Luminescent Carbon Dots From Biomass Waste for the Sensitive Determination of Ascorbic Acid in Tablet Dosage Forms.

Affordable and eco-friendly green spectrofluorometric (FL) methods can enhance the safety and cost-effectiveness of quality assurance and control in ascorbic acid (ASA) formulations. However, most current techniques for ASA analysis have faced challenges like complexity, delayed response times, low throughput, time-consuming procedures, and requirements for expensive equipment and hazardous chemicals for analyte modification. The study is aimed at producing natural carbon quantum dots (NACQDs) from pumpkin seed peels (PSPs), a natural waste material, using a rapid microwave-assisted method.

Garlic peel-based carbon quantum dots as a sustainable alternative for the sensitive and green spectrofluorometric quantification of molnupiravir in pharmaceutical capsules.

Searching for natural alternatives to replace environmentally harmful chemical reagents in analysis is just as crucial as finding easily accessible analytical tools. To reinforce these concepts, this study proposes a simple spectrofluorometric approach using natural carbon quantum dots (n-CQDs) as fluorescence probes for sensitive and environmentally friendly measurement of molnupiravir, an antiviral drug that was initially developed for influenza and has demonstrated potential efficacy against COVID-19. n-CQDs were synthesized using garlic peels (GP), a waste material, via a microwave-assisted method.

Rapid back flushed direct sample injection bio-analytical HPLC-UV method for therapeutic drug monitoring of terbinafine.

A rapid back flushed (BF) direct sample injection (DSI) high-performance liquid chromatography (HPLC) with UV detection (BF-DSI-HPLC-UV) has been developed to determine terbinafine (TERB) in human serum. For online solid phase extraction step, an isocratic mobile phase of phosphate buffer saline (pH 7.4) at 1 mL/min and a short protein-coated ODS column (PC-ODS-column) were used for the purification and enrichment of TERB.

Bio-analytical liquid chromatographic-based method with a mixed mode online solid phase extraction for drug monitoring of fluconazole in human serum.

A simple, cost-effective and sensitive liquid chromatography-based bio-analytical method has been developed and validated for therapeutic drug monitoring of fluconazole (FLUC) in human serum. Integration of online mixed-mode solid-phase extraction (SPE) into the analytical system was the key for direct injection of untreated serum samples. A short protein-coated (PC) µBondapak CN silica column (PC-µB-CN-column) as a SPE tool and phosphate buffer saline (PBS) (pH 7.

Direct infusion nano-electrospray ionization mass spectrometry for therapeutic drug monitoring of ciprofloxacin and its metabolites in human saliva.

A rapid and sensitive method based on direct infusion-nano-electrospray ionization mass spectrometry (DI-nESI-MS) has been developed for the detection and quantification of ciprofloxacin and its metabolites in human saliva. Saliva samples were collected after the oral administration of 500 mg ciprofloxacin tablets. Internal standard (IS), tamoxifen, was added to the collected samples, and then diluted with the ionization solvent, centrifuged and filtered.

Dilute-and-shoot-based direct nano-electrospray ionization tandem mass spectrometry as screening methodology for multivitamins in dietary supplement and human urine.

Introduction: In recent years, analytical screening methods for simultaneous detection of multivitamins have gained substantial attention to ensure quality and public confidence in dietary supplements. Even so, few analytical methods have been proposed for simultaneous analysis of multivitamin constituents due to the large divergence in chemical characteristics.

Objectives: In the present study, the objective was to develop a simple and rapid direct nano-electrospray ionization-tandem mass spectrometry (DI-nano-ESI-MS/MS) method for targeted detection of water soluble vitamins, fat soluble vitamins, amino acids, royal jelly, ginkgo biloba, and ginseng in a dietary supplement.

Integration of Solid-Phase Extraction and Reversed-Phase Chromatography in Single Protein-Coated Columns for Direct Injection of Bupivacaine in Human Serum.

A rapid, reliable and precise integrated solid-phase extraction (SPE) and reversed-phase liquid chromatography method was developed and validated to determine bupivacaine in human serum using single protein-coated analytical columns. The protein-coated columns were packed with four different sorbents: TSK-ODS, LiChrosorb RP-8, LiChrosorb RP-2 and μ-Bondapak CN-bonded silica. The method involved direct injection of serum sample onto the columns for trapping of the analyte, clean-up from weakly retained serum endogenous components, as well as the final separation.

Direct nano-electrospray ionization tandem mass spectrometry for the quantification and identification of metronidazole in its dosage form and human urine.

A rapid, sensitive and direct nano-electrospray ionization-tandem mass spectrometry (NS-ESI-MS/MS) method, using an offline nanospray (NS) capillary, has been developed and validated for the analysis of metronidazole (MTZ). A mixture of 2 µl MTZ sample solution prepared in an ionization solvent consisting of methanol : water : formic acid in a ratio of 80 : 20 : 0.3, together with 2 µl of an internal standard (IS), 1,3,6-polytyrosine, is loaded into the back of the NS capillary.

Sensitivity Enhancement for Direct Injection Capillary Electrophoresis to Determine Morphine in Human Serum via In-capillary Derivatization.

Rapid and simple micellar electrokinetic chromatography (MEKC) with in-capillary derivatization and fluorescence detection has been developed to determine morphine in human serum. The sample was introduced into a background electrolyte (BGE) containing potassium ferricyanide, whereas morphine was oxidized into highly fluorescent product, pseudomorphine. Different parameters for derivatization and subsequent separation were systematically investigated for the analysis of morphine in serum.

Single-Cell Metabolomics.

The dynamics of a cell is always changing. Cells move, divide, communicate, adapt, and are always reacting to their surroundings non-synchronously. Currently, single-cell metabolomics has become the leading field in understanding the phenotypical variations between them, but sample volumes, low analyte concentrations, and validating gentle sample techniques have proven great barriers toward achieving accurate and complete metabolomics profiling.

Quantitative Live Single-cell Mass Spectrometry with Spatial Evaluation by Three-Dimensional Holographic and Tomographic Laser Microscopy.

The locations and volumes of the contents of a single HepG2 cell were visualized under three-dimensional (3D) holographic and tomographic (HT) laser microscopy, colored by refractive index, not staining. After trapping the specific area of a target cell in a nanospray tip, quantification was performed by live single-cell mass spectrometry. Comparison of the HepG2 cells' before and after 3D-HT images allowed the inference of the precise volume and original location of the trapped cell contents.

Direct Lipido-Metabolomics of Single Floating Cells for Analysis of Circulating Tumor Cells by Live Single-cell Mass Spectrometry.

Direct trapping of a single floating cell, i.e. a white blood cell from a drop of blood, within a nanospray tip was followed by super-sonication after the addition of ionization solvent.

An Eco-Friendly Direct Injection HPLC Method for Methyldopa Determination in Serum by Mixed-Mode Chromatography Using a Single Protein-Coated Column.

A simple, rapid and environment-friendly direct injection HPLC method for the determination of methyldopa (MTD) in human serum has been developed and validated. The method was based on cleanup and separation of MTD from serum by mixed-mode liquid chromatography using a single protein-coated TSK gel ODS-80 TM analytical column (50 × 4.0 mm i.

Field-amplified sample stacking β-cyclodextrin modified capillary electrophoresis for quantitative determination of diastereomeric saponins.

Successful simultaneous diastereomeric separation and sensitive determination of two pairs of triterpenoidal saponins have been achieved by capillary electrophoresis (CE) using β-cyclodextrin (β-CD) as a stereoselective agent to cooperate with borate complexation. A usual technique for isolation and group separation of saponins was developed as an appropriate purification step prior to the determination of individual saponins by CE. Soyasaponin I ( S1: ), azukisaponin V ( S2: ), bersimoside I ( S3: ) and bersimoside II ( S4: ) could be well separated within 14 min in a fused-silica capillary (60 cm long to the detector with an additional 10 cm to the cathode; 75 µm i.

On-line coupling of derivatization with pre-concentration to determine trace levels of methotrexate.

A new simple, sensitive and precise green analytical procedure using an automated packed-reactor derivatization technique coupled with on-line solid-phase enrichment (SPEn) has been developed and evaluated to determine trace levels of methotrexate (MTX). The method was based on injection of MTX into a flowing stream of phosphate buffer (0.04 M, pH 3.

On-line solid-phase enrichment coupled to packed reactor flow injection analysis in a green analytical procedure to determine low levels of folic acid using fluorescence detection.

Background: Analysis of folic acid (FA) is not an easy task because of its presence in lower concentrations, its lower stability under acidic conditions, and its sensitiveness against light and high temperature. The present study is concerned with the development and validation of an automated environmentally friendly pre-column derivatization combined by solid-phase enrichment (SPEn) to determine low levels of FA.

Results: Cerium (IV) trihydroxyhydroperoxide (CTH) as a packed oxidant reactor has been used for oxidative cleavage of FA into highly fluorescent product, 2-amino-4-hydroxypteridine-6-carboxylic acid.

Online pre-column derivatization with chromatographic separation to determine folic acid.

A simple, sensitive, and selective online pre-column derivatization high-performance liquid chromatographic method was developed and validated for the first time to determine trace levels of folic acid (FA). An oxidant cerium (IV) trihydroxyhydroperoxide packed reactor was used for pre-column oxidation and was combined by column switching with a C18 analytical column for sample enrichment and separation. The method was based on oxidative cleavage of FA into highly fluorescence products, 2-amino-4-hydroxypteridine-6-carboxaldehyde and the corresponding 2-amino-4-hydroxypteridine-6-carboxylic acid, during the flow of 0.

Validated and optimized high-performance liquid chromatographic determination of tizoxanide, the main active metabolite of nitazoxanide in human urine, plasma and breast milk.

A high-performance liquid chromatographic method was optimized and validated for the determination of desacetyl nitazoxanide (tizoxanide), the main active metabolite of nitazoxanide in human plasma, urine and breast milk. The proposed method used a CN column with mobile phase consisting of acetonitrile-12mM ammonium acetate-diethylamine in the ratio of 30:70:0.1 (v/v/v) and buffered at pH 4.

Determination of glucosamine and carisoprodol in pharmaceutical formulations by LC with pre-column derivatization and UV detection.

A simple and reliable precolumn derivatization liquid chromatography method with ultraviolet detection has been developed and validated for the analysis of glucosamine (GS) in various dietary supplement formulations and raw materials. Additionally, the proposed method was used for analysis of carisoprodol (CR) found in ternary mixture with paracetamol (PR) and caffeine (CF). The linearity ranges were 1-100 μg/mL for GS, 1-150 μg/mL for CR, PR and CF.

On-line sample cleanup and enrichment chromatographic technique for the determination of ambroxol in human serum.

A sensitive and efficient on-line clean up and pre-concentration method has been developed using column-switching technique and protein-coated µ-Bondapak CN silica pre-column for quantification of ambroxol (AM) in human serum. The method is performed by direct injection of serum sample onto a protein-coated µ-Bondapak CN silica pre-column, where AM is pre-concentrated and retained, while proteins and very polar constituents are washed to waste using a phosphate buffer saline (pH 7.4).

Optimized and validated flow-injection spectrophotometric analysis of topiramate, piracetam and levetiracetam in pharmaceutical formulations.

Application of a sensitive and rapid flow injection analysis (FIA) method for determination of topiramate, piracetam, and levetiracetam in pharmaceutical formulations has been investigated. The method is based on the reaction with ortho-phtalaldehyde and 2-mercaptoethanol in a basic buffer and measurement of absorbance at 295 nm under flow conditions. Variables affecting the determination such as sample injection volume, pH, ionic strength, reagent concentrations, flow rate of reagent and other FIA parameters were optimized to produce the most sensitive and reproducible results using a quarter-fraction factorial design, for five factors at two levels.

Validation and application of chemometrics-assisted spectrophotometry and liquid chromatography for simultaneous determination of two ternary mixtures containing drotaverine hydrochloride.

Three methods were developed for the determination of two ternary mixtures containing drotaverine hydrochloride (DR) with caffeine and paracetamol (mixture 1) and DR with metronidazole and diloxanide furoate (mixture 2). The first method depends on HPLC separation on an RP C18 column at ambient temperature with the mobile phase methanol-water, pH 3.1 (50 + 50, v/v) and UV detection at 213 nm for mixture 1, and the mobile phase acetonitrile-25 mM potassium dihydrogen phosphate, pH 4.

Development and validation of a stability-indicating RP-HPLC method for the determination of paracetamol with dantrolene or/and cetirizine and pseudoephedrine in two pharmaceutical dosage forms.

A stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed which can separate and accurately quantitate paracetamol, dantrolene, cetirizine and pseudoephedrine. The method was successfully validated for the purpose of conducting stability studies of the four analytes in quality control (QC) laboratories. The stability-indicating capability of the method was demonstrated by adequate separation of these four analytes from all the degradant peaks.

UV partial least-squares calibration and liquid chromatographic methods for direct quantitation of levofloxacin in urine.

Levofloxacin was determined in human urine samples by application of a spectrophotometric multivariate calibration partial least-squares (PLS-1) method. A calibration set consisting of standards was prepared by using a multilevel multifactor experimental design. In order to ensure accurate results, the calibration matrix included a urine sample free of levofloxacin (i.

Stability-indicating method for determination of oxyphenonium bromide and its degradation product by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) method was developed for determination of oxyphenonium bromide (OX) and its degradation product. The method was based on the HPLC separation of OX from its degradation product, using a cyanopropyl column at ambient temperature with mobile phase of acetonitrile-25 mM potassium dihydrogen phosphate, pH 3.4 (50 + 50, v/v).