A new method is described for the determination of the most common diuretic and laxative adulterants found in formulations of anorexics and antidepressants. The method is based on the separation of furosemide, hydrochlorothiazide, chlorthalidone and amiloride (diuretics), phenolphthalein (laxative), amfepramone (anorexic) and fluoxetine and paroxetine (antidepressants) by capillary zone electrophoresis with capacitively coupled contactless conductivity detection. The method showed a precision ranging from 1.9% to 6.9% for a concentration of 25 mg/L, 0.6% to 5.3% for a concentration of 50 mg/L and 1.6% to 6.0% for a concentration of 100 mg/L for all analytes. The accuracy was 99% for amiloride, 102% for chlorthalidone, 101% for hydrochlorothiazide, 101% for furosemide, 94% for phenolphthalein, 105% for fluoxetine, 114% for paroxetine and 117% for amfepramone. The method allowed the drugs to be determined in the formulations at concentrations higher than 5.1 mg/kg for amiloride, 7.7 mg/kg for chlorthalidone, 6.8 mg/kg for hydrochlorothiazide, 10.7 mg/kg for furosemide, 8.4 mg/kg for phenolphthalein, 11.0 mg/kg for fluoxetine, 9.4 mg/kg for paroxetine and 11.0 mg/kg for amfepramone. Three of the 26 analysed herbal formulations were found to be adulterated (not declared on the label) with the diuretic hydrochlorothiazide. Five other samples contained diuretics declared on the label on the formulation. Thus, a total of eight samples, which were marketed as natural products, contained diuretics (declared or not) on the formulation.

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A wide range of chromatographic methods for the analysis of phenolic compounds in medicinal plants has been published over the years. However, no chromatographic methods with pulsed amperometric detection using a gold electrode have been described to analyze phenolic acids and flavonoids. Moreover, there is a lack of information regarding a modified mobile phase with b-cyclodextrin to determine these compounds in plants by RP-HPLC. For this reason, the present study developed and validated an HPLC-PAD method to determine 12 phenolic compounds in medicinal plants from Amazonia. The isocratic mobile phase was constituted by sodium phosphate 50 m mol L À1 , methanol 30% (v/v), and b-cyclodextrin 1 m mol L À1 at pH 2.0. The method demonstrated low detection and quantification limits and robustness. The accuracy ranged from 82-114% for chlorogenic acid and rutin, respectively. Six species of medicinal plants from Amazonia used for medicinal and nutritional purposes were characterized and showed the presence of at least one of the phenolic compounds in the study.

Background: Alpha-lipoic acid (ALA) has become a common ingredient in food supplements and multivitamin formulas. ALA is widely used as therapy for preventing diabetic polyneuropathies, scavenges free radicals, and restores intracellular glutathione levels. This study aimed to develop a simple and fast analytical method to determine ALA content in dietary supplements using highperformance liquid chromatography with pulsed amperometric detection (HPLC PAD). Methods: ALA was analyzed by HPLC in a mobile phase composed of 25 mmol/L potassium phosphate in 50% (v/v) acetonitrile (pH 4.0) and PAD at a gold electrode (vs. solid-phase hydrogen reference electrode). The PAD cycle was performed by applying a detection potential (E1) of +0.7 V for 0.4 s, an oxidation potential (E2) of +1.0V for 0.4 s and a reduction potential (E3) of -0.2 V for 1.2 s. Results: The runtime method was shown a rapid procedure for the analysis of α-lipoic acid. The sampling rate of 8 injections per hour was attained and measurements of the reproducibility of successive injections (20 µL) showed an RSD of 1.89% for 16 successive injections. The method presented low quantification limit of 0.21 mg/L. The industrialized ALA-based supplements ranged from to 97.8 to 104.1%, while manipulated capsules ranged from 69.2 to 95.4%. Conclusion: Electrochemical detector has been presented as an effective alternative for ALA determination, which has weakly UV-absorbing. This detection has the benefits of sensitivity, simplicity and low costs. The developed HPLC-DAD method proposes to be analytical tool applicable to quality control of ALA supplements.