Integrated pervaporation/detection for the determination of fluoride in pharmaceuticals

A novel UV-photolysis approach with acetone and isopropyl alcohol for the rapid determination of fluoride in organofluorine-containing drugs by spectrophotometry

A UV photolysis decomposition (UVPD) method for the determination of fluoride in fluorine containing pharmaceuticals by spectrophotometry is reported. It is based on the use of high intensity UV-irradiation in the presence of a digesting solution comprising a mixture of acetone and isopropanol. For the optimization of the UVPD procedure, three bulk drugs (levofloxacin, nebivolol and efavirenz) were chosen as representatives of three diverse compounds containing a single fluorine atom, two fluorine atoms, and trifluoromethyl groups respectively. Operational conditions of the UVPD method, such as concentration and volume of reagents (acetone and isopropyl alcohol), and UV irradiation time (1–6 minutes) were optimized. The efficiency of digestion was evaluated by the determination of fluoride in sample digests. Using the developed method, it was possible for complete conversion of the organofluoride to free fluoride ion for its subsequent determination by spectrophotometry based on bleaching of Zr–xylenol orange-color complex. Quantitative recovery (>98%) of the fluorine in the drug samples could be achieved using a mixture of 2% acetone + 2% isopropyl alcohol + 0.003% Na₂CO₃ in just 5 minutes of UV irradiation, which can be considered an important aspect considering the difficulties involved in the cleavage of the C–F bond. Accuracy was evaluated by comparison of results obtained by the UVPD method with the values estimated using formula weight of the compound and no statistical difference was observed between the results. Therefore, the proposed method is suitable for application in routine analysis of fluoride in organofluorine-containing drugs.

Prophylactic effects of methyl-3-O-methyl gallate against sodium fluoride-induced oxidative stress in erythrocytes in vivo

OBJECTIVES

The purpose of this study was to demonstrate the effect of methyl-3-O-methyl gallate (M3OMG), a rare polyphenolic natural product with a potent in-vitro antioxidant effect, against sodium fluoride (NaF)-induced oxidative stress in rat erythrocytes in vivo.

METHODS

Male Wistar rats were treated daily with either M3OMG (10 and 20 mg/kg) obtained through synthesis, vitamin C (10 mg/kg) or vehicle intraperitoneally for 7 days. Oxidative stress was then induced by exposing animals to NaF (600 ppm) through drinking water for 7 days. At the end of intoxication period, rats were killed and erythrocytes isolated. The activity of antioxidant enzymes (catalase and superoxide dismutase) and levels of reduced glutathione and thiobarbituric acid reactive substances were measured in erythrocyte haemolysates.

RESULTS

NaF intoxication resulted in a 1.9-fold increase in erythrocyte lipid peroxidation associated with significant (P < 0.001) depletion of reduced glutathione level. Superoxide dismutase and catalase activity was suppressed by NaF treatment by 3.069 and 2.3 fold when compared with untreated control groups. Pretreatment of rats with M3OMG or vitamin C afforded protection against NaF-induced oxidative stress as assessed through the measured oxidant/antioxidant markers.

CONCLUSION

This finding provided in-vivo evidence for the therapeutic potential of M3OMG in combating fluoride-induced oxidative damage in cellular systems.

Simple, rapid reagent-injection spectrophotometric determination of fluorides in pharmaceutical formulations

A new simple and rapid reagent-injection method is reported for the determination of fluorides in pharmaceutical formulations. The method is based on the inhibitory effect of fluoride ions upon the Fe(III) catalytic oxidation of 2,4-diaminophenol (DAP) by H2O2. Free fluoride ions form stable complexes with Fe(III), thus reducing its catalytic effect. The decrease in the absorbance of the oxidation product is monitored spectrophotometrically at 500 nm. The various chemical and physical variables of the FI system were optimized and a study of interfering ions was also carried out. A linear calibration graph was obtained from 0 to 750 mg x l(-1) for F- ions. The precision was very good (sr=0.3%) and the 3sigma detection limit was satisfactory (cL=0.471 mg x l(-1)). The sampling rate was 90 injections x h(-1). The method has been successfully applied to the determination of F- ions in pharmaceutical formulations.