A fluorescent (340/380 nm) photochemical product, identified at m/z 206 by mass spectrometry was obtained by photo-derivatization (15 s ultraviolet exposure) in water/acetonitrile 10/90 v/v. The photoproduct was used for indirect determination of trifloxystrobin in water and soy grape juice by high-performance liquid chromatography and fluorescence detection. Separation was made under isocratic conditions (acetonitrile/water 70/30% v/v, at 1.0 mL min 1 and 35 ºC) with trifloxystrobin photo-derivative eluting at 3.2 min. The influence of ultraviolet exposure was evaluated in short and long terms with photoproduct showing stability up to 120 min after 15 s of ultraviolet exposure. The limit of detection was 57 µg L-1 in water (87-109% recoveries). For soy grape juice, dispersive liquid-liquid micro-extraction was used to clean up and for pre-concentration (limit of detection of 9.5 µg kg 1 and 93-101% recoveries) attending to the maximum residue limits for citrus juices established by regulatory agencies. Potential interference by triazoles was evaluated.

A simple and sensitive method has been proposed for the determination of sibutramine-HCl in energy drinks, green tea and pharmaceutical formulations using differential pulse voltammetry performed on a hanging mercury drop electrode. In the chosen experimental condition (Mcllvaine pH 4.0 buffer, 50 mV pulse amplitude and 40 mV s-1 scan velocity), sibutramine-HCl presented a reversible behavior and a peak maximum at -80 mV. Detection limit was 0.4 mg L-1 and the working linear range extended up to 33.3 mg L-1 (r = 0.99). Analysis of real and fortified samples enabled recoveries between 91 and 102%. The electroanalytical method was compared with a HPLC method which indicated it accuracy.

Room-temperature phosphorimetry was used to quantify trace levels of chrysene in sugar-cane spirits and in fish bile. A selective phosphorescence enhancer (AgNO3) and synchronous scanning allowed the detection of ng amounts of chrysene. Accuracy (113 ± 17%) and selectivity was evaluated using the CRM-NIST-1647d - Priority Pollutant Polycyclic Aromatic Hydrocarbons in acetonitrile. Analysis of sugar-cane spirit samples enabled recovery of 108 ± 18% which agreed with the one achieved using HPLC. Method's uncertainty was equivalent to 3.4 ng of the analyte, however, the analyte pre-concentration (SPE) improved sensibility and minimized the relative uncertainty. Characterization and homogeneity studies in fish bile were also performed.