A water-soluble preparation for intravenous administration of isorhamnetin and its pharmacokinetics in rats.

Flavonoids are considered as health-protecting food constituents. The testing of their biological effects is however hampered by their low oral absorption and complex metabolism. In order to investigate the direct effect(s) of unmetabolized flavonoid, a preparation in a biologically friendly solvent for intravenous administration is needed.

Columns in analytical-scale supercritical fluid chromatography: From traditional to unconventional chemistries.

Within this review, we thoroughly explored supercritical fluid chromatography (SFC) columns used across > 3000 papers published from the first study carried out under SFC conditions in 1962 to the end of 2022. We focused on the open tubular capillary, packed capillary, and packed columns, their chemistries, dimensions, and trends in used stationary phases with correlation to their specific interactions, advantages, drawbacks, used instrumentation, and application field. Since the 1990s, packed columns with liquid chromatography and SFC-dedicated stationary phases for chiral and achiral separation are predominantly used.

Carbon dioxide expanded liquid: an effective solvent for the extraction of quercetin from South African medicinal plants.

Background: Quercetin is one of the most important bioflavonoids having positive effects on the biological processes and human health. Typically, it is extracted from plant matrices using conventional methods such as maceration, sonication, infusion, and Soxhlet extraction with high solvent consumption. Our study aimed to optimize the environmentally friendly carbon dioxide-based method for the extraction of quercetin from quince fruit with an emphasis on extraction yield, repeatability, and short extraction time.

Featuring ultimate sensitivity of high-resolution LC-MS analysis of phenolics in rat plasma.

Sensitive analysis of very low-molecular weight metabolites using liquid chromatography with quadrupole-time-of-flight mass spectrometry is challenging due to the high losses of ions in a time-of-flight analyzer. Improvement in sensitivity for these analytes via the optimization of advanced parameters, including quadrupole profile, ion guide parameters, and duty cycle, has been achieved. The optimization of the method was carried out using a large spectrum of structurally different compounds including (iso)flavonoids and their known metabolites.

Development of water-soluble 3,5-dinitrophenyl tetrazole and oxadiazole antitubercular agents.

In this work, four series of tertiary amine-containing derivatives of 3,5-dinitrophenyl tetrazole and oxadiazole antitubercular agents were prepared, and their in vitro antimycobacterial effects were evaluated. We found that the studied compounds showed lipophilicity-dependent antimycobacterial activity. The N-benzylpiperazine derivatives, which had the highest lipophilicity among all of the series, showed the highest in vitro antimycobacterial activities against Mycobacterium tuberculosis CNCTC My 331/88 (HRv), comparable to those of the first-line drugs isoniazid and rifampicin.

Micro-SPE in pipette tips as a tool for analysis of small-molecule drugs in serum.

Aim: Micro-SPE in pipette tips (μ-SPE-PT) with particle sorbent has never been used in small-molecule drug analysis. Methodology & results: μ-SPE-PT was used for the extraction of statins from biological materials followed by UHPLC-MS/MS. The commercial and homemade μ-SPE-PT tips filled with particle sorbent were compared.

Development of MEPS-UHPLC-MS/MS multistatin methods for clinical analysis.

Background: Statins are the microsomal 3-hydroxy-3methylglutaryl-coenzyme A reductase inhibitors used for the treatment of hypercholesterolemia. Some recent studies revealed also the extra-lipid effects and anticancer activities. Due to the wide incidence of cancer diseases, the number of studies dealing with anticancer statin activities has grown in recent years.

Development and validation of UHPLC-MS/MS method for determination of eight naturally occurring catechin derivatives in various tea samples and the role of matrix effects.

A complete analytical procedure combining optimized tea infusion preparation and validated UHPLC-MS/MS method was developed for routine quantification of eight naturally occurring catechin derivatives in various tea samples. The preparation of tea infusions was optimized in terms of temperature, time and water-to-tea ratio in green, white and black teas. The catechins were analyzed using ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry in a run of only 4 min including equilibration of the system.

Determination of amphetamine and methadone in human urine by microextraction by packed sorbent coupled directly to mass spectrometry: an alternative for rapid clinical and forensic analysis.

Speed and low cost, together with regulatory approval, are the most important requirements of clinical assays. Therefore, a fast and automated on-line sample preparation method is essential for the routine analysis of biological samples. Microextraction by packed sorbent is an option for optimal sample preparation due to its easy automation, minimal requirements for the sample and elution solvent volumes, elimination of evaporation and reconstitution steps, and ability to integrate sample preparation and injection into one step.

Study of the retention behavior of small polar molecules on different types of stationary phases used in hydrophilic interaction liquid chromatography.

The retention behavior of a large group of analytes (35) with varied properties (pKa and logP) was studied on eight hydrophilic interaction LC columns with different surfaces, stationary phase chemistries, and types of particles. The acetonitrile content (5-95%), buffer concentration (0.5-200 mM), and pH of the mobile phase (3.

How to address the sample preparation of hydrophilic compounds: Determination of entecavir in plasma and plasma ultrafiltrate with novel extraction sorbents.

Two fast, simple, selective and economical sample preparation methods for the determination of entecavir in biological materials available at low amounts are reported. The choice of optimal extraction techniques was performed with regard to analyte hydrophilicity, sample volumes, selectivity, method recovery and rapidity. The compatibility of the eluate with the hydrophilic interaction chromatography (HILIC) mobile phase was crucial to allow the elimination of the evaporation and reconstitution steps and to obtain acceptable peak shapes.

HILIC UHPLC-MS/MS for fast and sensitive bioanalysis: accounting for matrix effects in method development.

Background: Matrix effects are considered to be a main obstacle of quantitative bioanalytical LC-MS/MS methods. Therefore it is often required to minimize them in order to increase method reliability. HILIC has been referenced as one of possible approaches.

Highly sensitive fast determination of entecavir in rat urine by means of hydrophilic interaction chromatography-ultra-high-performance liquid chromatography-tandem mass spectrometry.

Entecavir is a deoxyguanosine nucleotide antiviral agent with the activity against hepatitis B virus (HBV). The agent possesses a polar structure, which is predetermined for hydrophilic interaction chromatography (HILIC). Novel, fast and sensitive HILIC-UHPLC method developed in this study included separation from matrix component on BEH Amide stationary phase by isocratic elution using binary mobile phase composed of acetonitrile/5mM ammonium acetate pH 4.

Evaluation of new mixed-mode UHPLC stationary phases and the importance of stationary phase choice when using low ionic-strength mobile phase additives.

In this study, the selectivity, retention properties, peak shape and loading capacity for bases were practically evaluated using two UHPLC mixed-mode hybrid CSH stationary phases modified by C18 or Phenyl group. The data were compared with the data obtained on other UHPLC hybrid stationary phases (BEH C18, BEH C8, BEH Phenyl and BEH Shield RP18) at both basic and acidic conditions using conventional HPLC buffers (50mM ammonium formate/acetate) as well as low ionic-strength additives such as, e.g.

Determination of pravastatin and pravastatin lactone in rat plasma and urine using UHPLC-MS/MS and microextraction by packed sorbent.

A simple and reproducible method for the determination of pravastatin and pravastatin lactone in rat plasma and urine by means of ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) using deuterium labeled internal standards for quantification is reported. Separation of analytes was performed on BEH C(18) analytical column (50 mm × 2.1mm, 1.

Microextraction by packed sorbent as sample preparation step for atorvastatin and its metabolites in biological samples--critical evaluation.

Atorvastatin belongs to the group of lipid-lowering drugs known as statins. They significantly reduce the levels of total cholesterol, low-density cholesterol and plasma triglycerides therefore they are widely used in the treatment of hypercholesterolemia. Recently developed methods for the determination of atorvastatin and its metabolites in plasma used SPE (solid phase extraction) or LLE (liquid-liquid extraction) as the sample preparation step.

Ultra high performance liquid chromatography tandem mass spectrometry analysis of quorum-sensing molecules of Candida albicans.

Candida albicans is generally one of the most commonly isolated fungal pathogen from human body. It is a frequent cause of nosocomial infections, bloodstream infections, urinary infections and mucosal infections of oral cavity and vagina C. albicans can grow as hyphae, pseudohyphae, or budding yeast.

A review of current trends and advances in modern bio-analytical methods: chromatography and sample preparation.

Any bio-analytical method includes several steps, all of them being important in order to achieve reliable results. The first step is taking aliquots of samples for the analysis, followed by the extraction procedure and sample clean-up, chromatographic analysis and detection. Chromatographic methods, particularly liquid chromatography, are the methods of choice in bio-analytical laboratories.

HPLC method for simultaneous determination of retinoids and tocopherols in human serum for monitoring of anticancer therapy.

A simple and rapid HPLC method requiring small volumes (250 microL) of human serum after C18 SPE sample preparation was developed using monolithic technology for simultaneous determination of all-trans-retinoic acid, 13-cis-retinoic acid, retinol, gamma- and alpha-tocopherol. The monolithic column, Chromolith Performance RP-18e (100x4.6 mm), was operated at ambient temperature.

Ultra high performance liquid chromatography tandem mass spectrometric detection in clinical analysis of simvastatin and atorvastatin.

Simvastatin and atorvastatin belong to the group of hypolipidemic drugs, more exactly to the second generation of inhibitors of microsomal 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. They induce a significant reduction in total cholesterol, low-density lipoprotein cholesterol and plasma triglycerides, therefore they are widely used in the treatment of hypercholesterolemia even of its severe form-familiar hypercholesterolemia. Simvastatin and atorvastatin as the most widely used statins in clinical treatment and their hydroxy-acid/lactone forms were determined by means of UPLC in connection with triple quadrupole mass spectrometer.