Estudo da presença de fármacos como adulterantes em suplementos alimentares empregando detecção amperométrica e voltamétrica

Abstract

The use of food supplements grows around the world every day. In order to improve physical performance, prevent disease, maintain and improve health, obtain and / or maintain desired body weight and still fill nutritional gaps in the diet, many individuals consume these products even without proven efficacy or safety. As a result of the growth of this market, cases of adulteration by synthetic substances increase. This implies the need to develop rapid, sensitive, selective methodologies that reach a considerable number of drugs of analytical interest. In this work two methods of analysis of multi-drug classes are described. The method of chromatographic separation with pulse-amperometric detection comprises 15 drugs: anorexigenics (amfepramone and femproporex), stimulants (caffeine, yohimbine, sildenafil and tadalafil), diuretics (furosemide), antidepressants (fluoxetine and sertraline), anxiolytics (lorazepam, clonazepam, midazolam and diazepam) and laxatives (bisacodyl). The characteristics related to the separation column (biphenyl) favored the study of a large number of compounds. The optimized conditions were: ammonium acetate 10 mmol L-1, methanol 64%, pH 4.0, 1.0 mL min -1, 40ºC, detection potential +0.8 V. The second method, using voltammetric pulse technique on the mercury electrode in organic medium, comprises a total of 10 pharmaceutical compounds being anxiolytics (alprazolam, bromazepam, clonazepam, chlordiazepoxide, midazolam and diazepam), diuretics (amiloride), antidepressants (bupropion) and anorectics (amfepramone and femproporex). The optimized conditions were: 0.01 mol L-1 NaClO4 in ACN, HMDE operating in differential pulse mode, scanning speed 30 mV/s. Of the two methods, a total of 20 drugs can be studied in real samples. Both methods were validated according to AOAC recommended parameters. Selectivity, linearity, limits of detection and quantification, precision and accuracy were evaluated. The chromatographic method (HPLC-PAD) was applied in 81 samples of food supplements marketed in Brazil. 1.23% of the samples had a positive signal for femproporex, 1.23% for amfepramone, 6.17% for yohimbine, 53.10% for caffeine, 1.23% for furosemide, 1.23% for tadalafil and 9.87 % for diazepam. From this total of samples containing drugs declared or not, two or more drugs were found in approximately 15% of the supplements analyzed. The concentration of the drugs varied from 0.20 to 866.88 mg/daily dose recommended by the manufacturer. The voltammetric method was applied only to samples with dilutions of at least one hundred times, since there is interference of the matrix in the redox reactions in the mercury electrode. The great differential of this work is the screening of 20 drugs as possible adulterants in food supplement samples, due to the characteristics of the stationary phase in chromatography and to the non-aqueous medium in voltammetry.