ABSTRACT
A method for the determination of 4-aminophenol, the main impurity of paracetamol, by high-performance liquid chromatographic (HPLC) method with amperometric detection has been developed. The analysis was performed in an isocratic mode on a reversed phase Luna column 5 microm C-18 (100 x 4.6 mm). A mobile phase (0.05 mol l(-1) LiCl solution containing 18% methanol adjusted to pH 4.0 with orthophosphoric acid) was suitable for the separation and determination of 4-APh. Chromatograms were recorded for 250 s by means of an amperometric detector at a potential of +325 mV of the glassy carbon electrode versus the reference electrode Ag/AgCl. The proposed liquid chromatographic method was successfully applied to the analysis of commercially available multicomponent dosage forms. The sensitivity of the detection for 4-aminophenol was 1 ng ml(-1) for substance and 4 ng ml(-1) for tablets or capsules. The method developed in this study is sensitive and selective and can be applied for routine studies of pharmaceuticals in the form of tablets or capsules.
Subject(s)
Aminophenols/analysis , Analgesics/analysis , Drug Contamination , Technology, Pharmaceutical/methods , Chromatography, High Pressure Liquid/methods , Pharmaceutical Preparations/analysisABSTRACT
4-Aminophenol (4-APh) is the main impurity present in preparations containing paracetamol. Using the cyclic voltammetry and differential pulse voltammetry methods, the electrode behaviour of 4-APh has been studied in various non-buffered and buffered solutions at glassy carbon and golden electrodes. By means of the high-performance liquid chromatography with amperometric detection (HPLC-EC), the dependency of current intensities of the 4-APh peaks on the potential in the range (0-600 mV in the pH range 2-5, the ionic strength of mobile phase ranging from 0.01 mol (-1) to 0.20 mol l(-1) LiCl, has been studied. While employing the HPLC-EC method in this work, a glassy carbon electrode was used as the amperometric detector. The optimal potential selected in this research was +325 mV. It was found that a 0.05 mol l(-1) LiCl solution, containing 18% of methanol, at pH 4.0 adjusted with orthophosphoric acid, is suitable for the separation of 4-APh and paracetamol from each other and from other pharmaceutical excipients present in tablets. By using the elaborated HPLC-EC method, the content of 4-APh (at concentrations from 4 ng ml(-1)) in the paracetamol from Aldrich and in tablets from different producers, containing 500 mg of paracetamol in a tablet was found. Statistical evaluation of the obtained results has shown that the proposed HPLC-EC method for the determination of 4-APh is characterized by a good accuracy and precision (RSD about 6%) and can be applied to routine investigations of pharmaceutical preparations in the form of tablets.
Subject(s)
Aminophenols/analysis , Pharmaceutical Preparations/analysis , Acetaminophen/analysis , Chromatography, High Pressure Liquid , Electrochemistry , Electrodes , Sensitivity and Specificity , TabletsABSTRACT
The purpose of the study was determination of the occurrence of E. coli O157 in faeces samples of healthy subjects and characterization of the isolated strains with respect to their potential pathogenicity. The study was carried out in two stages. In the first one in 5 sanitary-epidemiological stations samples were tested from healthy subjects after inoculation onto McConkey (MC) or/and McConkey with sorbitol (SMC) media and isolating from each culture 10 lactose-positive (on MC medium) or sorbitol-negative (on SMC) colonies. Then latex test was done with each isolate for E. coli O157 presence. In all, 1005 samples were studied, including 260 taken from children aged 0-2 years, 180 samples from children aged 3-10 years, and 565 samples from older children and adults. E. coli O157 rods were cultured from 6 adults (0.6%). In the second stage carried out at the Laboratory of Enterobacteriaceae, Bacteriology Department, National Institute of Hygiene strains obtained from territorial laboratories were studied determining their phenotypic and genotypic traits regarded as virulence markers of verotoxic E. coli O157 strains, such as inability to ferment sorbitol and MUG breakdown, and production of verotoxins and enterohaemolysin. By the PCR method fragments were sought of genes coding for production of verotoxins, intimin and enterohaemolysin. The results showed that no E. coli O157 strain obtained from healthy individuals produced verotoxins, but three studied strains contained the eae gene determining intimin production and they were regarded as enteropathogenic.
