A robust method for simultaneous determination of eight B vitamins in human serum by liquid chromatography tandem mass spectrometry.

The level of vitamin B group in human serum is an important index of human health. Among B vitamins, cyanocobalamin in serum is unstable and its content is extremely low. Rapid and simultaneous detection of multiple B vitamins including cyanocobalamin is a challenge. Herein, we have developed a rapid and stable method that can realize the determination of thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin simultaneously in 6 min. The method was established based on protein precipitation with methanol and then chromatographic separation was achieved using Waters acquity ultra-high-performance liquid chromatography high strength silica T3 column, which was stable and sensitive especially for cyanocobalamin. Limit of quantification, precision, trueness, and matrix effect were validated according to the European Medicines Agency and United States Food and Drug guidelines and Clinical and Laboratory Standards Institute guidelines on bioanalytical method. The limit of quantification for thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin was 0.4, 0.4, 0.8, 2.0, 0.4, 0.1, 0.4, and 0.04 ng/mL separately, respectively. Intra- and interday precisions were 1.1%-12.4% and 2.0%-13.5%, respectively. The relative errors were between 0.3% and 13.3%, and the matrix effects were between 2.6% and 10.4%.

Content and stability of B complex vitamins in commercial cosmetic products.

BACKGROUND: Individual B vitamins have many favorable effects on the skin and are common cosmetic ingredients. However, their formulation is demanding due to stability issues, which consequently affect the products' quality. AIMS: We aimed to determine the quality (labeling accuracy, content determination, and content-related quality control) and stability under long-term and accelerated storage conditions of a representative sample of commercial cosmetics containing the most common B vitamins - nicotinamide, dexpanthenol, pyridoxine, and cyanocobalamin. METHODS: Cyanocobalamin was determined by a previously published stability-indicating HPLC- diode array detector (DAD) method for the simultaneous determination of all hydrophilic vitamins. This method was additionally simplified and adjusted for the time-effective analysis of nicotinamide, dexpanthenol, and pyridoxine. Both methods were properly validated. RESULTS: All labeled B vitamins were present in the 36 tested products, mostly in contents, reported effective on the skin. Thus, a straightforward correlation between vitamin contents and product prices were not observed. The content-related quality control of eight products, which quantitively specify their content, revealed significantly lower nicotinamide contents (47% and 57%) in two products and appropriate or higher nicotinamide (102%-112%) and dexpanthenol (100%-104%) contents than declared in the remaining products. The 6-month long-term and accelerated stability studies demonstrated the products' physical stability, but also revealed dexpanthenol, pyridoxine, and cyanocobalamin degradation, while nicotinamide was mostly stable in the tested products. CONCLUSIONS: The obtained results provide an inside into the quality of commercial vitamin B cosmetics and highlight the importance of stability testing in the formulation of quality, efficient, and safe cosmetics.

[Rapid determination of 22 functional components in cosmetics using ultra-high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry].

Plant components from extracts of Sophora flavescens, rhodiola, ginseng, Centella asiatica, and tea play important roles in skin whitening, moisturizing, anti-aging, sun protection, anti-inflammation, antiseptic, bacteriostatic, and other effects of cosmetics. At present, no relevant standard methods have been established to detect the addition amounts of plant extracts in cosmetics. In addition, plant extracts listed in product labels may be undetectable due to their addition in trace quantities and the lack of technical support. Therefore, a quantitative method for the simultaneous determination of 22 functional components in cosmetics was established by ultra-high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UHPLC-LTQ/Orbitrap MS). Target compounds were extracted with methanol from samples using ultrasonic extraction, and then separated on a C18 column (100 mm × 2.1 mm, 1.8 µm) with gradient elution of 0.1% (v/v) formic acid aqueous solution (A) and acetonitrile (B). The gradient elution program were as follows: 0-5 min, 5%B-8%B; 5-25 min, 8%B-60%B; 25-35 min, 60%B-80%B; 35-36 min, 80%B-5%B; 36-45 min, 5%B. The flow rate was 0.3 mL/min and the injection volume was 5 µL. Accurate masses of precursor ions were used to detect cosmetic functional components in positive ionization mode. The fragment ions obtained by higher energy collisional dissociation were used for confirmation of the functional components. Each compound showed good linearity. The limits of detection (LODs) were in the range of 0.003-2.01 mg/kg, and the limits of quantification (LOQs) were in the range of 0.02-4.36 mg/kg. Recoveries at three levels were 63.2%-125.1%, and relative standard deviations (RSDs) were 0.18%-10.9%. Fifty-four batches of samples labeled with four monomer functional components and nine plant extracts were tested. In the 17 batches of samples labeled with nicotinamide, 4 batches labeled with caffeine, and 6 batches labeled with Sophora flavescens root extract, the labeled functional components were detected. One out of 11 batches of samples labeled with D-panthenol was not detected. Three of the seven batches of samples labeled with ascorbyl glucoside were not detected. In the 21 batches of samples labeled with licorice extracts, the corresponding functional components were not detected in 9 batches. In the 21 batches of samples labeled with Centella asiatica extract, the corresponding functional components were not detected in 11 batches. In the 13 batches of samples labeled with tea extract, the corresponding functional components were not detected in 8 batches. In 11 of the 12 batches containing ginseng root extract, the corresponding functional components were not detected. In five of the six batches of astragalus membranaceus root extract samples, the corresponding functional components were not detected. In samples labeled with Polygonum cuspidatum root extract, Rehmannia glutinosa root extract, and Ophiopogon japonicus root extract, the corresponding functional components were detected. The method is simple, rapid, reliable, accurate, and suitable for the determination of the 22 functional components in cosmetics.

Investigation of the dissipation behaviour and exposure of spitotetramat, flonicamid, imidacloprid and pymetrozine in open field strawberries in Egypt.

The dissipation behaviour and the consumer risk assessment of spitotetramat, flonicamid, imidacloprid and pymetrozine in open field strawberries were studied. Insecticides were applied at the authorised levels and the more critical good agricultural practice regimes (GAP). The initial concentrations varied from 0.069 to 1.75 mg kg-1 depending on the compound, while the dissipation half-lives and terminal residues, 14 days from the last applications, were similar. After application according to the authorised pattern the half-lives were 2.8 days for flonicamid and 3.2 days for spitotetramat, imidacloprid and pymetrozine. The dietary risk assessment, performed using the hazard quotient and the EFSA PRIMo model showed no concern to consumer health with exposure values <2% of the acceptable daily intake (ADI) and <32% of the acute reference dose (ARfD) of each compound.

Determination of Vitamin B3 Vitamer (Nicotinamide) and Vitamin B6 Vitamers in Human Hair Using LC-MS/MS.

Water-soluble B vitamins participate in numerous crucial metabolic reactions and are critical for maintaining our health. Vitamin B deficiencies cause many different types of diseases, such as dementia, anaemia, cardiovascular disease, neural tube defects, Crohn's disease, celiac disease, and HIV. Vitamin B3 deficiency is linked to pellagra and cancer, while niacin (or nicotinic acid) lowers low-density lipoprotein (LDL) and triglycerides in the blood and increases high-density lipoprotein (HDL). A highly sensitive and robust liquid chromatography-tandem mass spectroscopy (LC/MS-MS) method was developed to detect and quantify a vitamin B3 vitamer (nicotinamide) and vitamin B6 vitamers (pyridoxial 5'-phosphate (PLP), pyridoxal hydrochloride (PL), pyridoxamine dihydrochloride (PM), pridoxamine-5'-phosphate (PMP), and pyridoxine hydrochloride (PN)) in human hair samples of the UAE population. Forty students' volunteers took part in the study and donated their hair samples. The analytes were extracted and then separated using a reversed-phase Poroshell EC-C18 column, eluted using two mobile phases, and quantified using LC/MS-MS system. The method was validated in human hair using parameters such as linearity, intra- and inter-day accuracy, and precision and recovery. The method was then used to detect vitamin B3 and B6 vitamers in the human hair samples. Of all the vitamin B3 and B6 vitamers tested, only nicotinamide was detected and quantified in human hair. Of the 40 samples analysed, 12 were in the range 100-200 pg/mg, 15 in the range 200-500 pg/mg, 9 in the range of 500-4000 pg/mg. The LC/MS-MS method is effective, sensitive, and robust for the detection of vitamin B3 and its vitamer nicotinamide in human hair samples. This developed hair test can be used in clinical examination to complement blood and urine tests for the long-term deficiency, detection, and quantification of nicotinamide.

Plain 1 H nuclear magnetic resonance analysis streamlines the quality control of antiviral favipiravir and congeneric World Health Organization essential medicines.

Favipiravir is an established antiviral that is currently being assessed as an investigational drug for the treatment of COVID-19. Favipiravir is strikingly similar to two molecules that the World Health Organization (WHO) lists as essential medicines, which also consist of a six-membered aromatic N-heterocycle bearing a carboxamide function: the anti-tuberculosis agent, pyrazinamide, and nicotinamide, also known as vitamin B3 . We demonstrate the utility of 1 H nuclear magnetic resonance (NMR) profiling, an emerging pharmacopoeial tool, for the highly specific identification, selective differentiation of congeners, and subsequent detection of drug falsification or adulteration of these medicines. The straightforward comparison of basic 1-D 1 H NMR spectra, obtained with benchtop or advanced NMR instruments alike, offers a rapid identity assay and works independently of physical reference materials. This approach accelerates and advances pharmaceutical quality control measures under situations of increased drug demand and altered economy, such as during a pandemic.

Determination of selected water-soluble vitamins (thiamine, riboflavin, nicotinamide and pyridoxine) from a food matrix using hydrophilic interaction liquid chromatography coupled with mass spectroscopy.

Water-soluble vitamins are essential dietary components with a multitude of important functions that require quantification from food sources to characterise the nutritional status of food. In this study, we have developed a hydrophilic interaction chromatography (HILIC) based method coupled to single-quadrupole mass spectrometry (MS) for the analysis of selected water-soluble vitamins. Due to their involvement in energy release from macronutrients, the quantification of thiamine (B1), riboflavin (B2), nicotinamide (B3) and pyridoxine (B6) offers significant value in food analysis. A commercially available vegetable soup was selected as the food matrix for this study and utilised to develop an efficient extraction procedure for the vitamins of interest. Vitamins were extracted using meta-phosphoric acid coupled with a reducing agent, DL-dithiothreitol (DTT) to produce the parent compound. The extracted vitamins were then analysed using an LC-MS system with electrospray - atmospheric pressure ionization (ES-API) source, operated in positive single ion monitoring (SIM) mode. The MS provided good linearity within the investigated range from 5 to 400 ng/mL with coefficient of determination (r2) ranging from 0.98 to 0.99. Retention times (0.65-9.04 min) were reproducible and no coelution between vitamins was observed. Limit of detection (LOD) varied from 2.4 to 9.0 ng/mL and limit of quantification (LOQ) was from 8 to 30 ng/mL, comparable to previously published studies. The extraction method provided good intra-day (%CV 1.56-6.56) and inter-day precision (%CV 8.07-10.97). Standard injections were used as part of quality control measures and provided excellent reproducibility (%CV 0.9-3.4). The overall runtime of this method was 19 min, including column reconditioning. Using this method, the quantity of thiamine (67 ±â€¯7 ng/g), riboflavin (423 ±â€¯39 ng/g), nicotinamide (856 ±â€¯77 ng/g) and pyridoxine (133 ±â€¯11 ng/g) was determined from a complex food matrix. In conclusion, we have developed a rapid and reliable, HILIC-single quad MS method utilising SIM for the low-level quantification of four B vitamins in a vegetable soup matrix in under 20 min. This method has shown excellent linearity, intra- and inter-day reproducibility and is directly applicable to other plant-based food matrices.

Equilibrative Nucleoside Transporters Mediate the Import of Nicotinamide Riboside and Nicotinic Acid Riboside into Human Cells.

Nicotinamide riboside (NR), a new form of vitamin B3, is an effective precursor of nicotinamide adenine dinucleotide (NAD+) in human and animal cells. The introduction of NR into the body effectively increases the level of intracellular NAD+ and thereby restores physiological functions that are weakened or lost in experimental models of aging and various pathologies. Despite the active use of NR in applied biomedicine, the mechanism of its transport into mammalian cells is currently not understood. In this study, we used overexpression of proteins in HEK293 cells, and metabolite detection by NMR, to show that extracellular NR can be imported into cells by members of the equilibrative nucleoside transporter (ENT) family ENT1, ENT2, and ENT4. After being imported into cells, NR is readily metabolized resulting in Nam generation. Moreover, the same ENT-dependent mechanism can be used to import the deamidated form of NR, nicotinic acid riboside (NAR). However, NAR uptake into HEK293 cells required the stimulation of its active utilization in the cytosol such as phosphorylation by NR kinase. On the other hand, we did not detect any NR uptake mediated by the concentrative nucleoside transporters (CNT) CNT1, CNT2, or CNT3, while overexpression of CNT3, but not CNT1 or CNT2, moderately stimulated NAR utilization by HEK293 cells.

Determination of residue of diflufenican in wheat and soil by ultra-high-pressure liquid chromatography and mass spectrometry conditions.

BACKGROUND: In order to clarify whether the application of diflufenican in the wheat field will produce residues in wheat plants and soil. In this experiment, ultra-high-pressure liquid chromatography was used to determine the residues of diflufenican in wheat plants, grains, and soil, which provided a new theoretical basis and technical guidance for the safe production of wheat. RESULTS: The results showed that the average diflufenican recovery per added level in wheat and soil were in the range of 85.7% to 91.3%, relative standard deviations were all in a range of 2.43% to 6.00%, and the minimum detectable amount of diflufenican was 1.0 × 10-10 g kg-1 . With the increase of wheat growing days and soil layers, the residues of diflufenican in wheat plants and soil became lower. The order of residual amount of diflufenican in the growth period were heading period, flowering period, filling period and maturing period. The order of residual amount of diflufenican in different soil layers was 0-20, 20-40, 40-60, 60-80 and 80-100 cm respectively from the top to the bottom. In addition, with the increase of the dosage of diflufenican, the residual amount of diflufenican becomes higher. Thus, the residual amount of diflufenican after 2.0 times applied amount was higher than the 1.0 time applied amount. CONCLUSION: The residual amounts of diflufenican in wheat and soil were very small, far below the value of the maximum residue limit (MRL) on wheat provided by China. Under the applied amount administered in this experiment, a single spray of diflufenican in wheat trifoliate is safe for wheat, humans and livestock. © 2020 Society of Chemical Industry.

Dissipation, Processing, Leaching, and Safety Evaluation of Flonicamid and Its Metabolites in Tea.

BACKGROUND: Tea is a popular traditional non-alcoholic beverage worldwide. Flonicamid is a selective systemic pyridine carboxamide insecticide that is widely used for controlling tea leafhopper in tea. OBJECTIVE: The leaching rates, dissipation dynamics, and residue levels of flonicamid and its metabolites in tea leaves during processing and transferring were investigated to validate the safe risk in tea and transfer behavior using high performance liquid chromatography-tandem mass spectrometry with a convenient pretreatment method. METHOD: The extracting method and immersion rate experiments were optimized by single factor analysis and orthogonal tests. The acetonitrile extracting solvent with 0.5% formic acid was used and optimal leaching conditions were obtained with a regime of 15 min immersion time, 100°C temperature, three immersions and a tea-to-water ratio of 1:50. RESULTS: Average recoveries in processed green tea and infusions were 80.85-98.75% with relative standard deviations <5.87%. LODs and LOQs of flonicamid, 4-trifluoromethylnicotinic acid (TFNA), N-(4-trifluoromethylnicotinoyl) glycine (TFNG), and 4-trifluoromethylnicotinamide (TFNA-AM) were 0.0013-0.350 and 0.004-1 µg/g, respectively. The processing factor of flonicamid was 0.36-5.52 during green tea manufacture. The leaching rates were 22.9-97.4% from processed tea to infusion. CONCLUSIONS: The risk of long-term and short-term dietary intake of flonicamid was safe in tea infusions with the risk quotient (RQ) values <1 for the Chinese consumer. This work may provide guidance for safe and reasonable consumption of flonicamid in tea in China. HIGHLIGHTS: The suitable leaching factors of flonicamid and its metabolites in tea infusions were optimized by orthogonal experimentation for the first time.

Organic Reaction Monitoring of a Glycine Derivative Using Signal Amplification by Reversible Exchange-Hyperpolarized Benchtop Nuclear Magnetic Resonance Spectroscopy.

Currently, signal amplification by reversible exchange (SABRE) using para-hydrogen is an attractive method of hyperpolarization for overcoming the sensitivity problems of nuclear magnetic resonance (NMR) spectroscopy. Additionally, SABRE, using the spin order of para-hydrogen, can be applied in reaction monitoring processes for organic chemistry reactions where a small amount of reactant exists. The organic reaction monitoring system created by integrating SABRE and benchtop NMR is the ideal combination for monitoring a reaction and identifying the small amounts of materials in the middle of the reaction. We used a laboratory-built setup, prepared materials by synthesis, and showed that the products obtained by esterification of glycine were also active in SABRE. The products, which were synthesized esterified glycine with nicotinoyl chloride hydrochloride, were observed with a reaction monitoring system. The maximum SABRE enhancement among them (approximately 147-fold) validated the use of this method. This study is the first example of the monitoring of this organic reaction by SABRE and benchtop NMR. It will open new possibilities for applying this system to many other organic reactions and also provide more fruitful future applications such as drug discovery and mechanism study.

High-Performance Multiporous Imprinted Microspheres Based on N-Doped Carbon Dots Exfoliated from Covalent Organic Framework for Flonicamid Optosensing.

High-performance, multiporous imprinted microspheres were prepared from nitrogen-doped carbon dots (N-CDs) using a one-pot reverse microemulsion surface-imprinting method. Here, the N-CDs were exfoliated from a common layer covalent organic framework in a top-down preparation, and an ionic liquid was added to improve the sensitivity and the fluorescence stability. The multiporous imprinted microspheres were successfully applied to flonicamid optosensing in fruits and vegetables with simultaneous analysis of 96 samples by multifunctional enzyme labeling. The fluorescence sensing procedure was performed on recyclable multiporous imprinted microspheres coupling with the interface of N-CDs by taking advantage of the fluorescence-resonance charge-transfer strategy between the N-doped carbon dots and flonicamid molecules, quenching the fluorescence intensity. The multiporous imprinted microspheres exhibited purple fluorescence, which decreased sharply in intensity as the concentration of flonicamid increased. The fluorescence quenching correlation with the concentration of flonicamid showed good linearity in the range of 0.02-0.2 µg g-1 with a detection limit of 0.0059 µg g-1. This research not only enriches the foundational study of flonicamid residues but also greatly expands the potential applications of multiporous imprinted microspheres for analysis of pesticide residues in agricultural, food, and environmental monitoring.

GC-FID-based quantification of the sum of the three forms of vitamin B3 from animal liver.

Vitamin B3 (nicotinic acid, nicotinamide) is an essential water-soluble vitamin and cellular energy metabolism depends on the vitamin B3-derived cofactors. Inaccessible covalently-linked nicotinic acid in food such as maize can cause vitamin B3 deficiency in animals since maize is also deficient in tryptophan, the precursor of nicotinic acid. A sensitive and reproducible GC-FID-based method for the quantification of the sum of the three forms of vitamin B3 from animal liver was developed. Free nicotinic acid, free nicotinamide and nicotinamide moiety of NAD+/NADP+ (and their riboside precursors) were simultaneously derivatized as methyl nicotinate. Reaction time and temperature and the extraction procedure for methyl nicotinate were optimized. Starting from wild boar liver, removal of proteins, solvent exchange, derivatization, and chloroform extraction resulted in sufficient enrichment and baseline separation of methyl nicotinate. The within-laboratory reproducibility of the full procedure was determined with RSD <10%. On-column limit of detection and lower limit of quantification for methyl nicotinate were both sub-picomole. The accuracy of the method was determined from the recoveries of the pre-extraction spiked-in vitamin B3 standards. The overall recovery for the full procedure was 16% but very consistent (RSD = 7%), enabling determination of apparent vitamin B3 concentrations for relative quantitative comparison.

Metabolomic characterization of semen from asthenozoospermic patients using ultra-high-performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry.

Asthenozoospermia (AS) is a common factor of male infertility, and its pathogenesis remains unclear. The purpose of this study was to investigate the differential seminal plasma metabolic pattern in asthenozoospermic men and to identify potential biomarkers in relation to spermatogenic dysfunction using sensitive ultra-high-performance liquid chromatography-tandem quadruple time-of-flight MS (UHPLC-Q-TOF/MS). The samples of seminal plasma from patients with AS (n = 20) and healthy controls (n = 20) were checked and differentiated by UHPLC-Q-TOF/MS. Compared with the control group, the AS group showed a total of nine significantly different metabolites, including increases in creatinine, uric acid, N6 -methyladenosine (m6 A), uridine, and taurine and decreases in carnitine, nicotinamide, N-acetylputrescine and l-palmitoylcarnitine. By analyzing the correlation among these metabolites and clinical computer-assisted semen analysis reports, we found that m6 A is significantly correlated with not only the four decreased metabolites but also with sperm count, motility, and curvilinear velocity. Furthermore, nicotinamide was shown to correlate with other identified metabolites, indicating its important role in the metabolic pathway of AS. Current results implied that sensitive untargeted seminal plasma metabolomics could identify distinct metabolic patterns of AS and would help clinicians by offering novel cues for discovering the pathogenesis of male infertility.

Preparation of dummy molecularly imprinted polymers based on dextran-modified magnetic nanoparticles Fe3O4 for the selective detection of acrylamide in potato chips.

Novel dummy magnetic molecularly imprinted polymers (dex-MMIPs) were prepared for highly selective recognition and fast enrichment of acrylamide (AA) in potato chips. Propionamide (PA) was used as dummy template molecule and the Fe3O4 nanoparticles modified with carboxymethyl dextran were developed as supports. Methacrylic acid (MAA) and ethyleneglycoldimethacrylate (EGDMA) were chosen as the functional monomer and cross-linker, respectively. Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) were used to characterize the synthesized dex-MMIPs. The adsorption of dex-MMIPs reached equilibrium within 20 min, and the maximum adsorption quantity (Qm) was 19.28 mg/g with the dissociation constant (Kd) of 35.7 mg/L. Moreover excellent recognition toward acrylamide was achieved compared to analogs, such as N, N'-methylenebisacrylamide (MBA) and nicotinamide (VPP). The satisfactory recoveries of 83.9-96.8% were achieved for selective separation and enrichment of AA in spiked potato chips by dex-MMIPs.

Influence of low O2 and high CO2 environment on changes in metabolite concentrations in harvested vegetable soybeans.

Influence of atmosphere and storage period on the physicochemical and biological properties of harvested vegetable soybeans stored for 10 d at 25 °C was investigated. Storing vegetable soybeans under modified atmosphere (low O2 and high CO2), was more effective in maintaining its green color and mass than storing them under normoxia. Principal component 1 (PC1; contribution rate: 25%) was related to the atmospheres, whereas PC2 (contribution rate: 19%) was related to storage period. Cluster analysis showed that some types of sugars decreased, whereas some types of organic and amino acids increased with deterioration. Alanine, an indicator of low O2 stress, was maintained for 3 d under modified atmospheres, whereas alanine significantly decreased under normoxia. The concentrations of inositol and niacinamide (functional ingredients) under the modified atmospheres were significantly higher than those under normoxia. Thus, storage under modified atmospheres was effective in maintaining freshness and increasing the nutritional content of vegetable soybeans.

Sorbent-excluding sample preparation method for GC-MS pesticide analysis in apple peel.

Apple peel is frequently exposed to pesticides, especially in the last stages of the pesticide treatment practice. For a certain period, peel retains most of the applied pesticides, which precisely indicates the presence of pesticide residues. This study was conducted to establish and evaluate the method for the residue analysis of pyrimethanil, cyprodinil, trifloxystrobin, bifenthrin and boscalid by GC-MS in peel of Granny Smith, Golden Delicious and Idared varieties. The method consisted of few steps, without the routine usage of sorbents, and resulted in efficient removal of waxes, targeted as main interferences in GC-MS analysis. The matrix effect, boscalid selectivity issue, trend of lower trueness for bifenthrin in all matrices and for all analytes in Granny Smith matrix were in some way associated with the waxes. Finally, the method was applied to the analysis of three varieties of apple orchard samples, after 9 and 5 months of treatment with commercial formulations that contain pyrimethanil, cyprodinil and boscalid as active ingredients. Since the developed method consisted of few steps and used nontoxic and economic reagents, it could be implemented as a fast, economic and reliable screening method.

Dissipation pattern and residual levels of boscalid in cucumber and soil using liquid chromatography-tandem mass spectrometry.

To stipulate the rationale of spraying doses and to determine the safe interval period of boscalid suspension concentrate (SC), the degradation dynamics and residual levels were investigated in cucumber and soil using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Field trials were conducted according to Chinese Guideline on pesticide residue trials. Following application, the degradation kinetics was best ascribed to first-order kinetic models with half-life of 2.67-9.90 d in cucumber. Spraying boscalid SC at 1.5-fold the recommended dosage yield terminal residues, which are clearly lower than the maximum residue limit (MRL) established by China (MRL =5 mg.kg-1) in cucumber. At variance, the dissipation dynamics in soil did not fit to first-order kinetics and the half-life was more than 17 days, the finding which denotes that the degradation behavior of boscalid in soil proceeds slowly. It has therefore been shown that boscalid is safe for use on cucumbers under the recommended dosage.

Spectroelectrochemical elucidation of B vitamins present in multivitamin complexes by EC-SERS.

Raman spectroelectrochemistry based on electrochemical surface-enhanced Raman scattering (EC-SERS) effect is an interesting alternative to overcome the lack of sensitivity of normal Raman spectroscopy. Electrochemical activation of metallic screen-printed electrodes (SPEs) leads to the reproducible generation of nanostructures with excellent SERS properties. In that way, gold SPEs circumvent the traditional reproducibility limitation and produce the enhancement of the Raman intensity to favor the detection of low concentrations. Furthermore, fingerprint features of Raman spectroscopy make possible the dynamic spectroelectrochemical analysis of B vitamins. The accuracy assignments of Raman bands associated with B1, B2, B3, B6 and B12 vitamins present in multivitamin complexes provides valuable information, allowing us not only the detection of B vitamin present in mixtures, but also to understand the interaction between vitamins and metallic SERS surfaces.

Determination of pesticide residual levels in strawberry (Fragaria) by near-infrared spectroscopy.

BACKGROUND: In this study, an infrared-based prediction method was developed for easy, fast and non-destructive detection of pesticide residue levels measured by reference analysis in strawberry (Fragaria × ananassa Duch, cv. Albion) samples using near-infrared spectroscopy and demonstrating its potential alternative or complementary use instead of traditional pesticide determination methods. Strawberries of Albion variety, which were supplied directly from greenhouses, were used as the study material. A total of 60 batch sample groups, each consisting of eight strawberries, was formed, and each group was treated with a commercial pesticide at different concentrations (26.7% boscalid + 6.7% pyraclostrobin) and varying residual levels were obtained in strawberry batches. The strawberry samples with pesticide residuals were used both to collect near-infrared spectra and to determine reference pesticide levels, applying QuEChERS (quick, easy, cheap, rugged, safe) extraction, followed by liquid chromatographic-mass spectrometric analysis. RESULTS AND CONCLUSION: Partial least squares regression (PLSR) models were developed for boscalid and pyraclostrobin active substances. During model development, the samples were randomly divided into two groups as calibration (n = 48) and validation (n = 12) sets. A calibration model was developed for each active substance, and then the models were validated using cross-validation and external sets. Performance evaluation of the PLSR models was evaluated based on the residual predictive deviation (RPD) of each model. An RPD of 2.28 was obtained for boscalid, while it was 2.31 for pyraclostrobin. These results indicate that the developed models have reasonable predictive power. © 2019 Society of Chemical Industry.