in the rivers and aquatic organisms of the Chaoshan area, and the concentrations of PPCPs in the rivers and organisms ranged from 0.30-2223 ng ·L-1 to 0.143-80.3 ng ·g-1, respectively, with a high detection rate for many pollutants. Significant differences were observed in the samples of water and organisms. The total concentration of PPCPs in the rivers of the Chaoshan area was in the order of Huanggang River > Lianjiang River > Huangjiang River > Longjiang River > Luohe River > Rongjiang River > Hanjiang River, with the dominance of sulfamethoxazole (SMX) and caffeine (CAF). The total concentrations of PPCPs in the aquatic organisms from the Huanggang River, Hanjiang River, Lianjiang River, and Luohe River were higher than the concentrations of PPCPs in the aquatic organisms from the Longjiang River and Rongjiang River, with a dominance of trimethoprim (TMP), SMX, and CAF. The total concentration of PPCPs in fish was significantly higher than that in crab and shellfish. The results of bioconcentration factor (BCF) showed that a variety of PPCPs were accumulated in the organisms from the Chaoshan rivers; among them, the BCF value in fish was higher, which was more likely to bioaccumulate than crabs and shellfish. The ecological risks in terms of risk quotient (RQ) for 12 typical PPCPs were assessed in the Chaoshan area. It was discovered that the risk for fleas and algae was significantly higher than that for fish. The RQ values of SMX, erythromycin (ERY), and sulfadiazine (SDZ) were all greater than 1, which posed potential ecological risks for algae in the Huanggang River and Lianjiang Rivers and for fleas in the Huangjiang River.

Determination of phenolic compounds in water-ethanol extracts of &lt;i&gt;Populus tremula&lt;/i&gt; L. leaves using high-performance liquid chromatography

The analytical task of determining the phenolic compound content of water-ethanol extracts of Populus tremula L. (common aspen) leaves is complicated by the heterogeneity of compound groups having different polarities and appearing in varying concentrations. The purpose of the present work is to study the conditions of solid-phase extraction and high-performance liquid chromatography used to analyse the content of different groups of phenolic compounds in water-ethanol extracts of leaves from the P. tremula plant. In order to facilitate the derivation of phenolic compounds, an exhaustive extraction process was carried out using ethanol. Solid-phase extraction was carried out using a Diapak C16 cartridge, after which the eluates were passed through a membrane filter having a pore diameter of 0.45 μm. The high-performance liquid chromatography method was used to determine the content of phenolic acids and flavonoid glycosides, as well as salicin and individual flavonoid glycoside components: hyperoside, rutin, astragalin and two unidentified flavonoid glycosides in aqueous (analyte 1) and aqueous-alcoholic fractions (analyte 2) in two systems along the gradient elution. The requirement of analysing the primary aqueous eluate together or in parallel with the main aqueous-alcoholic fraction in the preparation of P. tremula leaf extracts for high-performance liquid chromatography using solid-phase extraction cartridges was substantiated. For separating the extract to determine the hydroxycinnamic and hydroxybenzoic acid content, it is preferable to use system 2; for determining the phenologlycoside (salicin) content, system 1 is more effective. Flavonoid glycosides (hyperoside, rutin, astragalin and two unidentified flavonoids) make the most significant contribution to the difference between the aqueous and aqueous-alcoholic fractions.

Determination of Amphetamine and Methamphetamine in Human Hair by Gas Chromatography Mass Spectrometry

This article develops a combined solid phase extraction (SPE) and gas chromatography – mass spectrometry (GC-MS) procedure for determining amphetamine-type stimulants Amphetamine (AM) and Methamphetamine (MA) in human hair. Hair samples were incubated in methanol containing 1% hydrochloric acid in 18 hours and then subjected to SPE. The obtained extracts were evaporated to dryness, derivatized with heptafluorobutyric anhydride (HFBA) at 70 °C for 30 minutes prior to GC–MS analysis. Gas chromatography mass spectrometry was run on HP5-MS column (30 m × 0.25 mm × 0.25 µm) with detector MS 5975C. Experimentally, the proposed method proved sensitive, simple and time-saving, but quite accurate with a low limit of detection (LOD = 0.05ng/mg) and quantitation (LOQ = 0.15ng/mg).&#x0D; Keywords:&#x0D; SPE, GC – MS, hair samples, amphetamine, methamphetamine.&#x0D; References&#x0D; [1] Ming-Ren Fuh, Ti-Yu Wu and Tzuen-Yeuan Lin, Determination of amphetamine and methamphetamine in urine by solid phase extraction and ion-pair liquid chromatography–electrospray–tandem mass spectrometry Talanta, 68 (3) (2006), 987-991. https://doi.org/10.1016/j.talanta.2005.06.057[2] Naresh C. Jain, Thomas C. Sneath, and Robert D. Budd, Rapid Gas-Chomatographic Determination of Amphetamine and Methamphetamine in urine, Clinical Chemistry, 20 (11) (1974) 1460-1462. https://doi.org/10.1093/clinchem/20.11.1460.[3] Dong-liang Lin, Rea-Ming Yin, Ray H. Liu, Gas Chromatography-Mass Spectrometry (GC-MS) Analysis of Amphetamine, Methamphetamine, 3,4-Methylenedioxy- amphetamine and 3,4-Methylenedioxymethamphetamine in Human Hair and Hair Sections, Journal of Food and Drug Analysis, 13(2) (2005) 193-200. https://doi.org/10.38212/2224-6614.2526[4] María Jesús Tabernero, Maria Linda Felli, Ana María Bermejo, Marcello Chiarotti, Determination of ketamine and amphetamines in hair by LC/MS/MS, Anal Bioanal Chem, 395(2009), 2547–2557. https://doi.org/10.1007/s00216-009-3163-4.[5] D.V. Doan, D.Q. Huy, N.D. Hue, T.M. Tri, Determination of methamphetamine in urine samples by gas chromatography mass spectrometry combined with solid phase extraction technique, Journal of Science and Technology 47 (6) (2009) 53-58 (in Vietnamese).[6] Rodger L. Foltz, Allison F. Fentiman, Ruth B. Foltz, GC/MS Assays for Abused Drugs in Body Fluids, National Institute on Drug Abuse, Maryland, 1980.[7] AOAC, Appendix F: Guidelines for Standard Method Performance Requirements, AOAC official methods of analysis, Maryland, 2016.[8] Eunyoung Han, Martin P. Paulus, Marc Wittmann, Heesun Chung, Joon myong Song, Hair analysis and self-report of methamphetamine use by methamphetamine dependent individuals, Journal of Chromatography B, 879 (2011) 541–547. https://doi.org/10.1016/j.jchromb.2011.01.002.&#x0D; &#x0D; &#x0D;

Determination of benzomercaptans in environmental complex samples by combining zeolitic imidazolate framework-8-based solid-phase extraction and high-performance liquid chromatography with UV detection

In this work, the synthesis of zeolitic imidazolate framework-8 (ZIF-8) crystals and their subsequent application as effective sorbents for extraction and preconcentration of several benzomercaptans from environmental complex samples is described. These materials were prepared by solvothermal approach varying the concentration of n-butylamine modulator to modify the surface of the metal-organic framework. The resulting materials were characterized by scanning and transmission electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. The ZIF-8 material that gave the best features was selected as extractive phase and the influence of various parameters (sample pH and elution solvent composition, among others) on the extraction efficiency of target compounds were investigated. Under the optimal conditions of the method, the tested analytes (2-mercaptobenzothiazole, 2-mercaptobenzoxazole and 2-mercapto-6-nitrobenzothiazole) were retained and eluted quantitatively with alkaline 50:50 (v:v) methanol-water mixture. Using the proposed method, low limits of detection, in the range of 16–21 ng L−1 for aqueous samples and 0.4–0.5 µg kg−1 for soil samples, were achieved whereas the precision (expressed as relative standard deviation) was lower than 7%. The resulting solid-phase extraction protocol, using the zeolitic material as sorbent, was combined with liquid chromatography and ultraviolet-vis detector and successfully applied to determine traces of these organic pollutants in environmental samples.

Facile Synthesis of Mixed-Mode Weak Anion-Exchange Microspheres via One-Step Pickering Emulsion Polymerization for Efficient Simultaneous Extraction of Strongly and Weakly Acidic Drugs from Reservoir Water.

Poly(2-(diethylamino)ethyl methacrylate-co-divinylbenzene) (poly(DEAEMA-co-DVB)) microspheres with mixed-mode weak anion-exchange (WAX) character were successfully fabricated for the first time via facile one-step Pickering emulsion polymerization. The obtained poly(DEAEMA-co-DVB) particles had good spherical geometry, uniform particle size in the range of 30–40 µm, a large specific surface area of 575 m2/g, and a pore size range of 5–30 nm, according to the SEM and nitrogen adsorption–desorption results. Using these mixed-mode WAX microspheres as packing material, a reliable and robust analytical method based on solid phase extraction and high performance liquid chromatography with ultraviolet detection (SPE-HPLC-UV) was developed for simultaneous determination of six strongly and weakly acidic nonsteroidal anti-inflammatory drugs (NSAIDs, niflumic acid, diflunisal, naproxen, ketoprofen, mefenamic acid, and diclofenac) in reservoir water. Under optimized conditions, it was applicable to preconcentrate up to 500 mL of reservoir water samples on the WAX cartridges with satisfying recoveries (88–96%) for all the NSAIDs tested. The limits of detection were in the range of 0.002–0.025 μg L−1, respectively. Our results showed that the developed mixed-mode WAX poly(DEAEMA-co-DVB) phase containing a tertiary amine with a pKa value of approximately 10.7 could be used for simultaneous clean-up and preconcentration of strongly and weakly acidic organic pollutants in real environmental water, which could not be achieved by single use of quaternary ammonium strong anion-exchange phase or weaker primary and secondary amine anion-exchange.

Characterization and Quantitative Determination of a Diverse Group of Bacillus subtilis subsp. subtilis NCIB 3610 Antibacterial Peptides.

Five antibacterial peptides produced by Bacillus subtilis NCIB 3610 were purified, quantified, characterized, and identified in the present study. Cell-free extracts were subjected to three purification protocols employing ammonium sulfate or organic solvent precipitation and their combination, followed by ion-exchange chromatography, solid-phase extraction, and preparative high-performance liquid chromatography (HPLC). The combined ammonium sulfate and organic solvent precipitation extraction protocol presented the best results for peptide purification. In the five fractions that presented antimicrobial activity, antibacterial peptides were quantified by the turbidometric method and by HPLC using nisin for external calibration, with the second providing more accurate results. All peptides were pH- and temperature-resistant and their sensitivity to proteases treatment indicated their proteinic nature. The five peptides were subjected to microwave-assisted acid hydrolysis (MAAH) and following derivatization were analyzed using norleucine as the internal standard, to determine their amino acid content. The identification of the isolated peptides using the UniProt and PubChem databases indicated that the four peptides correspond to UniProt entries of the bacteriocins Subtilosin-A (Q1W152) Subtilosin-SbOX (H6D9P4), Ericin B (Q93GH3), Subtilin (P10946), and the fifth to the non-ribosomal antibacterial lipopeptide surfactin (CID:443592). The amino acid content determination and computational analyses, applied in the present work on the antimicrobial peptides of B. subtilis, proved an efficient screening and quantification method of bacteriocins that could potentially be applied in other bacterial strains. The constructed phylogenetic trees heterogeneity observed across the five peptides investigated might be indicative of competitive advantage of the strain.

Dissipation and residue determination of penicillin G and its two metabolites in citrus under field conditions by DSPE/UPLC-MS/MS.

A rapid determination method of residual penicillin G and its two metabolites in citrus was developed and validated by dispersive solid-phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry (DSPE/UPLC-MS/MS). The samples were extracted with 80% acetonitrile and purified with octadecylsilane. High linearity was obtained with correlation coefficients (r2 ) >0.9981. The limits of quantification were 0.005-0.01 mg/kg. The recoveries of penicillin G and its metabolites spiked in blank citrus were within 76.7-107%, with relative standard deviations of 1.3-9.6%. The dissipation dynamics and distribution of penicillin G in citrus followed first-order kinetics, with half-life of 1.7-2.7 days. Penicillin G degraded easily in citrus and the metabolite was mainly penilloic acid, which can exist stably for long time. The terminal residues of penicillin G in pulp, whole citrus and peels were 0.015-0.701, 0.047-7.653 and 0.162-13.376 mg/kg, respectively. The hazard indexes for risk assessment of citrus were significantly <1, suggesting that the health risks to humans after consumption of citrus were insignificant and negligible. These results could provide necessary data for evaluating the safe and proper use of penicillin G in citrus.

Identification of indicator PPCPs in landfill leachates and livestock wastewaters using multi-residue analysis of 70 PPCPs: Analytical method development and application in Yangtze River Delta, China

The source apportionment of pharmaceuticals and personal care products (PPCPs) in the water environment based on indicators (i-PPCPs) requires a comprehensive characterization of various emission sources using reliable analytical methods for a wide spectrum of PPCPs. In this study, a robust and sensitive method based on solid phase extraction (SPE) and ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) for analyzing 70 PPCPs belonging to 17 therapeutic classes in landfill leachates and livestock wastewaters was developed. The SPE cartridges, sample pH, elution solvents and chelating agent additions were optimized, and acceptable recoveries (60– 130% for 67 target compounds), low method quantification limits (landfill leachate: 3– 1309 ng/L; livestock wastewater: 3– 686 ng/L) and high precisions (repeatability: 0– 20% for over 99% injections; reproducibility: 0– 20% for over 90% injections) were obtained. Using the optimized analytical method to characterize PPCPs in the typical landfill leachate and livestock wastewater in Yangtze River Delta, China, we found anthelmintics, which were first reported in landfill leachates globally, exhibited the highest concentration (albendazole, maximum concentration of 61.6 μg/L), and therefore proposed albendazole as one of the promising i-PPCP candidates in landfill leachates. In livestock wastewaters, antibiotics lincomycin was the most abundant PPCP (maximum concentration: 735 μg/L) and identified as an i-PPCP candidate for livestock-originated contamination. In addition, 15 non-antibiotic PPCPs were first investigated in the livestock wastewater in China and some non-steroidal anti-inflammatory drugs, acetaminophen, diclofenac and naproxen, were detected at similar concentration level (1.16– 91.1 μg/L) to antibiotics, highlighting the necessity to include representative non-antibiotic PPCPs in the studies of emerging contaminants in livestock wastewaters. The developed method provides a tool to comprehensively investigate PPCPs in high-strength wastewater, and the preliminary findings in the characterization of typical landfill leachates and livestock wastewaters are helpful to select i-PPCPs for the source apportionment of PPCPs in Yangtze River Delta, China.

Development and Validation of an LC–MS-MS Method for the Detection of 40 Benzodiazepines and Three Z-Drugs in Blood and Urine by Solid-Phase Extraction

An analytical method for the detection of 40 benzodiazepines, (±)-zopiclone, zaleplon and zolpidem in blood and urine by solid-phase extraction liquid chromatography-tandem mass spectrometry was developed and validated. Twenty-nine of 43 analytes were quantified in 0.5mL whole blood for investigating postmortem, drug-facilitated sexual assault (DFSA) and driving under the influence of drugs cases (DUID). The four different dynamic ranges of the seven-point, linear, 1/x weighted calibration curves with lower limits of quantification of 2, 5, 10 and 20μg/L across the analytes encompassed the majority of our casework encountered in postmortem, DFSA and DUID samples. Reference materials were available for all analytes except α-hydroxyflualprazolam, a hydroxylated metabolite of flualprazolam. The fragmentation of α-hydroxyflualprazolam was predicted from the fragmentation pattern of α-hydroxyalprazolam, and the appropriate transitions were added to the method to enable monitoring for this analyte. Urine samples were hydrolyzed at 55°C for 30min with a genetically modified β-glucuronidase enzyme, which resulted in >95% efficiency measured by oxazepam glucuronide. Extensive sample preparation included combining osmotic lysing and protein precipitation with methanol/acetonitrile mixture followed by freezing and centrifugation resulted in exceptionally high signal-to-noise ratios. Bias and between-and within-day imprecision for quality controls (QCs) were all within ±15%, except for clonazolam and etizolam that were within ±20%. All 29 of the 43 analytes tested for QC performance met quantitative reporting criteria within the dynamic ranges of the calibration curves, and 14 analytes, present only in the calibrator solution, were qualitatively reported. Twenty-five analytes metall quantitative reporting criteria including dilution integrity. The ability to analyze quantitative blood and qualitative urine samples in the same batch is one of the most useful elements of this procedure. This sensitive, specific and robust analytical method was routinely employed in the analysis of >300 samples in our laboratory over the last 6 months.