The Brazilian regulations for processed coconut water establish the range concentrations of Na and K, being necessary high-throughput analytical methods, as microwave-induced plasma optical emission spectrometry (MIP OES) for quality control. Samples of natural (green and mature) and processed coconut water were treated by acid decomposition assisted by microwave radiation before their MIP OES analysis. Recoveries for Na and K were 103 and 95%, whereas the relative standard deviation (RSDs) were 7.6 and 1.3%, respectively. The limit of detection (LOD) was 1.77 mg kg-1 for K and 2.31 mg kg-1 for Na. Na and K were determined in the ranges of, respectively, 27-490 and 1,600-3,500 mg L-1 in natural samples, whereas in processed samples the ranges were 26-168 and 814-2,054 mg L-1. K-means cluster analysis identified a group of processed samples with compositions similar to green coconut water. All the processed samples were in accordance with the established regulation, except one dehydrated sample for which K content was below the accepted range. Natural coconut water is an excellent source of K in the diet as its daily consumption can supply more than 20% of the recommended daily ingestion of K for adults and 30% for children.

An automated method based on open-source hardware was created for the separation of porphyrins fractions from crude oil, an essential step for the quantification of V and Ni as metalloporphyrins. Preparative liquid chromatography was implemented with a reverse phase gradient from MeOH to toluene. The system allows three solvents and fractions changes by using quaternary valves connected to an Arduino microcontroller, programmed on the basis of the absorbance signal measured and its first derivative. Additionally, the method was applied to crude oils (Venezuelan National Institute of Standards and Technology (NIST) 8505 and from a marine reservoir). V and Ni were determined by inductively coupled plasma mass spectrometry (ICP-MS) and the V-porphyrin profile was determined by high performance liquid chromatography (HPLC)-ICP-MS. The concentrations of the metals grow in the last eluting toluene fractions, associated with asphaltenes. On the other hand, V-porphyrins in the first eluting MeOH fractions showed profiles of labile compounds, with a higher percentage in the Brazilian crude oil (4.9 mg L-1, corresponding to 18% of total V), in comparison to the one from the biodegraded NIST 8505 (59 mg L-1, corresponding to 7% of total V). The overall methodology has a good reproducibility and provides information on elements concentrations associated with porphyrin class compounds.

Perfis de distribuição de elementos traços foram determinados em óleos crus de reservatórios biodegradados situados ao longo de um caminho de migração secundaria (Bacia de Potiguar, Brasil). As amostras foram fracionadas em asfaltenos, parafinas, aromáticos e polares e resina para determinação de 22 elementos traços por ICP-MS. Esses se concentram nas frações de resina e asfaltenos, exceto V e Ni também encontrados na fração de aromáticos e polares. V, Co, Ni e Mo foram influenciados por processos de biodegradação e acumulam-se nas amostras mais afetadas e de maior distância de migração. Variações semelhantes da razão Ni/V nos aromáticos e polares e dos índices de homohopano e gamacerano nas parafinas evidenciaram também a influencia da biodegradação. As distribuições elementares foram similares para os óleos e seus asfaltenos, sugerindo que esses últimos, mais refratários que o óleo original, possam ser usados como uma ferramenta geoquímica inorgânica robusta de impressão digital para caracterização de óleos.

Trace element distribution patterns were determined in crude oils from onshore biodegraded reservoirs along a secondary migration trend (Potiguar Basin, Brazil). Samples were fractionated into asphaltenes, paraffins, aromatics and polars and resins for the determination of 22 trace elements by ICP-MS. Most of them are strongly enriched in the resin and asphaltene fractions, but V and Ni are also associated with the aromatic and polar fractions. V, Co, Ni and Mo were influenced by biodegrading processes and accumulate in the most affected and migrated samples. Variations of the Ni/V ratio in aromatics and polars, matching those of homohopane and gammacerane indexes in paraffin, evidenced also the influence of biodegradation. Very similar elemental distribution patterns in oil and corresponding asphaltenes were observed, suggesting that the latter fraction, more refractory than the original oil, can be used as a robust inorganic geochemical fingerprint for oil characterization.