ABSTRACT:Introduction -Although medicinal plants are widely used throughout the world, few studies have been carried out concerning the levels of heavy metal contaminants present. Such metals are highly toxic to living organisms even in low concentrations owing to their cumulative eff ect. The present paper describes the the development of a pre-concentration fl ow injection analysis-fl ame atomic absorption spectrometric system to determine the lead content in medicinal plants at the ppb level. Objective -To develop a pre-concentration fl ow injection analysis-fl ame atomic absorption spectrometric system to determine the lead content in medicinal plants at the ppb level. Methodology -A pre-concentration fl ow system was coupled to a fl ame atomic absorption spectrometer. The plant samples were analysed after nitroperchloric digestion. The proposed system was optimised by evaluating the following parameters: nature, concentration and volume of the eluent solution, elution fl ow rate, elution effi ciency, pre-concentration fl ow rate and pre-concentration time. Results -The proposed system exhibited good performance with high precision and repeatability (RSD £ 2.36%), excellent linearity (r = 0.9999), low sample consumption (10.5 mL per determination) and an analytical throughput of 55 samples/h. Lead concentrations ranged from 3.37 ± 0.25 to 7.03 ± 0.51 mg/g in dry material. This concentration interval is greater than that previously published in the literature. Conclusion -The inclusion of a pre-concentration column in the fl ow manifold improved the sensitivity of the spectrometer. Thus, it was possible to determine the analyte at the ng/mL level in sample solutions of medicinal plants. This is a very important accomplishment, especially when the cumulative eff ect of heavy metals in living organisms is considered.

A solid-phase microextraction (SPME) procedure has been developed to extract eight organophosphorus pesticides (OPs) in water and the method was compared with a conventional solid phase extraction (SPE) technique. The extracted OPs were analyzed by gas chromatography using thermionic specific detection. Both extraction methods presented linear calibration at least over the concentration range investigated (100 to 1000 ng x mL(-1) for SPE and 1 to 100 ng x mL(-1) for SPME). SPME method presented higher sensitivity than SPE. The quantitation limits were between 0.1 to 1.0 ng x mL(-1) for SPME depending upon the analyte, and 100 ng x mL(-1) for SPE. The precision, as measured by the standard deviations (RSD), were in the range 3.6% to 5.8% for SPME and 2.4% to 9.2% for SPE. Along with the feature of being a solvent - free sampling technique, SPME offers additional benefits due to its high sensitivity, simplicity, and small size sample required (typically: SPE - 500 mL, SPME - 5 mL).

Farmers in the State of Piauí in northeastern Brazil reported nervous signs in ruminants and donkeys after ingestion of Brunfelsia uniflora at the start of the rainy season when the plant is flowering. Leaves of the plant, collected at the start or at the end of the rainy season, were administered in single doses of 5-20 g/kg body weight to 8 sheep and 3 donkeys. Two sheep and 1 donkey that ingested 10 g/kg of the plant in November at the start of the rainy season, when the plant was flowering, developed severe convulsions and diarrhea. One sheep was euthanized and autopsied, and no significant lesions were found. The other sheep and the donkey recovered. Four sheep and one donkey that ingested 10 or 20 g/kg of leaves collected in April, at the end of the rainy season, did not show clinical signs. One donkey that ingested 5 g/kg of leaves collected in November developed diarrhea and recovered. These results demonstrate the toxicity of B. uniflora for livestock and suggest that the plant is toxic at these doses only during the start of the rainy season.