A quantitative method for fluoride determination using RP HPLC and UV detection was developed. The method is based on the reaction of fluoride with triphenylhydroxysilane in highly acidic conditions and extraction of the reaction product into n-heptane. Chromatographic conditions as well as the derivatization parameters were optimized. LOQ for fluoride ion was evaluated as 0.25 μM (4.75 ppb) and linear range of response up to 75 μM (1.42 ppm) was obtained. The method was developed as a part of a procedure designed for the determination of total organic fluorine in natural waters, using SPE on a carbon sorbent and sodium biphenyl reagent for the defluorination reaction. LOD for a model compound, perfluorooctanoic acid, calculated for the complete procedure with 2000-fold preconcentration, is 20 ppt (n=4). Initial results show feasibility of total organic fluorine determination for environmental purposes.

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Chelidonium majus L. is a latex-bearing plant used in traditional folk medicine to treat human papillomavirus (HPV)-caused warts, papillae, and condylomas. Its latex and extracts are rich in many low-molecular compounds and proteins, but there is little or no information on their potential interaction. We describe the isolation and identification of a novel major latex protein (CmMLP1) composed of 147 amino acids and present a model of its structure containing a conserved hydrophobic cavity with high affinity to berberine, 8-hydroxycheleritrine, and dihydroberberine. CmMLP1 and the accompanying three alkaloids were present in the eluted chromatographic fractions of latex. They decreased in vitro viability of human cervical cancer cells (HPV-negative and HPV-positive). We combined, for the first time, research on macromolecular and low-molecular-weight compounds of latex-bearing plants in contrast to other studies that investigated proteins and alkaloids separately. The observed interaction between latex protein and alkaloids may influence our knowledge on plant defense. The proposed toolbox may help in further understanding of plant disease resistance and in pharmacological research.

Since the perfluorinated organic compounds have been recognized as persistent organic pollutants present in the environment, food and living organisms, new analytical methods are being developed for their determination. Many of the described earlier methods focus on determination of particular fluorinated compounds, however, the specific compounds are only a part of all organic fluorine compounds present in environmental or biological samples.

An original method based on liquid chromatography with single quadrupole electrospray ionization mass spectrometry was developed for the determination of sunitinib in human plasma. The quantitation limit of the method at 0.10 ng/mL is comparable to that of tandem mass spectrometry assays. The handling of all solutions containing sunitinib was performed under low-intensity red light to avoid the isomerization of sunitinib and enable quantitation using a single peak. Liquid-liquid extraction with a mixture of n-hexane/isopropanol (90:10 v/v) allowed recoveries at the level of 70%. Measurements were performed using a Zorbax SB-C18 column (3.0 mm × 150 mm, 3.5 μm) and isocratic elution with (A) 0.1% aqueous formic acid and (B) acetonitrile/methanol (80:20 v/v) in an A/B ratio of 55:45 at 35°C. Under these conditions, sunitinib is eluted at 3.8 min in 6 min of the total run time. The linearity of the calibration curve ranges from 0.10 to 150 ng/mL. The baseline separation of sunitinib and its primary metabolite, N-des-ethyl sunitinib (SU12662), as well as sharp peak shapes, suggest a possibility of extending the applied methodology to the quantitative determination of both compounds. Isotopically labeled sunitinib was used as the internal standard. All required validation tests met the acceptance criteria and proved the method's reliability and robustness. The method may be conveniently applied to study the pharmacokinetics of sunitinib in humans.

Olmesartan belongs to a class of drugs called angiotensin II receptor blockers (ARBs). It works by relaxing blood vessels so that blood can flow more easily and is used to treat high blood pressure (hypertension). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. Olmesartan medoxomil is an ester prodrug that is hydrolysed during absorption from gastrointestinal tract to the active form olmesartan. Due to rapid metabolism determination of the concentration of the prodrug in plasma is impossible. Previous human pharmacokinetic studies indicated that olmesartan is the only metabolite of olmesartan medoxomil. The aim of the study was to develop a method for the determination of olmesartan in human plasma. The developed LC-MS method is linear within the range of 5.00-2500.00 ng/mL which is suitable for pharmacokinetic studies after administration of 40 mg olmesartan medoxomil single oral dose. The sample preparation procedure is fast and allows examination of large numbers of samples in a short time. The method was validated according to European Medicines Agency (EMA) and Food and Drug Administration (FDA) guidelines, in compliance with the principles of Good Laboratory Practice (GLP). All of the validation parameters met acceptance criteria and the method was successfully applied in the pharmacokinetic study in humans.