Jana Sádecká

Determination of ibuprofen and naproxen in tablets.

Ibuprofen and naproxen have been quantified in tablets by capillary isotachophoresis. Hydrochloric acid (10 mmol/l) adjusted with creatinine to pH 5.0 plus 0.1% polyvinylpyrrolidone was used as the leading electrolyte and 10 mmol/l 4-morpholineethanesulfonic acid as the terminating electrolyte. Linearity was observed from 40.0 to 200.0 mg/l of ibuprofen (naproxen), with a coefficient of determination (r2) of 0.999. Good quantitation was obtained in short analysis time. The isotachophoretic results were compared with those obtained by the fluorescence spectrometry. Experimental parameters for ibuprofen were: lambdaEX=224 nm and lambdaEM=290 nm. Experimental parameters for naproxen were: lambdaEX=230 nm and lambdaEM=355 nm. The calibration plot was found to be linear in the range 0.4-2.4 mg/l for ibuprofen and 5.0-20.0 microg/l for naproxen. The minimal sample pretreatment and relatively low running cost make isotachophoresis a good alternative to existing methods.

Determination of organic acids in tobacco by capillary isotachophoresis.

Nine organic acids and phosphate have been separated and quantified in tobacco by capillary isotachophoresis. Two operating systems for the separation were found: hydrochloric acid (10 mmol l(-1)) adjusted with beta-alanine to pH 2.9 plus 0.1% poly(vinylpyrrolidone) was used as the leading electrolyte and 10 mmol l(-1) nicotinic acid as the terminating electrolyte and hydrochloric acid (10 mmol l(-1)) including 5.5 mmol l(-1) 1,3-bis[tris(hydroxymethyl)methylamino]propane plus 0.1% poly(vinylpyrrolidone) was used as the leading electrolyte and 5 mmol l(-1) 2-morpholinoethanesulfonic acid as the terminating electrolyte. Linearity was observed from 0.008 to 0.100 mmol l(-1) with a coefficient of determination (r2) of 0.999. The separation of anions was achieved in less than 16 min. The minimal sample pretreatment and relatively low running cost make isotachophoresis a good alternative to existing methods.

Determination of inorganic anions in saliva by capillary isotachophoresis

Nitrite, nitrate, iodide and thiocyanate have been quantified in non-smoker and smoker saliva by capillary isotachophoresis (CITP). Hydrochloric acid (10 mmol l(-1)) adjusted with histidine to pH 6.0 plus 6% poly(vinylpyrrolidone) was used as the leading electrolyte (LE) and 5 mmol l(-1) acetic acid as the terminating electrolyte (TE). Linearity was observed from 0.005 to 0.500 mmol l(-1) with a coefficient of determination (r(2)) of 0.999. The separation of anions was achieved in less than 19 min. The minimal sample pretreatment and relatively low running cost make isotachophoresis good alternative to existing methods.

Fluorescence spectroscopy and multivariate methods for the determination of brandy adulteration with mixed wine spirit

The addition of mixed wine spirit to brandy is easy way to adulterate brandy. To avoid the misleading of the consumers, it is necessary to develop reliable method to detect adulteration of brandy. In this work excitation emission matrix fluorescence in combination with parallel factor analysis (PARAFAC) and partial least squares (PLS) regression was used to determine the content of mixed wine spirit in adulterated brandy samples. Excitation emission matrix fluorescence spectra were measured in the emission wavelength range of 485-580 nm and in the excitation wavelength range of 363-475 nm. The model created using PARAFAC-PLS was able to predict the mixed wine spirit level in adulterated brandy with the root mean square error of prediction (RMSEP) value of 1.9% and a square of the correlation (R(2)) between the reference contents and the predicted values of 0.995.

Determination of geographical origin of alcoholic beverages using ultraviolet, visible and infrared spectroscopy: A review

The identification of the geographical origin of beverages is one of the most important issues in food chemistry. Spectroscopic methods provide a relative rapid and low cost alternative to traditional chemical composition or sensory analyses. This paper reviews the current state of development of ultraviolet (UV), visible (Vis), near infrared (NIR) and mid infrared (MIR) spectroscopic techniques combined with pattern recognition methods for determining geographical origin of both wines and distilled drinks. UV, Vis, and NIR spectra contain broad band(s) with weak spectral features limiting their discrimination ability. Despite this expected shortcoming, each of the three spectroscopic ranges (NIR, Vis/NIR and UV/Vis/NIR) provides average correct classification higher than 82%. Although average correct classification is similar for NIR and MIR regions, in some instances MIR data processing improves prediction. Advantage of using MIR is that MIR peaks are better defined and more easily assigned than NIR bands. In general, success in a classification depends on both spectral range and pattern recognition methods. The main problem still remains the construction of databanks needed for all of these methods.

Isotachophoretic determination of naproxen in the presence of its metabolite in human serum

An isotachophoretic method with conductivity detection was developed to determine naproxen in the presence of its metabolite 6-O-desmethylnaproxen in human serum. The leading electrolyte contained 10 mM hydrochloric acid, beta-alanine, pH 4.0 and 0.1% methylhydroxypropylcellulose. The terminating electrolyte was 10 mM 2-(N-morpholino)ethanesulfonic acid-tris(hydroxymethyl)aminomethane, pH 6.9, containing 20% (v/v) of ethanol. Naproxen was determined in serum supernatant after simple deproteination of the sample with ethanol. The isotachophoretic results were compared with those obtained by synchronous fluorescence spectrometry.

Simultaneous determination of caffeine, caramel and riboflavin in cola-type and energy drinks by synchronous fluorescence technique coupled with partial least squares

The aim of this work was to develop a multivariate method for the rapid determination of caffeine and Class IV caramel in cola-type soft drinks and of caffeine, Class III caramel and riboflavin in energy drinks using synchronous fluorescence spectra. The synchronous fluorescence spectra were recorded at constant wavelength difference 90 nm from 200 to 500 nm. Reference values of analyte concentrations by high performance liquid chromatography (HPLC) with fluorescence detection combined with the standard addition method were used to create the partial least squares (PLS) models. High coefficients of determination (>0.99) were obtained in 0.2-4.2, 0.25-5.25, 0.4-10.0 and 0.007-0.054 mg L(-1) range for caffeine, Class III caramel, Class IV caramel and riboflavin, respectively. The PLS models were used to determine the concentration of analytes in different drink samples. The method provided comparable results with those found using the HPLC method.

Classification of plum spirit drinks by synchronous fluorescence spectroscopy.

Synchronous fluorescence spectroscopy was used in combination with principal component analysis (PCA) and linear discriminant analysis (LDA) for the differentiation of plum spirits according to their geographical origin. A total of 14 Czech, 12 Hungarian and 18 Slovak plum spirit samples were used. The samples were divided in two categories: colorless (22 samples) and colored (22 samples). Synchronous fluorescence spectra (SFS) obtained at a wavelength difference of 60 nm provided the best results. Considering the PCA-LDA applied to the SFS of all samples, Czech, Hungarian and Slovak colorless samples were properly classified in both the calibration and prediction sets. 100% of correct classification was also obtained for Czech and Hungarian colored samples. However, one group of Slovak colored samples was classified as belonging to the Hungarian group in the calibration set. Thus, the total correct classifications obtained were 94% and 100% for the calibration and prediction steps, respectively. The results were compared with those obtained using near-infrared (NIR) spectroscopy. Applying PCA-LDA to NIR spectra (5500-6000 cm(-1)), the total correct classifications were 91% and 92% for the calibration and prediction steps, respectively, which were slightly lower than those obtained using SFS.

Isotachophoretic analysis of some antidepressants

Abstract Optimal electrolyte systems for the analysis of the substances with tricyclic structure, clomipramine and imipramine, and tetracyclic, maprotiline, were determined. The analysis conditions were applied to the determination of these compounds in antidepressant drugs.

Spectrofluorimetric determination of ellagic acid in brandy

Two spectrofluorimetric methods have been developed for the rapid determination of ellagic acid. The first method is based on the complex formation between ellagic acid and borax in methanol solution. The fluorescence of the complex is monitored at an emission wavelength of 456nm with excitation at 383nm. Linear calibration curve was obtained from 2.5×10(-8) to 7.5×10(-7)molL(-1) and the limit of determination was 4×10(-9)molL(-1). The second method is based on the complex formation between ellagic acid and boric acid in ethanol solution. The fluorescence of the complex is monitored at an emission wavelength of 447nm with excitation at 387nm. Linear calibration curve was obtained from 1.25×10(-7) to 1.00×10(-6)molL(-1) and the limit of determination was 7×10(-9)molL(-1). The methods were successfully applied for the determination of ellagic acid in brandy samples. The results were found to be in good agreement with those obtained by HPLC method.