RESUMO:Oito amostras, provenientes do Brasil, Chile e Argentina, de Peumus boldus Molina (Monimiaceae), espécie comum e abundante no Chile, cujas folhas são amplamente empregadas pela medicina tradicional para o tratamento de uma variedade de afecções do sistema digestivo e hepatobiliar, foram analisadas, após digestão nítrica, para a quantifi cação de ferro, manganês, cobre, chumbo, cromo, cobalto e níquel, por espectrofotometria de absorção atômica. Chumbo, cromo e cobalto não foram detectados (limite de detecção de 5 g/g) em nenhuma das amostras. Todas as amostras apresentaram maior teor em ferro, que variou de 109,7 mg/kg a 315,7 mg/kg, seguido por manganês (65,5 mg/kg a 158,8 mg/kg), cobre (3,04 mg/kg a 9,16 mg/kg) e níquel (0,77 mg/kg a 4,31 mg/kg).Unitermos: Peumus boldus, metais pesados, absorção atômica. ABSTRACT: "Analysis of heavy metals in samples of Peumus boldus Mol. (Monimiaceae)".Eight samples, obtained from Brazil, Chile and Argentina, of Peumus boldus Molina (Monimiaceae), an abundant and widespread native tree in Chile, which leaves are widely used in folk medicine for the treatment of digestive and hepatobiliary disorders, were analyzed, after nitric digestion, for the content of iron, manganese, copper, lead, chromium, cobalt and nickel, by atomic absorption spectrophotometry. Lead, chromium and cobalt were not detected (detection limit of 5 g/g) in any sample. The samples showed a high level of iron, which ranged from 109.7 mg/kg to 315.7 mg/kg, followed by manganese (65.5 mg/kg to 158.8 mg/kg), copper (3.04 mg/ kg to 9.16 mg/kg) and nickel (0.77 mg/kg to 4.31 mg/kg).

Atomic absorption spectrophotometry is considered the method of choice for hepatic iron quantification. The objective of the present study was to perform full validation assays of hepatic iron quantification by atomic absorption spectrophotometry, using a fast sample preparation procedure, following the guidelines from the International Conference on Harmonization. The following parameters were evaluated: specificity, linearity/range, precision, accuracy, limit of detection and limit of quantification. A good linear correlation was found (0.9948) in the concentration range evaluated (20- 120 ppb). The relative standard deviations were below 15% for accuracy, and below 10% for both day-to-day reproducibility and within-days precision, and the repeatability of injections was 0.65%. Limit of detection was 2 ppb, and limit of quantification was 6 ppb. Fresh bovine liver tissue was used to evaluate the procedure of collecting samples by liver biopsies. These findings indicate that hepatic iron quantification by atomic absorption spectrophotometry can be reliably performed at the established conditions, and suggest the method is suitable for further use in clinical practice. Hepatic iron quantification by AAS is validated by the experiments performed in the present study.

The objective of this work was to develop and fully validate an analytical assay to quantify zinc in hepatic tissue. The procedure should be as simple and fast as possible in order to avoid sample contamination. The amount of sample used should also reflect the sample size usually obtained in clinical biopsies, which are about 3–4 mg at most. The validation protocol is in accordance to international guidelines, such as ICH and FDA. The parameters evaluated were precision, accuracy, range, limit of detection and limit of quantification. The method was evaluated in the 2.0–32.0 parts per billion (μg/l) range. Under the described conditions intra and inter day precision of the three levels of quality controls were lower than 9.06 and 5.27, respectively, expressed as relative standard deviation (RSD). The accuracy ranged from 86.35 to 114.71%. Limit of detection and limit of quantification were 0.60 and 2.0 μg/l, respectively. Fresh bovine liver samples were used in order to evaluate the clinical procedure used to collect biopsies. According to the results and experimental protocol, the method is fully validated and ready to use in clinical trials involving zinc quantitation using hepatic samples as small as 2.00 mg of dry tissue.