Rare earth elements in drill cutting samples from off-shore oil and gas exploration activities in ultradeep waters.

Rare earth elements (REEs) are essential in high technology industries and have great economic value. The monitoring of REEs concentrations in rocks from oil well drill cuttings is critical to avoid environmental contamination and evaluate new sources of these elements. However, information is scarce about the REEs concentrations in drill cuttings. In this work, the concentration of REEs in drill cuttings from oil and gas exploration wells in ultradeep coastal water of Brazilian were investigated at different depths. The drill cutting samples were submitted to microwave-assisted acid digestion prior to the determination of concentration by ICP-MS, using Rh as internal standard for calibration. The limits of quantification (LoQ) ranged from 3.3 µg kg-1 for Ho to 198 µg kg-1 for Sm. The accuracy was evaluated by analyzing certified reference materials for rocks. The obtained REEs concentrations agreed with the certified values, reaching 83%-105% agreement. The drill cutting depth profile analysis indicates Ce, La, Nd, Sm, and Eu concentrations up to mg kg-1. The REEs concentrations obtained in drill cutting depth profile was analyzed by principal component analysis (PCA), and hierarchical cluster analysis (HCA) identified tendency and similarity between drill cutting samples. Three groups were formed according to the composition of the REEs. In addition, the concentration of these chemicals elements varied at different depths. The analysis of drill cuttings revealed REEs concentrations up to the mg per kg-range (ppm), potentially making this disposable material an alternative source for REEs extraction, and adding value to this material.

Evaluation of the Mineral Content in Forage Palm (Opuntia ficus-indica Mill and Nopalea cochenillifera) Using Chemometric Tools.

An acid digestion procedure of the forage palm (Opuntia ficus-indica Mill and Nopalea cochenilifera) employing a closed digestor block applied full 24 factorial design was optimized. The optimal conditions were HNO3 5.0 mol L-1, 2.0 mL of H2O2 30% m m-1, 120 min of digestion, and heating temperature of 180 °C. The certified reference materials of apple leaves (NIST 1515) and tomato leaves (Agro C1003a) were used to evaluate the accuracy of the analytical method. The concentrations of the macroelements were (in % m m-1) Ca (1.32-3.71), K (0.88-5.29), Mg (0.70-1.78), and P (0.03-0.32). For the microelements, the concentrations (in µg g-1) obtained were As (< 1.39), Cd (< 0.10), Cu (< 0.17-5.6), Fe (8.0-50.2), Na (< 1.85), Sr (41-348), and Zn (17.3-159). Essential elements such as Ca, Mg, and Zn made good contributions to daily intake, being an alternative to meet the nutritional needs of these macroelements and microelements in humans. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to evaluate the results, obtaining trends between the samples in relation to their mineral composition.

Assessment of cadmium and lead in commercial coconut water and industrialized coconut milk employing HR-CS GF AAS.

In this work, an analytical method for the determination of Cd and Pb in natural coconut water samples, industrialized coconut water samples and coconut milk using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS), after minimum treatment of the sample was developed. The analytical method was applied to 46 samples collected in Salvador, Bahia (Brazil). The ranges of concentrations obtained were: 0.42-18.72 µg L-1 Cd and <0.70-36.32 µg L-1 Pb for natural coconut water samples (n = 14); <0.06-1.49 µg L-1 Cd and 6.57-29.02 µg L-1 Pb for industrialized water coconut samples (n = 16); and <0.10-5.93 ng g-1 Cd and <0.85-22.41 ng g-1 Pb for coconut milk samples (n = 16). For all samples, Cd and Pb concentrations were below the maximum tolerated values recommended by Brazilian Health Surveillance Agency (Agência Nacional de Vigilância Sanitária, ANVISA).