BackgroundCiprofloxacin (CIP), moxifloxacin (MOX), norfloxacin (NOR) and ofloxacin (OFL), are the antibacterial synthetic drugs, belonging to the fluoroquinolones group. Fluoroquinolones are compounds susceptible to photodegradation process, which may lead to reduction of their antibacterial activity and to induce phototoxicity as a side effect. This paper describes a simple, sensitive UPLC-MS/MS method for the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products.ResultsChromatographic separations were carried out using the Acquity UPLC BEH C18 column; (2.1 × 100 mm, 1.7 μm particle size). The column was maintained at 40°C, and the following gradient was used: 0 min, 95% of eluent A and 5% of eluent B; 10 min, 0% of eluent A and 100% of eluent B, at a flow rate of 0.3 mL min-1. Eluent A: 0.1% (v/v) formic acid in water; eluent B: 0.1% (v/v) formic acid in acetonitrile. The method was validated and all the validation parameters were in the ranges acceptable by the guidelines for analytical method validation. The photodegradation of examined fluoroquinolones in solid phase in the presence of excipients followed kinetic of the first order reaction and depended upon the type of analyzed drugs and coexisting substances. Photodegradation process of analyzed drugs was confirmed by differential scanning calorimetry. In addition, the identification of degradation products was carried out by mass spectrometry.ConclusionThe developed UPLC-MS/MS method enables the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products and identification of photodegradation products.

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A HPLC method was developed for determination of danofloxacin (DAN) in the presence of its photodegradation products.

The lipophilicity of fifteen fluoroquinolones has been investigated.

Vitamin K is a group of lipophilic molecules. Forms of vitamin K play an essential role in the activation of specific proteins involved in blood clotting cascade or bone metabolism. Another molecule belonging to the fat-soluble vitamins group that also plays an important role in calcium metabolism is vitamin D3. The dietary supplements containing vitamins K and D3 are one of the most frequently consumed by patients. The objective of this work was to develop a simple, fast and sensitive thin-layer chromatography (TLC)-densitometric procedure for the simultaneous quantitative analysis of vitamins K and D3 in pharmaceutical products and dietary supplements. The analysis of vitamins was performed on the silica gel RP-18 F₂₅₄s plates with methanol-ethanol-isopropanol in a volume ratio of 15:1:4 as a mobile phase. The densitometric measurements were made at 254 nm. The method was validated by checking the specificity, linearity, precision, recovery, limit of detection, limit of quantification and robustness in accordance with International Conference on Harmonization (ICH) guidelines. The method was shown to be specific, accurate (recoveries were from 95.78 to 104.96%), linear over the tested range (correlation coefficient, exceeding 0.99), and precise (precision and intermediate precision RSD below 2.70% for all analytes). The satisfactory results of the validation of the method indicate that it can be used in the quality control of dietary supplements and pharmaceutical products containing vitamins K and D3.

A TLC-densitometric method was developed for the determination of sparfloxacin in the presence of its photodegradation products. Silica gel TLC F 254 plates were used as the stationary phase and methylene chloride : methanol : 2-propanol : ammonia 25% (4 : 4 : 5 : 2 v/v/v/v) as the mobile phase. The developed method meets the acceptance criteria for specificity, linearity, sensitivity, accuracy, and precision. The linear regression analysis for the calibration curve showed a good linear correlation over the concentration range 1.00-3.00 mg per band, with the determination coefficient, R 2 , exceeding 0.9958. The method was shown to have good precision and intermediate precision, as reflected by the relative standard deviation values, lower than 2.72% and characterized by a recovery rate at three concentration levels from 93.60% to 103.90%. The limits of detection and quantification were respectively 0.16 and 0.48 mg per band. The photodegradation process of sparfloxacin followed the kinetics of a first order reaction for the substrate. Nine products of photodegradation were identified by UPLC-MS/MS. The structure of a product previously not identified was determined.

& TLC-densitometric method was developed for determination of danofloxacin (DAN) in presence of its photodegradation products. Silica gel HPTLC Lichrospher 60 F 254 plates were used as the stationary phase and methanol:acetone:1 M citric acid:triethylamine (2.8:2:0.2:0.5, v=v=v=v) as the mobile phase. The elaborated method meets the acceptance criteria for specificity, linearity, sensitivity, accuracy, and precision. The linear regression analysis for the calibration curve showed a good linear correlation over the concentration range 1.25-3.75 lg per band, with determination coefficient, exceeding 0.9806. Accuracy of the method expressed as % recovery at three concentration levels was from 95.56% to 97.30%. Good precision and intermediate precision with % RSD less than 0.92% was also observed. The limits of detection and quantification were respectively 1.10 and 3.40 ng per band. Satisfactory results of validation of the method were also confirmed by determination of DAN in veterinary commercial preparation. The photodegradation process of DAN followed kinetics of the first order reaction for the substrate.