Determination of quinolones by fluorescent excitation emission

Development of a new liquid chromatographic method for the simultaneous separation of ciprofloxacin degradation products with 5-hydroxymethyl-furfural, impurity of D-glucose, in an intravenous solution for perfusion

The place occupied by fluoroquinolones is very important clinically. Ciprofloxacin has been the most widely prescribed one which exhibits good activity against Pseudomonas aeruginosa and Acinetobacter. D-glucose is frequently used as an excipient in most formulations for perfusion solutions. Since there is much interest in pharmaceutical quality control of such formulations, separation of impurities from the main drug substances and accurate assay quantification, and since there is no reference or monograph until nowadays that has been reported for the simultaneous separation of ciprofloxacin degradation products along with 5-hydroxymethyl-furfural (5-HMF), impurity of D-glucose, classified as a high toxic substance, thus our aim of this work is to develop a new simple, sensitive and stability indicating method allowing this separation by high-performance liquid chromatography. We have started from the chromatographic conditions recommended by the British Pharmacopoeia, and by optimizing the nature of the stationary phase, the composition of the mobile phase and the injection volume. After optimisation, the retained chromatographic conditions have enabled the separation of all impurities with good resolution factor greater than 1.5 for each pair of peaks and with good symmetry peak shape. The developed method was validated according to the International Conference of Harmonisation (ICH) guidelines for specificity, detection and quantification limits, and then it was applied to stability study of the formulation subjected to different ICH prescribed stress conditions. The 5-HMF was checked to be the impurity issued from D-glucose hydrolysis by high temperature mainly after autoclaving of pharmaceuticals. The developed method was proved to be simple, specific with very low limit of quantification. Hence, it can be considered as a method for stability indicating and routine quality control analysis in pharmaceutical industries.

Performance characteristics according to Commission Decision 2002/657/EC in the fluorimetric determination of tetracycline in the absence and in the presence of magnesium

The fluorimetric determination of tetracycline is usually carried out in the presence of some metals that, through the formation of a complex with this antibiotic, enhance its fluorescence emission, giving more sensitive determination methods. It is well established that magnesium is one of these metals. However, it is possible that higher signals do not mean a real improvement in the quality of the analytical method. In this work, the univariate and multivariate fluorescence determination of tetracycline is performed in the presence and absence of Mg(2+), comparing the quality of the analyses through some performance characteristics that, according to Commission Decision 2002/657/EC define the functional qualities of analytical methods. The methods with the best performance characteristics were multivariate determinations carried out in the absence of Mg(2+), both when emission or excitation spectra were taken, the decision limits (CCalpha) being 13.1 and 20.1 microg/L and the detection capabilities (CCbeta) 25.3 and 38.5 microg/L, respectively. This study points out through a case study that higher analytical signals do not necessarily mean better performance characteristics of a method of analysis.

Rapid determination of sulfonamides in milk samples using fluorescence spectroscopy and class modeling with n-way partial least squares

In this paper, a methodology to evaluate the probability of false non-compliance and false compliance for screening methods, which give first or second-order multivariate signals is proposed. For this task 120 samples of 6 different kinds of milk have been measured by excitation-emission fluorescence. The samples have been spiked with different amounts of three sulfonamides (sulfadiazine, sulfamerazine and sulfamethazine). These substances have been classified in group B1 (veterinary medicines and contaminants) of annex I of Directive 96/23/EC. The European Union (Commission Regulation EC no. 281/96) has set the maximum residue level (MRL) of total sulfonamides at 100 microg kg(-1) in muscle, liver, kidney and milk. The work shows that excitation-emission fluorescence together with the partial least squares class modeling (PLS-CM) procedure may be a suitable and cheap screening method for the total amount of sulfonamides in milk. Three models, PLS-CM, have been built, for the emission and excitation spectra (first-order signals) and for the excitation-emission matrices (second-order signals). In all the cases it reaches probabilities of false compliance below 5% as required by Decision 2002/657/EC. With the same flourescence signals, the total quantity of sulfonamide was calibrated using 2-PLS, 3-PLS and PARAFAC regressions. Using this quantitative approach, the capability of detection, CCbeta, around the MRL has been estimated between 114.3 and 115.1 microg kg(-1) for a probability of false non-compliance and false compliance equal to 5%.

Identification and quantification of enrofloxacine in poultry feeding water through excitation emission fluorescence and three-way PARAFAC calibration

In this work an excitation emission molecular fluorescence technique with PARAFAC calibration is proposed for enrofloxacine determination in feeding water from poultry farms. In accordance with the working criteria of the 2002/657/EC European Decision, the proposed method has a capability of detection, CCbeta, of 6.8 microg l(-1), for both probabilities of false positive and false negative of 5%. The accuracy of the method is demonstrated and its precision is 1.7 microg l(-1), expressed as standard deviation. This method allows one to identify and determine the quantity of enrofloxacine present in water samples from poultry farms without it being necessary to determine the possible interferents, nor separate them in a step previous to calibration.