Method Quantitation Limits Research Articles

Occurrence of Selected Pharmaceuticals in the East London Coastline Encompassing Major Rivers, Estuaries, and Seawater in the Eastern Cape Province of South Africa.

This study investigated the occurrence of ibuprofen, naproxen, sulfamethoxazole, trimethoprim, and efavirenz in water resources (river, estuarine, and sea waters) of the East London coastline, South Africa. These pharmaceuticals were previously reported to be dominant in wastewater and inland rivers of South Africa. Hence, it is important to monitor their occurrence in the coastal and marine environment. The pharmaceuticals of interest were extracted with a solid-phase extraction method and analyzed by using a liquid chromatography-quadrupole time-of-flight mass spectrometry instrument. The analytical method was validated by spiking the environmental samples with a mixture of pharmaceuticals at two concentration levels (5 and 15 μg L-1). The analytical method yielded acceptable recoveries ranging from 75 to 107%, with method quantitation limits from 0.16 to 9.44 ng of L-1. All five targeted pharmaceuticals were detected in seawater samples, with ibuprofen recording the highest concentration of 90 ng L-1. However, it was efavirenz and sulfamethoxazole with the highest concentrations of 572 and 60 ng L-1, respectively, in the Gonubie River that showed high ecotoxicological risks toward the aquatic organisms. There were no risks associated with the occurrence of other targeted pharmaceuticals. The suspect screening showed the occurrence of 57 additional pharmaceuticals in samples, with antibiotics being more dominant. The results of the present study demonstrate a need to perform a more robust investigation on the occurrence of a wide range of pharmaceuticals along the South African coasts.

Study on determination of PAEs in water samples by using solid phase extraction combined with gas chromatography-mass spectrometry

Phthalic acid diesters (PAEs) are industrial chemicals used as plasticizers in a variety of commercial products. Due to wide usage, PAEs have been found in various environments and their human exposure risks have also attracted a lot of concerns. However, little information about the distributions of PAEs in the water samples collected from Vietnam was reported. In this study, the method for the determination of nine typical PAEs in water samples by using the solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) technique was optimized. The method detection limits (MDLs) and method quantitation limits (MQLs) of PAEs in water samples were in ranges of 0.2–0.4 ng/L and (0.6-1.2) ng/L, respectively. The recoveries of surrogate compounds in blank and real samples ranged from (74.8 to 93.9) %, with RSD < 9.2 %. The calibration curve for all standards was linear over a concentration range of (1.0-1,000) ng/mL (with R2 ≥ 0.998). The total concentrations of PAEs measured in bottled water of six brands were ranged from 10.0 ng/L to 6,690 ng/L. Among the studied PAEs, di-(2-ethylhexyl) phthalate (DEHP) was found at the highest frequencies and concentrations. Overall, the distribution of PAEs in plastic bottled water is significantly lower than the permitted regulations (only with DEHP) in drinking water by the Ministry of Health of Vietnam in 2011. ® 2023 Journal of Science and Technology - NTTU

A high-throughput small volume matrix based calibration using isotope dilution liquid chromatography tandem mass spectrometry analysis for 42 per and polyfluoroalkyl substances in groundwater

A novel method for the determination of per- and polyfluoroalkyl substances (PFAS) in groundwater is presented using a subsample, matrix-matched calibrators, 96-well plate solid phase extraction (SPE), and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Accuracy, precision, measurement of uncertainty (MOU), method detection limit (MDL), method quantitation limit (MQL), analytical measurement range, interferences/ion suppression, and analyte stability were determined as part of the in-house method validation. The method quantitates 42 PFAS compounds from nine different compound classes. Accuracy for the reference material (RM) and matrix spike (MS) ranged from 52.3 to 117.8 %, and precision for the MS and matrix spike duplicate (MSD) had a coefficient of variation (CV) from 2.0 % to 23.3 %. MDLs spanned from 0.07 to 1.97 ng L−1, with MQLs ranging from 0.20 to 5.90 ng L−1. Suppression studies determined that iron and manganese have effects on analytes that do not have paired isotopically labeled standards. The results from the in-house validation indicated that this Michigan Department of Health and Human Services laboratory developed test meets the necessary accuracy, precision, MDL, MQL and reporting limits requirement established by the laboratory's quality system essentials (QSEs) and select criteria from the Department of Defense (DoD) Quality Systems Manual for Environmental Laboratories and American Industrial Hygiene Association Laboratory Accreditation Program, LLC (AIHA LAP, LLC) accrediting International Standard Organization (ISO/IEC 17025:2017) check list.

Single reaction chamber microwave digestion coupled with ICP-MS for the determination of ultra-trace mercury in rocks.

In this study, a method for rock digestion using a single reaction chamber (SRC) microwave system was established. Nitric acid (HNO3) and hydrofluoric acid (HF) were used as digestion agents, and the determination of mercury (Hg) in rocks was performed by inductively coupled plasma mass spectrometry (ICP-MS). The optimal conditions for the SRC microwave system were achieved at 260 °C and 70 bar, with a mixture of 3 mL of 65-68 wt% HNO3 and 1 mL of 49 wt% HF when the sample weight is in the range of 0.025-0.05 g. The method quantitation limit (MQL) was determined to be 0.0016 mg kg-1. Measurement accuracy was evaluated using five Chinese nationally certified reference materials, demonstrating good consistency between measurement results and certified values. The method was applied to two rock samples, resulting in a recovery rate ranging from 105% to 109%. This method exhibits high sensitivity, stability, and low acid consumption. Importantly, it provides a reliable and efficient determination method for Hg in rocks, which is of great significance in geochemical analysis.

Study on determination of PAEs in water samples by using solid phase extraction combined with gas chromatography-mass spectrometry

Phthalic acid diesters (PAEs) are industrial chemicals used as plasticizers in a variety of commercial products. Due to wide usage, PAEs have been found in various environments and their human exposure risks have also attracted a lot of concerns. However, little information about the distributions of PAEs in the water samples collected from Vietnam was reported. In this study, the method for the determination of nine typical PAEs in water samples by using the solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) technique was optimized. The method detection limits (MDLs) and method quantitation limits (MQLs) of PAEs in water samples were in ranges of 0.2–0.4 ng/L and (0.6-1.2) ng/L, respectively. The recoveries of surrogate compounds in blank and real samples ranged from (74.8 to 93.9) %, with RSD < 9.2 %. The calibration curve for all standards was linear over a concentration range of (1.0-1,000) ng/mL (with R2 ≥ 0.998). The total concentrations of PAEs measured in bottled water of six brands were ranged from 10.0 ng/L to 6,690 ng/L. Among the studied PAEs, di-(2-ethylhexyl) phthalate (DEHP) was found at the highest frequencies and concentrations. Overall, the distribution of PAEs in plastic bottled water is significantly lower than the permitted regulations (only with DEHP) in drinking water by the Ministry of Health of Vietnam in 2011.
 ® 2023 Journal of Science and Technology - NTTU

Improved liquid-liquid extraction followed by HPLC-UV for accurate and eco-friendly determination of tetramethylpyrazine in vinegar products

Tetramethylpyrazine (TMP) is an important bioactive compound in vinegars, contributing to their health-enhancing attributes. It serves as a crucial benchmark for the assessment of vinegar quality. Unfortunately, inaccuracies have arisen due to incomplete extraction techniques and the use of an inappropriate standard substance. These challenges have significantly curtailed comprehensive exploration into the underlying TMP formation mechanisms, impeding advancements within prevailing benchmarks and methodologies governing vinegar products. To address these challenges, several critical parameters, encompassing pH, solvent type, centrifugal force, extraction times and reference materials were investigated and optimized. The TMP content was determined by adjusting the pH to 9 using a sodium hydroxide solution, followed by extraction with ethyl acetate and subsequent re-extraction of the ethyl acetate layer with 0.2 mol/L HCl. A high-performance liquid chromatography method with an ultraviolet detector (UV) was developed and validated. This method demonstrated superior sensitivity compared to existing methods, with a limit of detection (LOD) of 0.0237 μg/g, limit of quantification (LOQ) of 0.0829 μg/g, method limit of detection (MLOD) of 0.10 μg/g and method limit of quantitation (MLOQ) of 0.25 μg/g. The modified method exhibited excellent linearity for TMP in the range of 0.1–118.4 μg/mL, with a good correlation coefficient (R2 > 0.999). The recovery rate of TMP in vinegar products ranged from 82.4 to 96.2%. Consequently, the proposed method exhibits substantial promise for systematic inquiry into TMP formation mechanisms and for ensuring consistent quality control during the production of premium-grade vinegars.

Simultaneous determination of 11 nootropic substances potentially adulterated in dietary supplements for improving brain function using ultra-performance liquid chromatography and liquid chromatography–quadrupole-time-of-flight mass spectrometry

Recently, the demand for improved brain function and concentration has increased in the dietary supplement market. However, to artificially enhance their pharmacological efficacy, dietary supplements may be illegally adulterated with unauthorised substances. Therefore, we developed a rapid and accurate method to simultaneously determine 11 nootropic substances using an ultra-high-performance liquid chromatography (UPLC) system equipped with a photodiode array (PDA) detector. In addition, sample preparation procedures were semi-optimised for various types of matrices, including solid (hard capsule, tablet, powder, and pill) and liquid (oil and extract) samples. The method was validated to determine the limit of detection (LOD), limit of quantification (LOQ), method detection limit (MDL), method quantitation limit (MQL), specificity, linearity, precision, accuracy, recovery, stability, and matrix effects. The validation results satisfied international validation guideline requirements. To test the applicability of the method, 55 real samples advertised as effective brain health, memory, and cognition supplements were analysed. Among the real samples, vinpocetine (2.483 and 7.296 µg/g), and kavain (69–44.056 µg/g) were detected. In addition, the detected compounds were confirmed by comparing their fragmentation patterns with those of the reference standards using liquid chromatography–quadrupole-time-of-flight mass spectrometry (LC-QTOF/MS). In conclusion, the UPLC-PDA method not only rapidly and accurately quantifies illegal nootropics but also enables the pre-emptive investigation and identification of 11 nootropic substances in illegal dietary supplements to protect public health.

Study on the determination of some diamine in urine by LC-MS/MS

Isocyanate is a common name for chemical compounds containing one or more - NCO groups. There have been many studies showing that isocyanates pose a risk to human health when exposed and can cause occupational poisoning. When absorbed into the body, the isocyanates will be converted into the corresponding amines. Therefore, the determination of these diamines in urine will contribute to the assessment of exposure to isocyanates. This article presents a study on simultaneous determination of 4,4′-methylenedianiline (MDA), hexamethylene diamine (HDA), isophoron diamine (IPDA) in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method detection limit (MDL) were 0.074, 0.059, and 0.053 ng/mL for HDA, MDA, IPDA, respectively. The method quantitation limit (MQL) were 0.243, 0.194 and 0.177 ng/mL for HDA, MDA, IPDA, respectively. The method's recovery ranged from 86.38 to 105.3% with the repeatability RSDr < 6%. The method was successfully applied to simultaneously determine the content of HDA, MDA and IPDA in 30 urine samples of workers at auto repair garages in Bac Ninh province. The results showed that HDA, MDA and IPDA were detected in these samples with different concentrations.

Uptake of Per- and Polyfluoroalkyl Substances by Fish, Mussel, and Passive Samplers in Mobile-Laboratory Exposures Using Groundwater from a Contamination Plume at a Historical Fire Training Area, Cape Cod, Massachusetts.

Aqueous film-forming foams historically were used during fire training activities on Joint Base Cape Cod, Massachusetts, and created an extensive per- and polyfluoroalkyl substances (PFAS) groundwater contamination plume. The potential for PFAS bioconcentration from exposure to the contaminated groundwater, which discharges to surface water bodies, was assessed with mobile-laboratory experiments using groundwater from the contamination plume and a nearby reference location. The on-site continuous-flow 21-day exposures used male and female fathead minnows, freshwater mussels, polar organic chemical integrative samplers (POCIS), and polyethylene tube samplers (PETS) to evaluate biotic and abiotic uptake. The composition of the PFAS-contaminated groundwater was complex and 9 PFAS were detected in the reference groundwater and 17 PFAS were detected in the contaminated groundwater. The summed PFAS concentrations ranged from 120 to 140 ng L-1 in reference groundwater and 6100 to 15,000 ng L-1 in contaminated groundwater. Biotic concentration factors (CFb) for individual PFAS were species, sex, source, and compound-specific and ranged from 2.9 to 1000 L kg-1 in whole-body male fish exposed to contaminated groundwater for 21 days. The fish and mussel CFb generally increased with increasing fluorocarbon chain length and were greater for sulfonates than for carboxylates. The exception was perfluorohexane sulfonate, which deviated from the linear trend and had a 10-fold difference in CFb between sites, possibly because of biotransformation of precursors such as perfluorohexane sulfonamide. Uptake for most PFAS in male fish was linear over time, whereas female fish had bilinear uptake indicated by an initial increase in tissue concentrations followed by a decrease. Uptake of PFAS was less for mussels (maximum CFb = 200) than for fish, and mussel uptake of most PFAS also was bilinear. Although abiotic concentration factors were greater than CFb, and values for POCIS were greater than for PETS, passive samplers were useful for assessing PFAS that potentially bioconcentrate in fish but are present at concentrations below method quantitation limits in water. Passive samplers also accumulate short-chain PFAS that are not bioconcentrated.

Simultaneous Determination of Nine Phthalates in Vegetable Oil by Atmospheric Pressure Gas Chromatography with Tandem Mass Spectrometry (APGC-MS/MS).

Although the use of phthalates has been restricted worldwide, they remain an issue due to health concerns. Diet is one of the most important exposure pathways for humans and due to their solubility in oil, phthalates are commonly found in edible oil and food high in fat. Gas chromatography-mass spectrometry (GC-MS) using electron ionization (EI) has been commonly used for the analysis of the phthalates in foodstuffs, including edible oil. However, this method suffers from issues with sensitivity and selectivity, as most phthalates are fragmented to generate a common phthalic anhydride fragment ion at m/z 149. The molecular ion cannot be observed due to strong fragmentation in EI. In contrast, atmospheric pressure gas chromatography (APGC) is a soft ionization technique with less fragmentation, whereby the molecular ion can be used as the precursor ion for multiple reaction monitoring (MRM). In this study, a simple and quick method for the determination of phthalates in vegetable oil using APGC-MS/MS was developed, and performance was assessed. The method was based on dilution of the oil in solvent and direct injection without the need for further cleanup. The established method was evaluated for linearity, recovery, precision, method detection limit (MDL), and method quantitation limit (MQL). The obtained MQL in vegetable oil was in the range of 0.015-0.058 mg/kg, despite limiting the injection volume to 1 µL, which is suitable for investigating dietary exposure and future proof against decreases to the regulatory limit. Finally, the developed method was successfully applied to analyze nine phthalates in eight commercially available vegetable oil.

Ribbon-shaped supramolecular solvents: Synthesis, characterization and potential for making greener the microextraction of water organic pollutants

Liquid-liquid microextraction (LLME) techniques have experienced a tremendous growth over the last years but still face major challenges related to the use of more efficient and environmentally friendly solvents. Supramolecular solvents (SUPRASs) have proved outstanding efficiency in LLME, but many of the experimental conditions required for SUPRAS formation and/or application cannot be considered green or experimentally convenient. This paper was intended to make greener both SUPRAS formation and their application to the LLME of low-concentration organic pollutants in environmental waters. For this purpose, a variety of SUPRASs were produced at room temperature by simply mixing alkyl phosphonates (A6-12PO3H− and A6-12PO3−2) and tetrahexylammonium (He4N+) ions in aqueous media. Among them, the SUPRASs produced from decyl hydrogen phosphonate (DePO3H−) and He4N+ allowed, for the first time, the development of SUPRAS-based LLMEs where the SUPRAS previously synthesized was added to the liquid sample, instead of being formed in situ as usual, which was proved particularly advantageous for analyses involving large sample/SUPRAS volume ratios. At near equimolar amounts of DePO3H− and He4N+, the amphiphile arranged in the SUPRAS as planar ribbons consisting of water (21 ± 3%, w/v) and DePO3H− and He4N+ in the concentration range 1.0–1.4 M. The application of these SUPRASs to LLMEs was proved by extracting carcinogenic polycyclic aromatic hydrocarbons (CPAHs) from drinking (tap and bottled) and natural (river, reservoir and underground) water (recoveries between 84 and 117% with standard deviations varying between 1 and 14%). The developed method was simple (it only required the addition of 500 μL of SUPRAS to 75 mL of sample, stirring and centrifugation), sensitive (method quantitation limits were below the maximum allowed limits set by the EU; were 0.6–7.1 ng L−1) and selective (SUPRAS extracts were directly analyzed by liquid chromatography-fluorimetry). This research proves that SUPRASs can be operationally used in LLMEs similarly to conventional solvents, which should favor their routine application in high-sample throughput laboratories.

Simultaneous Determination of Pyrethroid Insecticides in Foods of Animal Origins Using the Modified QuEChERS Method and Gas Chromatography-Mass Spectrometry.

Pyrethroid insecticides are used in agriculture to treat parasites in livestock. This study developed a simultaneous residue analysis method to measure seventeen pyrethroid insecticides in foods of animal origin, including beef, pork, chicken, milk, and eggs. The method, which comprises instrumental analysis using gas chromatography-tandem mass spectrometry and a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for pretreatment, was optimized to verify the applicability of the method. A mixture of acetonitrile, ethyl acetate, and original salt (MgSO4 4 g, NaCl 1 g) was used as the extraction solvent and salt. MgSO4 (150 mg) primary secondary amine (25 mg) and graphitized carbon black (25 mg) were selected for dispersive solid phase extraction (d-SPE). The method limit of quantitation was 0.01 mg/L, and the linearity of the matrix-matched calibration curves was reasonable (R2 > 0.99). Recovery tests were performed at three concentrations (LOQ, 10 LOQ, and 50 LOQ). Good recoveries (75.2109.8%) and reproducibility (coefficient of variation <10%) were obtained. The matrix effects were in the range of -35.8 to 56.0%. The established method was fully validated and can be used as an official analytical method for quantifying pyrethroid insecticides in animal commodities.

Analysis, identification and confirmation of synthetic opioids using chloroformate chemistry: Retrospective detection of fentanyl and acetylfentanyl in urine and plasma samples by EI-GC-MS and HR-LC-MS.

Electron Impact Gas Chromatography-Mass Spectrometry (EI-GC-MS) and High Resolution Liquid Chromatography-Mass Spectrometry (HR-LC-MS) have been used in the analysis of products arising from the trichloroethoxycarbonylation of fentanyl and acetylfentanyl in urine and plasma matrices. The method involves the initial extraction of both synthetic opioids separately from the matrices followed by detection of the unique products that arise from their reaction with 2,2,2-trichloroethoxycarbonyl chloride (Troc-Cl), namely Troc-norfentanyl and Troc-noracetylfentanyl. The optimized protocol was successfully evaluated for its efficacy at detecting these species formed from fentanyl and acetylfentanyl when present at low and high levels in urine (fentanyl: 5 and 10 ng/mL and acetylfentanyl: 20 and 100 ng/mL) and plasma (fentanyl: 10 and 20 ng/mL and acetylfentanyl: 50 and 200 ng/mL), values that reflect levels reported in overdose victims. The HR-LC-MS method's LOQ (limit of quantitation) for the Troc-norfentanyl and Troc-noracetylfentanyl products was determined to be ~10 ng/mL for both species. Even though the superiority in the detection of these species by HR-LC-MS over EI-GC-MS, the latter method proved to be important in the detection of the second product from the reaction, namely 2-phenylethyl chloride that is crucial in the determination of the original opioid. This observation highlights the importance of using complimentary analytical techniques in the analysis of a sample, whether biological or environmental in nature. The method herein serves as a complementary, qualitative confirmation for the presence of a fentanyl in collected urine, plasma and by extension other biological samples amenable to the common extraction procedures described for opioid analysis. More importantly, the method's main strength comes from its ability to react with unknown fentanyls to yield products that can be not only detected by EI-GC-MS and HR-LC-MS but can then be used to retrospectively identify an unknown fentanyl.

Mass Diffusion of Modern Digital Technologies as the Main Driver of Change in Sports-Spectating Audiences.

The rapid uptake of digital technologies is constantly transforming the modern culture of sports spectating; however, relatively little is known about the impact of digitalization on the changing face of global sports-consuming audiences, particularly from a qualitative perspective. In this article, the relationship between modern mass digital technologies (i.e., mobile applications and big data) and audiences of sports spectators is described and explained by taking a customer-centric approach to grounded theory using a literature review and in-depth qualitative semi-structured interviews (N = 12) with sports marketing, management, and technology professionals. The qualitative approach permits the gathering of in-depth insights into a problem, generates new concepts through data synthesis and analysis, and captures changing attitudes within the sports industry. Moreover, the qualitative approach to research is not bound by the limitations of quantitative methods and focuses on the primary questions of “how” and “why” digital technology’s mass deployment and diffusion have transformed content consumption in the sports industry. The analysis first systematizes and codes the collected data. Second, all the materials are iteratively read and the key points are outlined. Using the iterative analysis, the theoretical and empirical insights and findings are synthesized in order to achieve the results. Finally, dimensions of the transformation of sports spectators’ consumption are identified and explained. The research implications highlight “how” and “why” modern digital technologies have changed the sports-consuming audience by making it more inclusive in terms of age, gender, demographics, social and health status. These findings are useful for sport managers to better understand their audiences and processes in an ever-changing global society.

HPLC-ESI-HRMS2 Determination of N-(2-Hydroxyethyl)-l-valyl-l-leucine in Human Urine: Method Validation.

Biomonitoring of human exposure to reactive electrophilic chemicals such as ethylene oxide (EO) has been commonly based on the determination of adducts with N-terminal valine in blood protein globin, but a systematic search has also been undertaken to find surrogate markers enabling non-invasive sampling. Recently, N-(2-hydroxyethyl)-L-valyl-L-leucine (HEVL) has been identified as an ultimate cleavage product of EO-adducted globin in the urine of occupationally exposed workers. Herein, full validation of the analytical procedure consisting of solid-phase extraction of HEVL from urine samples (2 mL) followed by high-performance liquid chromatography-electrospray ionization-high-resolution mass spectrometry determination using deuterium-labeled HEVL as an internal standard (IS) is described. Method limit of quantitation is 0.25 ng/mL, and its selectivity is excellent as demonstrated by the invariable ratio of the qualifier and quantifier ion intensities across diverse urine samples and synthetic standard. The linear calibration model was applicable over the whole concentration range tested (0.25-10 ng/mL). The method accuracy assessed as a recovery of HEVL using a spiking experiment was 98-100%. Within-day precision of the method ranged from 1.8% to 3.0%, while the results from consecutive analytical runs conducted within 1 week or within 10-150 weeks differed in the range of 2.2-9.7%. The stability study on urine samples (-20°C up to 3 years, freeze-and-thaw up to 10 cycles) as well as on aqueous solutions (5°C up to 4 months) indicated no relevant changes in HEVL concentration (≤4%) over the time tested. Analytical responses of both HEVL and IS correlated with urinary creatinine as an index of matrix composition, but this matrix effect was mostly eliminated using the HEVL/IS peak area ratio, attaining the IS-normalized relative matrix effect <3%. In conclusion, the method complied successfully with the bioanalytical method validation criteria, making it a reliable tool for HEVL determination in human biomonitoring.

Diquat and Paraquat Analysis in Rice using a Zwitterionic Hydrophilic Interaction Chromatography – tandem Mass Spectrometry

The analysis of polar herbicides by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is challenging due to their complicated interactions. Diquat and paraquat, the bipyridilium group of polar herbicides, are widely used worldwide. This study aimed to optimize analytical conditions of diquat and paraquat in rice matrix using a hydrophilic interaction liquid chromatography column (Obelisc R; 2.1 x 150 mm, 5 µm). The mixtures of acetonitrile and ammonium formate buffer in water were used as mobile phase. All buffer solutions were acidified to a pH of 2.5 using concentrated formic acid. The results showed that 10 mM buffer concentration of ammonium formate was optimal compared to others, including 5, 20, and 50 mM. A mixture of methanol and water (6:4, v/v) containing 1% formic acid was used as an extractable solvent for sample preparation. Method quantitation limit (MQL) of diquat and paraquat in rice samples was 10 µg kg-1. Recoveries at different concentrations (i.e., 20, 50, and 100 µg kg-1) were higher than 70% for diquat, and 80% for paraquat with RSD &lt; 20%, respectively. Diquat and paraquat in rice samples purchased from the local market were lower than MQL, with good recoveries for standard spiked samples.

A QuEChERS-based UPLC-MS/MS method for rapid determination of organophosphate flame retardants and their metabolites in human urine

Organophosphate flame retardants (OPFRs) have been widely used in consumer products to prevent fire spread. However, once released into the atmospheric environment, they may accumulate in humans and undergo metabolic transformation and excretion by urine. In order to clarify the human exposure to OPFRs, a quick, easy, cheap, effective, rugged, and safe method for the simultaneous determination of urinary OPFRs and their metabolites by ultra-performance liquid chromatography-tandem triple quadrupole mass spectrometry was developed. After the optimization by a single-factor or orthogonal experiment, the satisfactory recovery (87.8–119%), matrix effect (−8.88–9.29%), method quantitation limit (3.66–159 ng/L), and inter-day repeatability (1.24 − 10.6%) of most analytes were achieved in artificial urine samples. Based on a monitoring test by the developed method, we propose that urinary bis(1-chloro-2-propyl) phosphate and di-p-cresyl phosphate could be used to trace human exposure to tris(1-chloro-2-propyl) phosphate and tricresyl phosphate, respectively. Most importantly, this is the first study to reveal that 4-hydroxyphenyl diphenyl phosphate (4-OH-TPHP) was dominantly presented in its conjugated form rather than its free form in urine (p = 0.037). Overall, the obtained results contribute a relatively rapid method to help conduct large-scale urine monitoring for revealing the human exposure and risk of OPFRs.

Simultaneous screening of 21 potential adulterants in dietary supplements for the treatment of prostate diseases using ultra-performance liquid chromatography and liquid chromatography-electrospray ionization-tandem mass spectrometry.

Reports of the number of adulteration cases using illegal therapeutic substances in dietary supplements have increased. In recent years, various dietary supplements are being distributed that exaggerate the efficacy of treatment for prostate-related diseases. To develop the preemptive monitoring method, we selected 21 prostate-related therapeutic substances and optimized the simultaneous ultra-performance liquid chromatography and liquid chromatography-electrospray ionization-tandem mass spectrometry and pretreatment procedures for various types of matrices including solid, liquid, and soft capsule samples. The methods were validated by determining the specificity, linearity, limit of detection, limit of quantification, method detection limit, method quantitation limit, precision, accuracy, recovery, stability, and matrix effect. The simultaneous methods were validated according to the international guidelines. In addition, using the validated methods, 81 real samples, which were searched and purchased by focusing on promotional phrases, such as prostate and prostatic hyperplasia, were successfully screened. As a result, sildenafil and tadalafil were detected in one seized capsule sample (5.15 and 14.6mg/g, respectively). Synthetically, our approach could be useful for the determination of illegal therapeutic substances potentially adulterated in various types of dietary supplements.

Environmentally friendly analytical method to assess enantioselective behaviour of pharmaceuticals and pesticides in river waters

Reported herein is the first enantioselective method for simultaneous separation of chiral pharmaceuticals and pesticides using ultra-high-performance liquid chromatography-tandem mass spectrometry. Separation was achieved using a ChiralPak IG-U® column (amylose tris(3-chloro-5-methylphenylcarbamate) stationary phase) and ethanol as a ‘green’ mobile phase organic modifier. Minimum enantiomer resolutions ranged from 0.5 to 6.9 for 28 pharmaceuticals, herbicides, fungicides and insecticides. The total run time was 26 min and is considerably shorter than other multi-residue enantioselective methods for similar numbers of pesticides, and is the first to facilitate simultaneous pharmaceutical separation. Direct injection of river water samples enabled omission of acetonitrile and methanol from the sample treatment step (and the whole methodology). This approach was considerably faster than enantioselective methodologies that rely on solid phase extraction and avoids the need for large sample volumes for analysis. The suitability of this approach was demonstrated by the method's sensitivity with enantiomer method quantitation limits in the range 0.005–0.6 μg L-1. The new method was applied to river water microcosms to investigate enantiospecific transformation of racemic pharmaceuticals and pesticides. The pharmaceutical omeprazole, fungicide prothioconazole and insecticide profenofos were all subject to enantioselective transformation under biotic conditions, represented by a change in enantiomeric fraction of ≥0.1 units. Individual enantiomer microcosms revealed chiral inversion of R-omeprazole to S-omeprazole in the environment for the first time. In conclusion, this method offers comparatively fast enantioselective analysis for a high number of pharmaceuticals and pesticides in river water, and is achieved in an environmentally friendlier way than previously reported liquid chromatography methods.

Survey on set‐based design (SBD) quantitative methods

AbstractProduct development efforts now more than ever are in need of methodologies that can address the challenges of increased system complexities, shortening time to market, increased demands in mass customization, market instabilities, geographical barriers, improved innovation, and adaptability to emerging technologies. To address these challenges most companies will need to make key decisions early in the product development life‐cycle. In this early phase there are high levels of information uncertainty and information ambiguity. Under these circumstances many companies will converge too early to a point design (Point Based Design—PBD) which will lead to increased cost and schedule delays due to reworking the design later in the product development life cycle. To overcome these challenges many researchers have proposed the Set‐Based Design (SBD) methodology. However, there has been limited guidance on how to define, reason, and narrow sets while improving the level of abstraction of the design. To address such concerns, a literature review was conducted. The contributions of this research include: (1) aggregated literature from over 100 sources on quantitative methods (QM) that has not been considered SBD but does support set‐based thinking, (2) consolidated body of knowledge on QM to help industrial practitioners implement SBD, (3) ​defined gaps and opportunities for future research, and (4) defined strengths and limitations of QM and techniques to define, reason and narrow sets.