Method For Simultaneous Determination Research Articles

Development and validation of a rapid HPLC‐MS/MS method for simultaneous determination of cyclosporine A and tacrolimus in whole blood for routine therapeutic drug monitoring in organ transplantation

BackgroundTherapeutic drug monitoring is an integral part of organ transplantation. A rapid, simple, economical, and robust high‐performance liquid chromatography‐tandem mass spectrometry (HPLC‐MS/MS) method for simultaneously determining the immunosuppressants cyclosporine A and tacrolimus might increase detection efficiency.MethodsIn this study, we developed and validated a rapid HPLC‐MS/MS method. Whole blood samples of 100 μL were prepared by protein precipitation with acetonitrile and 0.5 mol. L−1 ZnSO4. Chromatography was performed on a pre‐column using a gradient elution with 20 mmol. L−1 ammonium formate and 0.1% (v/v) formic acid in water (mobile phase A) and 0.1% (v/v) formic acid in methanol (mobile phase B) at a flow rate of 1.5 mL.min−1. The analysis time was 2.2 min. Electrospray ionization and multiple reaction monitoring were performed. The lower limit of quantification was set at 1 ng. L−1 for tacrolimus and 50 ng. L−1 for cyclosporine A.ResultsThe method showed adequate accuracy and precision with a sufficient linear range. The calibration curve range of tacrolimus and cyclosporine A was 1–30 and 50–1500 ng·mL‐1, respectively. All correlation coefficients were >0.99.ConclusionsThe developed HPLC‐MS/MS is rapid and can be used for simultaneous monitoring of tacrolimus and cyclosporine A.

Novel RP-HPLC method for simultaneous determination of dapagliflozin and teneligliptin in tablet formulation and identification of degradation products by LC-MS/MS

Abstract Background Diabetes mellitus affects millions globally, necessitating effective management strategies. Glenmark Pharmaceutical Limited introduced a fixed-dose combination of teneligliptin and dapagliflozin in 2022 to address this need. However, existing methods for their simultaneous detection are limited, lacking forced degradation studies essential for assessing drug stability. Results A stability-indicating RP-HPLC method was developed for the simultaneous determination of dapagliflozin and teneligliptin in pharmaceutical formulations. The separation was efficiently achieved employing a Zorbax Eclipse Plus C18 column (150 mm × 4.6 mm, 5 µm). The mobile phase comprised a mixture of 10 mM ammonium acetate buffer in water, methanol, and acetonitrile in a suitable proportion and delivered at a flow rate of 0.6 mL/min. Detection of the isocratic eluents was performed at 224 nm using a photodiode array (PDA) detector. Validation against various stress conditions, as per ICH guidelines, revealed significant degradation of teneligliptin primarily under acidic, basic, and oxidative stress. Moreover, liquid chromatography tandem mass spectrometry (LC-MS/MS)-based characterization was conducted for the primary degradation products of teneligliptin generated under acidic, basic, and oxidative conditions. Conclusions The developed RP-HPLC method with a stability-indicating approach provides an efficient means for the simultaneous determination of dapagliflozin and teneligliptin in pharmaceutical formulations. The significant degradation was observed under various stress conditions and also successfully separated the degradation products by this method. The proposed method directly applied for the characterization of degradation products and based on LC-MS/MS data the structure of degradation products was generated and also degradation pathways under various stress conditions were predicted. The proposed method ensured accurate and precise results in quality control process in pharmaceutical industry, and adherence to ICH validation guidelines affirms its reliability in assessing the stability of these compounds.

A high-performance thin-layer chromatography densitometric method for the separation of isomeric ceftriaxone in powder for injection formulation

The aim of this study was to develop and validate a High-Performance Thin Layer Chromatographic (HPTLC) method for simultaneous determination of ceftriaxone and ceftriaxone e-isomer in powder for injection formulation. Ceftriaxone sodium injection is an antibiotic that used globally. It has Z/E geometrical conformation, in which ceftriaxone sodium and 3 ene-isomer have Z- conformation while (E)-isomer has E- conformation and the potential toxicity of ceftriaxone (E)-isomer has been reported. Thus, to safeguard the public health, a simple and easy to use, rapid and reliable method was developed for qualitative and quantitative determination of ceftriaxone sodium and its (E)–isomer. Samples were applied on HPTLC glass plates precoated with silica gel 60F254 by using Linomat semi-auto sampler. Separation was carried out using acetone, triethyl amine, water, chloroform and ethyl acetate as a mobile phase in different ratios. The Rf values of separated compounds were 0.51 ± 0.01 and 0.62 ± 0.01 for ceftriaxone sodium and ceftriaxone (E)-isomer respectively. The method was validated by studying Specificity, Linearity, Accuracy, Precision, Robustness, Limit of Detection (LOD) and Limit of Quantification (LOQ) and Solution stability. The developed method was successfully, sensitive, simple, precise, accurate, robust and applicable for the simultaneous determination of ceftriaxone sodium and ceftriaxone (E)-isomer in powder for injection formulation.

A simple, robust and high-throughput LC-MS/MS method for the therapeutic drug monitoring of polymyxin B1, polymyxin B2, polymyxin B3, isoleucine-polymyxin B1, polymyxin E1 and polymyxin E2 in human plasma.

To facilitate clinical therapeutic drug monitoring (TDM) of polymyxin B (PB) and polymyxin E (PE), we developed and validated a simple LC-MS/MS method for simultaneous determination of PB (including polymyxin B1 (PB1), polymyxin B2 (PB2), polymyxin B3 (PB3) and isoleucine-polymyxin B1 (ile-PB1)) and PE (including polymyxin E1 (PE1) and polymyxin E2 (PE2)) in human plasma. PB or PE was extracted from 20.0μL plasma using a 5% (v/v) formic acid acetonitrile solution and separated on a BEH-C18 column (2.1 × 100 mm, 1.7μm) with a mobile phase consisting of 0.8% formic acid aqueous solution and 0.2% formic acid acetonitrile solution. Gradient elution was performed over 5.5min at a flow rate of 0.250 mL/min. Quantitative analysis was conducted in positive ion scanning mode by electrospray ionization and multiple reaction monitoring. The method validation was conducted based on bioanalytical method validation guidance, including specificity, calibration curve, precision, accuracy, recovery, matrix effect, stability and dilution integrity and all of the results satisfied the requirements. The method was simple, robust and high-throughput and is currently being used to provide a TDM service to enhancing therapeutic efficacy and safety use of the PB and PE.

Efficient Online TurboFlow Method for Simultaneous Determination of 60 Emerging Per- and Polyfluoroalkyl Substances in Milk.

Emerging perfluoroalkyl and polyfluoroalkyl substances (PFASs) have received much attention in recent years. Milk has usually low concentrations of PFASs, but it remains an important PFAS exposure route due to its high consumption. In this study, a method for simultaneous determination of 60 PFASs in milk was developed by online TurboFlow liquid chromatography-tandem mass spectrometry. A pH-dependent cold-induced liquid-liquid extraction was developed for precleanup and enrichment. Method quantification limits ranged from 0.003 to 0.500 ng/mL. For PFASs without corresponding isotope-labeled internal standards, Tanimoto coefficient and logP were introduced for the selection of internal standards. The matrix spiked recoveries ranged from 47 to 190%. The method was applied for PFAS analysis in 35 milk samples. PFBS, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, PFNS, PFPeA, perfluorooctanoic acid, PFNA, and 6:2 FTS were detected. The developed online TurboFlow method was simple, reliable, efficient, and applicable for trace analysis of PFASs in milk.

Novel sulphur-selective method for simultaneous determination of thiram and asomate based on carbon dots and its application in fruits

Thiram (THI) and asomate (ASO) are frequently detected agrochemicals in food samples due to widespread use as fungicides. However, their detection suffers from matrix interference, or the necessity of derivatization before measurement. Integrating HPLC with a post-column carbon dots (CDs)–enhanced chemiluminescence (CL) system makes it possible to simultaneously separate and selectively detect ASO and THI in fruit samples free of derivatization and deep purification. The studies on mechanisms demonstrated that CD intermediates of anionic radical were responsible for the remarkable CL enhancement of ASO or THI. The CL intensity is directly proportional to the fungicide concentration, with the ranges of linearity for ASO and THI being 5–250 μg·L−1 (R2 = 0.9993) and 4–200 μg·L−1 (R2 = 0.9986), respectively, and the corresponding limits of detection (S/N = 3) being 1.61 and 1.33 μg·L−1, respectively. The developed method enables the exploration of the novelly sulphur-targeted CL application based on carbon nanomaterials.

Spectrofluorimetric Method for Simultaneous Determination of Trimethoprim and Sulfamethoxazole with <i>O</i>-phthaladehyde Reagent by H-point Standard Addition Method

Simultaneous spectrofluorometric method described for the determination of trimethoprim (TMP) and sulfamethoxazole (SMZ) in pure and pharmaceutical preparations using H-point standard addition method (HPSAM) according to the reaction of nanograms of drugs with O-phthaladehyde (OPA) reagent to forms highly fluorescence compounds. The formed fluorophore excitation and emission at 342 and 458 nm, respectively, for OPA-TMP compound, at 424 and 508 nm, respectively, for OPA-SMZ compound under basic condition (pH 9.8) in the presence of 2-mercabtoethanol. A simple and accurate HPSAM is reported to resolve the overlapping in the fluorescence spectrum of these two drugs without prior separation of samples. The linear range was 100–1200 ng/mL for TMP and 100–1100 ng/mL for SMZ. The LOD and LOQ were 16.64 and 36.80 ng/mL, as well as 15.76 and 33.88 ng/mL for TMP and SMZ, respectively. The relative standard deviations and recovery percentages were 0.641% and 101.29% for TMP as well as 0.558% and 100.96% for SMZ, respectively. The procedure has been applied successfully in various pharmaceutical preparations. It was discovered that the experimental F- and t-values at a 95% confidence level were no higher than the theoretical values, showing that the HPSAM method is accurate and valid.

Buffer-free high pH mobile phase LC-MS/MS for determination of the alcohol biomarker phosphatidylethanol 16:0/18:1 and 20 drugs and metabolites in whole blood

BackgroundAcidic mobile phases are commonly used in reversed phase liquid chromatography tandem mass spectrometry (LC-MS/MS) bioanalysis. However, increased sensitivity, improved peak symmetry, and increased retention, especially for basic hydrophilic drugs have been observed using basic mobile phases. In our previous acidic mobile phase LC-MS/MS method we needed two injections (0.4 and 2.0 μL) of each sample for this task, which is inefficient. The aim of this study was to investigate if basic mobile phase LC-MS/MS could be used to determine phosphatidylethanol 16:0/18:1 and 20 other drugs and metabolites with satisfactory sensitivity in one single run. MethodsWhole blood was prepared by 96-well supported-liquid extraction using heptane/ethyl acetate/2-propanol (16:64:20, v:v:v). Chromatographic separation was achieved on an Acquity BEH C18 column (50 × 2.1 mm I.D.), using a mobile phase with 0.025 % ammonia, pH 10.7 (Solvent A) and methanol (Solvent B). All compounds had isotope-labelled internal standards. ResultsThe method was fully validated. Recovery was between 63 and 91 % for 20 compounds and 10 % for benzoylecgonine. Matrix effects were low, except for ion enhancement of buprenorphine and ion suppression for THC. However, internal standards compensated for these effects. Inter-assay precision and accuracy were < ± 20 % for all compounds at five tested concentrations, except for methamphetamine at the highest concentration. ConclusionAn LC-MS/MS method for simultaneous determination of PEth 16:0/18:1 and 20 drugs and metabolites in whole blood were for the first time developed and validated. Retention of PEth 16:0/18:1 was, in contrast to the other 20 compounds, largely affected by mobile phase buffer concentration. The buffer free basic mobile phase ensured that phosphatidylethanol 16:0/18:1 eluted before most of the unwanted phospholipids.

Development and validation of High-Performance Thin Layer Chromatographic methods for simultaneous determination of antibacterial pharmaceutical formulations containing Clindamycin phosphate.

The main objective of this research is to establish and authenticate the High-Performance Thin-Layer Chromatographic techniques for the simultaneous assessment of Clindamycin phosphate in combination with Tretinoin (formulation-1) and Clindamycin phosphate with Adapalene (formulation-2), both of which are antimicrobial combinations. In the developed HPTLC methods, for combination-1, the optimized mobile phase was a mixture of n-Hexane: Ethyl acetate: ACN: Methanol (5:2:2:1 by volume) with observed Rf values of 0.413 and 0.787 for Clindamycin phosphate and Tretinoin, respectively. Similarly, for combination-2, the mobile phase comprised n-Hexane: Diethyl ether: Dichloromethane: Acetic acid (4:4:2:0.1 by volume) with recorded Rf values of 0.407 and 0.559 for Clindamycin phosphate and Adapalene, respectively. The developed methods are successfully validated as per the regulatory guidelines. This approach proves to be significantly time-saving and costeffective, rendering it suitable for routine analyses of the formulations containing selected antibacterial active pharmaceutical ingredients and commercial formulations.

A general and rapid LC-MS/MS method for simultaneous determination of voriconazole, posaconazole, fluconazole, itraconazole and hydroxyitraconazole in IFI patients

ObjectiveTo establish a rapid and universal quantitative liquid chromatography tandem mass spectrometry (LC-MS/MS) method for measuring the exposure levels of five triazole antifungal drugs in human plasma, including voriconazole, fluconazole, posaconazole, itraconazole, and hydroxyitraconazole. MethodsA triple quadrupole mass spectrometer operating in positive ionization mode was used to detect the analyte, and multiple reaction monitoring mode was employed to gather data. The mobile phase included 0.05 % formic acid in water (phase A) and acetonitrile (phase B). The analytes were separated on an Agilent EclipsePlusC18 RRHD column (30 × 50 mm, 1.8 μm) using gradient elution. The flow rate was 0.3 mL/min with the column temperature set at 35 °C. The acetonitrile was used to pretreat the plasma sample, and the itraconazole-D5 and hydroxyitraconazole-D5 were utilized as the internal standards. ResultsThe calibration range was from 100 to 10,000 ng/mL for posaconazole, itraconazole, and hydroxyitraconazole, from 200 to 20,000 ng/mL for fluconazole and from 50 to 5000 ng/mL for voriconazole, with linear correlation coefficients more than 0.99 for all regression curves. The intra- and inter-day accuracy and precision of the method were within ±15 %. The mean extraction recovery of all the analytes ranged from 74.32 % to 117.83 %, and the matrix effect was from 72.54 % to 111.2 %. The results of stability fell into the scope of ±15 % deviation. ConclusionThis newly developed method is sensitive, simple, and robust, and successfully applied in determining triazole antifungal drugs in plasma from 66 IFI patients to provide reference for safe and effective drug administration in clinical practice.

Trifluoroacetic acid modified MOF-808 composite coating for solid-phase microextraction of six phenols followed by gas chromatography analysis

The development of adsorption materials with good stability and high efficiency is significant in solid-phase microextraction (SPME). In this work, metal–organic framework MOF-808 (Zr) was modified by trifluoroacetic acid (TFA) to improve its hydrophobicity. MOF-808-TFA was electrochemically deposited on stainless steel wire with poly (3, 4-ethylenedioxthiophene) (PEDOT) to increase its extraction efficiency. The main parameters in the synthesis and extraction procedure were optimized. The prepared MOF-808-TFA@PEDOT nanocomposite coating was characterized by scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, Fourier transform infrared spectrometry and thermogravimetric analysis. A direct immersion solid-phase microextraction (DI-SPME) method for six phenols was developed based on the nanocomposite coating which had good service life (150 times). The extraction efficiency was 12 times higher than the commercial PDMS coating. Combined with gas chromatography-flame ionization detector (GC-FID), a simultaneous determination method for the six phenols was established, which exhibited wide linear range with 0.05–50 μg L−1 (R2 > 0.99). The limit of detection was 0.01–0.08 μg L−1 (S/N = 3), and the limit of quantification was 0.05–0.25 μg L−1. The method was applied to determine the migration quantity of phenols from four metal cans with recovery rate between 85.6–116.8 % (RSD < 13.9 %), and it was verified by standard GC–MS method and SPSS statistical analysis. These results indicated the DI-SPME-GC-FID method had reliability and potential application in security testing for food contact materials.

Development of a Simultaneous HPLC Determination Method of Cacao Polyphenols, Caffeine and Theobromine in High Cacao Chocolate by Core-Shell Type Reversed-Phase Columns

Development of a Simultaneous HPLC Determination Method of Cacao Polyphenols, Caffeine and Theobromine in High Cacao Chocolate by Core-Shell Type Reversed-Phase Columns

UPLC-PDA factorial design assisted method for simultaneous determination of oseltamivir, dexamethasone, and remdesivir in human plasma

A green and simple UPLC method was developed and optimized, adopting a factorial design for simultaneous determination of oseltamivir phosphate and remdesivir with dexamethasone as a co-administered drug in human plasma and using daclatasvir dihydrochloride as an internal standard within 5 min. The separation was established on UPLC column BEH C18 1.7 μm (2.1 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 100.0 mm) connected to UPLC pre-column BEH 1.7 μm (2.1 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 5.0 mm) at 50 °C with an injection volume of 10 μL. The photodiode array detector (PDA) was set at three wavelengths of 220, 315, and 245 nm for oseltamivir phosphate, the internal standard, and both dexamethasone and remdesivir, respectively. The mobile phase consisted of methanol and ammonium acetate solution (40 mM) adjusted to pH 4 in a ratio of 61.5:38.5 (v/v) with a flow rate of 0.25 mL min−1. The calibration curves were linear over 500.0–5000.0 ng mL−1 for oseltamivir phosphate, over 10.0–500.0 ng mL−1 and 500.0–5000.0 ng mL−1 for dexamethasone, and over 20.0–500 ng mL−1 and 500.0–5000.0 ng mL−1 for remdesivir. The Gibbs free energy and Van't Hoff plots were used to investigate the effect of column oven temperatures on retention times. Fluoride-EDTA anticoagulant showed inhibition activity on the esterase enzyme in plasma. The proposed method was validated according to the M10 ICH, FDA, and EMA’s bioanalytical guidelines. According to Eco-score, GAPI, and AGREE criteria, the proposed method was considered acceptable green.

Development and validation of a green spectrophotometric method for simultaneous determination of combined pharmaceutical dosage form (paracetamol and caffeine) using chemometrics technique in comparison with HPLC

Development and validation of a green spectrophotometric method for simultaneous determination of combined pharmaceutical dosage form (paracetamol and caffeine) using chemometrics technique in comparison with HPLC

Development of a UPLC-MS/MS Method to Simultaneously Measure 13 Antiepileptic Drugs with Deuterated Internal Standards.

The goal of this study was to develop and validate a UPLC-MS/MS method for simultaneous mea-surement of 13 AEDs, including carbamazepine, oxcarbazepine, lamotrigine, levetiracetam, topiramate, primidone, zonisamide, gabapentin, lacosamide, perampanel, pregabalin, rufinamide, and vigabatrin, in whole blood samples. A UPLC-MS/MS method for simultaneous determination of 13 AEDs in whole blood was developed, and validation was conducted for accuracy, precision, limit of quantification (LOQ), matrix effect, and stability. Our method was compared to two different hospitals using UPLC-MS/MS. All AEDs exhibited linearity across the AMR (analytical measurement range), with R2 values ranging from 0.994 to 1.000. The imprecision and inaccuracy for low and high quality control (QC) levels were within an acceptable range, with the coefficient of variation (CV) < 15%. The LOQ was 0.62 µg/mL for carbamazepine, 1.61 µg/mL for oxcarbazepine, 1.30 µg/mL for lamotrigine, 13.20 µg/mL for levetiracetam, 1.26 µg/mL for topira-mate, 1.01 µg/mL for primidone, 1.59 µg/mL for zonisamide, 1.09 µg/mL for lacosamide, 1.61 µg/mL for gabapentin, 0.50 µg/mL for pregabalin, 0.07 ng/mL for perampanel, 3.00 µg/mL for rufinamide, and 2.06 µg/mL for vigabatrin. All AEDs demonstrated acceptable assay parameters for carryover, stability, and matrix effects. Moreover, the assay showed satisfactory results compared to two different hospitals with a bias of less than 15%. We successfully developed and validated a fast and robust UPLC-MS/MS method for routine therapeutic drug monitoring of thirteen antiepileptic drugs simultaneously.

Eco-friendly second derivative synchronous fluorescence spectroscopic method for simultaneous determination of rosuvastatin and ezetimibe in pharmaceutical capsules

The fixed dose combination of Rosuvastatin and ezetimibe has recently received approval from the FDA for the treatment of elevated levels of low-density lipoprotein cholesterol in adults. Herein, an eco-friendly and highly sensitive spectrofluorimetric method was developed and validated for simultaneous determination of rosuvastatin and ezetimibe in commercial capsules. The developed method involved synchronous fluorescence spectroscopy combined with second derivative spectroscopy to resolve the overlapping fluorescence spectra of rosuvastatin and ezetimibe. The studied drugs were measured in synchronous mode at Δλ of 40 and their recorded synchronous fluorescence spectra were derivatized into second-order spectra, enabling the selective quantification of rosuvastatin and ezetimibe at 370 nm and 312 nm, respectively. Optimization studies regarding to the influence of buffer pH, incorporation of surfactant, choice of diluting solvent, and synchronous Δλ were carried out. The method was validated using the validation characteristics listed in ICH Q2(R1). The calibration curves displayed satisfactory linear relationships across the calibration range of 0.1–2 µg/mL for rosuvastatin and 0.05–3 µg/mL for ezetimibe. The methodology demonstrated robustness to minor modifications in the procedural parameters and selectivity in quantifying the studied drugs in synthetic mixed solutions and commercial capsules without interference. Furthermore, the level of environmental friendliness and sustainability of the suggested spectrofluorimetric approach was assessed in relation to two previously documented methodologies utilizing the AGREE metric. The findings indicated that the suggested method demonstrated a notably superior level of sustainability in comparison to the documented methods.

Derivative spectrophotometric method for simultaneous determination of ascorbic acid and folic acid in the pharmaceutical formulation; Comparative greenness assessment

Ascorbic acid and folic acid are frequently included together in multivitamin pharmaceutical products due to their complementary roles in maintaining human health. The quality and efficiency of supplements can vary depending on the manufacturer and the specific ingredients used, which are vital factors to consider. This research presents the development and validation of a simple, sensitive, accurate, and environmentally friendly derivative spectrophotometric technique utilizing the zero-crossing method for the simultaneous determination of ascorbic acid and folic acid, both in their pure form and in pharmaceutical formulations. The derivative spectrophotometry technique demonstrated measurable amplitude and substantial linearity for both analytes. At the zero-crossing points of folic acid (249.6 and 281 nm), ascorbic acid showed a measurable amplitude with a linear range of 0.17–12.0 μg/mL and 0.37–12 μg/mL, and detection limits of 0.057 μg/mL and 0.121 μg/mL, respectively. Conversely, folic acid displayed an observable amplitude at the zero-crossing point of ascorbic acid (265.6 nm) with a linear range from 0.26 to 15.0 μg/mL and a detection limit of 0.088 μg/mL.The greenness of the proposed derivative spectrophotometric method was evaluated using the White Analytical Chemistry (WAC) framework and the Green Analytical Procedure Index (GAPI). The method scored highly in both evaluations, confirming its minimal environmental impact and alignment with the principles of Green Analytical Chemistry. The GAPI assessment highlighted low environmental and health risks throughout the analytical process, making this method a green and sustainable choice for the simultaneous determination of ascorbic acid and folic acid. The method was successfully applied to synthetic laboratory mixtures and formulated tablets, showing excellent precision, accuracy, and recovery, while also being environmentally friendly.

Development of Simultaneous Drug Concentration Measurement Method Using an Automated Pretreatment Liquid Chromatography/Tandem Mass Spectrometry System for Therapeutic Drug Monitoring.

Therapeutic drug monitoring (TDM) is a personalized treatment approach that involves optimizing drug dosages based on patient-specific factors, such as drug plasma concentrations, therapeutic efficacy, or adverse reactions. The plasma concentration of drugs is determined using liquid chromatography/tandem mass spectrometry (LC-MS/MS) or various immunoassays. Compared with immunoassays, LC-MS/MS requires more pretreatment time as the number of samples increases. Recently, fully automated pretreatment LC-MS/MS systems have been developed to automatically perform whole-sample pretreatment for LC-MS/MS analysis. In this study, we developed a method for simultaneous concentration determination of five analytes (clozapine, mycophenolic acid, sunitinib, N-desethylsunitinib, and voriconazole) using LC-MS/MS for clinical TDM using a fully automated LC-MS/MS pretreatment system. In the developed method, the intra- and inter-assay relative error (RE) values ranged between -14.8% and 11.3%; the intra- and inter-assay coefficient of variation (CV) values were <8.8% and <10.5%, respectively. The analytes showed good stability, with RE values ranging between -13.6% and 10.9% and CV values <8.9%. Furthermore, the plasma concentrations in clinical samples using this method and the conventional manual pretreatment method showed similar results. Therefore, the method developed in this study could be considered a useful pretreatment method for routine TDM in patients.

A Robust Method for Simultaneous Determination and Risk Assessment of Multiresidual Pesticides in Fishery Products.

In this study, we developed and validated a multiresidue analytical method for the simultaneous detection of 24 pesticides in fishery products. Using the EN15662 extraction method and C18 as the adsorbent for purification, the validation results complied with Codex guidelines, achieving recovery rates between 70% and 120% and relative standard deviation values (%RSD) within 20%, indicating excellent performance. The limit of detection ranged from 0.25 to 0.8 ng/kg, and the limit of quantification was between 3 and 10 ng/g, providing sufficient sensitivity to comply with future regulatory standards. The calibration curves for all 24 pesticides exhibited great linearity (R2 > 0.98), also satisfying the Codex requirements. The matrix effect was less than 30% for some pesticides-within ±20%-indicating minimal interference from impurities. An analysis of 300 fishery samples from nine regions across South Korea detected lufenuron at 10 ng/g in eels; however, the risk assessment was below 0.19%, posing no significant hazard to public health. This newly developed analytical method proved effective for the multi-analysis of pesticide residues in fishery products, offering rapid and reliable monitoring of the import and export safety of fishery products.

Validation of an Analytical Method for Organochlorine Pesticide Residues in Beef Products by GC-MS Using Sampling with Increment Reduction

We developed a simultaneous determination method for the environmentally persistent organochlorine pesticides aldrin/dieldrin, γ-BHC, DDT, endrin, and heptachlor in beef products. In the method, we adopted incremental reduction for sample collection in order to improve the uniformity of the samples. In incremental reduction, a sample was ground and spread to an even thickness, divided into sections, and collected in an equal amount from each section. After extraction with an acetonitrile/ethanol mixture (1 : 1 v/v), sample clean-up was performed by refrigerated centrifu-gation and solid-phase extraction. This process was easy and did not require gel permeation chromatography. The sample was analyzed by GC-MS. A validation study of the development method showed that the tested pesticides met the target values indicated in the validity evaluation guideline.