A new analytical protocol has been developed for the determination of mercury in surface sediments using dithiothreitol (DTT) as a new chelating reagent for the extraction. This protocol requires a small sample mass (250 mg), 4.0 mL of a 0.1 M (pH = 9.0) aqueous DTT solution, and sonication for 30 min, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). The limits of detection and quantification determined were 6 and 18 ng g−1, respectively. The method was validated using three standard reference materials, SRM NIST 1646a, PACS-2, and MESS-3, with recoveries in the range of 102-124%. The new analytical protocol was successfully applied in riverine surface sediments, revealing concentrations in the range of 220-340 ng g−1. The results obtained by CV-AFS were compared to those obtained by DMA-80 (direct mercury analyzer). The linear regression equation obtained was [CV-AFS] = (0.91 ± 0.07)[DMA-80] + (0.04 ± 0.02), revealing no systematic difference between the analytical methods. Hence, the proposed method does not require the complete digestion of the sediment, and was found to be comprehensive, simple, accurate and suitable to be employed for determination of mercury in sediment samples.

Abstract Honey is a food of nutritional, medicinal and commercial importance. The physicochemical characteristics, pollen spectrum and mineral composition of eighteen honey samples obtained from regions (Cachoeira, Coqueiros, Maragojipe and Santiago do Iguape) near the Paraguaçu River, Bahia, Brazil were evaluated. Botanical families Asteraceae, Leguminosae, Malvaceae, Myrtaceae and Palmae were most frequently found. Five samples had water contents above the maximum limit established by the Brazilian legislation (> 20%). The mineral composition was determined by ICP OES, after microwave digestion. Ca, K, Mg and Na were measured (mg Kg-1) in the range from: 18.85 to 79.61; 366.74 to 1214.98; 12.46 to 44.59 and 11.56 to 85.39, respectively. Cu, Fe, Mn and Zn had variable concentration ranges, between 0.05 and 6.13 mg Kg-1. Al, Ba, Cd, Co, Cr, Ni, Pb, Se and V showed values below the LOD. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) demonstrated that there are no similarities of mineral composition among honey samples.