Inter-day Accuracy Research Articles

Simple and rapid paper-based colorimetric spot test for promethazine screening in recreational drug beverages and pharmaceuticals

This study introduces a paper-based colorimetric spot test for the rapid and cost-effective detection of promethazine, featuring enhanced stability and user-friendliness. The developed device employs a potassium persulfate reagent encapsulated in a xerogel matrix, facilitating a simple chemical oxidation reaction that produces a pink color upon promethazine detection. Color quantification is efficiently achieved using a digital camera, with image analysis performed through ImageJ software to convert color image into a blue intensity scale. Under optimized conditions, the method demonstrates a linear calibration curve within the range of 100–600 mg/L and a detection limit of 20 mg/L. The paper-based colorimetric spot test exhibited good intra-day and inter-day accuracy of the recoveries of 98–102 % and 99–101 %, respectively. Good precision of measurement was also achieved (5.6 % RSD). The xerogel matrix ensures the long-term storage stability of the reagent for three months when stored at both 25 °C and 4 °C, making the device suitable for field applications. When applied to detection of promethazine in recreational drug beverage samples and pharmaceutical formulations, the performance of the proposed method showed no significant statistical differences compared to gas chromatography–flame ionization detection (GC–FID). This low-cost, portable, and disposable tool is suited for onsite screening of promethazine, representing a significant advancement in rapid drug detection methodologies.

MCM-41 based dispersive micro-solid phase extraction of selected cephalosporin antibiotic residues from water samples prior to liquid chromatographic quantification

The occurrence of antibiotics in water bodies is of concern owing to the serious risk they pose to the environment, water security, aquatic organisms, and human health. In this study, mesoporous silica (MCM-41) nanostructured material was synthesised and characterized by various analytical techniques to determine its morphology and dimension, functional groups, surface charge, and textural properties. The nanostructured MCM-41 was used as an adsorbent in ultrasound-assisted dispersive micro solid-phase extraction (UA-D-µ-SPE) of cefadroxil (CFDX) and cephalexin (CPLX) in water samples. The concentration of the analytes in aqueous solution and real water samples was determined using high-performance liquid chromatography coupled with diode array detection (HPLC-DAD). The developed method for CFDX and CPLX in various water samples exhibited relative linear ranges of 0.1–600 µg/L and 0.1–550 µg/L, respectively, and correlation coefficients ranging from 0.9923–0.9993. Under optimum condition, the UA-D-µ-SPE/HPLC-DAD method displayed low limits of detection (LOD) and quantification (LOQ), with values ranging from 0.02–0.16 µg/L and 0.067–0.53 µg/L, respectively. The investigated intraday and interday accuracy in spiked water samples showed acceptable extraction efficiencies with a range of 73.5–98.1% and a relative standard deviation less than 6.0%. Moreover, the performance of MCM-41 was also assessed for the removal of cephalosporin antibiotics aqueous solutions. The kinetic and isotherm studies revealed that the adsorption process followed pseudo-second order and the Langmuir model, respectively. Furthermore, the maximum adsorption capacities for CFDX and CPLX were 43.2 and 47.8 mg/g. Lastly, the UA-D-µ-SPE/HPLC-DAD method was successfully applied in extracting, preconcentrating, separating and determining CFDX and CPLX in wastewater and surface water samples. These results demonstrated that MCM-41 can be applied in the removal of cephalosporin antibiotics from aquatic environments.

Determination of Sennoside A in Rat Plasma by Liquid Chromatography/Electrospray Ionization Tandem Mass Spectrometry and Its Application to a Rat Pharmacokinetic Study.

To characterize pharmacokinetic profile of sennoside A in rats after intravenous and oral administration, a simple and sensitive liquid chromatography tandem mass spectrometry method was established and validated for quantitative determination of sennoside A in rat plasma. After prepared by protein precipitation with acetonitrile, sennoside A and internal standard were separated on a Waters ACQUITY HSS T3 (2.1 × 100 mm, 1.8 μm) column using acetonitrile and 5-mM ammonium acetate in water as mobile phase by gradient elution. The method showed excellent linearity over the range of 0.5-1000 ng/mL with acceptable intra- and inter-day precision, accuracy, matrix effect, and recovery. The stability assay indicated that sennoside A was stable in plasma during the sample collection, preparation, and analysis. Next, the method was applied to pharmacokinetic study of sennoside A in rats. After intravenous and intragastric administrated to rats, the concentrations of sennoside A in plasma at different time points were quantitated and the pharmacokinetic parameters were calculated by software of DAS 2.0. Pharmacokinetic parameters suggested that after oral administration, sennoside A was reached to the peak at 2.9-3.6 h with a Cmax value of 13.2-31.7 ng/mL. Sennoside A was eliminated slowly from the plasma with T1/2 value between 15.4 and 18.3 h. The oral absolute bioavailability was among 0.9%-1.3%, which indicated low blood exposure level.

Hydrophobic deep eutectic solvent-ferrofluid microextraction followed by liquid chromatography-mass spectrometry for the enantioselective determination of chiral agrochemicals in natural waters.

The increasing use of chiral agrochemicals sold as racemic formulations raises concern for the negative impacts that inactive enantiomers can have on aquatic life and human health. The present work just focuses on the determination of ten chiral pesticides in river water samples by applying a ferrofluid-based microextraction followed by their stereoselective liquid chromatography analysis. To develop the ferrofluid, magnetite nanoparticles were prepared and coated with oleic acid and then dispersed in a hydrophobic natural deep eutectic solvent (NaDES), composed ofL-menthol and thymol (1:1). The stable colloidal dispersion was characterised by scanning electron microscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. The analyte microextraction from 5ml river samples was performed using 50µl of ferrofluid, while acidified acetonitrile (150µl) was used to break down the ferrofluid and solubilise the NaDES containing the analytes. All the extracts were analysed by high-performance liquid chromatography-tandem mass spectrometry. For each analyte, the baseline separation of isomers was achieved on a Lux i-Amylose-3 column (amylose tris(3-chloro-5-methylphenylcarbamate) working in reversed-phase mode; the combination with mass spectrometry detection allows the overall separation of 24 isomers (ten chiral analytes among which eight containing a single (one) chiral centre, one with two chiral centres and the last one existing in four stereoisomeric forms, due to the presence of two regioisomers with a chiral carbon) within 37min. The method showed very good figures of merit in terms of recoveries (77.7-97.5%), intra-day and inter-day precision (2.7-7.7% and 6.9-14.9%, respectively), limit of detection (0.01-0.35µg/L), limit of quantitation (0.03-1.20µg/L), linear dynamic range, and intra-day and inter-day accuracy (1.2-14.8% and 1.8-15.0%, respectively). The presented method was able to detect 14 out of 24 isomers at the preventive limit established by the Italian legislation for single pesticide (that for a chiral pesticide is the sum of all its isomers) in surface waters, set at 0.1µg/l. Finally, the method was evaluated using AGREEprep and ComplexGAPI metrics, compared with other ferrofluid-based methods, and applied to the analysis of water samples from two Italian rivers (the Nera River and the Tiber River), providing to be sustainable and reliable for the application to real river matrices.

Determination of naturally derived propionic, benzoic, and sorbic acids in seafood, meats, and fruits during storage

Propionic acid, benzoic acid, and sorbic acid are common preservatives in processed foods, but their natural concentrations in raw foods are not well understood. In Korea, if propionic acid or benzoic acid exceeds certain levels in processed plant-based foods, manufacturers must prove they are naturally occurring to avoid recalls. This regulation applies to both local and imported products, with non-compliance leading to economic costs and damage to brand reputation. To address this, further research is needed to build a database of naturally occurring preservatives in raw foods and develop food safety standards. This study quantified the levels of propionic, benzoic, and sorbic acids in 37 raw foods stored at different temperatures for 2 weeks, using gas chromatography and high-performance liquid chromatography. The changes in acid concentrations during storage were examined, with preservatives identified by mass spectrometry. Sensory evaluation and total viable count were used to assess spoilage in seafood and meat samples. The matrix effects were evaluated, and the quantification methods were validated using seven food matrices. The intra- and interday accuracies and precisions (% relative standard deviation, %RSD) values met the Codex guidelines. In general, the propionic acid contents of most seafood and meat samples increased during storage, with the highest content being found in manila clams. Interestingly, the fresh sea squirt sample contained a higher propionic acid content (456 mg/kg) than the other samples. However, benzoic acid and sorbic acid were not detected in most samples, with the exception of the jujube and apple samples.

Pipette-tip microextraction using carboxymethylated wooden-based sawdust sorbent for the determination of antidepressants in oral fluid by direct infusion mass spectrometry

Matrix complexity is a challenging scenario in sample preparation and the scientific community is in the search of novel materials capable of replacing the classical sorbents to overcome the sensitivity and selectivity issues it presents. In this article, the use of a carboxymethylated wooden-based sawdust sorbent pipette-tip microextraction is introduced for the determination of four antidepressants (imipramine, amitriptyline, fluoxetine, and clomipramine) in human oral fluids. The different variables affecting the extraction and elution procedures, including sample pH, ionic strength, number of pushing cycles, dilution of the sample, eluent, and volume of the eluent have been evaluated by liquid chromatography – ultraviolet detection. Moreover, the proposed method was validated by direct infusion coupled to tandem mass spectrometry with limits of detection of 0.2 μg/L, limits of quantification of 0.6 μg/L, linear range spanning from 0.6 to 320 μg/L and intra-day precision (expressed as relative standard deviation) better than 14.2 %. Intra-day accuracy (expressed as relative recovery) ranged from 85.4 to 102.9 %, while inter-day accuracy was between 97.0 and 103.9 %. Finally, the analysis of two oral fluids from a patient under amitriptyline treatment were analyzed, providing values within the linear range of the proposed method.

Determination of adalimumab by HPLC with fluorescence detection using the König reaction

Monoclonal antibody drugs (mAb) are widely used to treat various diseases. Keeping quality of mAbs is crucial to maximize efficacy and minimize adverse effects. To this end, mAb content in the drug product must be precisely quantified. As methods for the determination of mAbs, absorbance measurement at 280 nm, the ligand binding assay based on ELISA, or the LC-MS/MS method based on the surrogate peptide approach is usually used. However, these methods have drawbacks in terms of selectivity, reliability, and cost, respectively. The present method is based on the surrogate peptide approach where a peptide specific to the mAb is determined by a post-column derivatization LC system with fluorescence detection and the König reaction, which is usually used for the detection of cyanide and its derivatives. The detection mechanism was the production of cyanide from the surrogate peptide by chloramine T and the generated cyanide was detected by the König reaction. In this study, adalimumab was used as a model target protein. The calculated LOD and LOQ of the present method were 0.31 μg/mL and 0.94 μg/mL, respectively. The intra-day accuracies and precisions were 127.1 % and 2.94 % for 5 μg of adalimumab and 101.6 % and 10.2 % for 50 μg of adalimumab, respectively. The inter-day accuracies and precisions were 121.8 % and 5.71 % for 5 μg of adalimumab and 101.8 % and 6.98 % for 50 μg of adalimumab, respectively. Our quantitatively determined amount of adalimumab in Humira® was in good agreement with the specified value. This method only requires a conventional LC system, not an LC-MS/MS system. By extending the application of the König reaction, we open the door to a new surrogate peptide approach for the determination of proteins including monoclonal antibody drugs.

Development of a UHPLC-MS/MS Method for the Determination of Moxidectin in Rat Plasma and Its Application in Pharmacokinetics.

The aim of the present study was to establish a simple and reliable ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method and apply it for the determination of pharmacokinetics of moxidectin-loaded microspheres (MOX-MS) in rats. Plasma samples were processed using a simplified liquid-liquid extraction method and were separated using an Agilent Zorbax Eclipse Plus C18 column (50 mm × 2.1 mm, 1.8 μm) with a mobile phase consisting of a 10 mM ammonium formate solution with 0.1% formic acid (A) and acetonitrile (B) at a flow rate of 0.4 mL/min for 5 min. Avermectin B1a was used as an internal standard (IS). The sample was injected at a volume of 10 μL with a column temperature of 35 °C and detected in a positive ion mode. A good linear response across the concentration range of 1.00-200 ng/mL (r2 > 0.99) and a lower limit of quantification (LLOQ) of 1.00 ng/mL were achieved. The extraction recovery of moxidectin exceeded 94.1%, the matrix effect was between 91.2% and 96.2%, the accuracy ranged from 100.1 to 103.6%, and the relative standard deviation (RSD) did not exceed 15% for the intra- and inter-day accuracy and precision. The pharmacokinetic results showed that MOX-MS significantly decreased Cmax, prolonged T1/2, and improved bioavailability. The developed method significantly reduced the assay volume, shortened detection time, simplified sample processing methods and saved assay costs, which may contribute to the development of the new antiparasitic drug.

An Ultra-Fast Green UHPLC-MS/MS Method for Assessing the In Vitro Metabolic Stability of Dovitinib: In Silico Study for Absorption, Distribution, Metabolism, Excretion, Metabolic Lability, and DEREK Alerts.

Background and Objectives: Dovitinib (DVB) is a pan-tyrosine kinase inhibitor (TKI) that can be administered orally. In September 2023, the FDA granted Oncoheroes approval to proceed with an Investigational New Drug (IND) application for dovitinib. This application is intended for the treatment of relapsed or advanced juvenile solid tumors, namely, osteosarcoma. Materials and Methods: The target of the present study was to develop a rapid, green, accurate, and sensitive UHPLC-MS/MS method for measuring DVB levels in human liver microsomes (HLMs). The validations of the HLMs were performed via the established UHPLC-MS/MS approach, as stated in the US FDA reported guidelines for the standards of bioanalytical method validation protocol. The StarDrop in silico software package (version 6.6), which involves the DEREK and WhichP450 in silico modules, was used to check the DVB structure for hazardous alerts and metabolic instability. The DVB and encorafenib (EFB), internal standard, and chromatographic peaks were successfully separated using a reversed phase column (an Eclipse Plus Agilent C8 column) and an isocratic mobile phase. The production of DVB parent ions was accomplished by utilizing the positive ionization mode of an ESI source. The identification and measurement of DVB daughter ions were conducted using the MRM mode. Results: The inter-day accuracy and precision exhibited a spectrum of values in the range of -0.56% to 9.33%, while the intra-day accuracy and precision showcased a range of scores between 0.28% and 7.28%. The DVB calibration curve showed a linear relationship that ranged from 1 to 3000 ng/mL. The usefulness of the currently validated UHPLC-MS/MS method was approved by the lower limit of quantification (LLOQ) of 1 ng/mL. The AGREE findings demonstrate that the UHPLC-MS/MS method had a noteworthy degree of ecological greenness. The in vitro half-life (t1/2) and intrinsic clearance (Clint) of DVB were calculated to be 15.48 min and 52.39 mL/min/kg, respectively, which aligned with the findings from the WhichP450 software (version 6.6). Conclusions: Via the usage of in silico software, it has been observed that making small changes to the structure of the aryl piperazine ring and quinolinone moieties, or replacing these groups in the drug design process, shows potential for enhancing the metabolic safety and stability of newly developed derivatives compared to DVB.

Quantitative determination by UHPLC-MS/MS of 18 common drugs of abuse and metabolites, including THC and OH-THC, in volumetric dried blood spots: a sustainable method with minimally invasive sampling

The increased use of drugs of abuse urges forensic toxicologists to create quick, simple, minimally invasive sampling techniques for biological fluids combined with analytical methods assuring accurate results. To this purpose, a method was developed aimed at quantifying 18 drugs of abuse and metabolites in DBS. Validation of the method was conducted by spiking blank whole blood with the analytes on Capitainer® B cards. The extracts were analyzed by a targeted UHPLC-MS/MS method. Linear calibration was achieved in the range of 1–100 ng/mL for: amphetamine, MDA, MDMA, methamphetamine, cocaine, codeine, benzoylecgonine, cocaethylene, morphine, 6-MAM, buprenorphine, methadone, EDDP, ketamine, norbuprenorphine norketamine, THC, and OH-THC. Experimental LOD was found at 0.5 ng/mL for all analytes except for norbuprenorphine, THC and THC-OH which yielded a LOD of 1 ng/mL. Intra- and inter-day accuracy was satisfactory with bias% resulting within 5%. Evaluation of intra- and inter-day precision yielded CV% values within 20%, for all compounds except EDDP. Average extraction recovery calculated at low (2 ng/mL) and high (75 ng/mL) concentration levels was 63% while average matrix effect determined at the same levels was found to be within 85% − 115% for all analytes except from codeine (70%) and MDMA (131%). The method was applied to authentic blood samples spotted onto the DBS card and the minimum value detected was 1.3 ng/mL. HPLC-MS/MS proved capable to identify all the targeted analytes at low concentrations in the small blood volumes obtainable from DBS cards, which in turn confirmed to be effective and sustainable micro-sampling devices.

Simultaneous Determination of Levo-tetrahydropalmatine and Naltrexone in Rat Plasma by LC-MS/MS and its Application in a Pharmacokinetic Study.

Levo-tetrahydropalmatine and low-dose naltrexone are used in association with reducing cocaine-related cravings, but there are no analytical methods for the quantitative simultaneous analysis of this drug combination. A highly selective and sensitive LC-MS/MS assay was developed and validated to simultaneously quantify l-THP and naltrexone. The analytical method for l-THP offers improved sensitivity compared to previously published methods. The product ion transitions of l-THP and naltrexone were 357.0→193.0 and 342.2→324.1, respectively. Chromatographic separations were performed using a BEH-C18 column by an isocratic elution mode with acetonitrile and 0.1% formic acid in water containing 3 mM ammonium acetate. L-THP and naltrexone were extracted from rat plasma using a liquidliquid extraction method. For l-THP and naltrexone, the assay displayed good linear response over a concentration range of 0.5-1000 ng/mL and 0.25-500 ng/mL, respectively. The intra-day accuracy of the method for l-THP and naltrexone was 93.8-101% with a precision (%CV) of 2.43-8.15% and 93.4-108% with a precision of 3.47-8.22%. The inter-day accuracy for l-THP and naltrexone was 91.2-102% with a CV of 2.46-8.06% and 91.5-97.8% with a CV of 3.29-8.92%, respectively. The assay has been used for pharmacokinetic studies of l-THP and naltrexone in the rat.

Application of UHPLC-QqQ-MS/MS Method for Quantification of Beta-Adrenergic Blocking Agents (β-Blockers) in Human Postmortem Specimens.

Betablockers are one of the most frequently used medications in cardiology. They can lead to fatal drops in blood pressure and heart rhythm disturbances. Death is functional, and poisoning with this group of drugs can be difficult to detect. The liquid-liquid extraction (LLE) method developed using ethyl acetate at pH 9 successfully identified 18 β-blockers in human blood. The method's limit of quantification (LOQ) was in the range of 0.1 to 0.5 ng/mL. No carryover of substances between samples was detected, and no interfering ion current signals were observed in the biological samples at the retention times of the compounds or internal standards. All compounds had a coefficient of determination (R2) above 0.995. Intraday and interday precision (RSD%) and accuracy (RE%) for low and high QC levels were within 1.7-12.3% and -14.4 to 14.1%, respectively. Very good recovery (80.0-119.6%) and matrix effect (±20.0%) values were achieved for all compounds. In addition, fragmentation spectra were collected for all the examined substances, and high-resolution spectra were presented for landiolol and metipranolol, because they are not available in commercial HRMS spectra databases. The developed method was applied in authentic postmortem samples.

Assessment of the in vitro metabolic stability of CEP-37440, a selective FAK/ALK inhibitor, in HLMs using fast UPLC-MS/MS method: in silico metabolic lability and DEREK alerts screening.

CEP-37440 was synthesized and supplied by the research and development division of Teva Branded Pharmaceutical Products (West Chester, PA, United States). CEP-37440 represents a newly developed compound that exhibits selectivity inhibition of Focal Adhesion Kinase and Anaplastic Lymphoma Kinase FAK/ALK receptors, demonstrating novel characteristics as an orally active inhibitor. The simultaneous inhibition of ALK and FAK can effectively address resistance and enhance the therapeutic efficacy against tumors through a synergistic mechanism. The objective of this research was to create an LC-MS/MS method that is precise, efficient, environmentally friendly, and possesses a high level of sensitivity for the quantification of CEP-37440 in human liver microsomes (HLMs). The aforementioned approach was subsequently employed to evaluate the metabolic stability of CEP-37440 in HLMs in an in vitro setting. The validation procedures for the LC-MS/MS analytical method in the HLMs were performed following the bio-analytical method validation guidelines set out by the US-FDA. The AGREE program was utilized to assess the ecological impacts of the current LC-MS/MS methodology. The calibration curve linearity was seen in the range of 1-3000ng/mL. The inter-day accuracy (% RE) exhibited a range of -2.33% to 3.22%, whilst the intra-day accuracy demonstrated a range of -4.33% to 1.39%. The inter-day precision (% RSD) exhibited a range of 0.38% to 3.60%, whilst the intra-day precision demonstrated a range of 0.16% to 6.28%. The determination of the in vitro half-life (t1/2) and moderate intrinsic clearance (Clint) of CEP-37440 yielded values of 23.24min and 34.74mL/min/kg, respectively. The current manuscript is considered the first analytical study for CEP-37440 quantification with the application to metabolic stability assessment. These results suggest that CEP-37440 can be categorized as a pharmaceutical agent with a moderate extraction ratio. Consequently, it is postulated that the administration of CEP-37440 to patients may not lead to the accrual of dosages within the human organs. According to in silico P450 metabolic and DEREK software, minor structural alterations to the ethanolamine moiety or substitution of the group in drug design have the potential to enhance the metabolic stability and safety profile of novel derivatives in comparison to CEP-37440.

Bioanalytical Method Development and Validation of MEM-PLGANanoparticles via Nasal Route Administration.

The aim of this effort is to increase extended pharmaceutical release by systematizing PN elaboration for ME, a novel treatment for Alzheimer’s disease. Bioanalysis is an essential part in drug discovery and development. Bioanalysis is related to the analysis of analytes (drugs, metabolites, biomarkers) in biological samples and it involves several steps from sample collection to sample analysis and data reporting. A simple, sensitive, and quick LC-MS technique for quantifying MEM in rat plasma was developed and validated. Chromatography was carried out on a C18 column (4.6 × 75mm, 3.5μm). ME and its internal standard, NLB, were extracted by direct protein precipitation and were chosen as the sample treatment method rather than liquid-liquid extraction techniques and evaluated with LC-MS/MS in multiple-reaction monitoring (MRM) mode. This approach demonstrated intra- and interday precision in the ranges of 2.1-3.7 and 1.4-7.8%. Furthermore, intra- and interday accuracy ranged from 95.6 to 99.8, and 95.7-99.1%, respectively. MEM and NLB showed mean recovery rates of 86.07 ± 6.87 and 80.31 ± 5.70%, respectively. The stated method was effectively applied in the bioequivalence study of MEM and evaluated its potential for treating Alzheimer’s disease via the nasal route. MEM administered via the nasal route will demonstrate improved bioavailability and efficacy in the treatment of Alzheimer’s disease compared to current therapies.

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.

Development and validation of an LC-MS/MS method for simultaneous quantification of eight drugs in plasma and brain: Application in a pharmacokinetic study in mice

A selective and sensitive liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) method was developed and validated for simultaneous quantitation of a cassette of 8 drugs, including docetaxel, erlotinib, loperamide, riluzole, vemurafenib, verapamil, elacridar and tariquidar. Stable isotopically labeled compounds were available for use as internal standards for all compounds, except for tariquidar for which we used elacridar-d4. Sample pre-treatment involved liquid–liquid extraction using tert-butyl-methyl ether as this resulted in good recovery and low ion suppression. Chromatographic separation was achieved using a Zorbax Extend C18 analytical column and a linear gradient from 20 % to 95 % methanol in 0.1 % (v/v) formic acid in water. MS/MS detection using multiple reaction monitoring was done in positive ionization mode. We validated this assay for human and mouse plasma and mouse brain homogenates. The calibration curves were linear over a range 1–200 nM for each drug in the mix, except for tariquidar probably due to the lack of a stable isotope labeled analog. The intra-day and inter-day accuracies were within the 85–115 % range for all compounds at low, medium and high concentrations in the three different matrices. Similarly, the precision for all compounds at three different concentration levels ranged below 15 %, with the exception of tariquidar in mouse plasma and brain homogenate and riluzole in brain homogenate. Pilot studies have confirmed that the method is suitable for the analysis of mouse plasma samples and brain homogenates following cassette dosing of this mixture in mice.

Bar adsorptive microextraction and liquid chromatography-diode array detection of synthetic cannabinoids in oral fluid

In recent years, synthetic cannabinoids (SCs) have become a major public health issue. For this reason, there is a need for innovative analytical methods that allow its monitoring in biological matrices. In this work, we propose a novel methodology to screen eight SCs (AM-694, cumyl-5F-PINACA, MAM-2201, 5F-UR-144, JWH-018, JWH-122, UR-144 and APINACA) in oral fluids. A bar adsorptive microextraction method followed by microliquid desorption combined with high-performance liquid chromatography with diode array detection (BAµE-µLD/HPLC-DAD) was developed to monitor the target SCs. The main factors affecting the BAµE technology were fully optimized for oral fluid analysis. Under optimized experimental conditions, the proposed methodology showed good linear dynamic ranges from 20.0 to 2000.0 µg L−1 (r2 > 0.99, relative residuals < 15%), limits of detection between 2.0 and 5.0 µg L−1 and suitable average recovery yields (87.9–100.5%) for the eight studied SCs. The intra- and interday accuracies (bias ≤ ± 14.7%) and precisions (RSD ≤ 14.9%) were also evaluated at three spiking levels. The validated methodology was then assayed to oral fluid samples collected from several volunteers. The proposed analytical approach showed remarkable performance and could be an effective alternative for routine monitoring of the target compounds in oral fluid.Graphical

A selective, sensitive and fast LC-MS/MS method for cabotegravir quantification in rat plasma and pharmacokinetic investigations.

This study presents a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying cabotegravir (CAB) in rat plasma. A novel, sensitive, and rapid LC-MS/MS method has been developed and validated. Furthermore, protein precipitation technique allowed us to lowered the limit of quantification (LOQ) to nanogram levels, allowing detection of smaller CAB amounts in plasma samples. A review of scientific literature reveals that this method is superior than published methods in terms of runtime, sensitivity, wide linearity, and cost, using LC-MS/MS to quantify CAB in biological samples. CAB reached its maximum concentration (Cmax) of 78.401 μg/mL in rat plasma at 1.50 h (Tmax). Linearity was evaluated across 0.05-1000 μg/mL for CAB using five calibration curves with at least nine standards each with r2 > 0.9997. The intra- and inter-day precision and accuracy results were below 15% and acceptable as per Food and Drug Administration (FDA) guidelines. Stability of compounds were established in a battery of stability studies, that is, benchtop, autosampler, and long-term storage stability as well as freeze thaw cycles. The validated method can be used as a routine method to support pharmacokinetic studies.

Determination of morphine, codeine, thebaine, papaverine and noscapine in rat plasma by UPLC-MS/MS

AbstractIn this work, a UPLC-MS/MS assay was established for the determination of morphine, codeine, thebaine, papaverine and noscapine in rat plasma. ACQUITY UPLC BEH C18 column was employed for chromatographic separation with the mobile phase comprised acetonitrile-10 mmol L−1 ammonium acetate aqueous solution (0.05% aqueous ammonia) using gradient elution. Midazolam was used as internal standard (IS). Electrospray ionization (ESI) in positive-ion mode with reaction monitoring (MRM) was used for quantitative analysis. The calibration curves for morphine, codeine, thebaine, papaverine and noscapine demonstrated good linearity (r &gt; 0.995) in the range of 5–500 ng mL−1 for morphine and codeine, and 1–100 ng mL−1 for thebaine, papaverine and noscapine. The intra-day and inter-day precisions of morphine, codeine, thebaine, papaverine and noscapine were within 15%, the intra-day and inter-day accuracies were 89–114%, the recovery was better than 65%, and the matrix effects were 96–112%. The developed UPLC-MS/MS assay was successfully applied in the pharmacokinetics of papaverine and noscapine.

Microwave-assisted sample preparation for screening of heavy metal elements in food additives by ICP-MS

The screening of heavy metals in food additives is important for public health due to their probable critical effects, induced by excessive intakes, and difficulties in tracing in food matrix. This study aimed to assess the applicability of microwave (MW)-based digestion and inductively coupled plasma-mass spectrometry (ICP-MS) for quantification of heavy metals in food additives. MW-assisted diluted acid digestion (1550 W at 220 °C, 0.79 mol/L of HNO3 solution) was applied as a pretreatment and ICP-MS was used for 19 different heavy metals at different concentrations, up to 20 ng/g. The optimized protocol was validated by spiking heavy metals to glycerin and applied to 18 food additives. The method was linear for 14 heavy metals (R2 > 0.990). For 11 heavy metals, both intra- and inter-day accuracies in glycerin were estimated to 88.5%–123.7%, with intra- and inter-day precisions of less than 5.5% and 4.9%, respectively, and their contents in food additives were discussed. The findings in this work provide an alternative analytical method for regulatory compliance and quality control in food industries.