Calibration Range Research Articles

A Novel Fluorescent Chemosensor for Sensitive and Rapid Determination of Pb(II) Ions in Aqueous Environments.

This investigation devised an eco-friendly spectrofluorometric Pb(II) ion measurement approach. To determine Pb(II) ions, a polymeric fluorescence sensor membrane with excellent selectivity has been developed. It contains photoinitiators, functional monomers that can be cured under UV radiation, and cross-linking agents. After the characterization of the membrane, the most suitable parameters for the measurement of Pb(II) ions were determined. The measurement was performed in a short time-roughly 40s-at emission and excitation wavelengths of 488nm and 277nm, respectively, at pH 6.0. The developed method's detection limit was calculated as 1.42 × 10- 9 mol L- 1, and its calibration range was recorded as 4.83 × 10- 9 to 9.66 × 10- 8 mol L- 1. Recovery studies and the sensor's stability, lifetime, and repeatability have been evaluated. Real sample applications have been implemented using wastewater samples. The suggested approach may be used to quickly and accurately determine Pb(II) ions at low concentrations with good selectivity and sensitivity.

OPTIMIZATION OF ROBUST HPLC APPROACH FOR ASSESSING PROCESS RELATED IMPURITIES OF LEMBOREXANT AND ELUCIDATION OF STRESS-INDUCED DEGRADATION PRODUCTS THROUGH LCMS/MS

This study primarily aimed to establish an uncomplicated yet highly responsive HPLC technique to effectively separate and quantify process-related impurities of Lemborexant. Additionally, it aimed to explore the forced degradation behavior of lemborexant through systematic assessments by utilizing LCMS. The chromatographic separation of drug substance, process related impurities and its degradation products (DPs) was achieved on Kinetex C18 (150×4.6 mm, 5 μm) column at that was maintained at 350C temperature using 10 mM ammonium formate buffer pH 4.2, acetonitrile and methanol in 65:25:10 (v/v) isocratic elution at 0.7 mL/min. Detection wavelength was selected as 265 nm. In the proposed conditions, lemborexant is identified at 4.06 and 6.19, 9.33 min and 1.60 min respectively for impurity 1, 2 and 3 min with acceptable system suitability and specificity. The method produces LOD at 0.009 for impurities with calibration range of 40–280 µg/mL for lemborexant and 0.04 - 0.28 µg/mL for impurities. The remaining validation parameters were observed to fall within acceptable ranges for both lemborexant and its impurities. The compound underwent exposure to various stress conditions (acid, base, peroxide, thermal, and UV light) as outlined in accordance with ICH Q1A (R2) guidelines. The degradation products formed during the stress study were detected and characterized using LCMS/MS in ESI positive mode. This involved a thorough comparison of collision-induced dissociation mass spectrometry data between the degradation products and lemborexant. Consequently, potential structures for five degradation compounds were proposed. The outcomes of supplementary validation investigations were equally satisfactory, confirming their appropriateness for the regular quantification of lemborexant and its related impurities in both bulk drug and pharmaceutical formulations. Furthermore, these findings have the potential to shed light on the mechanism of stress-induced degradation in lemborexant

A simultaneous analysis strategy of glycerophospholipids and lipid mediators based on secondary extraction scheme.

Lipid peroxidation plays an important role in physiological and pathophysiological conditions; it occurs mainly in the vicinity of the membrane. Glycerophospholipids are indispensable for normal structure of membranes. Lipid mediators are final products of lipid peroxidation. Glycerophospholipids as a source of lipid mediators are closely related with lipid mediators in lipid peroxidation process. This study developed a strategy for simultaneous analysis of glycerophospholipids and lipid mediators in a sample based on a secondary extraction scheme. Due to differences in physicochemical properties of glycerophospholipids and lipid mediators, we used different solvents and methods to extract glycerophospholipids and lipid mediators based on a sample. In addition, we compared three methods of extracting glycerophospholipids to select the best extraction method. In this study, a UPLC-MRM absolute quantification strategy for three deuterated internal standards of lipid mediator was established. The calibration range of all standards is linear, and the correlation coefficients are greater than 0.999. Quantitative range, precision, and accuracy of all analytes-based analysis method meet requirements of method validation. And the accuracy and precision of this method for glycerophospholipids meet the requirements of method verification. It is satisfactory to apply this method in the analysis of the changes of enzymes in lipid peroxidation during the treatment of asthma with dexamethasone. The quantitative results of phospholipids and lipid mediators in mouse lung tissue were obtained by this method, indicating that dexamethasone may inhibit the activity of phospholipase As enzyme and thus slow down the lipid peroxidation process. This work may be of great significance for exploring the changes of enzymes in lipid peroxidation metabolism.

Targeted and Untargeted Amine Metabolite Quantitation in Single Cells with Isobaric Multiplexing.

We developed a single cell amine analysis approach utilizing isobarically multiplexed samples of 6 individual cells along with analyte abundant carrier. This methodology was applied for absolute quantitation of amino acids and untargeted relative quantitation of amines in a total of 108 individual cells using nanoflow LC with high-resolution mass spectrometry. Together with individually determined cell sizes, this provides quantification of intracellularconcentrations within individual cells. The targeted method was partially validated for 10 amino acids with limits of detection in low attomoles, linear calibration range covering analyte amounts typically from 30 amol to 120 fmol, and correlation coefficients (R) above 0.99. This was applied with cell sizes recorded during dispensing to determine millimolar intracellular amino acid concentrations. The untargeted approach yielded 249 features that were detected in at least 25% of the single cells, providing modest cell type separation on principal component analysis. Using Greedy forward selection with regularized least squares, a sub-selection of 100 features explaining most of the difference was determined. These features were annotated using MS2 from analyte standards and accurate mass with library search. The approach provides accessible, sensitive, and high-throughput method with the potential to be expanded also to other forms of ultrasensitive analysis.

Application of salt-assisted liquid extraction in bioanalytical methods

This review provides a comprehensive analysis of bioanalytical methods employed for the quantification of drug molecules in various biological matrices, including human plasma, urine, breast milk, and mouse plasma. The study not only examines traditional sample preparation techniques such as protein precipitation (PP), liquid-liquid extraction (LLE), and solid-phase extraction (SPE), but also delves into the relatively new and innovative salting-assisted liquid-liquid extraction (SALLE). It offers a thorough comparison of analytical methods utilizing SALLE, focusing on key parameters such as analysis time, calibration range, and the type and quantity of salts and organic solvents used. This review aims to serve as an essential resource for researchers and practitioners in selecting the most suitable bioanalytical methods for pharmacokinetic studies and drug monitoring, ultimately enhancing data quality and analytical efficiency in both clinical and research settings.

A Method to Determine Metoclopramide Hydrochloride in Oral Dosage Forms by Micellar Liquid Chromatography

Background: Metoclopramide is a widely prescribed antiemetic drug. Its analysis in pharmaceutical formulations often involves procedures using high amounts of toxic chemicals. Objective: A method based on micellar liquid chromatography to determine metoclopramide hydrochloride in several oral dosage forms has been developed. Methods: The drug was resolved from matrix compounds within 6 min using a C18 column with isocratic elution at 1 mL/min utilizing a solution of 0.10 mol/L sodium dodecyl sulfate – 6 % 1- pentanol phosphate buffered at pH 7 as mobile phase, and detection by absorbance at 210 nm. Samples were dissolved or diluted in the mobile phase and directly injected; thus, only one solution had to be prepared for the entire procedure. Besides, it contained mainly harmless chemicals and a minimal amount of organic solvent. Results The procedure was validated by the International Council of Harmonization guidelines and the results were: specificity, calibration range (0.5 – 5.0 mg/L), linearity (r2 > 0.9990), trueness (98.1 – 100.3 %), precision (< 0.7%), robustness, carry-over effect, and system suitability. It was used to analyze commercial samples. Otherwise, it was found the influence of the surfactant on elution strength was nearly three times stronger than that of 1-pentanol. Conclusion: The procedure was reliable, easy-to-conduct, safe, eco-friendly, short-time, widely available and highly sample-throughput, and then useful for routine analysis of metoclopramidebased dosage forms in pharmaceutical quality control.

Personalization of pharmacotherapy with sirolimus based on volumetric absorptive microsampling (VAMS) in pediatric renal transplant recipients-from LC-MS/MS method validation to clinical application.

The benefits of pharmacotherapy with sirolimus (SIR) in pediatric transplant recipients are well established. Traditionally, whole blood samples have been used to measure SIR concentrations. Volumetric Absorptive Microsampling (VAMS) is an alternative sampling strategy suitable for Therapeutic Drug Monitoring (TDM). In this study, we developed and validated two liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for determining SIR concentrations in whole blood (WB) and capillary whole blood samples collected using a VAMS-Mitra™ device. We used protein precipitation during WB sample preparation and dispersive liquid-liquid microextraction (DLLME) with methyl tert-butyl ether for VAMS sample preparation to optimise the analyte extraction process. The described validation protocols were cross-validated, confirming the equivalence of the whole-blood and VAMS-based methods. Furthermore, the developed methods were evaluated in two three-level rounds of an external proficiency-testing scheme. The analytical methods were successfully validated within the calibration range of SIR (0.5-60 ng/ml). The validation parameters met the European Medicines Agency (EMA) and the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDM&CT) acceptance criteria. No hematocrit (tested in the range of 24.3-64.1%), matrix, or carry-over effects were observed. Cross-validation confirmed the interchangeability between VAMS-LC-MS/MS and WB-LC-MS/MS methods. The developed methods were successfully implemented for SIR determination in 140 clinical samples (70 each of WB and VAMS) from pediatric renal transplant recipients, demonstrating their practicality and reliability. The VAMS-based method has been rigorously tested and is clinically equivalent to the reference WB-LC-MS/MS method. Additionally, clinical validation confirmed the utility of the presented methods for TDM of the SIR in the pediatric population after renal transplantation.

Assessment of OH femtosecond thermally assisted fluorescence thermometry for hydrogen non-premixed flames

In this work, we further developed the planar temperature measurement method based on thermally assisted laser-induced fluorescence (TALF) with a single femtosecond (fs) laser and investigated the temperature distribution in the nitrogen-diluted oxygen–hydrogen cross-jet non-premixed flames at 1 kHz. Fs-TALF thermometry was firstly calibrated and assessed in a series of unconfined methane/air laminar flames at atmospheric pressure. In the calibration process, although the calibrated energy difference between OH v′ = 0 and 1 energy level was different from the theoretical value, the measured fluorescence ratio accurately reflected the temperature change from 1600 K to 2200 K in different methane flames. By comparing the calculated OH fluorescence spectrum, we believed that the main reason was the overlap of the OH (1-1) and (0-0) fluorescence bands. After the calibration, experiments were conducted with changing hydrogen flow velocity from 60 to 100 m/s and constant oxidizer flow velocity, where the dilution ratio, D varies from 0.46 to 0.7, and the equivalence ratio, ϕ, varies from 0.5 to 0.9. It is found, within the calibration range, fs-TALF thermometry can correctly measure the flame temperature. However, with ϕ further increases, the difference between the measured and theoretical temperatures gradually increases. At the same time, it was noted that the error in the measured temperature rises gradually as D decreases. In conclusion, fs-TALF thermometry can measure turbulent non-premixed hydrogen flames accurately in a range of temperature with acceptable temporal and partial resolution, while the errors within 200 K and spatial resolution is 170μm. The main error source should be the collisional effect due to the different local concentration of N2 and H2O. The results of this work will contribute to the further development the temperature measurement method hydrogen turbulent flames.

Intensity- and time-based strategies for micro/nano-sizing via single-particle ICP-mass spectrometry: A comparative assessment using Au and SiO2 as model particles

BackgroundSingle-particle ICP-mass spectrometry (SP-ICP-MS) is a powerful method for micro/nano-particle (MNP) sizing. Despite the outstanding evolution of the technique in the last decade, most studies still rely on traditional approaches based on (1) the use of integrated intensity as the analytical signal and (2) the calculation of the transport efficiency (TE). However, the increasing availability of MNP standards and advancements in hardware and software have unveiled new venues for MNP sizing, including TE-independent and time-based approaches. This work systematically examines these different methodologies to identify and summarize their strengths and weaknesses, thus helping to determine their preferred application areas. ResultsDifferent SP-ICP-MS methods for MNP sizing were assessed using AuNPs (20–70 nm) and SiO2MNPs (100–1000 nm). Among TE-dependent approaches, the particle frequency method was characterized by larger uncertainties than the particle size method. The results of the latter were dependent on the appropriate selection of the reference MNP, making the use of multiple reference MNPs recommended. TE-independent methods were based on external (linear and polynomial) calibrations and a relative approach. These methods exhibited the lowest uncertainties of all the strategies evaluated. External calibrations benefited from simpler calculations, but their application could be hindered by a lack of reference MNPs within the desired size range or by the need for interpolations outside the calibration range. Finally, transit time signals are directly proportional to the MNP size rather than its mass. The time-based method demonstrated adequate performance for sizing AuNPs but failed when sizing the largest SiO2MNPs (1000 nm). Significance and noveltyThis work provides further insights into the application of different SP-ICP-MS methodologies for MNP sizing. Both TE-independent approaches and the monitoring of the transit time as the analytical signal are underused strategies; in this context, a Python script was developed for accurate transit time measurement. After 20 years of development, a quantitative comparison of the different methodologies, including the most novel approaches, is deemed necessary for further growth on solid theoretical ground.

B-167 Quantification of Thyroglobulin in Serum for Clinical Research using SISCAPA Workflow Combined with LC-MS/MS

Abstract Background Accurate measurement of Thyroglobulin (Tg) using existing immunoassay-based techniques can be challenging in the presence of anti-Tg antibodies (TgAb), which can prevent the binding of Tg to assay antibodies thus leading to non-quantifiable Tg concentrations. The Stable Isotope Standards and Capture with Anti-Peptide Antibodies (SISCAPA™) Workflow combined with LC-MS/MS has been successfully employed to circumvent this problem by digesting the serum sample thus eliminating interfering TgAb and measuring a Tg-specific surrogate peptide instead. Methods Using a Andrew+™ Pipetting Robot, denaturation and reduction buffer was added to 250µL serum samples and incubated at 37°C. Internal standard and trypsin were added and samples incubated at 37°C. The samples were quenched with protease inhibitor and Anti-Tg FSP mAb SISCAPA was added to the serum samples and mixed for 60 minutes. Using a magnetic array plate, the beads were left to pull down, samples were discarded, and the beads were twice washed with PBS/CHAPS prior to elution with acetonitrile with formic acid. Using an ACQUITY™ UPLC™ I-Class PLUS FL System, samples were injected onto a Waters™ XSelect™ HSS T3 Column using a water/acetonitrile/formic acid gradient elution profile and the Tg FSP peptide was quantified using a Waters Xevo™ TQ Absolute Mass Spectrometer. Results The method demonstrated no significant carryover or matrix effects and was shown to be linear from 0.1 - 50 ng/mL. Analytical sensitivity investigations indicate the analytical sensitivity of this method would allow precise quantification (<20%) at 0.1 ng/mL with S/N (PtP) >10:1. Coefficients of variation (CV) for total precision and repeatability on 5 analytical runs for low, mid and high QCs were all < 9.5% (n = 25) for both automated and manual precision assessments. Comparison with samples from the UK NEQAS scheme demonstrated significant method bias of -40% for the developed LC-MS/MS method. Re-assignment of the calibrator concentrations using the EQA samples reduced the bias to -5.5%, indicating differences in the calibration materials used for these measurements. Conclusions A LC-MS/MS clinical research method for serum thyroglobulin was developed using SISCAPA, followed by analysis using ACQUITY UPLC I-Class PLUS FL System and the Xevo TQ Absolute Mass Spectrometer. The method provides analytical sensitivity down to 0.1 ng/mL from 250 µL serum, while providing sufficient sample for re-analysis. The method demonstrates excellent linearity across the calibration range, with no significant carryover, interferences, and matrix effects. Total reproducibility and repeatability of the method was ≤9.5% RSD for manual and automated sample preparation, using the Andrew+ Pipetting Robot. In addition, the Andrew+ Pipetting Robot can minimize user touch-time, allowing a full plate to be prepared within four hours without user intervention.

B-357 Siemens CA 72-4: an assay for measurement of Tumor Associated Glycoprotein (TAG) 72

Abstract Background The tumor associated glycoprotein (TAG) 72, also known as CA 72-4 is a mucin protein of high molecular weight. CA 72-4 is found on the surface of many cancer cells, including stomach (gastric), ovary, breast, colon and pancreatic cells. CA 72-4 is currently one of the primary markers for the diagnosis of gastric cancer and monitoring the course and efficacy of gastric cancer. In ovarian cancer, it has a higher sensitivity for mucin- type ovarian cancer, and its combination with CA125 for detection can significantly improve the clinical sensitivity. In colorectal cancer, CA 72-4 combined with CEA detection was also found to significantly improve the sensitivity of the initial diagnosis. An assay for CA 72-4 on Siemens Atellica IM (Siemens CA 72-4) is being developed and analytical performance is being presented. Methods The Siemens CA 72-4 assay (in development) is a one-step chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of CA 72-4 in human serum and plasma. The specimen is incubated with paramagnetic microparticles coated with the monoclonal antibody (mAb) B72.3 and acridinium-labeled mAb CC49 conjugate on the Siemens Atellica IM® System. After incubation and washing, Acid and Base reagents are added. The resulting relative light units (RLUs) are directly proportional to the amount of CA 72-4 in the sample allowing for the quantitative determination of CA 72-4 in the specimen. Results The following performance were determined using 3 unique lots of reagents and calibrators with the calibration range for the assay being 0.00 to 200.00 U/mL. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation at 20% CV (LoQ) were determined and met the goal of ≤ 1.00 U/mL. Linearity according to CLSI EP06 Ed2 was demonstrated for a range of 1.00 through 200.00 U/mL. A Precision study of 2 controls and 5 panels spanning the range of the assay demonstrated a total %CV ≤ 6% for samples ≥ 5.00 U/mL and ≤ 0.25 SD for samples <5.00 U/mL. In the sample tube type study, a matrix comparison of 23 matched serum and plasma samples were evaluated. Passing-Bablock slopes of < 8% and r > 0.99 were observed when evaluating samples within the measurement range for plasma (LiHep, LiHep separator, K2EDTA and K3EDTA) tubes and serum separator tubes (SST) compared to the Red Top serum samples. Five endogenous substances were evaluated for interference in the CA 72-4 assay. The average percent difference between test and control samples for all endogenous interferents was < 10%. Percent difference in the presence of 28 potentially interfering drugs was ≤ 4.0%. Conclusions The Siemens CA 72-4 assay currently in development is a sensitive and precise assay for the quantitative determination of CA 72-4 in human serum and plasma.

B-356 Siemens CYFRA 21-1: an assay for measurement of cytokeratin fragment 21-1

Abstract Background Cytokeratins are structural proteins forming the subunits of epithelial intermediary filaments. The soluble fragment of cytokeratin 19, cytokeratin fragment 21-1 (CYFRA 21-1), can be found in the blood of lung cancer patients, primarily those with non-small cell lung cancer (NSCLC). CYFRA 21-1 is the preferred biomarker in the management of NSCLC, particularly squamous cell and large cell carcinoma subtypes. An assay for CYFRA 21-1 on Siemens ADVIA Centaur® XPT and Siemens Atellica® IM (Siemens CYFRA) is being developed and analytical performance is being presented. Methods The Siemens CYFRA 21-1 assay (in development) is a one-step chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of CYFRA 21-1 in human serum and plasma. The specimen is incubated with paramagnetic microparticles coated with the monoclonal antibody (mAb) BM19.21 and acridinium-labeled mAb KS19.1 conjugate on the Siemens ADVIA Centaur XPT System and Siemens Atellica IM System. After incubation and washing, Acid and Base reagents are added. The resulting relative light units (RLUs) are directly proportional to the amount of CYFRA 21-1 in the sample allowing for the quantitative determination of CYFRA 21-1 in the specimen. Results The following performance were determined using 3 unique lots of reagents and calibrators with the calibration range for the assay being 0.00 to 100.00 ng/mL. For the ADVIA Centaur XPT and Atellica IM systems were shown to be equivalent within 4%. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation at 20% CV (LoQ) were determined and met the goal of ≤ 1.00 ng/mL. Linearity according to CLSI EP06 Ed2 was demonstrated for a range of 0.66 through 100.00 ng/mL. A Precision study of 2 controls and 5 panels spanning the range of the assay demonstrated a total %CV ≤ 8% at all levels. In the sample tube type study, a matrix comparison of 61 matched serum and plasma samples were evaluated. Passing-Bablock slopes of < 5% and r > 0.99 were observed when evaluating samples within the measurement range for plasma (LiHep, LiHep separator, K2EDTA and K3EDTA) tubes and serum separator tubes (SST) compared to the Red Top serum samples. Six endogenous substances were evaluated for interference in the CYFRA 21-1 assay. The average percent difference between test and control samples for all endogenous interferents was < 10%. Percent difference in the presence of 20 potentially interfering drugs was ≤ 4.0%. Conclusions The Siemens CYFRA 21-1 assay currently in development is a sensitive and precise assay for the quantitative determination of CYFRA 21-1 in human serum and plasma.

B-358 Siemens NSE: an assay for measurement of human Neuron-Specific Enolase

Abstract Background Neuron-specific enolase (NSE), a glycolytic enzyme (2-phospho-D-Glycerate hydrolase) can be found in a variety of non-neuroendocrine cells. Determination of NSE is used for monitoring response to therapy and detection of recurrent disease, such as SCLC and neuroendocrine tumors. An assay for NSE on Siemens ADVIA Centaur® XPT System and Siemens Atellica® IM system (Siemens NSE) is being developed and analytical performance is being presented. Methods The Siemens NSE assay (in development) is a one-step chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of NSE in human serum. The specimen is incubated with paramagnetic microparticles coated with the monoclonal antibody (mAb) NSE21, and acridinium-labeled mAb NSE17 conjugate on the Siemens ADVIA Centaur XPT system and Siemens Atellica IM system. After incubation and washing, Acid and Base reagents are added. The resulting relative light units (RLUs) are directly proportional to the amount of NSE in the sample allowing for the quantitative determination of NSE in serum. Results The following performance were determined using 3 unique lots of reagents and calibrators with the calibration range for the assay being 0.0 to 400.0 ng/mL. For the ADVIA Centaur XPT and Atellica IM systems were shown to be equivalent within 2%. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation at 20% CV (LoQ) were determined and met the goal of ≤ 1.6 ng/mL. Linearity according to CLSI EP06 Ed2 was demonstrated for a range of 1.6 through 400.0 ng/mL. A Precision study of 2 controls and 6 panels spanning the range of the assay demonstrated a total %CV ≤ 7% at all levels. Comparison of 50 specimens collected in Red Top serum and Serum Separator Tubes (SST) had a Passing-Bablock slope of < 2% and r of > 0.99 when evaluating samples within the measurement range. Five endogenous substances were evaluated for interference in the Siemens NSE assay. The average percent difference between test and control samples for all endogenous interferents was < 10%. Percent difference in the presence of 38 potentially interfering drugs was ≤ 10.0%. The potential cross-reactant αα enolase was evaluated at concentration of 900 ng/mL and the percent cross-reactivity was ≤ 2%. Conclusions The Siemens NSE assay currently in development is a sensitive and precise assay for the quantitative determination of NSE in human serum.

Evaluation of 4 quantification methods for monitoring 16 antidepressant drugs and their metabolites in human plasma by LC-MS/MS

BackgroundTherapeutic drug monitoring for antidepressants (ADs) is vital due to the potentially serious consequences and disputes related to medical events. Therefore, we created a quick and convenient analysis way for separation and quantification of ADs. MethodsTo ensure quantitative stability, we divided the 16 ADs or their metabolites into 4 pools (AD1-AD4), considering the hospital frequency that the clinician prescribed, the physicochemical properties of medicines, and the calibration range of selected ADs. After precipitation with methanol, the analytes were eluted for at least 3.5 min on a BEH C18 analytical column by different gradient elution methods. Results: The LLOQ and LOD were 1.25–10 ng/mL and 0.42–5 ng/mL, respectively. High precision (<12 %) and accuracy (87.07–111.47 %) were demonstrated by quality control samples both within and between days. All the compounds were stable at room temperature and within −80 °C. ConclusionThe method is of wide clinical and laboratory interest due to simpler sample cleanup, shorter chromatographic run times, and wider calibration range compared to other methods.

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.

Sensitive and selective determination of upadacitinib using a custom-designed electrochemical sensor based on ZnO nanoparticle-assisted molecularly imprinted polymer.

Upadacitinib (UPA) is a selective and reversible oral Janus kinase (JAK) 1 inhibitor and is of great importance in treating inflammatory bowel disease (Zheng et al., Int Immunopharmacol 126:111229, 2024; Foy et al., JAAD Case Rep 42:20-22, 2023). Although there are limitations to the effectiveness of UPA, it has received positive responses in clinical trials and is approved for the treatment of atopy dermatitis (AD) (Li et al., Int Immunopharmacol 125:111193, 2023). In this study, a nanoparticle-doped molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for sensitive and selective detection of UPA. The developed sensor was designed as a thin film layer using the photopolymerization method on the surface of the prepared nanoparticle-doped polymerization solution glassy carbon electrode (GCE). Various nanoparticles, such as multi-walled carbon nanotube, titanium dioxide, oxide, and zinc oxide (ZnO) nanoparticles, were the most suitable for UPA. Surface characterization of the developed sensor was done by scanning electron microscopy (SEM), and electrochemical characterization was done by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The quantitative analysis of UPA was performed in 5.0mM [Fe (CN)6]3-/4- solution using the differential pulse voltammetry (DPV) technique. Under optimum conditions, the calibration range was between 0.1 and 1pM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.005pM and 0.017pM, respectively. The sensor's accuracy was proven by performing a recovery study in serum. The sensor's selectivity was also evaluated using common interfering substances such as KNO3, CaCl2, Na2SO4, uric acid, ascorbic acid, dopamine, and paracetamol. According to the results obtained, the performance of the designed sensor was found to be quite sensitive and selective in determining UPA. The developed UPA-ZnO/3-APBA@MIP-GCE sensor showed high sensitivity and selectivity towards UPA. In addition, the selectivity, the most important feature of the MIP-based sensor, was confirmed by imprinting factor (IF) calculations using tofacitinib (TOF) and ruxolitinib (RUX). The sensor's unique selectivity is demonstrated by its successful performance even in the presence of UPA impurities.

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.

Characterisation studies of two front-end electronics chips designed for SiPM readout

A new front-end ASIC named ”PIST” (pico-second timing) has been successfully developed using 55 nm CMOS technology for the silicon photomulplier (SiPM) readout with a single channel with a major aim of fast timing. We performed extensive tests to evaluate the timing performance of a dedicated test stand equipped with a PIST chip. The results show that the system timing resolution can reach sub 10 ps for large SiPM signals, while the PIST intrinsic timing resolution is better than 5 ps. The PIST dynamic range has been further extended using the time-over-threshold (ToT) technique. Meanwhile, we fully characterised a new commercially available SiPM-readout 32-channel ASIC for developments of future high-granularity crystal calorimetry, including the single photon calibration and the dynamic range of different gain regions. Other promising potentials include fast timing resolution, fast readout speed and low power dissipation. Comprehensive measurements were made with a laser beam and high-energy particle beams with crystals and SiPMs. First testing results show that this chip has an excellent signal-to-noise and a large dynamic range. This contribution will introduce the ASICs as well as dedicated test stands and also present highlighted results including the timing resolution, single photon calibration and dynamic range.

Sequential Injection Analysis Method for the Determination of Glutathione in Pharmaceuticals.

A sequential injection analysis method for the determination of glutathione (GSH) in pharmaceuticals has been developed. It is based on the reduction of the Cu(II)-neocuproine complex by GSH and the formation of an orange-yellow colored Cu(I)-neocuproine complex with maximum absorbance at 458 nm. Under optimal conditions the method is characterized by a linear calibration range of 6.0 × 10-7-8.0 × 10-5 mol L-1 (Amax = 3270 CGSH - 0.0010; R2 = 0.9983), limit of detection of 2.0 × 10-7 mol L-1, limit of quantification of 6.7 × 10-7 mol L-1, repeatability (expressed as relative standard deviation) of 3.8%, and sampling rate of 60 h-1. The newly developed method has been successfully applied to the determination of GSH in pharmaceutical samples with no statistically significant difference between the results obtained and those produced by the standard Pharmacopoeia method.

A data science pipeline applied to Australia's 2022 COVID-19 Omicron waves

The field of software engineering is advancing at astonishing speed, with packages now available to support many stages of data science pipelines. These packages can support infectious disease modelling to be more robust, efficient and transparent, which has been particularly important during the COVID-19 pandemic. We developed a package for the construction of infectious disease models, integrated it with several open-source libraries and applied this composite pipeline to multiple data sources that provided insights into Australia's 2022 COVID-19 epidemic. We aimed to identify the key processes relevant to COVID-19 transmission dynamics and thereby develop a model that could quantify relevant epidemiological parameters.The pipeline's advantages include markedly increased speed, an expressive application programming interface, the transparency of open-source development, easy access to a broad range of calibration and optimisation tools and consideration of the full workflow from input manipulation through to algorithmic generation of the publication materials. Extending the base model to include mobility effects slightly improved model fit to data, with this approach selected as the model configuration for further epidemiological inference. Under our assumption of widespread immunity against severe outcomes from recent vaccination, incorporating an additional effect of the main vaccination programs rolled out during 2022 on transmission did not further improve model fit. Our simulations suggested that one in every two to six COVID-19 episodes were detected, subsequently emerging Omicron subvariants escaped 30–60% of recently acquired natural immunity and that natural immunity lasted only one to eight months on average. We documented our analyses algorithmically and present our methods in conjunction with interactive online code notebooks and plots.We demonstrate the feasibility of integrating a flexible domain-specific syntax library with state-of-the-art packages in high performance computing, calibration, optimisation and visualisation to create an end-to-end pipeline for infectious disease modelling. We used the resulting platform to demonstrate key epidemiological characteristics of the transition from the emergency to the endemic phase of the COVID-19 pandemic.