Limit Of Quantitation Research Articles

Computational simulation-assisted template selection of magnetic MOFs molecularly imprinted materials applying the adsorption and detection of multiple fluoroquinolones

This study utilized computational simulation and surface molecular imprinting technology to develop a magnetic metal-organic framework molecularly imprinted polymer (Fe3O4@ZIF-8@SMIP) capable of selectively recognizing and detecting multiple fluoroquinolones (FQs). The Fe3O4@ZIF-8@SMIP material was synthesized using the “common” template-ofloxacin, identified by computational simulation, demonstrating notable adsorption capacity (88.61–212.93 mg g−1) and rapid mass-transfer features (equilibration time: 2–3 min) for all tested FQs, consistent with Langmuir adsorption model. Subsequently, this material was employed as a magnetic solid-phase-extraction adsorbent for adsorption and detection of multiple FQs by combining with high performance liquid chromatography. The developed method exhibited good linearity for various FQs within the concentration range of 0.1–500 μg L−1, with low limit of detection (0.0605–0.1529 μg L−1) and limit of quantitation (0.2017–0.5097 μg L−1). Satisfactory recoveries (88.38–103.44%) were obtained when applied to spiked food samples, demonstrating the substantial potential of this Fe3O4@ZIF-8@SMIP material for rapid enrichment and identification for multiple FQs residues.

Development and validation of a precise flow injection method for the assessment of brexpiprazole, with application to pharmaceutical dosage forms and human plasma analysis

A novel antipsychotic medication named brexpiprazole (BRX) is currently employed for the treatment of schizophrenia and other psychotic disorders. Because BRX’s molecular structure includes a benzothiophene ring, it natively fluoresces. To detect BRX with precision and speed, a flow injection-fluorometric method, which is both sensitive and selective, is recommended. The fluorescence detection was conducted at 364 nm following excitation at 326 nm to capture the strong intrinsic fluorescence of BRX. The carrier solution employed was a mixture of phosphate buffer (pH 4, 10 mM) and acetonitrile (50: 50, v/v), with a flow rate of 0.5 mL min− 1. The calibration curve, based on peak areas, exhibited linearity within the concentration range of 20–350 ng mL− 1, with a remarkable correlation coefficient (r2) of 0.9999. The limit of quantitation was 9.7 ng mL− 1, and the limit of detection was found to be 3.2 ng mL− 1. This method was applied to quantify BRX in Neopression® tablets, achieving recovery within an acceptable range without interference from the tablet’s additives. Additionally, the proposed approach was successfully utilised to quantify the drug in spiked human plasma. The approach underwent validation following ICH requirements.

Electrochemical aptasensor based on RGO/PPy/Au*NPs for diagnostic biosensing of SARS-CoV-2 in clinical samples: Experimental and molecular dynamics simulations approaches

A highly sensitive and selective E-DNA biosensor was fabricated on a gold substrate using a reduced graphene oxide/polypyrrole/gold nanoparticle/oligonucleotide (RGO/PPy/Au*NPs/Apt) nanocomposite electrode to detect the nucleocapsid protein of SARS-CoV-2 in the patient blood plasma. The modified electrode was characterized by physicochemical techniques such as Fourier transform-infra red (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS) analyses, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) analyses. Moreover, electrochemical analyses were employed to study the electrochemical performance of the electrodes including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). Computational investigations of N protein bindings such as hydrogen bonding, Van der Waals binding, and Gibbs binding energies of the N-protein, and aptamer were studied by Molecular Dynamics Simulations (MDS). The unique synergistic effect of RGO, PPy, and the well-known effect of Au nanoparticles makes the DNA probe immobilized on the gold electrode surface. After optimizing the systems, the E-DNA biosensor exhibited a fast SWV response, higher sensitivity (33.77 μA.nM−1.cm−2) and selectivity, high efficiency, good storage stability, and acceptable repeatability for monitoring DNA. The results of real samples based on SWV indicated the correct functioning of the aptasensor in the presence of the SARS-CoV-2 virus. The limit of detection was 3.16×10−17 M and the limit of quantitation was 1.42×10−16 M. The MDS results indicated the stable dynamic folding of the aptamer for beneficial binding. The results indicated that the RGO/PPy/Au*NPs/Apt biosensor is promising for detecting of SARS-CoV-2 virus.

Analytical and Clinical Validation of a Non-Ristocetin Based VWF Assay on 2 Automated Analyzers in a Large Reference Laboratory.

Historically, von Willebrand factor (VWF) activity assays utilized ristocetin despite limitations including poor limits of detection and high imprecision. Newer VWF activity assays such as the INNOVANCE® VWF Ac assay, however, do not rely on ristocetin to measure platelet-dependent VWF function. The purpose of this study was to evaluate the analytical and clinical performance of the Siemens Healthineers INNOVANCE VWF Ac Assay on the Siemens BCS® XP and the Sysmex® CS-2500 systems in a large reference laboratory setting. Performance indicators for the INNOVANCE VWF Ac assay were the limit of quantitation (LoQ), precision, and method comparison. Method comparison studies were performed using remnant plasma patient samples from routine coagulation tests and analyzed using both the INNOVANCE VWF Ac assay and the Siemens Healthineers ristocetin-dependent BC von Willebrand Reagent. Evaluation of the INNOVANCE VWF Ac assay on the BCS® XP and CS-2500 systems demonstrated good precision and a lower LoQ compared to the BC von Willebrand Reagent. Method comparisons support the use of the INNOVANCE VWF Ac assay on the BCS® XP and CS-2500 systems to measure platelet-dependent VWF function. The INNOVANCE VWF Ac assay was able to further assist in von Willebrand disease classification in 6/7 (86%) samples when the result was below the LoQ for the BC von Willebrand Reagent (ristocetin cofactor activity). These data are consistent with the 2021 American Society of Hematology/International Society on Thrombosis and Haemostasis/National Hemophilia Foundation/World Federation of Hemophilia von Willebrand disease guidelines that suggest using newer assays such as the INNOVANCE VWF Ac assay in place of ristocetin cofactor activity assays.

Molecularly imprinted polymer based on covalent organic framework coated steel substrate as the mass spectrometric ionization source for the direct detect of aflatoxins in complex food matrices

Ambient mass spectrometry allows direct analysis of various sample types with minimal or no pretreatment. However, due to the influence of matrix effects, there are sensitivity and issues in analyzing trace analytes in complex food samples. In this work, we developed a spray mass spectrometry platform based on SSS@TPBD-TPA@MIPs (Stainless steel substrate (SSS), terephthalaldehyde (TPA), N, N, N′, N′-tetrakis(p-aminophenyl)-p-phenylenediamine (TPBD), molecularly imprinted polymer (MIP)), for rapid, in situ, high-throughput, highly enrichment efficiency and highly selective trace analysis of aflatoxins. By simplifying the sample pretreatment and directly applying high voltage for ESI-MS, the analysis can be completed within 1 min. The established method base on SSS@TPBD-TPA@MIPs exhibited high sensitivity and accuracy when determine trace level AFs in maize and peanuts. The results demonstrated a good linear relationship within the range of 0.01–10 μg/L, with the determination coefficient (R2) ≥ 0.9956. The limits of detection (LODs) was 0.035–0.3 ng/mL and limits of quantitation (LOQs) was 0.12–0.99 ng/mL, with acceptable recovery rate of 82.09–115.66 % and good repeatability represented by the relative standard deviation (RSD) less than 17.43 %. Furthermore, SSS@TPBD-TPA@MIPs exhibited excellent reusability, with more than 8 repeated uses, and showed good adsorption performance.

Miniaturized green capillary electrophoresis system for the simultaneous analysis of Linagliptin and cefiximein in plasma

A novel combination therapy, consisting of the antidiabetic drug linagliptin (LIN) and the third-generation cephalosporin antibiotic cefixime (CEF), has recently been introduced to combat infections in diabetic patients. However, there is no published method for their in-vivo simultaneous determination in clinical biological specimens to support their pharmacokinetics and therapeutic monitoring. This study focuses on the development of a miniaturized capillary electrophoresis system-assisted with photodiode array detection (CE-PDA) for the simultaneous determination of LIN and CEF in clinical settings for analysis of plasma samples containing LIN and CEF. The conditions of electrophoretic separation of LIN, CEF, and Ibuprofen (as an internal standard), and the analysis procedures were successfully established. The linear range of the CE-PDA method was determined to be 0.5–100 µg mL−1 for LIN and 1–100 µg mL−1 for CEF. The CE-PDA approach exhibited high sensitivity, with limits of quantitation of 0.9 µg mL−1 for LIN and 1.2 µg mL−1 for CEF. In addition, the CE-PDA system was validated, and subsequently applied to real plasma samples withdrawn from rats received concurrent administration of LIN and CEF. The plasma protein was precipitated by acetonitrile. The miniaturized features of the system and its environmental impact were confirmed using three different metric tools. Additionally, the proposed CE-PDA system proved to be time-saving and cost-effective, making it highly suitable for therapeutic drug monitoring of LIN and CEF in clinical settings.

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

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

An HPLC-UV Method to Assess Human Plasma 25(OH)D3.

The aim of this study was to validate an HPLC-UV method to assess vitamin D status by determining the linearity and precision of the 25-hydroxyvitamin D3 (25(OH)D3) calibration curve, the limits of detection, quantitation and robustness of the method, and its accuracy. A second stock solution of 25(OH)D3 was prepared (500 ng/mL), and working dilutions (5, 10, 20, 30, 40, and 50 ng/mL) were prepared for a calibration curve. The HPLC equipment had a UV-Vis diode-array detector and utilized an AcclaimTM 120 C18 column (5 µm, 4.6 × 250 mm) with a flow rate of 1.2 mL/min, a column temperature of 30 °C, and the standards and samples were maintained at 4 °C, with an injection volume of 100 µL. Detection of 25(OH)D3 was determined at 265 nm, with a retention time of 4.0 min. The validation was conducted according to the FDA Validation of Analytical Procedures: Guidance for Industry. Vitamin D was extracted from plasma samples using acetonitrile (ACN)-0.1% formic acid (2:1 v/v), and the percentage of recovery was calculated. The proposed method conditions gave excellent linearity (R2 = 0.9989) and the linearity coefficient was R2 > 0.99 for 25(OH)D3. The detection and quantification limits were 1.1703 ng/mL and 3.5462 ng/mL, respectively. Decreasing or increasing the reading temperature by 1 °C decreased the response units (AU) of vitamin D, 25(OH)D3. When the current flow rate decreased by 0.2 mL/min (1.0 mL/min), the retention time increased to 4.913 min, whereas an increase of 0.2 mL/min of the proposed flow rate (1.4 mL/min) decreased the retention time to 3.500 min. The percentage of recovery varied from 92.2% to 97.1%. The proposed method to quantify a vitamin D metabolite (25(OH)D3) in human plasma samples was reliable and validated.

Real-time cationic sensing using plasmonic fiber optic sensor based phosphoryl-carrageenan

We report Fiber Optic-Localized Surface Plasmon Resonance (FO-LSPR) spectroscopy sensors comprising a coating of spherical silver nanoparticles (AgNPs) embedded in phosphoryl-carrageenan. This is a novel report on modified carrageenan namely phosphoryl-carrageenan as sensing materials for cations specifically ammonium ions (NH4+). The morphology of carrageenan and phosphoryl-carrageenan coatings on the fiber optic probe was uneven and wavelike topography, indicating the successful coating on the fiber optic probe surface. The FO-LSPR showed a distinct dip in reflectivity in the region of 370–400 nm due to the resonance frequency of spherical AgNPs. The response and recovery times of FO-LSPR sensors for 1 ppm NH4+ and deionized water were <20 s and ∼1.2 minutes, respectively, with five times stable repeatability. The sensitivity of the FO-LSPR phosphoryl-carrageenan was 3.441 nm/ppm. Equally, the limits of detection and quantitation of fiber optic FO-LSPR were 0.336 and 1.018 ppm, respectively. Meanwhile, the dynamic range of the FO-LSPR was 0.3 – 2.0 ppm. The proposed sensor demonstrated strong selectivity towards NH4+ over common cationic interferents. Furthermore, the reported FO-LPSR sensor offered a comparable measurement performance to current methods, while being low cost and portable, and allowing in-situ real-time monitoring of cation ammonium. Thus, reported FO-LPSR sensors are highly promising for water monitoring applications.

A green, fluorescent probe employing erythrosine-B for tracing the accidental administration of levamisole in milk and plasma samples.

A simple and sensitive fluorescent probe has been developed and optimized to detect the non-intentional administration of levamisole (LVM). LVM is used as an anthelmintic therapy in cows, and hence, its residues appear in the drained milk until 60 hours after administering the drug. Meanwhile, levamisole is known to be an adulterant to cocaine and could be detected in addicts' plasma samples. Owing to its severe side effects, including agranulocytosis, which is lethal in many cases, detection and quantification of LVM in milk and plasma samples are of utmost importance. Therefore, a sensitive and selective analytical method is required for this purpose. This work develops a highly fluorescent probe obtained through the reaction between LVM and erythrosine-B in an acidic medium, where the produced ion pair complex has been measured at 553 nm after excitation at 528 nm. The proposed method provides linearity over the concentration range of 0.5-2.0 μg mL-1 for LVM, with a corresponding detection and quantitation limit of 0.5 and 0.3 μg mL-1. Full validation was performed, permitting the application of the suggested method to perform simple extraction steps. All the applied procedures followed the guidelines offered by green analytical chemistry, where the Green Analytical Procedure Index (GAPI) assessed the greenness of the proposed tool, and the yielded pictograms proved the eco-friendliness of the offered tool.

Analytical Method Development and Validation of Faricimab Injection by RP-HPLC

A robust and reliable Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) method was developed and validated for the quantitative analysis of Faricimab in Vabysmo injections. Faricimab, an IgG1-based bispecific antibody targeting VEGF-A and Ang-2, is used for treating retinal vascular disorders like age-related macular degeneration and diabetic macular edema. The method development involved the use of an Inertsil C18 column (250 x 4.6 mm, 5 µm) with a mobile phase composed of KH2PO4 (pH 4.6) and methanol in a 1:1 ratio, sonicated for 20 minutes. The developed method was evaluated for various validation parameters as per ICH guidelines, including linearity, precision, accuracy, and sensitivity. Linearity was demonstrated within the concentration range of 50-150 µg/ml with a correlation coefficient (R²) of 0.999. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.050 µg/ml and 0.166 µg/ml, respectively, indicating high sensitivity. Precision, expressed as relative standard deviation (RSD), was below 0.1%, confirming the method's reliability. Accuracy was assessed, with mean assay values ranging between 97-101%, and RSD below 0.2%, indicating the method's precision. Robustness tests confirmed the method's resilience against slight variations in analytical conditions such as acetonitrile ratio, flow rate, detection wavelength, and pH. Stability studies showed that Faricimab remains stable under various stress conditions, including exposure to 0.1N HCl, 0.1N NaOH, 30% peroxide, heat, and sunlight, with assay values ranging from 88.93% to 94.07%. The optimized RP-HPLC method ensures good peak shape and resolution, making it suitable for routine quality control of Faricimab in pharmaceutical formulations. The validated method adheres to ICH guidelines, ensuring its reliability for consistent and accurate quantification of Faricimab

Ecofriendly micellar mediated spectrofluorimetric method for ultrasensitive quantification of the antiparkinsonian drug safinamide in pharmaceutical formulation and spiked human plasma

A novel, highly sensitive and eco-friendly micellar-mediated spectrofluorimetric method was developed and validated for the determination of the novel antiparkinsonian drug safinamide mesylate in the presence of its related precursor impurity, 4-hydroxybenzaldehyde. The proposed approach relies on increasing the inherent fluorescence emission at 296 nm of safinamide, by forming hydrogen bonds between the mentioned drug and sodium dodecyl sulfate in the micellar system using 0.1 N HCl as a solvent, following excitation at 226 nm. A thorough investigation was conducted into the experimental factors affecting spectrofluorimetric behavior of the studied drug. A linearity plot of safinamide over the concentration range of 10.0–1000.0 ng/mL against the relative fluorescence intensities was established. The proposed method demonstrated excellent sensitivity down to the nano-gram level with detection and quantitation limits of 1.91 and 5.79 ng/mL, respectively. The studied drug was effectively determined in Parkimedine® Tablets. Furthermore, the proposed method allows for ultrasensitive quantification of safinamide in spiked human plasma, with satisfactory percentage recovery (98.97–102.28%). Additionally, the greenness assessment using the advanced green certificate classification approach, the complementary green analytical procedure index (Complex-GAPI), and the analytical GREEness metric approach (AGREE), along with the practicality check using the Blue Applicability Grade Index in addition to the all-inclusive overall whiteness evaluation using the RGB-12 model were carried out. The outcomes demonstrated the effectiveness and whiteness of the proposed technique. Clearly, the suggested approach has the advantages of being simple, requiring no pretreatment steps, and relying solely on direct measuring procedures.

Determination of Nicotine in Juices, Soft and Energy Drinks collected from Libyan Local Markets Using UV–Visible Spectrophotometer

This study aims to determine the nicotine in juices, soft and energy drinks using a UV-Visible spectrophotometer. In the presented study, sixteen samples (four juices, seven soft drinks, and five energy drinks) are collected from local markets in El-Beida - Libya. A rapid, simple, and reliable extraction method is developed and validated for the determination of nicotine in the samples under study using spectrophotometric methods. The method is validated over a wide linear range of 1.62–81.06 µg/mL with correlation coefficients being consistently greater than 0.9999 by UV-Visible Spectrophotometer. The minimum nicotine level was observed in the juices samples, while the energy drinks samples showed the highest nicotine content. The spectrophotometric measurement indicates that the results of nicotine concentrations in juices samples are in the range of 0.3233 - 0.5238 µg/mL, whereas its concentrations in soft drinks samples are in the range of 0.7251 - 0.9949 µg/mL, and the concentrations in energy drinks samples are in the range of 0.8521 - 1.3471 µg/mL. The criteria considered for validation are linearity, the limit of detection, and the limit of quantitation. The nicotine contents in all the samples analyzed in our study were below the allowable limits set by the US Food and Drugs Administration.

Preparation of pyridoxine-based polyurethane modified sensors and their use in simultaneous determination of Cu(II) – Co(II) ions

In this study, pyridoxine-based polyurethane-modified electrodes were prepared to simultaneously and sensitively measure copper (Cu(II)) and cobalt (Co(II)) ions in complex matrix samples. For the production of the electrodes, firstly, the synthesis of pyridoxine-based polyurethane structures was carried out. In these syntheses, the polymer structure was diversified by using different isocyanates. Polyethyleneglycol-200 (PEG), pyridoxine (B6), and β-cyclodextrin (β-CD) groups were used as the source of polyol. The synthesized polyurethane structures were characterized by different instrumental techniques and used in gold electrode surface modification. Modified sensor surfaces were examined by scanning electron microscopy and atomic force microscopy techniques. The prepared modified sensors were used for the simultaneous detection of Cu(II) and Co(II) ions using the differential pulse voltammetry technique. The limit of detection (LOD), limit of quantitation (LOQ), and R2 values for Cu(II) ions were calculated as 8.81 μM, 29.4 μM, and 0.993, respectively. LOD, LOQ, and R2 values for Co(II) ions were calculated as 9.84 μM, 32.8 μM, and 0.9935, respectively. For repeatability, the relative standard deviation (RSD %) of the prepared simultaneous sensors was determined as 1.54 and 1.71 for Cu(II) and Co(II), respectively. As a result, Cu(II) and Co(II) ions were measured independently and simultaneously with high sensitivity. According to these results, it is predicted that pyridoxine-based polyurethane-modified sensors may be suitable for the simultaneous detection of Cu(II) and Co(II) in medical, food, and agricultural samples.

Impact of environmental regulation on M&As in the manufacturing sector

We test the influence of environmental regulation (ER) on the location decision of cross-border Mergers and Acquisitions (M&As) for a large sample of countries, sectors, and years using a structural gravity model. Unlike other studies, our results confirm the pollution haven hypothesis according to which more stringent ER makes countries less attractive to foreign investors planning to invest through M&As, compared with domestic investors. Policies that set quantitative limits on emissions have similar discouraging effects on cross-border investment to taxes on emissions. We find no evidence that the impact could be stronger in dirty sectors than in clean sectors. The impact of ER differs depending on country type according to their level of development, reflecting the fact that investments in developed countries and BRICS respond to different motivations. In emerging countries, lax ER could attract significantly more inward M&As. In developed countries, ER has a less discouraging effect.

Routine method for the analysis of microplastics in natural and drinking water by pyrolysis coupled to gas chromatography-mass spectrometry

The presence of microplastics (MPs) in water intended for human consumption represents a growing concern due to their ubiquity in the aquatic environments and the potential adverse effects on human health. In this context, validated and standardized analytical methods are required to minimize uncertainties associated with the determination of MPs in water, especially during the drinking water treatment process. In this study, a simple water sampling and extraction procedure and analysis using pyrolysis with gas chromatography coupled to mass spectrometry (Py-GC–MS) was developed to determine 7 types of polymers in water. Quality parameters associated with the method were evaluated, including limits of detection (MDL) and quantitation (MQL), linearity, precision, accuracy, and extended uncertainty. The developed methodology was validated by participating in the EUROQCHARM interlaboratory exercise, and the Z-scores were within the acceptable range for 4 of the 5 polymers tested. Finally, MPs were determined in river water, reclaimed water, and drinking water from the urban area of Barcelona and total concentrations ranged from 11.3 µg/L to 77.1 µg/L. The proposed methodology allows for simple (direct filtration of 100–500 mL of water with a 13 mm glass fiber filter), quantitative (µg/L), and rapid (with a total analysis time of 20 min per sample, including both pyrolysis and GC–MS) analysis of MPs in water intended for drinking.

Characterization of the alcohol biomarker phosphatidylethanol in donor whole blood and apheresis red blood cells: Implications for transfusion recipients.

Phosphatidylethanol (PEth) is a long-term marker of alcohol consumption used frequently in clinical scenarios such as liver transplant evaluation. Recent cases have demonstrated that packed red blood cell (pRBC) transfusion creates the potential for artificial elevation or decrease of observed PEth concentrations in recipients. Very little is known about the prevalence or stability of PEth in pRBCs. Apheresis and whole-blood (WB) donations were tested for PEth using liquid chromatography - tandem mass spectrometry with limit of quantitation 10 ng/mL. Units were stored under routine blood bank conditions to evaluate the stability of PEth and the impact of irradiation. Over 40% of apheresis and WB donors had PEth ≥10 ng/mL (maximum observed 587 ng/mL). As WB units were processed into component pRBCs, PEth concentrations increased and were higher than donor WB levels (EDTA sample) prior to collection (maximum observed 711 ng/mL). Storage for up to 5 weeks post donation resulted in mean 17.3% decrease in PEth-positive units; in contrast to a prior report, we observed no PEth formation in units with negative (<10 ng/mL) baseline concentrations. Irradiation of pRBCs did not substantially affect PEth concentrations in either PEth-positive or PEth-negative units. PEth concentrations in healthy blood donors may potentially confound alcohol use or abstinence assessment in pRBC recipients. Transfusion medicine services and clinical practices such as transplantation and behavioral medicine should recognize this phenomenon and collaborate on testing protocols to appropriately interpret PEth in pRBC recipients.

A green liquid phase microextraction using phthalic acid as switchable hydrophilicity solvent for the HPLC determination of sildenafil (Viagra®) in human urine

Herein, a green liquid phase microextraction protocol using phthalic acid as switchable hydrophilicity solvent (SHS) is reported for the quantification of sildenafil in authentic human urine. The analyte was extracted onto phthalic acid solid particles which were produced through acidification of the sample. Its solidification was accomplished at ambient conditions without sample cooling. The determination of the sildenafil was carried out using high performance liquid chromatography-ultraviolet detection (HPLC-UV). The microextraction parameters that affect the extraction efficiency of the drug (i.e. SHS type and its concentration, acid type and concentration, extraction time, filter type) have been studied. The optimized analytical protocol involved the mixing of 300 μL of phthalate solution (0.75 M) with 600 μL of sample, followed by the addition of 50 μL of concentrated H3PO4. The produced solid was collected using membrane syringe filter (0.45 μm) and was finally dissolved in 500 μL of CH3OH. Method validation data showed determination coefficient ≥ 0.99 for the linear range of 50 – 2000 ng/mL. The limit of detection (LOD) and the lower limit of quantitation (LLOQ) were 30 and 100 ng/mL, respectively. The accuracy (expressed as % recovery) of the method ranged between 88.0 – 108.9 % while the precision (expressed as % RSD) was less than 17.8 % in all cases. The robustness of the microextraction procedure and the instrumental method were investigated using Plackett-Burman experimental designs. The applicability of the method was demonstrated by analyzing both spiked and authentic human urine samples after oral administration of drug-containing pharmaceutical formulation. The developed protocol offers cost-efficiency, handling simplicity, and high throughput. Its green character was evaluated using Green Analytical Procedure Index and Blue Applicability Grade Index.

Possibility of using the imaged capillary isoelectric method as a multi-attribute method for bispecific antibodies.

An imaged capillary isoelectric focusing (icIEF)-based method was developed and validated as a multi-attribute method for a bispecific antibody (BsAb). First, as the traditional application of the icIEF method, it serves as an identity assay and purity assay for the BsAb. Second, the method can also be used as an impurity assay for the homodimer monoclonal antibodies generated during BsAb assembly. The homodimer impurity analysis for BsAb is usually done by hydrophobic interaction chromatography methods in the industry. The icIEF method has good sensitivity (down to 4µg/mL in a limit of quantitation) when UV fluorescence detection is used, which detects the native fluorescence of proteins. This is the first report that an icIEF method has been applied as impurity assay.

Determination of capsaicin at trace levels in different food, biological and environmental samples by quadruple isotope dilution-gas chromatography mass spectrometry after its preconcentration

Despite the therapeutic properties of capsaicin for some diseases, it shows some side effects for human health. The goal of this study was to develop a precise and accurate analytical strategy for the trace determination of capsaicin in different food, biological and environmental samples including pepper, saliva and wastewater by gas chromatography–mass spectrometry (GC–MS) after spraying-based fine droplet formation-liquid phase microextraction (SFDF-LPME) and quadruple isotope dilution (ID4) method. Acetic anhydride was used as derivatizing agent, and the extraction method was used to enrich the analyte derivative to reach low detection limits. Under the optimum conditions, limit of detection (LOD) and limit of quantitation (LOQ) were determined to be 0.33 and 1.10 µg/kg, respectively. Percent recoveries calculated for SFDF-LPME-GC-MS method ranged between 84.1 and 131.7 %. After the application of ID4-SFDF-LPME-GC-MS method, percent recoveries were obtained in the range of 94.9 and 104.0 % (%RSD ≤ 2.8) for the selected samples. It is obvious that the isotope dilution-based method provided high accurate and precise results due to the elimination of errors during the derivatization, extraction and measurement steps.