Oasis MCX Research Articles

Evaluation of ceramic passive samplers using a mixed-mode strong cation-exchange sorbent to monitor polar contaminants in river water

Although most of the analytical methods developed for the monitoring of contaminants in environmental waters are based on discrete grab sampling, an alternative of increasing interest is the use of passive sampling. Methods based on passive sampling provide the sampling and pre-concentration of the analytes in-situ, which makes the sample treatment less time consuming and costly than using discrete grab sampling. In this study, ceramic passive samplers (CPSs) using mixed-mode strong cation-exchange sorbent (Oasis MCX) as retention phase were evaluated for the determination of a group of 21 therapeutic and illicit drugs and some of their metabolites in river water samples that were determined by liquid chromatography-tandem mass spectrometry. After assessing the stability of the analytes, the CPSs were calibrated for 9 days with bottled water and river water, obtaining, for the 19 stable compounds, sample rates (Rs) ranging between 0.180 and 1.767 mL/day and diffusion coefficients (De) between 2.02E-8 and 2.81E-7 cm2/s. Once calibrated, CPSs were deployed for the determination of contaminants in the Ebre River, with good reproducibility, and some of the analytes were determined, including amongst others, gabapentin at 76 ng/L, caffeine at 203 ng/L or diclofenac amine at 57 ng/L. The passive sampling method herein presented is simple and feasible and allows the time-integrated analysis of pharmaceuticals and drugs at trace levels in river water. This study opens the possibility of using other mixed-mode sorbents or other types of sorbents as retaining phase on CPSs for the determination of very polar contaminants in water.

Testing of Ion Exchange Solid Phase Extraction Media for Extraterrestrial In Situ Sample Preparation on Liquid Samples

The search for life on other bodies in our solar system is currently focused on Ocean Worlds, those bodies known to contain liquid water, as water is one of the requirements for life as we understand it. In the search for organic biosignatures that would indicate the presence of past or current life, liquid samples from these bodies would utilize an initial sample preparation step in which interfering substances such as salts can be removed before analysis. Previous work on potential sample preparation techniques for these samples evaluated solid phase extraction (SPE) on cation exchange media, but only explored amino acid analytes at low salt to analyte ratios and used high concentration eluents. This work utilized mixed-mode ion exchange solid phases, developing methods for elutions in low concentration solutions and evaluating polar analytes with a range of functionalities. Method development revealed the need for a pre-elution step in the process to decrease the elution volume required. Both anion and cation exchange media were evaluated for the capture of analytes from solutions that simulated Earth’s oceans. The Oasis MCX and Strata X-C cation exchange media provided the best results, with >90% retention of all analytes including amino acids, organic amines, nucleotides, peptides, and an oligonucleotide. These cation exchange media retained even anionic components, including glutamic acid and organic acids, with >90% efficiency. These analytes were released in the wash step, but salt ion removal was completed before release, allowing this technique to be used for desalting of these analytes. Extraction of a 14 component mixed analyte solution also showed retention of all analytes, with testing of analyte concentrations down to 100 nM in 35 g/L simulated ocean solution. Oasis MAX and Strata X-A anion exchange media did not retain glutamic acid, fumaric acid, or dipicolinic acid when the salt concentration was high; these anionic analytes were easily extracted from low salt solutions. The anion exchange media showed a range of functionality for extracting other analytes from the simulated ocean water, capturing >90% of tryptophan and phenylalanine, but retaining <50% of the valine and >20% of the glycine. Irradiation exposure, as a model for the solar irradiation expected during deployment to extraterrestrial locations, did not affect the performance of any ion exchange media tested. A reversed-phase SPE column was directly coupled to a cation exchange column, to investigate removal of nonpolar compounds that might bind to and block the mixed-mode ion exchange media.

3D printed device coated with solid-phase extraction resin for the on-site extraction of seven sulfonamides from environmental water samples preceding HPLC-DAD analysis

A 3D printed device coated with Oasis MCX resin was developed allowing both the on-site and laboratory extraction and pre-concentration of sulfonamides (SAs) and subsequent determination by HPLC with diode array detection (DAD). The device has been designed and printed by stereolithographic 3D printing and functionalized with a SPE resin by stick and cure immobilization technique. Images of 3D printed coated devices obtained by scanning electron microscopy (SEM) allowed its characterization. Various parameters that affect the extraction efficiency (eluent solution, eluent volume, extraction and elution times) were studied and under optimal conditions, seven sulfonamides (Sulfanilamide, SAM; Sulfadiazine, SDZ; Sulfamerazine, SMR; Sulfamethazine, SMZ; Sulfamethoxypyridazine, SMP; Sulfamethoxazole, SMX; and Sulfadimethoxine, SDX) have been satisfactorily quantified after the 3D coated-device extraction. Detection limits of 6, 6, 0.9, 0.9, 0.8, 0.7, and 0.6 µg L-1 were achieved for SAM, SDZ, SMR, SMZ, SMP, SMX, and SDX, respectively. In all cases, a good linearity was observed up to 1000 µg L-1 with R2 between 0.9987 and 0.9998. The interday precision expressed as relative standard deviation (n = 3) varied between 2.2 and 5.5 % RSD, showing the good precision of the proposed methodology. Finally, the developed method was successfully used for the simultaneous analysis of seven SAs in samples of tap water and wastewater. Therefore, the 3D printed device is an efficient, miniaturized, and simple alternative for monitoring emerging contaminants derived from Pharmaceutical and Personal Care Products such as SAs in environmental water samples.

Розробка специфічної високочутливої методики визначення натрію диклофенаку в атмосферному повітрі з урахуванням особливостей мікроконцентрацій діючої речовини

Objective: to develop a specific, highly sensitive method for determining the concentration of sodium diclofenac in atmospheric air, taking into account the peculiarities of microconcentrations of the active substance. Materials and methods: Air sampling was carried out using a TYPHOON-S4 electric aspirator for 30 minutes at a speed of 20 l/min. The test to determine the concentration of sodium diclofenac in air was carried out by concentrating the analytical sample (aerosol of sodium diclofenac in water) by the method of solid-phase extraction, using Oasis MCX 6cc (150 mg) LP Extraction Cartridges, after which desorption was carried out with solvent - methanol. The obtained samples were analyzed by the method of high-performance liquid chromatography using a Dionex Ultimate 3000 chromatograph with a diode-matrix detector. The sensitivity of the method reaches ng/ml. It is shown that the concentration of the substance determined in the air is within (2-200 μg/m3). The results: As part of the work, a specific, highly sensitive method for determining the concentration of sodium diclofenac in the air was developed and testing was carried out by determining the concentration of sodium diclofenac in the air of the working area of the pharmaceutical enterprise «Lubnifarm» during certain analytical operations (pouring, weighing the substance, crushing tablets containing the active pharmaceutical ingredient under analysis, homogenization). The linear dependence of the diclofenac sodium peak area on the concentration of the substance in the solution (0.025-10 μg/ml) has been proven. The analysis showed that the volatile microparticles of the diclofenac sodium substance are exposed to air deposition, and as a result, a certain amount of this API penetrates into the analyzed samples of other drugs nearby. This fact can lead to obtaining unreliable results during the control of the quality and safety of medicinal products, which can have negative consequences for preserving the health of the population when using medicinal products of inadequate quality. Conclusions: Based on the results of the research, it was established that the developed technique is highly sensitive and will allow determination of nano- and micro-concentrations of sodium diclofenac in atmospheric air.

Optimization, validation and application of a high-throughput 96-well elution protocol for the quantification of psychoactive substances in influent wastewater.

Wastewater-based epidemiology (WBE) is based on the analysis of human metabolic excretion products (biomarkers) of xenobiotics in wastewater, to gain information about various lifestyles and health aspects of a population in an evidence-based manner. Due to the complex wastewater matrix and trace level occurrence of human biomarkers in the sewage network, it is crucial to have sensitive analytical procedures available. Additionally, to improve the value of WBE as a complementary epidemiological source, there is increasing pressure on the analysis of more compounds, more locations and more samples. A high-throughput method based on 96-well Oasis MCX solid-phase extraction (SPE), requiring less influent wastewater (2 mL), was developed in accordance with the European Medicines Agency guidelines. Validation was successful for 28 parent drugs and metabolites of antidepressants, opioids and drugs of abuse. The selection of biomarkers and quantification limit was chosen to be relevant for WBE and was predominantly 10 ng/L or below. The final method was successfully applied to 24-h composite samples of October 2019 (n= 27), obtained from an urban wastewater treatment plant in Leuven (Belgium).

ABOUT THE POSSIBILITY OF CONTAMINATION OF ANALYTICAL SAMPLES DURING QUALITY CONTROL OF MEDICINES AND WORK WITHIN THE SAME LABORATORY ROOM WITH DIFFERENT SUBSTANCES

The aim of the stady. To determine the concentration of diclofenac sodium in the air of the working area within the same room in order to determine the possible contamination of the sample being analyzed, when simultaneously working with different substances of medicinal products.&#x0D; Materials and methods. Air sampling was carried out using a TYPHOON-S4 electric aspirator for 30 minutes at a speed of 20 l/min. The test to determine the concentration of diclofenac sodium in air was carried out by concentrating the analytical sample with regard to the microconcentration of the substance by the method of solid-phase extraction, using Oasis MCX 6cc (150 mg) LP Extraction Cartridges, after which desorption was carried out with a solvent - methanol. The obtained samples were analyzed by the method of high-performance liquid chromatography using a Dionex Ultimate 3000 chromatograph with a diode-matrix detector. The sensitivity of the method reaches ng/ml.&#x0D; The results. As part of the work, a specific, highly sensitive method for determining the concentration of sodium diclofenac in the air was developed and testing was carried out by determining the concentration of sodium diclofenac in the air of the working area during certain analytical operations (pouring, weighing the substance, crushing tablets containing the active pharmaceutical ingredient under analysis, homogenization). The linear dependence of the diclofenac sodium peak area on the concentration of the substance in the solution (0.025-10 μg/ml) has been proven. Based on the obtained data, it was established that the volatile microparticles of diclofenac sodium substance are subject to air deposition, and as a result, a certain amount of this API penetrates into the analyzed samples of other drugs nearby. This fact can lead to obtaining unreliable results during the control of the quality and safety of medicinal products, which can have negative consequences for preserving the health of the population when using medicinal products of inadequate quality. At the same time, the research results show a proportional decrease in the concentration of sodium diclofenac in the air of the working area within one laboratory room as the air aspiration distance from the analytical operation being performed increases. However, at a distance of 0.2 m, the content of sodium diclofenac in the air of the working area exceeds the MPC by two times. These results indicate not only the possible background contamination of the analytical sample during the simultaneous work of several or one operator with different APIs or ready-made medicinal products, but also the possible harm to the analyst's health.&#x0D; Conclusions. A technique for determining microconcentrations of the active substance in the air of the working area has been developed. It has been found that samples can be easily contaminated with microparticles from other sources if proper precautions are not taken during collection, sample preparation and analysis. Special care should be taken, precautions should be taken, and operating procedures should be developed to minimize the risk of unwanted migration of contaminants in the quality and safety control of medicinal products.

Development of a Sensitive and High-Throughput Assay for Simultaneous Quantification of 5 Tyrosine Kinase Inhibitors and 2 Active Metabolites in Human Plasma Using Ultra-high Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry.

Breakpoint cluster region-Abelson (BCR-ABL) tyrosine kinase inhibitors (TKIs) demonstrate improved therapeutic efficacy in chronic myeloid leukemia (CML). However, drug-drug interactions, nonadherence, and host-related factors may influence plasma concentrations. Therefore, therapeutic drug monitoring may be necessary for patients presenting inadequate treatment responses or adverse events. Herein, the authors aimed to develop a more sensitive and high-throughput method than those previously reported to simultaneously quantify 5 TKIs (imatinib, nilotinib, dasatinib, bosutinib, and ponatinib) and 2 active metabolites (N-desmethyl imatinib and N-desmethyl ponatinib) using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Plasma samples were prepared according to a solid-phase extraction protocol using an Oasis MCX µElution plate. The assay fulfilled the requirements of the US Food and Drug Administration for assay validation, with a lower limit of quantification of 0.2 ng/mL for dasatinib, 0.3 ng/mL for N-desmethyl ponatinib, 0.5 ng/mL for N-desmethyl imatinib, bosutinib, and ponatinib, and 2.5 ng/mL for imatinib and nilotinib. Within-batch and batch-to-batch precision at the lower limit of quantification and quality control levels were within 14.3% and 10.9%, respectively. Within-batch and batch-to-batch accuracies ranged from 15.5% to 13.0% and 5.70% to 7.03%, respectively. A positive electrospray ionization mode was used with a run time of 6.0 minutes. The assay applicability was verified by the successful measurement of 78 clinical samples from patients undergoing CML therapy. The method allows assessment of trough concentrations of TKIs and active metabolites in patients with CML, and hence can be used to assess blood samples in routine clinical settings.

Preparation and application of polystyrene-divinylbenzene sorbent with weak cation-exchange character for the selective extraction of illicit drugs in environmental water

A novel mixed-mode weak cation-exchange sorbent (PS-DVB-WCX-II) was prepared by the modification of polystyrene-divinylbenzene with mercaptosuccinic acid for the selective extraction of illicit drugs in environmental water. The PS-DVB-WCX-II was synthesized through the Friedel-Crafts acylation reaction on the surface of polystyrene-divinylbenzene, followed by nucleophilic substitution reaction and thiol-ene click reaction. The sorbent can selectively absorb illicit drugs through the reverse-phase interactions provided by benzene ring on the polymer backbone and the ion-exchange interactions provided by functional group (-COOH). As compared with the extraction performance of three commercial SPE cartridges, it was found that the prepared sorbent had better adsorption performance with the recovery values between 84.1% and 106.0% for the selected 11 illicit drugs under the optimized SPE conditions. Illicit drugs in environmental water were extracted by the sorbent, prior to the detection of UHPLC-MS/MS. Two quantitative methods were established respectively for the detection of 11 illicit drugs in different matrices of river water and wastewater. Both methods had good determination coefficient (r2>0.992) in the range of 0.5–50 ng/L, 2.5–250 ng/L, 5–500 ng/L, and low limits of detection (S/N = 3) of 0.17–1.67 ng/L. In the real wastewater samples, the concentration of morphine was 18.3–126.3 ng/L, and the methamphetamine was 12.7–27.4 ng/L. Meanwhile, PS-DVB-WCX-II was compared with Oasis MCX and Oasis HLB in the detection of real wastewater samples. The results revealed that PS-DVB-WCX-II and Oasis MCX had better performance in absorbing methamphetamine than Oasis HLB, and PS-DVB-WCX-II had better ability to remove the matrix. The results suggested that the prepared weak cation-exchange sorbent had the potential in the application of illicit drug detection in environmental water.

Simultaneous Determination of Levamisole, Mebendazole, and the Two Metabolite Residues of Mebendazole in Poultry Eggs by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

The quantitative determination of levamisole (LMS), mebendazole (MBZ), and the two metabolites of MBZ, 5-hydroxymebendazole (HMBZ) and 2-amino-5-benzoylbenzimidazole (AMBZ), in poultry eggs (hen, duck, and goose) was achieved with high-performance liquid chromatography–tandem triple quadrupole mass spectrometry (HPLC–MS/MS). Samples were pretreated by liquid–liquid extraction and solid-phase extraction (LLE–SPE) to extract the target compounds, and an Oasis MCX SPE column was used for purification. Determination was performed on an Xbridge C18 column with 0.1% formic acid aqueous solution and acetonitrile as mobile phases. LMS, MBZ, HMBZ, and AMBZ were detected in a triple-quadrupole mass spectrometer with ESI in positive mode and quantified with an external standard. In blank eggs, the target analyte concentrations were within the limits of quantification (LOQs)—25 μg/kg (LMS) and 150 μg/kg (MBZ, HMBZ, and AMBZ)—and the matrix-matched calibration curves had good linearity (R2 ≥ 0.9990). In the same concentration range, the average recoveries of the target analytes were 85.98–97.38% (n = 6); the relative standard deviation (RSD), intraday RSD, and interday RSD ranged from 2.06 to 4.22%, 1.40 to 5.85%, and 2.34 to 6.32%, respectively. The limits of detection (LODs) ranged from 0.03 to 0.33 µg/kg, and the LOQs ranged from 0.08 to 1.00 µg/kg. Experimental verification showed that the HPLC–MS/MS method exhibited high specificity and sensitivity for quantitative analyses of egg samples. This study provides a rapid, efficient, and sensitive method for the simultaneous detection of LMS, MBZ, HMBZ, and AMBZ residues in foods of animal origin.

Determination of higenamine and tretoquinol in spices by solid phase extraction-isotope internal standard-high performance liquid chromatography-tandem mass spectrometry

A method was developed and validated for the determination of two plant-derived doping agents, higenamine (HG) and tretoquinol (TQ), in 26 kinds of spices. This was undertaken using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and isotope internal standards. The samples were extracted with ethanol containing 0.5% formic acid and purified using an Oasis MCX solid phase extraction cartridge. Subsequently, a C18 column was used for chromatographic separation using methanol and 0.05% formic acid aqueous solution as the mobile phase. UPLC-MS/MS in positive ESI and multiple reaction monitoring mode with HG-D4 and TQ-D9 as the internal standards were used for detection and quantification of analytes. The method was successfully calibrated in the range of 0.2–50 ng mL−1. The limit of detections (LODs) and limit of quantifications (LOQs) of HG were 0.57–0.88 µg kg−1 and 1.80–2.72 µg kg−1, respectively; the LODs and LOQs of TQ were 0.39–0.58 µg kg−1 and 1.27–1.88 µg kg−1, respectively. The average recoveries of the analytes fortified at four levels ranged from 77.1% to 98.7%, with a relative standard deviation < 15%. The proposed method has been successfully used to monitor real samples, and shown to be sensitive, rapid, and convenient. Hence, this method could be used for regulatory purposes to screen for the presence of HG and TQ in various spices.

Quantitative determination of Nε-(carboxymethyl)lysine in sterilized milk by isotope dilution UPLC-MS/MS method without derivatization and ion pair reagents

This study developed a sensitive and easy method to directly analyze Nε-(carboxymethyl)lysine (CML) by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Acetonitrile and water were used as the binary mobile phase without ion pair reagents, while BEH Amide column was applied to detect CML. The target substance without derivatization could be well retained and separated after the pretreatment conditions were optimized. Oasis MCX solid phase extraction (SPE) cartridge showed the best recovery rate of CML 96.7 % and purification ability among the tested SPE cartridges. There was no obvious difference in pretreatment abilities with or without protein precipitation on the CML quantitative analysis. The recovery rates 97–98 % for CML were achieved by UPLC-MS/MS, as well as the detection limit and quantification limit were 0.05 mg/kg and 0.15 mg/kg sample, respectively. This method was suitable for quantifying CML content with high recovery rate and low detection and quantification limit in sterilized milk.

Determination of Levamisole and Mebendazole and Its Two Metabolite Residues in Three Poultry Species by HPLC-MS/MS.

A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed to simultaneously analyze levamisole (LMS) and mebendazole (MBZ) and its two metabolites, 5-hydroxymebendazole (HMBZ) and 2-amino-5-benzoylbenzimidazole (AMBZ), in poultry muscle (chicken, duck and goose). In the sample preparation process, basic ethyl acetate was used as the extraction agent, and the extracted samples were back-extracted with hydrochloric acid, purified by Oasis MCX solid-phase extraction (SPE) cartridges, and reconstituted in the initial mobile phase after being blown dry with nitrogen. Chromatographic separation was performed on an Xbridge C18 column (4.6 mm × 150 mm, 5 μm) with 0.1% formic acid in water and acetonitrile as the mobile phases, and gradient elution was performed at a flow rate of 0.6 mL/min and a column temperature of 35 °C. In blank poultry muscle samples, the spiked concentrations of LMS, MBZ, HMBZ, and AMBZ were within the range of the limit of quantitation (LOQ) to 25 μg/kg. The peak areas of the four target drugs had a good linear relationship with the concentration, and the determination coefficient (R2) values were higher than 0.9990. The average recoveries of LMS, MBZ, HMBZ, and AMBZ were 86.77–96.94%; the intraday relative standard deviations (RSDs) were 1.75–4.99% at LOQ, 0.5 maximum residue limit (MRL), 1.0 MRL, and 2.0 MRL; the interday RSDs were 2.54–5.52%; and the LODs and LOQs were 0.04–0.30 μg/kg and 0.12–0.80 μg/kg, respectively.

A sensitive LC-MS/MS method for simultaneous quantification of ulotaront and its N-desmethyl metabolite in human plasma and application to a clinical study

Ulotaront (SEP-363856) is a novel non-D2-receptor-binding agent under development for the treatment of patients with schizophrenia. A highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with lower limit of quantitation of 0.0200 ng/mL (i.e. 20.0 pg/mL) was successfully developed and validated for the simultaneous quantitation of ulotaront and its N-desmethyl metabolite (M11A) in human plasma. Plasma samples were extracted by solid phase extraction with Oasis MCX 96-well plate, followed by a reversed phase LC separation coupled with MS/MS detection in positive mode (m/z 184.1 → 135.0 for ulotaront and 170.1 → 135.0 for M11A). Stable isotope-labeled compounds SEP-363856-d3 and M11A-d4 were used as internal standards (IS) for corresponding analytes. The validated calibration curve range was 0.0200–20.0 ng/mL for both analytes using a 0.200 mL plasma. Extraction recoveries were found to be 75.7% and 75.1% for ulotaront and IS1, and 82.7% and 83.9% for M11A and IS2, respectively. Frozen plasma samples were confirmed to be stable for up to 730 days at both −20 °C and −70 °C. The validated method has been successfully used to evaluate the pharmacokinetics (PK) of ulotaront and M11A in clinical studies. The application to the first-in-human PK study (single ascending dose) presented in this work demonstrated that ulotaront exhibited near dose proportionality for both Cmax (maximum concentration) and AUC (area under the curve) over the dose range from 5 to 125 mg. M11A was found as a minor metabolite with an exposure of about 2–3% of the parent compound.

Determination of Pyrrolizidine Alkaloids in Teas Using Liquid Chromatography-Tandem Mass Spectrometry Combined with Rapid-Easy Extraction.

This study developed an analytical method to determine pyrrolizidine alkaloids (PAs) in teas using liquid chromatography–tandem mass spectrometry combined with rapid-easy extraction. PAs were extracted with 40 mL of 0.05 M sulfuric acid in 50% methanol solution and cleaned up using Oasis MCX SPE cartridges. Chromatographic separation of 21 PAs was conducted on an X-Bridge C18 column with gradient elution. According to the AOAC official analysis methods, the developed method was verified to establish linearity, limits of detection, limits of quantification, accuracy, inter-day precision, and intra-day precision for each PA. Overall, the method showed excellent repeatability, sensitivity, and reproducibility. The verified method was applied to tea samples, including maté, lemon balm, fennel, hibiscus, chrysanthemum, lavender, oolong tea, chamomile, rooibos, peppermint, mix tea, black, and green tea. One of the main advantages of the method developed in this study is that it allows complete separation of lycopsamine and intermedine peaks. Therefore, the method could be used to monitor PAs in teas.

Automatic and renewable micro-solid-phase extraction based on bead injection lab-on-valve system for determination of tranexamic acid in urine by UHPLC coupled with tandem mass spectrometry.

An automatic micro-solid-phase extraction (μSPE) method using on-line renewable sorbent beads followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established for the determination of tranexamic acid (TXA) in urine. The μSPE method was based on the bead injection (BI) concept combined with the mesofluidic lab-on-valve (LOV) platform. All steps of the μSPE-BI-LOV were implemented by computer programming, rendering enhanced precision on time and flow events. Several parameters, including the type of sorbent, volume and composition of the conditioning solution, washing solution, and eluent composition, were evaluated to improve the extraction efficiency. The best results were obtained with ahydrophilic-lipophilic balanced mixed-mode sorbent, decorated with sulfonic acid groups (Oasis MCX), and 99% acetonitrile-water (50:50, v/v)-1% ammonium hydroxide as eluent. Chromatographic separation was performed using a BEH amide column coupled to MS/MS detection in positive ionization mode. Good linearity was achieved (R2 > 0.998) for TXA concentrations in urine ranging from 300 to 3000ngmL-1, with LOD and LOQ of 30 and 65ngmL-1, respectively. Dilution integrity was observed for dilution factors up to 20,000 times, providing the extension of the upper limit of quantification to 12mgmL-1. The method was validated according to international guidelines and successfully applied to urine samples collected during scoliosis surgery of pediatric patients treated with TXA.

Determination of antidepressants and benzodiazepines in paired hair and nail samples

Hair and nails are keratinized matrices that can be used in Toxicology as matrices for the long-term detection of substances. Whereas hair is an established matrix with decades of use in this field, nails have been less studied, especially including a comparison to hair samples. Specifically in the case of antidepressant and benzodiazepine drugs, very few publications analyzing these drugs in nail samples exist as of yet. For this reason, in the present study a method for the detection of 12 antidepressant and benzodiazepine drugs in hair and nail samples was developed. Samples were decontaminated with 3 washes of dichloromethane, and 25 or 30 mg of hair and nails, respectively, were pulverized. Then, the samples were incubated with 1.5 mL water:ACN (50:50, v/v) with horizontal agitation for 90 min. The supernatant was evaporated and reconstituted in 200 µL of methanol and 2 mL of 2% FA in water, submitted to solid phase extraction (SPE) using Oasis MCX cartridges and analyzed by LC-MS/MS. The method was satisfactorily validated in nail and hair samples for the following parameters: linearity, LOD (0.005–0.02 ng/mg), LOQ (0.01–0.02 ng/mg), selectivity, carryover, accuracy, imprecision, matrix effect, extraction efficiency, process efficiency and autosampler stability. Matched fingernail, toenail and hair samples were obtained from 21 patients under treatment with any of the studied drugs and analyzed with the developed method. The most frequently detected drugs were venlafaxine (n = 11), trazodone (n = 6), zolpidem (n = 5), alprazolam (n = 5) and nordiazepam (n = 5). Concentrations in hair, fingernails and toenails, respectively, were 44.31 ng/mg, 8.05–43.35 ng/mg and 7.02–22.69 ng/mg for venlafaxine; 5.40–19.08 ng/mg, 0.13–1.00 ng/mg and 0.42–1.04 ng/mg for trazodone; 13.86 ng/mg, 5.19 ng/mg and 9.11 ng/mg for fluoxetine; 7.42 ng/mg, 1.85 ng/mg and 0.03–2.81 ng/mg for sertraline; 0.40–1.42 ng/mg, 0.12 ng/mg and 0.16 ng/mg for zolpidem; and 0.02–0.11 ng/mg, 0.07–1.07 ng/mg and 0.05 ng/mg for alprazolam for the patients under active treatment. Hair concentrations were higher than nail concentrations for most drugs in patients under active treatment, with the exception of diazepam (n = 1; 0.12 ng/mg in hair and 0.41 ng/mg in fingernails). Fingernail concentrations were lower than toenail concentrations in patients under active treatment in most compared cases. Comparison of fingernails and toenails of a patient with antifungal treatment did not show an observable effect in concentrations.

Robust and Facile Automated Radiosynthesis of [18F]FSPG on the GE FASTlab

Purpose(S)-4-(3-18F-Fluoropropyl)-ʟ-Glutamic Acid ([18F]FSPG) is a radiolabeled non-natural amino acid that is used for positron emission tomography (PET) imaging of the glutamate/cystine antiporter, system xC-, whose expression is upregulated in many cancer types. To increase the clinical adoption of this radiotracer, reliable and facile automated procedures for [18F]FSPG production are required. Here, we report a cassette-based method to produce [18F]FSPG at high radioactivity concentrations from low amounts of starting activity.ProceduresAn automated synthesis and purification of [18F]FSPG was developed using the GE FASTlab. Optimization of the reaction conditions and automated manipulations were performed by measuring the isolated radiochemical yield of [18F]FSPG and by assessing radiochemical purity using radio-HPLC. Purification of [18F]FSPG was conducted by trapping and washing of the radiotracer on Oasis MCX SPE cartridges, followed by a reverse elution of [18F]FSPG in phosphate-buffered saline. Subsequently, the [18F]FSPG obtained from the optimized process was used to image an animal model of non-small cell lung cancer.ResultsThe optimized protocol produced [18F]FSPG in 38.4 ± 2.6 % radiochemical yield and >96 % radiochemical purity with a molar activity of 11.1 ± 7.7 GBq/μmol. Small alterations, including the implementation of a reverse elution and an altered Hypercarb cartridge, led to significant improvements in radiotracer concentration from <10 MBq/ml to >100 MBq/ml. The improved radiotracer concentration allowed for the imaging of up to 20 mice, starting with just 1.5 GBq of [18F]Fluoride.ConclusionsWe have developed a robust and facile method for [18F]FSPG radiosynthesis in high radiotracer concentration, radiochemical yield, and radiochemical purity. This cassette-based method enabled the production of [18F]FSPG at radioactive concentrations sufficient to facilitate large-scale preclinical experiments with a single prep of starting activity. The use of a cassette-based radiosynthesis on an automated synthesis module routinely used for clinical production makes the method amenable to rapid and widespread clinical translation.

Effects of Chronic Secondhand Smoke (SHS) Exposure on Cognitive Performance and Metabolic Pathways in the Hippocampus of Wild-Type and Human Tau Mice.

Background:Exposure to secondhand smoke (SHS) is a risk factor for developing sporadic forms of sporadic dementia. A human tau (htau) mouse model is available that exhibits age-dependent tau dysregulation, neurofibrillary tangles, neuronal loss, neuroinflammation, and oxidative stress starting at an early age (3–4 months) and in which tau dysregulation and neuronal loss correlate with synaptic dysfunction and cognitive decline.Objective:The goal of this study was to assess the effects of chronic SHS exposure (10 months’ exposure to ) on behavioral and cognitive function, metabolism, and neuropathology in mice.Methods:Wild-type (WT) and htau female and male mice were exposed to SHS (90% side stream, 10% main stream) using the SCIREQ® inExpose™ system or air control for 168 min per day, for 312 d, 7 d per week. The exposures continued during the days of behavioral and cognitive testing. In addition to behavioral and cognitive performance and neuropathology, the lungs of mice were examined for pathology and alterations in gene expression.Results:Mice exposed to chronic SHS exposure showed the following genotype-dependent responses: a) lower body weights in WT, but not htau, mice; b) less spontaneous alternation in WT, but not htau, mice in the Y maze; c) faster swim speeds of WT, but not htau, mice in the water maze; d) lower activity levels of WT and htau mice in the open field; e) lower expression of brain PHF1, TTCM1, , and HSP90 protein levels in WT male, but not female, mice; and f) more profound effects on hippocampal metabolic pathways in WT male than female mice and more profound effects in WT than htau mice.Discussion:The brain of WT mice, in particular WT male mice, might be especially susceptible to the effects of chronic SHS exposure. In WT males, independent pathways involving ascorbate, flavin adenine dinucleotide, or palmitoleic acid might contribute to the hippocampal injury following chronic SHS exposure. https://doi.org/10.1289/EHP8428

Simple new method for labelling of PSMA-11 with 68Ga in NaHCO3

BackgroundProstate specific membrane antigen (PSMA) is a type II membrane protein widely expressed on the surface of prostate cancer cells. One of its functions is to act as a receptor mediating the ligand internalization. This PSMA property is employed in the diagnostics and therapy of prostate cancer.Over the years, small molecules with high affinity for PSMA have been developed and labelled with positron emitters (e.g. 68Ga, 18F, 11C, 64Cu, or 86Y). One of these radiolabelled ligands, [68Ga] PSMA-11, is one of the most widespread tracers for PET imaging of the prostate cancer.Many techniques have been proposed and tested for the 68Ga labelling of PSMA-11. The aim of our work was to design a labelling method of PSMA-11 that minimizes number of the used chemicals and steps, providing quantitative labelling yield at laboratory temperature and may be easily automated. MethodologyA68Ge/68Ga generator eluate in 0.1 M HCl was loaded on an activated Oasis MCX cartridge, and the cartridge was then thoroughly washed with water. The radionuclide 68Ga was eluted from the cartridge with 0.1 M NaHCO3 (pH = 8.5, n = 36) or with the same solution with pH adjusted to 7.2–9.0 (n = 38). Precursor PSMA-11 was mixed directly with the cartridge eluate of 68Ga in 0.1 M NaHCO3 of given pH.For the stability test, samples of 68GaPSMA-11 in 0.1 M NaHCO3 (pH 8.5) were mixed in ratio 1 : 1 with the following solutions: 0.1 M NaHCO3 (pH 8.5), human serum, PBS and 0.9% NaCl.In order to estimate an effect of the time elapsed between 68Ga elution from the cartridge in 0.1 M NaHCO3 (pH 8.5) and the labelling onset of PSMA-11, the latter was initiated 0, 5, 10 and 20 min post elution and radiochemical yield was monitored.All the PSMA-11 labelled samples were subjected to radiochemical purity test using HPLC. The whole process starting from generator elution up to HPLC analysis commencement took 10–15 min. ResultsRecovery of 68Ga from cartridge Oasis MCX using 0.1 M NaHCO3 at pH 8.5 was 71.5 ± 1.4%. Thirty six PSMA-11 samples (10 μg in reaction mixture) were labelled at pH 8.5 with total average radiochemical yield of 98 ± 2%.Recovery of 68Ga from cartridge Oasis MCX using 0.1 M NaHCO3 at variable pH of 7.2–9.0 was 62.5 ± 1.8% showing certain decrease with decreasing pH. A total of 138 samples of PSMA-11 were labelled with 68 Ga at variable pH (7.2–9.0) and four different amounts of PSMA-11 (1, 2.5, 5 and 10 μg) resulting in the labelling yields of 54.0 ± 5.3%, 88.2 ± 3.2%, 99.4 ± 0.3% and 99.9 ± 0.1%, respectively. Irrespective of the pH, the radiolabelling yield was quantitative for the molar ratio PSMA-11: 68Ga > 5000 : 1 in the reaction mixture.Stability tests in 0.1 M NaHCO3 (pH 8.5), human serum, PBS and 0.9% NaCl revealed no observable release of 68Ga from the 68Ga-PSMA-11 complex within 3 h. Similarly, the delay between the 68Ga elution from the Oasis MCX cartridge in 0.1 M NaHCO3 (pH 8.5) and start of the labelling of PSMA-11 labelling has no effect on the radiochemical yield. ConclusionA new method of labelling PSMA-11 ligand with 68Ga in 0.1 M NaHCO3 using Oasis MCX cartridges was proposed, developed and tested. The results demonstrated that it is rapid, simple, reproducible and easy to automate.

Determination of gamithromycin residues in eggs, milk and edible tissue of food-producing animals by solid phase extraction combined with ultrahigh-performance liquid chromatography-tandem mass spectrometry

A high throughput method was developed and validated for the quantitation of gamithromycin residues in eggs, milk and animal tissues (leg muscle, kidney, liver and fat) of different species and genera. This was undertaken using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The samples were extracted with acetonitrile and purified using an Oasis MCX solid phase extraction cartridge. Subsequently, a C18 column was used for chromatographic separation using acetonitrile and 0.1% formic acid as the mobile phase. LC-MS/MS in positive ESI and multiple reaction monitoring mode with gamithromycin-D4 as the internal standard was used for detection and quantification of gamithromycin. The method was successfully calibrated in the range of 1.0–200 µg/kg. The limit of detection (LOD) and limit of quantification (LOQ) for gamithromycin was 0.30–0.40 µg/kg and 0.80 – 1.0 µg/kg, respectively. The average recoveries of the analyte fortified at three levels ranged from 84.2% to 115.9%, with a relative standard deviation <10%. The proposed method has been successfully used to monitor real samples, and shown to be sensitive, rapid, and convenient. Hence, this method could be used for regulatory purposes to screen for the presence of gamithromycin residues in eggs, milk and target tissues.