Development of LC-MS/MS method for quantification of Lurasidone using volumetric absorptive microsampling (VAMS); a comparative study between dried blood and plasma samples.

The ecological impact of biological, chemical, and analytical research practices, including toxic reagents and biohazardous waste, has led to the development of alternative sampling and extraction techniques for bioanalysis. Microsampling (sample volume < 50 µL) aligns with the 3Rs principle, allowing multiple sampling points from the same animal at different time points and improving animal welfare. A bioanalytical method was developed to investigate factors related to bioanalytical challenges and the implementation of microsampling techniques. An LC-MS/MS method for Volumetric Absorptive Microsampling (VAMS), 20 µL, was developed for quantifying Lurasidone using a liquid-liquid extraction technique. The method uses a C18, Phenomenex column for chromatographic separation and a mobile phase composition of Methanol, Acetonitrile, and Water with 0.1 % HFBA. The method was validated over a concentration range of 5.0 to 1200.0 ng/mL and achieved acceptable precision and accuracy. The recovery for analyte from VAMS was approximately 40% at four different concentrations and is consistent (%CV < 15), with no significant differences among HCT levels. The matrix factor ranged between 85.00 and 115.00 %, showing no substantial issues with reduced or enhanced signal. The stability data showed no significant degradation of LUR in VAMS samples when stored at room temperature for 15 days. The newly established method for Lurasidone confirmed the use of VAMS sampling method and its analysis on LC-MS/MS. Further, the data obtained from microsampling techniques was compared with conventional (plasma) technique, as proof-of-concept, and it confirms the agreement between the two methods. The study supports the advantages of microsampling in protecting the environment and animals while maintaining scientific judgement.

Linearity assessment: deviation from linearity and residual of linear regression approaches.

In this computer simulation study, we examine four different statistical approaches of linearity assessment, including two variants of deviation from linearity (individual (IDL) and averaged (AD)), along with detection capabilities of residuals of linear regression (individual and averaged). From the results of the simulation, the following broad suggestions are provided to laboratory practitioners when performing linearity assessment. A high imprecision can challenge linearity investigations by producing a high false positive rate or low power of detection. Therefore, the imprecision of the measurement procedure should be considered when interpreting linearity assessment results. In the presence of high imprecision, the results of linearity assessment should be interpreted with caution. Different linearity assessment approaches examined in this study performed well under different analytical scenarios. For optimal outcomes, a considered and tailored study design should be implemented. With the exception of specific scenarios, both ADL and IDL methods were suboptimal for the assessment of linearity compared. When imprecision is low (3 %), averaged residual of linear regression with triplicate measurements and a non-linearity acceptance limit of 5 % produces <5 % false positive rates and a high power for detection of non-linearity of >70 % across different types and degrees of non-linearity. Detection of departures from linearity are difficult to identify in practice and enhanced methods of detection need development.

A new method for quantification of tomatine-enriched extracts.

BACKGROUND: Green tomato extracts, an agro-food industry waste, are rich in the glycoalkaloid tomatine, which presents activity against several diseases. High-performance liquid chromatography (HPLC) with ultraviolet (UV) detection is one of the most used techniques for quantification of bioactive compounds. The aim of this study was to optimize and validate a selective HPLC method with diode array detector (DAD) for the quantitative analysis of tomatine extracted from green tomatoes by subcritical water. RESULTS: Chromatographic runs were performed on a InertSustain Phenyl (250 mm × 4.6 mm, 5 µm) analytical column, at a wavelength of 205 nm. A concentration range of 50-580 µg mL-1 was used. The validation process was performed considering the linearity, precision, trueness, limit of detection (LOD) and limit of quantitation (LOQ) of the method. The selected mobile phase composed of acetonitrile and a solution of 20 mmol L-1 potassium dihydrogen phosphate (KH2PO4) pH 3, resulted in suitable retention times and a standard calibration curve with adequate linearity (R2 = 0.9999). The method trueness was evaluated by the recovery assay, obtaining a mean recovery of 105% and the precisions were 1.4% and 0.9% (percentage relative standard deviation, RSD%) for the tomatine standard and extract samples, respectively. The inter-day variability was 2.7-9.0% (RSD%) for the standards and 6.9% (RSD%) for extract. The LOD and the LOQ of the method were determined at 8.0 and 24.1 µg mL-1, respectively. CONCLUSION: The herein described method was successfully used for the quantification of tomatine in a tomato-derived extract. Furthermore, the method constitutes a simple and rapid analytical approach able to be used as a routine protocol. © 2024 Society of Chemical Industry.

LC-MS/MS-based chemical profiling of water extracts of Moringa oleifera leaves and pharmacokinetics of their major constituents in rat plasma.

Moringa oleifera leaves (MOL) are native to India and have high biological activities. To better understand the basic pharmacodynamic materials, the chemical components in MOL and their pharmacokinetic properties were studied and quantitated using UPLC-Q-Exactive Orbitrap-MS. Forty-two compounds were identified, including phenolic acids and their derivatives, flavonoids, isothiocyanates, nucleosides, alkaloids, and other compounds. Two phenolic acids and six flavonoids were studied for their pharmacokinetic properties using UHPLC-MS/MS. Precision, accuracy, stability, matrix effects, and extraction recovery were verified. All substances that were measured reached their maximum within 0.5 h. Vicenin-2 had a high peak concentration and bioavailability. Kaempferol-3-O-rutinoside had a longer biological half-life than other components. The results from this study provide the data basis for subsequent comprehensive qualitative evaluation and potential MOL use in clinical applications.

Development and validation of a HPLC method for the determination of chemical and radiochemical purity of O-(2-[18F]fluoroethyl-l-tyrosine ([18F]FET)), a PET radiotracer for the imaging of brain tumor.

A novel HPLC method was developed and validated to determine radiochemical identity, radiochemical purity and chemical purity for the analysis of O-(2-[18F]fluoroethyl-l-tyrosine ([18F]FET). In this method, an analytical Phenomenex Gemini C18 column was used with an isocratic eluent of 7 % ethanol and 93 % 50 mM potassium phosphate buffer (pH = 6.9). The flow rate was 1.0 mL/min and the injection volume was 10 µL. A photo-diode array detector set at 220 nm was used for UV mass detection and a single channel, high sensitivity radiation detector was used. The method validation assays including specificity, linearity, precision, accuracy, and robustness were evaluated. Results show that the method was suitable for qualitative and quantitative determination of radiochemical and chemical purity of [18F]FET. This system has been routinely used for the analysis of more than 120 batches of [18F]FET with radiochemical yield 23.7 ± 6 % (no decay corrected) and molar activity 593 ± 284 GBq/µmole in our facility to support human use.

Dissipation and dietary risk assessment of fluoxapiprolin (and its metabolites) residues in cucumber and tomato samples under field conditions.

The present study was undertaken to understand the dissipation behaviour/kinetics of fluoxapiprolin and its metabolites in cucumber and tomato under field conditions. A QuEChERS based extraction method followed by liquid chromatography coupled to mass spectrometry (LC-MS/MS) analysis showed that all method validation parameters were within the acceptable range as per international standards with a limit of quantitation (LOQ) of 0.01 mg kg-1 for all analytes. As significant matrix effects were observed with a few metabolites, matrix matched standards were used for the whole study. Residues of fluoxapiprolin in cucumber at standard dose were steady from 0 to 3 day after application and were below LOQ on the 5th day after application. In cucumber fruit at double dose and in tomato at both the doses the residues followed second-order kinetics and were respectively ≤ LOQ from days 7 and 14 onwards. Pre-harvest intervals (PHI) of 5 days and 14 days are proposed for cucumber and tomato fruits respectively. All the metabolites were ≤ LOQ from day 0 in all the matrices. The consumer risk, assessed as Hazard Quotient (HQ), showed that HQ was ≤1 in all the cases. The results of the present study and earlier studies on other similar fungicides suggest that the use of fluoxapiprolin in cucumber and tomato fruits may not pose health or environmental hazards provided that good agricultural practices are followed and the proposed waiting period is observed. The data from the present study can be used by regulatory bodies in establishing maximum residue limits.

Endocannabinoid analysis in GlucoEXACT plasma: Method validation and sample handling recommendations.

Endocannabinoids (ECs), such as anandamide and 2-arachidonyl glycerol (2-AG), contribute to the pathology of inflammatory, malignant, cardiovascular, metabolic and mental diseases. The reliability of quantitative analyses in biological fluids of ECs and endocannabinoid-like (EC-like) substances depends on pre-analytical conditions such as temperature and "time-to-centrifugation". Standardization of these parameters is critical for valid quantification and implementation in clinical research. In this study, we compared concentrations obtained with GlucoEXACT blood collection tubes versus K3EDTA tubes and employed the optimized procedure to assess ECs profiles in patients with inflammatory skin disease and healthy controls. A UHPLC-MS/MS method was validated for human plasma from GlucoEXACT blood collection tubes according to EMA and FDA guidelines, and pre-analytical conditions were systematically modified to assess analyte stability and optimize the procedures. The results showed significantly lower concentrations of ECs and EC-like substance concentrations with GlucoEXACT tubes compared with K3EDTA tubes, and GlucoEXACT extended the time window of stable concentrations. The strongest method-disagreement occurred for 1/2-AG suggesting that GlucoEXACT delayed ex vivo isomer rearrangement. Hence, GlucoExact tubes were superior in terms of stability and reliability. However, although absolute concentrations obtained with GlucoExact and K3EDTA differed, linear regression studies showed high agreement (except for 1/2-AG), and both methods showed similar EC profiles and similar disease-dependent pro-inflammatory patterns in dermatology patients. Hence, despite the obstacles in EC analyses, implementation of optimized pre-analytical blood collection and sample processing procedures provide reliable insight into peripheral ECs.

Use of logit transformation within statistical analyses of experimental results obtained as proportions: example of method validation experiments and EQA in flow cytometry.

In laboratory medicine, measurement results are often expressed as proportions of concentrations or counts. These proportions have distinct mathematical properties that can lead to unexpected results when conventional parametric statistical methods are naively applied without due consideration in the analysis of method validation experiments, quality assessments, or clinical studies. In particular, data points near 0% or 100% can lead to misleading analytical conclusions. To avoid these problems, the logit transformation-defined as the natural logarithm of the proportion/(1-proportion)-is used. This transformation produces symmetric distributions centered at zero that extend infinitely in both directions without upper or lower bounds. As a result, parametric statistical methods can be used without introducing bias. Furthermore, homogeneity of variances (HoV) is given. The benefits of this technique are illustrated by two applications: (i) flow cytometry measurement results expressed as proportions and (ii) probabilities derived from multivariable models. In the first case, naive analyses within external quality assessment (EQA) evaluations that lead to inconsistent results are effectively corrected. Second, the transformation eliminates bias and variance heterogeneity, allowing for more effective precision estimation. In summary, the logit transformation ensures unbiased results in statistical analyses. Given the resulting homogeneity of variances, common parametric statistical methods can be implemented, potentially increasing the efficiency of the analysis.

Development and validation of QuEChERS-based LC-MS/MS method for simultaneous quantification of eleven N-nitrosamines in processed fish meat, processed meat, and salted fish products.

N-Nitrosamines (NAs) pose a threat to food safety due to their carcinogenic and mutagenic properties. In this study, we developed and validated a QuEChERS-based LC-MS/MS method for the simultaneous analysis of 11 NAs in 74 processed fish meat, processed meat, and salted fish products. Sample preparation was optimized by screening two versions of QuEChERS buffer, four extraction methods, and eight purification methods. The optimal analytical approach was validated for three product categories in terms of linearity, matrix effects, accuracy, and precision. Satisfactory precision and accuracy were demonstrated, with relative recoveries of 70-120% for the 11 NAs. The limits of detection for fish meat, processed meat, and salted fish products were 0.12-7.50, 0.12-4.14, and 0.10-7.81 ng·g-1, respectively. Among the 11 NAs, nine were detected in all 74 samples. This methodology could be applied to monitor NA levels to ensure the safety and quality of food products.

Residue and dissipation kinetics of novel nematicide fluopyram in rice assessed by QuEChERS-liquid chromatography-tandem mass spectrometry.

Supervised field trial was conducted to study the dissipation pattern of fluopyram in rice plant after application of fluopyram 400 g/L SC(Velum Prime) as soil drenching at the time of sowing in nursery bed at X (500 g a.i. ha-1) and 1.25X (625.2 g a.i. ha-1) doses. Samples of rice plant were collected on 0, 1, 3, 7, 10, 15, and 20 days after transplanting. QuEChERS-based extraction method was validated and adopted to determine the residues of fluopyram in rice seedlings, whole rice grains (with husk), polished rice grain, husk, straw, and soil using LC-MS/MS (liquid chromatography-tandem mass spectrometry).The initial deposit of fluopyram in rice plant recorded were 0.27 and 0.41 mg kg-1in X and 1.25X doses, respectively. Fluopyram residues dissipated following first-order kinetics with half-life of 2.53 and 2.57 days at X and 1.25X doses, respectively. Residues were detected in seedlings up to 15 days after transplanting and were at below LOQ in whole rice grains (with husk), polished rice grain, husk, straw, and soil collected at harvest. Monitoring study revealed that application of novel nematicide fluopyram for the management of nematodes in rice does not pose any risks to consumers.

An alternative silicone-based passive sampling device to derive organotin concentrations in the aqueous phase.

Organotin compounds (OTs) are well studied in various environmental compartments, with a critical focus on the water column as their primary entry point into aquatic ecosystems. In this context, a method for the analysis of organotin (OTs) in water using silicone rubber-based passive sampling was optimized, validated, and field-tested. Validation covered crucial parameters, including the limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, linearity, and matrix effect. The method was shown to be robust (R2 ≥ 0.99), with recoveries between 70.2 and 114.6%, and precise (CV < 12.8%) (N = 3). LODCw and LOQCw were ≤15 and ≤ 48 pg Sn L-1, respectively, for TBT and TPhT. The matrix effect showed to be low (>-20% ME < 20%) for all OTs but TPhT (69.4%). The silicone rubber-water partition coefficients (Log Ksr,w) were estimated at 3.37 for MBT, 3.77 for DBT, 4.17 for TBT, 3.49 for MPhT, 3.83 for DPhT, and 4.22 for TPhT. During the field study carried out between October 2021 and February 2022 at the entrance of the Port of Santos navigation channel (Southeastern Brazil), sampling rates ranged between 4.1 and 4.6 L d-1, and the equilibrium was achieved for MBT, DBT, MPhT, and DPhT after ∼45 days of deployment. The freely dissolved concentrations varied between 134 and 165 pg Sn L-1 for TBT, 388 and 610 pg Sn L-1 for DBT, and 1114 and 1509 pg Sn L-1 for MBT, while MPhT, DPhT, and TPhT were below the limit of detection. Results pointed out that J-FLEX® rubber-based passive sampling is a suitable and reliable alternative method for the continuous monitoring of OTs in the water column.

Validation of an Analytical Method of 3',4',5-Trihydroxy-3-Methoxy-6,7-Methylenedioxyflavone 4'-Glucuronide for Standardization of Spinacia oleracea.

Spinach (Spinacia oleracea) is one of the most famous vegetables worldwide, rich in essential metabolites for various health benefits. It is a valuable plant source that has the potential to be a nutraceutical. This study aimed to evaluate the single characteristic marker compound to establish the validation of HPLC-DAD methods applied to the development of a nutraceutical using spinach samples. Six metabolites (1-6) were identified from the spinach samples such as freeze-dried spinach (FDS) and spinach extract concentrate (SEC) by LC-Q-TOF/MS analysis. Among the six metabolites, 3',4',5-trihydroxy-3-methoxy-6,7-methylenedioxyflavone 4'-glucuronide (TMG) was selected as a marker compound due to its highest abundance and high selectivity. The specificity, accuracy, linearity, precision, repeatability, limit of detection (LOD), and limit of quantification (LOQ) of TMG in the spinach samples (FDS and SEC) were validated according to AOAC international guideline. The specificity was confirmed by monitoring the well separation of the marker compound from other compounds of spinach samples in the base peak intensity (BPI) and ultraviolet (UV) chromatogram. The calibration curve of TMG (15.625~500 µg/mL) had reasonable linearity (R2 = 0.999) considered with LOD and LOQ values, respectively. Recovery rate of TMG was 93-101% for FDS and 90-95% for SEC. The precision was less than 3 and 6% in the intraday and interday. As a result, the HPLC-DAD validation method of TMG in the spinach samples (FDS and SEC) was first established with AOAC and KFDA regulations for approving functional ingredients in functional foods.

Simultaneous Estimation of Quercetine and Betanine by RP-HPLC from Herbal Formulations Used in Nutritional Deficiencies.

BACKGROUND: Medicinal plants have curative properties due to the presence of various complex chemical substances of different compositions, which are found as secondary plant metabolites in one or more parts of the plants. Moringa oleifera from Moringaceae and Beta vulgaris root are, native to India, grows in the tropical and subtropical regions of the world. It is commonly known as 'drumstick tree' or 'horseradish tree' or 'miracle tree'. Incorporation of more herbal powder leads to much complexity. Above plants were chosen for their utmost nutritional values. RESULTS: Herbal tablet and granules were prepared and evaluated further for various Physico-chemical parameters as a nutritional supplement. Promising results indicate that prepared formulations have potential as supplements. CONCLUSIONS: Present communication mainly focused on estimation of marker components by Reverse Phase-High Performance Liquid Chromatography. It showed the presence of enough number of secondary metabolites and minerals which can be easily consumed by all age groups.

Analytical method development and validation for simultaneous estimation of Bempedoic acid and Ezetimibe in pure and its pharmaceutical dosage form by RP-HPLC.

A simple, accurate and precise method was developed for the simultaneous estimation of the bempedoic acid and ezetimibe in pure and tablet dosage form. The developed method was validated as per International Conference on Harmonization guidelines. The chromatographic separation was achieved isocratically on a Waters- C18, 250 × 4.6 mm, 5 µm column. Mobile phase containing K2HPO4-methanol in the ratio 60:40 in buffer at pH 4.3 was pumped through column at a flow rate of 1.0 ml/min. The temperature was maintained at 25°C. The optimized wavelength selected was 242 nm. The separation of bempedoic acid and ezetimibe showed retention times of 3.090 and 4.268 min respectively. The RSD values of the bempedoic acid and ezetimibe were 0.34 and 0.08 respectively. The accuracy of method was determined at three levels (50,100 and 150%). The percentage recovery was obtained as 100.0 and 100.0% for bempedoic acid and ezetimibe, respectively. The limits of determination and quantitation obtained from regression equations of bempedoic acid and ezetimibe were 1.065, 3.550 and 0.203, 0.677, respectively. The regression equation of bempedoic acid is y = 20,795x + 24,168, and it is y = 6,885.7x + 11,000 for ezetimibe. The retention times were decreased and the run time was decreased, so that the method developed is simple and economical that can be adopted for regular quality control tests in industry.

Validation of an FT-IR microscopy method for the monitorization of microplastics in water for human consumption in Portugal: Lisbon case study.

The growing anthropogenic contamination of natural water by microplastics (MPs) confirms the urgent need to preserve this precious resource. MPs are part of the group of contaminants of emerging concern, and the occurrence studies in surface water and water for human consumption (WHC) are mandatory for environmental and human health risk assessment. This study aims to optimize and validate a Fourier transform infrared spectroscopy method coupled with optical microscopy (micro-FTIR) in transmission mode to monitor MPs in WHC. Water sample (250 mL; without sample pre-treatment) was filtered through 5 µm silicon filters. The infrared spectra identification was performed by OMNIC mathematical correlation, using various spectra libraries for polymers (including the in-house IR spectra library), a background reading on a clean silicon filter, and an aperture of 100 µm × 100 µm. The validated method showed good accuracy, with an average recovery for representative polymers of 91%, a relative standard deviation of 13%, and a reporting limit (RL) of 44 MPs/L. Sixty WHC samples from the Lisbon water supply system showed MPs ranging from 0 (< RL) to 934 MPs/L, with an average value of 309 MPs/L. The most representative polymers were polyethylene (PE, 76.8%), polyethylene terephthalate (PET, 6.9%), polypropylene (PP, 6%), polystyrene (PS, 4%), and polyamide (PA,4%). In terms of size, the microplastic particles had an average length and width of 76 µm and 39 µm, respectively.

Dried blood spot sampling coupled with liquid chromatography-tandem mass for simultaneous quantitative analysis of multiple cardiovascular drugs.

Dried Blood Spots (DBS) revolutionize therapeutic drug monitoring using LC-MS for the precise quantification of cardiovascular drugs (CDs), enabling personalized treatment adapted to patient-specific pharmacokinetics with minimal invasiveness. This study aims to achieve simultaneous quantification of eight CDs in DBS, overcoming physicochemical challenges. A two-step protein precipitation method was used for simple and precise sample preparation. The drugs were analyzed using LC-MS/MS in ESI positive-ion mode, showing high sensitivity and linearity, with a correlation coefficient (r2) exceeding 0.999, after being separated on a reversed-phase chromatography by gradient elution of DW-acetonitrile containing 0.1 % formic acid + 2 mM ammonium formate. The validation results indicate good selectivity, with no observed matrix effect and carry-over. The intra- and inter-day accuracy and precision were within 6 % for most drugs, except for digoxin and deslanoside at low therapeutic levels where the variation was within 20 %. Stability tests confirmed suitable DBS handling and storage conditions, indicating drug stability for at least 30 days at room temperature. The analysis of whole spot has demonstrated remarkable precision and reliability in all target drugs. The analysis of 3 mm internal diameter discs, punched in and out of DBS, presumed to contain 3 µL of blood, showed acceptable accuracy for most drugs, with less polar drugs like digoxin and deslanoside showing lower accuracy, indicating a need for further correction due to non-uniform drug distribution. Consequently, the developed LC-MS/MS method enables the quantification of multiple CDs in a single DBS analysis, while suggesting the potential for accuracy-based analysis.

Development and validation of a green analytical method for simultaneously determining plasticizers residues in honeys from different botanical origins.

A novel method has been proposed to determine nine plasticizers in honey samples by gas chromatography-mass spectrometry. An efficient sample treatment was proposed (average analyte recoveries between 77% and 118%) involving a double solvent extraction with ethyl acetate, followed by a clean-up step with florisil. Chromatographic analysis (< 21 min) was performed in an Agilent HP-5MS column under programmed temperature conditions. The greenness of the method was assessed with different tools that classified it as environmentally friendly. The method was validated in terms of selectivity, limits of detection (0.1-3.1 µg kg-1) and quantification (0.2-10.3 µg kg-1), linearity, matrix effect, trueness, and precision (relative standard deviation <9%). An analysis of thirty samples from different sources (commercial or experimental apiaries) revealed the presence of residues of five plasticizers in most of the samples. Finally, health risk assessment was evaluated, and the results indicated no associated health risks for consumers.

Quick and high-throughput quantification of ß-agonist residues in bovine liver, meat, milk, kidney, poultry, and egg using dispersive solid phase extraction.

A reliable liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry (LC-Q-Orbitrap HRMS) method was developed for the simultaneous identification and quantification of 13 ß-agonist residues in bovine liver, meat, milk, kidney, poultry, and egg. Dispersive-solid phase extraction (d-SPE) using acetonitrile (ACN) was used to prepare the samples. The analyte in the extracts was separated on a reversed-phase Accucore aQ (50 mm × 2.1 mm, 2.6 µm) using a mobile phase of an aqueous solution containing 2 mM ammonium acetate and acetonitrile (ACN) 0.1 % formic acid. The method was validated in accordance with Commission Implementing Regulation (CIR) EU 2021/808 at six different concentrations ranging from 0.1 to 5 µg/kg. The mean recoveries ranged from 65 to 94 %, while repeatability and reproducibility values were all below 13 %. The linearity, as correlation coefficients (R2) ranged from 0.9955 to 0.9999. The decision limit (CCα) and detection capability (CCß) ranges were 0.11-0.13 µg/kg and 0.12-0.15 µg/kg, respectively. The limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.004-0.048 µg/kg and 0.010-0.075 µg/kg, respectively. Of the 180 samples that were collected from local markets in Egypt, 21.11 % had ß-agonist residues. The mean concentration (µg/kg) and detection frequency (%) of the most frequently found ß-agonist in the samples were as follows: terbutaline (2.63 µg/kg and 90 %), ractopamine (5.14 µg/kg and 23.3 %). The method's applicability was verified by successfully completing two rounds of proficiency testing (PT).

Gas chromatography mass spectrometer determination of dimethylamine impurity in N,N-dimethylformamide solvent by derivatization of N,N-dimethylbenzamide with benzoyl chloride agent.

This study describes the development of a reliable and linear analytical method for precisely determining dimethylamine impurity in N,N-dimethylformamide solvent utilizing a benzoyl chloride derivatization reagent and a gas chromatography mass spectrometer. Benzoyl chloride was used to derivatize dimethylamine. At normal temperature, benzoyl chloride combined with dimethylamine, producing N,N-dimethylbenzamide. This method separated N,N-dimethylbenzamide using Rtx-5 amine (30 m × 0.32 mm × 1.50 µm) as the stationary phase, helium as the carrier gas, argon as the collision gas, and methanol as the diluent. The column flow rate was 2 mL/min. The retention time of N,N-dimethylbenzamide was determined to be 8.5 min. Precision, linearity, and accuracy were tested using ICH Q2 (R2) and USP<1225> guidelines. The percentage coefficient of variation (CV) for N,N-dimethylbenzamide in the system suitability parameter was 1.1%. The correlation coefficient of N,N-dimethylbenzamide was found to be >0.99. In the method precision parameter, the % CV for N,N-dimethylbenzamide was found to be 1.9%, whereas the % CV for N,N-dimethylbenzamide was 1.2% in intermediate precision. The percentage recovery of N,N-dimethylbenzamide was determined to be between 80% and 98%.

Bifenthrin Residues in Table Grapevine: Method Optimization, Dissipation and Removal of Residues in Grapes and Grape Leaves.

The QuEChERS method was adjusted to determine bifenthrin residues in grapes and grape leaves. Extraction and cleanup procedures were optimized to decrease co-extracted materials and enhance the detection of bifenthrin. The method was validated per the European Union (EU) Guidelines criteria. Accuracy ranged from 98.8% to 93.5% for grapes and grape leaves, respectively. Precision values were 5.5 and 6.4 (RSDr) and 7.4 and 6.7 (RSDR) for grapes and grape leaves, respectively. LOQs (the lowest spiking level) were 2 and 20 µg/kg for grapes and grape leaves, respectively. Linearity as determination coefficient (R2) values were 0.9997 and 0.9964 for grapes and grape leaves, respectively, in a matrix over 1-100 µg/L range of analyte concentration. This was very close to the value in the pure solvent (0.9999), showing the efficiency of the cleanup in removing the co-extracted and co-injected materials; the matrix effect was close to zero in both sample matrices. Dissipation of bifenthrin was studied in a supervised trial conducted in a grapevine field during the summer of 2023 at the recommended dose and double the dose. Dissipation factor k values were 0.1549 and 0.1672 (recommended dose) and 0.235 and 0.208 (double dose) for grapes and grape leaves, respectively. Pre-harvest interval (PHI) was calculated for the Maximum Residue Limit (MRL) values of the EU database. Residues of bifenthrin were removed effectively from grapes using simple washing with tap water in a laboratory study. Residues reached the MRL level of 0.3 mg/kg in both washing treatments, running or soaking in tap water treatments for 5 min. Removal from leaves did not decrease residue levels to the MRL in grape leaves.