Anion-exchange Cartridge Research Articles

A method for suppressing pH excursion during elution in ion-exchange chromatography

A simple method for reducing pH excursion during salt-induced elution in cation exchange chromatography is presented in this paper. Connecting a preequilibrated anion exchange cartridge in series in front of the cation exchange device just prior to the elution step significantly reduced the transient decrease in pH that is typically observed during elution. The working principle of the proposed method is hypothesized. Bind and elute chromatography experiments showed that the suppression of pH excursion during elution of a monoclonal antibody from a cation exchange chromatography device resulted in significantly sharper and narrower eluted protein peaks. Improvement in pH control during elution would not only result in better reproducibility and efficiency in separation but would also ensure greater stability of pH sensitive proteins during their purification using ion exchange chromatography.

Evaluating the Effects of Solid-Phase Cartridge Chemistry on Extraction of Bisphosphonates and ITPP From Equine Plasma.

Bisphosphonate drugs and myo-inositol trispyrophosphate are of concern to the racing industry and have been listed as prohibited substances in equine sports. The current bisphosphonate plasma screening analysis employed at the Australian Racing Forensic Laboratory involves the use of sequential solid-phase extraction procedures, passing the samples through a mixed mode cartridge, followed by a weak anion exchange cartridge. The eluates collected following the second extraction are then methylated and analysed by liquid chromatography-mass spectrometry. Under these extraction conditions, some bisphosphonates have shown poor recovery. To improve the extraction efficacy, the effects of cartridge chemistry were evaluated. In particular, the weak anion exchange cartridges used for screening were compared to an affinisep AttractSPE polymeric phase cartridge. The effectiveness of each extraction approach was assessed through both a visual comparison of signal to noise in extracted chromatograms and recovery measurements to determine the best approach for routine screening.

Determination of regulated perfluoroalkyl substances (PFAS) in drinking water according to Directive 2020/2184/EU.

Perfluoroalkyl substances (PFAS) are chemical compounds that have been widely used in industry and manufacture. Occurrence, together with persistence and recent toxicological effects data, has promoted the regulation of 20 PFAS (carboxylic and sulfonic) acids in drinking water through the recent Directive 2020/2184/EU. This Regulation included PFAS with different carbon chain lengths (from C4 to C13) and limited the total PFAS concentration (as sum) to a maximum of 0.1µg/L, for which law-enforcement analytical methods are required. In this work, three different methodologies have been developed and evaluated as regards their performance to determine those 20 PFAS in tap and bottled water, based on on-line and off-line solid-phase extraction (SPE) and direct injection. In all cases, ultra-high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used as a determination technique. Off-line SPE with Oasis Weak Anion Exchange (WAX) cartridges provided the best results in terms of limits of quantification (LOQ ≤ 0.3ng/L) and accuracy (R ≥ 70%) in drinking water samples. On-line SPE and direct injection presented some drawbacks such as background contamination problems and lower accuracies for the least polar compounds. This off-line SPE methodology was then applied to the analysis of 46 drinking water samples (11 commercial bottled samples, 23 Spanish and 12 international tap water samples). Ten PFAS were quantified in such samples at concentrations and detection frequencies ranging from 0.1 to 20.1ng/L and 2 to 91%, respectively. However, the sum concentration did not surpass the established limit in any sample.

Automation of Copper-Mediated 18F-Fluorination of Aryl Pinacol Boronates Using 4-Dimethylaminopyridinium Triflate.

Currently, the copper-mediated radiofluorination of aryl pinacol boronates (arylBPin) using the commercially available, air-stable Cu(OTf)2Py4 catalyst is one of the most efficient synthesis approaches, greatly facilitating access to a range of radiotracers, including drug-like molecules with nonactivated aryl scaffolds. Further adjustment of this methodology, in particular, the [18F]fluoride recovery step for the routine preparation of radiotracers, has been the focus of recent research. In our recent study, an organic solution of 4-dimethylaminopyridinium trifluoromethanesulfonate (DMAPOTf) was found to be an efficient PTC for eluting radionuclides retained on the weak anion exchange cartridge, Oasis WAX 1cc, employing the inverse sorption-elution protocol. Notably, the following Cu-mediated radiofluorination of arylBPin precursors in the presence of the Cu(OTf)2(Py)4 catalyst can be performed with high efficiency in the same solvent, bypassing not only the conventional azeotropic drying procedure but any solvent replacement. In the current study, we aimed to translate this methodology, originally developed for remote-controlled operation with manual interventions, into the automated synthesis module on the TRACERlab automation platform. The adjustment of the reagent amounts and solvents allowed for high efficiency in the radiofluorination of a series of model arylBPin substrates on the TRACERlab FXFE Pro synthesis module, which was adapted for nucleophilic radiofluorinations. The practical applicability of the developed radiofluorination approach with DMAPOTf elution was demonstrated in the automated synthesis of 6-L-[18F]FDOPA. The radiotracer was obtained with an activity yield (AY; isolated, not decay-corrected) of 5.2 ± 0.5% (n = 3), with a synthesis time of ca. 70 min on the TRACERlab FX N Pro automation platform. The obtained AY was comparable with one reported by others (6 ± 1%) using the same boronate precursor, while a slightly higher AY of 6-L-[18F]FDOPA (14.5 ± 0.5%) was achieved in our previous work using commercially available Bu4NOTf as the PTC.

Characterization of collagen and its hydrolysate from southern bluefin tuna skin and their potencies as DPP-IV inhibitors

Collagen-derived peptides have been gaining interest due to their potential to act as DPP-IV inhibitors, which are considered to have antidiabetic effects. This study focused on extracting type I collagen from discarded southern bluefin tuna skin, confirming its structure and properties, and then measuring the ability of its hydrolysates to act as DPP-IV inhibitors. First, type I collagen was purified from southern bluefin tuna skin, and the constituent subunit was found to contain the α3(I) chain. Next, enzymatic hydrolysates were prepared, and their DPP-IV inhibitory activity measurements were examined and compared. Collagenase hydrolysate showed the highest DPP-IV inhibitory activity (71.8 ± 0.3 %), and considering digestive degradation, collagenase-pepsin-trypsin hydrolysate was prepared and separated into fractions via anion exchange chromatography, cartridge column, and HPLC. Notably, the 70 % methanol eluted fraction separated via cartridge column was found to have an IC50 of 0.26 ± 0.01 mg/ml. Subsequently, a novel peptide GPSGGGYDV with the highest DPP-IV inhibitory activity (IC50 value 82±0.0 µM) was purified from this fraction and found to be a competitive inhibitor of DPP-IV. This is the first study to investigate the DPP-IV inhibitory potential of type I collagen hydrolysate from southern bluefin tuna.

Automated synthesis of [89Zr]ZrCl4, [89Zr]ZrDFOSquaramide-bisPh(PSMA) and [89Zr]ZrDFOSquaramide-TATE

BackgroundAutomated [89Zr]Zr-radiolabeling processes have the potential to streamline the production of [89Zr]Zr-labelled PET imaging agents. Most radiolabeling protocols use [89Zr][Zr(ox)4]4− as the starting material and oxalate is removed after radiolabeling. In some instances, radiolabeling with [89Zr]ZrCl4 as starting material gives better radiochemical yields at lower reaction temperatures. In this work, a fully-automated process for production of [89Zr]ZrCl4 is reported and its use for the synthesis of [89Zr]ZrDFOSq-bisPhPSMA and [89Zr]ZrDFOSq-TATE.ResultsA simple automated process for the isolation of [89Zr]ZrCl4 by trapping [89Zr][Zr(ox)4]4− on a bicarbonate-activated strong anion exchange cartridge followed by elution with 0.1 M HCl in 1 M NaCl was developed. [89Zr]ZrCl4 was routinely recovered from [89Zr][Zr(ox)4]4− in > 95% yield in mildly acidic solution of 0.1 M HCl in 1 M NaCl using a fully-automated process. The [89Zr]ZrCl4 was neutralized with sodium acetate buffer (0.25 M) removing the requirement for cumbersome manual neutralization with strong base. The mixture of [89Zr]ZrCl4 was used for direct automated radiolabeling reactions to produce [89Zr]Zr-DFOSquaramide-bisPhPSMA and [89Zr]ZrDFOSquaramide-TATE in 80–90% over all RCY in > 95% RCP.ConclusionsThis method for the production of [89Zr]ZrCl4 does not require removal of HCl by evaporation making this process relatively fast and efficient. The fully automated procedures for the production of [89Zr]ZrCl4 and its use in radiolabeling are well suited to support the centralized and standardized manufacture of multiple dose preparations of zirconium-89 based radiopharmaceuticals.

Determination of perfluorinated compounds in Eichhornia crassipes (Mart.) Solms using LC-MS/MS in combination with sample preparation by ultrasound-assisted extraction and solid-phase extraction

Fifteen perfluorinated compounds, including perfluorocarboxylic acids and perfluoroalkyl sulfonate salts (with 4 to 12 carbon atoms in their structure) in Eichhornia crassipes (Mart.) Solms samples underwent analysis using Liquid Chromatography- tandem Mass Spectrometry (LC-MS/MS). This analysis was conducted alongside sample preparation employing ultrasound-assisted extraction and solid-phase extraction. The optimization of solvent extraction involved the use of 5 ml of methyl tert-butyl ether (MTBE), 10 minutes of sonication, and three repeated extraction cycles. The weak anion exchange (WAX) cartridge was selected after evaluating and comparing the solid-phase extraction efficiencies of both WAX and C18 cartridges. The evaluated method demonstrated successful analysis of all 15 PFCs in plant samples, achieving favorable recoveries ranging from 71 to 116% (with a coefficient of variation of 1.2-6.6%). The quantification limits for these 15 PFCs in Eichhornia crassipes (Mart.) Solms samples ranged between 0.30 to 0.54 ng/g.
 ® 2023 Journal of Science and Technology - NTTU

Determination of highly polar anionic pesticides in beehive products by hydrophilic interaction liquid chromatography coupled to mass spectrometry.

The analysis of highly polar pesticides is challenging due to their unique physicochemical properties, requiring specialized chromatographic techniques for their accurate and sensitive detection. Furthermore, the high level of co-extracted polar matrix components that can co-elute with the analytes can interfere with the analysis. Consequently, there is lack of pesticide monitoring data, as the European Food Safety Authority has pointed out. This article explores the overcoming of such difficulties in the analysis of these compounds. Analytical methodologies for the extraction, clean-up, and direct determination of 11 highly polar anionic pesticides, including glyphosate, glufosinate, ethephon, fosetyl-aluminium, and their related metabolites in complex food matrices such as honey and pollen by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry were successfully developed and validated. Solid-phase extraction and micro-solid-phase extraction employing strong anion exchange (SAX) cartridges were implemented for clean-up. The automation and miniaturization of SAX clean-up for these compounds were achieved for the first time. For method validation, SANTE/11312/2021 guideline was followed. Recoveries were between 70 and 120%, with RSDs below 20%. Limits of quantitation ranged from 0.005 to 0.020 mg kg-1. Linearity was evaluated from 0.002 to 0.200 mg kg-1. Matrix effects were assessed, showing medium to low signal suppression for most compounds. AMPA and glufosinate presented the highest signal suppression, but it was reduced after SAX clean-up. Analysis of real honey and pollen samples revealed the occurrence of the studied compounds in beehive products and showed the applicability of the validated methodologies for routine control of these complex samples.

Radiofluorination of an Anionic, Azide-Functionalized Teroligomer by Copper-Catalyzed Azide-Alkyne Cycloaddition.

This study describes the synthesis, radiofluorination and purification of an anionic amphiphilic teroligomer developed as a stabilizer for siRNA-loaded calcium phosphate nanoparticles (CaP-NPs). As the stabilizing amphiphile accumulates on nanoparticle surfaces, the fluorine-18-labeled polymer should enable to track the distribution of the CaP-NPs in brain tumors by positron emission tomography after application by convection-enhanced delivery. At first, an unmodified teroligomer was synthesized with a number average molecular weight of 4550 ± 20 Da by free radical polymerization of a defined composition of methoxy-PEG-monomethacrylate, tetradecyl acrylate and maleic anhydride. Subsequent derivatization of anhydrides with azido-TEG-amine provided an azido-functionalized polymer precursor (o14PEGMA-N3) for radiofluorination. The 18F-labeling was accomplished through the copper-catalyzed cycloaddition of o14PEGMA-N3 with diethylene glycol-alkyne-substituted heteroaromatic prosthetic group [18F]2, which was synthesized with a radiochemical yield (RCY) of about 38% within 60 min using a radiosynthesis module. The 18F-labeled polymer [18F]fluoro-o14PEGMA was obtained after a short reaction time of 2-3 min by using CuSO4/sodium ascorbate at 90 °C. Purification was performed by solid-phase extraction on an anion-exchange cartridge followed by size-exclusion chromatography to obtain [18F]fluoro-o14PEGMA with a high radiochemical purity and an RCY of about 15%.

Development of ratiometric fluorescent probes based on peptides for sensing Pb2+ in aquatic environments and human serum.

The detection of Pb2+ ions in aquatic environments and biofluid samples is crucial for assessment of human health. Herein, we synthesized two fluorescent probes (1 and 2) consisting of the peptide receptor for Pb2+ and a benzothiazolyl-cyanovinylene fluorophore that exhibited excimer-like emission when it aggregated. The peptide-based probes sensitively detected Pb2+ in purely aqueous solution (1% DMF) through ratiometric fluorescent response with a decrease in monomer emission at 520nm and an increase in excimer emission at 570nm. Specially, probe 2 showed remarkable detection features such as high selectivity for Pb2+over 15 metal ions, high binding affinity (Kd=5.83×10-7 M) for Pb2+, significant emission intensity changes, low detection limit (3.8nM) of Pb2+, high water solubility, and visible light excitation (450nm). Probe 2 was successfully used to quantify nanomolar concentration (0∼800nM) of Pb2+ in real water samples (ground water and tap water). Specially, 2 was successfully applied for the quantification of Pb2+ in human serum by combination of microwave-assisted human serum digestion and filtration of digested serum by anion exchange cartridge. We clearly investigated the binding mode of 2 with Pb2+ using 1H NMR, IR spectroscopy, pH titration, confocal microscopy, and size analysis. The peptide-based fluorescent probe might have great application potential for sensing Pb2+ in aquatic environments and biofluid samples.

Development of a safer and improved analytical method for polycyclic aromatic hydrocarbons in creosote products

Polycyclic aromatic hydrocarbons (PAHs) in creosote products used for wood preservation are regulated in Japan. Although the analytical method for this regulation has been stipulated by law, two main problems have been highlighted, namely the use of dichloromethane, a potential carcinogen, as a solvent and inadequate purification. Therefore, an analytical method to solve these problems was developed in this study. Actual creosote-treated wood samples were examined, and it was found that acetone could be used as an alternative solvent. Purification methods using centrifugation, silica gel cartridges, and strong anion exchange (SAX) cartridges were also developed. It was found that the SAX cartridges strongly retained PAHs, and an effective purification method was developed using this phenomenon, in which contaminants were removed by washing with diethyl ether/hexane (1/9 v/v), which could not be achieved with a silica gel cartridge. This strong retention was attributed to cation–π interactions. The analytical method developed in this study yielded good recoveries (81.4–113.0%) with low relative standard deviations (<6.8%), and the limit of quantification (0.02–0.29 µg/g) was significantly lower than the current creosote product regulation. Therefore, this method can safely and effectively extract and purify PAHs from creosote products.

Copper-Mediated Radiobromination of (Hetero)Aryl Boronic Pinacol Esters.

A copper-mediated radiobromination of (hetero)aryl boronic pinacol esters is described. Cyclotron-produced [76/77Br]bromide was isolated using an anion exchange cartridge, wherein the pre-equilibration and elution solutions played a critical role in downstream deboro-bromination. The bromination tolerates a broad range of functional groups, labeling molecules with ranging electronic and steric effects. Bologically active radiopharmaceuticals were synthesized, including two radiobrominated inhibitors of poly ADP ribose polymerase, a clinically relevant chemotherapeutic target for ovarian, breast, and prostate cancers.

RESEARCH ON THE INFLUENCE OF DIFFERENT TYPES OF ANION-EXCHANGE CARTRIDGES ON THE QUALITY OF [18F]NAF RADIOPHARMACEUTICAL AS PART OF PRODUCTION PROCESS DEVELOPMENT

[18F]Sodium Fluoride radiopharmaceutical is a sterile solution for intravenous administration, intendedfor skeletal visualization by positron emission tomography (PET). [18F]Sodium Fluoride for bone imaging wasintroduced in early 1960's, but with the increased availability of PET scanners in the last two decades, thisradiopharmaceutical has growing use in clinical practice for the detection of bone metastases. The productionprocess of [18F]NaF includes production of the radioisotope [18F]F- and purification and formulation of the [18F]NaFradiopharmaceutical. The radioisotope [18F]F- is produced by a cyclotron via the 18O(p,n)18F nuclear reaction,followed by recovery of [18F]F- from [18O] proton-irradiated water by adsorption and desorption from anionexchangeresins. The fluoride anions are trapped on the anion-exchange SPE (solid-phase extraction) cartridge, andall other cationic and water-soluble radionuclide impurities present in irradiated enriched water are collected in thewaste vial. Next step is desorption of the fluoride anions from the cartridge by elution with saline solution (0.9%NaCl). This study aimed to define the most appropriate type of anion-exchange SPE cartridge which could be usedfor routine production [18F]Sodium fluoride radiopharmaceutical which meets the quality requirements defined inEuropean pharmacopeia monograph. For that purpose, as part of development of in-house production method,manual productions with four different types of anion-exchange cartridges were performed. The influence of sorbentsubstrate and counter-ion of the cartridge on the final yield and the quality of the produced radiopharmaceutical wasinvestigated. The study also aimed to define the minimum volume of physiological solution required for the pHparameter to be within limits.The results have shown that the quality parameters: appearance, chemical purity, radiochemical purity andradionuclide purity were in defined acceptance criteria and did not differ when using different anion-exchangecartridges. The pH analyses have demonstrated that the type of cartridge and counter-ion influence the final pH of[18F]NaF solution. This study confirmed that the three types of anion-exchange resins (QMA-Cl-, QMA-CO32- andPS-OH-) could be used for production. In the experiments where QMA-Cl- was used, the required pH level wasobtained even without dilution. The other cartridges could be used in the [18F]NaF production process, but furtherdilution is necessary in order to obtain the pH value in acceptance criteria. On the basis of this study, the QMA-Cl- ischosen as a cartridge to be used in the further development of the in-house method for [18F]NaF radiopharmaceuticalproduction.

Enzymatic bioconversion of beechwood xylan into the antioxidant 2′-O-α-(4-O-methyl-D-glucuronosyl)-xylobiose

Acidic xylooligosaccharides (XOS), also called aldouronics, are hetero-oligomers of xylose randomly branched with 4-O-methyl-D-glucuronic acid residues linked by α(1 → 2) bonds, which display bioactive properties. We have developed a simple and integrated method for the production of acidic XOS by enzymatic hydrolysis of a glucurono-xylan from beechwood. Among the enzymes screened, Depol 670L (a cellulolytic preparation from Trichoderma reesei) displayed the highest activity (70.3 U/mL, expressed in reducing xylose equivalents). High-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) analysis revealed the formation of a neutral fraction (corresponding to linear XOS, mainly xylose and xylobiose) and a group of more retained products (acidic XOS), which were separated using strong anion-exchange cartridges. The acidic fraction contained a major product, characterized by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry and mono- and two-dimensional nuclear magnetic resonance spectroscopy (NMR) as 2′-O-α-(4-O-methyl-α-D-glucuronosyl)-xylobiose (X2_MeGlcA). Starting from 2 g of beechwood xylan, 1.5 g of total XOS were obtained, from which 225 mg (11% yield) corresponded to the aldouronic X2_MeGlcA. The acidic XOS exhibited higher antioxidant activity (measured by the ABTS·+ discoloration assay) than xylan, whilst neutral XOS displayed no antioxidant activity. This work demonstrates that it is possible to obtain a safe and natural antioxidant by enzymatic biotransformation of hardwood hemicellulose.

Complementary biomarker detection for bisphosphonate use in racehorses

Determining the use of off-label bisphosphonates (BPs) in young horses (< 4 years old) is of interest due to the threat to racing integrity and welfare associated with this class of drugs that have the potential to manipulate bone structure. The analysis of BPs in biological matrices is challenging by liquid chromatography coupled to mass spectrometry (LC-MS/MS) and alternative sample preparation approaches are needed to detect their misuse in racehorses. There are currently two classes of BPs: non-nitrogen and nitrogen-containing with each having a distinct mode of action. Currently two non-nitrogenous based BPs are available for use in horses, tiludronic acid (or tiludronate) and chlodronate for the treatment of navicular syndrome (Mitchell et al. BMC Veterinary Research 2019;15(1):211) in horses over the age of 4. There is, however, evidence that BPs can persist in the bone for several years after administration since they can form hydroxyapatite crystals prior to being fully absorbed by active osteoclasts where full inhibitory action is performed (Riggs et al. Equine veterinary journal 2021;53(6):1287–1295). Therefore, with this prolonged detection time for the BPs, it is necessary to investigate whether the use of metabolomic biomarkers can provide a complementary method for the detection of their misuse. The aim of this research was to develop a biomarker approach for complementary direct detection of bisphosphonate drugs in equine plasma. BPs are hydrophilic therefore the targeted detection of tiludronic acid in equine plasma required an orthogonal solid phase extraction (SPE) method using both a polymeric reversed-phase sorbent and a weak anion exchange cartridge prior to derivatisation using trimethyl orthoacetate and reverse LC-MS/MS. Endogenous lipids and corticosteroids in equine plasma were detected after protein precipitation and SPE with a polymeric reverse phase cartridge prior to liquid chromatography high-resolution mass spectrometry. Data was analysed using the Shimadzu Insight Explore software to determine up- or down-regulation of biomarkers. Results were then profiled using a Parametric Empirical Bayes algorithm to propose individual reference limits (IRLs). Tiludronic acid was detected up to the final collection point of 28 days post-administration. Following a targeted approach, up- and down-regulation of the eicosanoid and corticosteroid ratios were observed with the corticosteroid ratio exceeding both the proposed population reference limit (PRL) and IRL. Using a semi-targeted approach, several additional lipids were identified to have activity during the administration and will require further confirmatory analysis. Monitoring the impact on endogenous biomarkers following an administration of Tiludronic Acid in racehorses is limited therefore little is known if BPs have a direct or indirect effect on the inflammatory pathways. However, research in humans has linked BPs with possible effects of analgesia in addition to bone remodelling that BPs are primarily used for. Therefore, it is necessary to further extend detection capabilities to ensure endogenous eicosanoids and corticosteroids are monitored. This, however, should not negate the need for the detection of the drug itself as tiludronic acid has the potential to be detected as far as 28 days post-administration. Therefore, a complementary biomarker approach would be preferable for the detection of non-nitrogen-based BPs, which can be further applied for the nitrogen-based BPs. A complementary biomarker approach to direct detection of administered drugs can improve the understanding of effect and support non-targeted detection strategies for analogues of specific drug classes.

Optimization of Solid-Phase Extraction Conditions for Perfluorooctanoic Acid in Leachate

In order to optimize the solid phase extraction (SPE) conditions of perfluorooctanoic acid (PFOA) in the raw leachate and treated leachate, the effects of activator properties, SPE cartridge, pH value, ionic strength, and eluent properties were studied through single factor experiments. The optimal results of each single factor were obtained. Considering that the concentration of PFOA in the treated leachate is lower than that of the raw leachate, the SPE conditions of the treated leachate have been further optimized. Based on the above single-factor experiment, the main influencing factors were screened out as the volume of activator, ionic strength, and volume of eluent, and the three-factor three-level response surface methodology (RSM) was optimized. The optimum SPE conditions of PFOA from treated landfill leachate were as follows: Activation of weak anion exchange(WAX) cartridge with 10 mL methanol, dosage of 600 mg KCl, 6 mL 1% ammonia methanol eluted PFOA, the theory recovery rate is over 95.67%. It has been verified that the error between the predicted value and the actual extraction recovery is small and has good repeatability.

Trace level enrichment and clean-up of β-lactam antibiotic residues in edible chicken tissues and feathers by solid phase extraction for quantitative determination utilizing liquid chromatography

ABSTRACT. A simple analytical method for the extraction and determination of three β-lactam antibiotics in chicken tissues and feather samples was developed and validated using solid phase extraction (SPE) and liquid chromatography-ultraviolet, LC-UV, detection. The analytes were extracted with strong anion exchange (SAX) cartridges for the extract clean-up and enrichment before introduction into the LC system. The validation was carried out based on the recommendations from Commission Decision 2002/657/EC. Under optimised conditions, the proposed method offers correlation coefficients of r2 ≥ 0.9991 for all the studied analytes in both matrices. Percent recovery results were found to vary between 79.7-101.8% and 94.2-101.6% for chicken feathers and tissues, respectively, with the relative standard deviation, RSD &lt; 8.4%. The limits of detection (LOD) were in the range of 0.1-0.13 µg kg-1 and 0.1-0.15 µg kg-1 while the limits of quantification (LOQ) were in the range of 0.3-0.38 µg kg-1 and 0.3-4.5 µg kg-1 in chicken feathers and tissues, respectively. The proposed method offers good sensitivity and selectivity and all the results demonstrating that the method would be widely used for determination of β-lactam antibiotics and other trace level antibiotics residues having similar physical and chemical properties in the matrices of varying origins.&#x0D; &#x0D; KEY WORDS: Chicken tissues, Chicken feathers, β-Lactams, Solid phase extraction, LC-UV&#x0D; &#x0D; Bull. Chem. Soc. Ethiop. 2022, 36(3), 503-519. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v36i3.2

Parallel quantitation of salt dioctyl sodium sulfosuccinate (DOSS) and fingerprinting analysis of dispersed oil in aqueous samples

In many jurisdictions, dispersants are included in contingency plans as a viable countermeasure that can help reduce the overall environmental impact of marine oil spills. When used, it is imperative to monitor the progression of dispersant and oil to assess their environmental fate and behaviour. Amphiphilic salt dioctyl sodium sulfosuccinate (DOSS) is the major effective component of the most commonly available dispersants, such as Corexit® EC9500A. Without proper sample preparation, dispersed oil in water samples could interfere with the accurate analysis of DOSS and easily contaminate the LC-MS system. In this work, solid phase extraction (SPE) weak anion exchange (WAX) cartridges were used to separate oil and DOSS in aqueous samples. DOSS was accurately determined by liquid chromatography coupled with a high resolution Orbitrap mass spectrometer (LC-HRMS). Oil fingerprinting analysis was conducted and total petroleum hydrocarbons (TPHs), polycyclic aromatic hydrocarbons (PAHs), and petroleum biomarkers were determined by gas chromatography-flame ionization detection (GC-FID) and mass spectrometry (GC-MS). This SPE-LC/GC-MS method was used for the analysis of oil-dispersant water samples containing a mixture of Corexit® EC9500A and a selection of crude oils and refined petroleum products. Nearly a 100% DOSS recovery was obtained for various oil-surfactant conditions. Parallel quantitation of oils with dispersants was achieved using this method. A portion of the TPH loss was possibly attributed to oil retained by the SPE column. Chemical fingerprints and diagnostic ratios of target compounds in recovered dispersed oil overall remain unchanged compared with those of all studied oils.

A Method for the Analysis of Glyphosate, Aminomethylphosphonic Acid, and Glufosinate in Human Urine Using Liquid Chromatography-Tandem Mass Spectrometry.

The extensive use of herbicides, such as glyphosate and glufosinate, in crop production during recent decades has raised concerns about human exposure. Nevertheless, analysis of trace levels of these herbicides in human biospecimens has been challenging. Here, we describe a method for the determination of urinary glyphosate, its degradation product aminomethylphosphonic acid (AMPA), and glufosinate using liquid chromatography-tandem mass spectrometry (LC–MS/MS). The method was optimized using isotopically labelled internal standards (13C2, 15N-glyphosate, 13C, 15N, D2-AMPA, and D3-glufosinate) and solid-phase extraction (SPE) with cation-exchange and anion-exchange cartridges. The method provides excellent chromatographic retention, resolution and peak shape of target analytes without the need for strong acidic mobile phases and derivatization steps. The instrument linearity was in the range of 0.1–100 ng/mL, with R > 0.99 in the matrix for all analytes. The method detection limits (MDLs) and the method quantification limits (MQLs) were in the ranges of 0.12 (AMPA and glufosinate)–0.14 (glyphosate) ng/mL and 0.40 (AMPA)–0.48 (glyphosate) ng/mL, respectively. The recoveries of analytes spiked into urine matrix ranged from 79.1% to 119%, with coefficients of variation (CVs) of 4–10%. Repeated analysis of samples for over 2 weeks showed intra-day and inter-day analytical variations of 3.13–10.8% and 5.93–12.9%, respectively. The matrix effects for glyphosate, AMPA, and glufosinate spiked into urine matrix averaged −14.4%, 13.2%, and 22.2%, respectively. The method was further validated through the analysis of external quality assurance proficiency test (PT) urine samples. The method offers optimal sensitivity, accuracy, and precision for the urine-based assessment of human exposure to glyphosate, AMPA, and glufosinate.

Extraction and Matrix Cleanup Method for Analyzing Novel Per- and Polyfluoroalkyl Ether Acids and Other Per- and Polyfluoroalkyl Substances in Fruits and Vegetables.

Per- and polyfluoroalkyl ether acids (PFEAs) are a subclass of per- and polyfluoroalkyl substances (PFAS) that are detected with increasing frequency in environmental matrices. Diet can be an important route of PFEA exposure, but the presence of PFEAs in food is poorly understood. Extraction methods for food samples exist for traditionally studied PFAS, but their suitability for PFEAs and other novel PFAS remains unknown. In this study, an extraction and matrix cleanup method was developed to quantify 45 PFAS, including 13 PFEAs, 3 perfluoroalkane sulfonamides, and 6 fluorotelomer carboxylic acids in 10 types of fruits and vegetables. Homogenized samples were extracted with basic methanol, and resulting extracts were diluted with water and cleaned up using solid-phase extraction with weak anion-exchange cartridges. The method was validated by performing spike-recovery experiments at spike levels of 1 ng/g in all 10 matrices and 0.1 ng/g in 2 matrices. For PFAS without a corresponding isotopically labeled internal standard (IS), adopting an IS with a similar chromatographic retention time generated the most accurate recoveries. Dependent upon the matrix, recoveries of 38-44 PFAS (including 10-13 PFEAs) fell within 50-150% for samples spiked at 1 ng/g. Recoveries of 40 and 38 PFAS in blueberries and corn, respectively, fell within 50-150% for samples spiked at 0.1 ng/g. Method quantification limits (MQLs) of PFAS in pure solvents were determined as the lowest calibration level with an accuracy between 70 and 130%. To compensate for matrix effects, a matrix factor was applied on the basis of the analyte response in different matrices relative to the pure solvent. The MQLs of 45 PFAS (including 13 PFEAs) in 10 matrices ranged from 0.025 to 0.25 ng/g. Overall, this method is capable of sensitively quantifying 45 PFAS in many fruits and vegetables.