Optimization of an analytical protocol for the extraction, fractionation and determination of aromatic and aliphatic hydrocarbons in sediments

Abstract

Neste trabalho foram aperfeiçoadas as etapas para determinação de hidrocarbonetos alifáticos e aromáticos em sedimentos. Durante as etapas de extração e concentração foram avaliados fatores determinantes como tempo, solvente extrator e sistema de resfriamento. Quanto ao cleanup, foram estudados diferentes volumes e misturas de solventes de eluição. Os resultados obtidos foram considerados aceitáveis (70-120%). A linearidade, limites de detecção e quantificação foram estudados construindo-se curvas analíticas (R > 0,99) com valores que demonstraram grande sensibilidade do método. A precisão e exatidão foram avaliadas com ensaios envolvendo material de referência certificado e adição e recuperação de analitos em sulfato de sódio. Nos testes de adição e recuperação os desvios ficaram abaixo de 20%, com recuperação dos alifáticos e aromáticos de 59-105% e 55-113%, respectivamente. Para os sedimentos de referência, os desvios obtidos foram inferiores aos valores certificados, com recuperações satisfatórias. O presente trabalho proporcionou a melhoria de um método já consolidado, possibilitando obter resultados com elevada confiabilidade analítica.The main steps involved in the determination of aliphatic and aromatic hydrocarbons in sediments were evaluated in this work. In the extraction, factors such as the cooling system, time and solvent were evaluated. During the extraction and concentration, steps aspects such as time, extraction solvent and cooling system were evaluated. In the cleanup different solvents and elution mixtures were studied. The results were considered satisfactory (70-120%). Linearity and limits of detection and quantification were studied by means of calibration curves (R > 0.90) and the results demonstrated high sensitivity of the method. Precision and accuracy were studied by recovery tests using a certified reference material and sodium sulfate. In recovery tests, the standard deviations were below 20%, with percent recoveries for aliphatic and aromatics ranging from 59 to 105% and 55 to 113%, respectively. For the reference sediment, the standard deviations were lower than the certified values, with satisfactory recovery values. The present work provided a way of improving an already established method with high analytical reliability.

Poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] Oligomer Single-Crystal Nanowires from Supercritical Solution and Their Anisotropic Exciton Dynamics

“…To help verify this material, we separately synthesized BTTT1.5; detailed synthesis is available in the Supporting Information. Fractionation of aliphatic polymers in SCF has previously been reported, , but this result is the first to show the fractionation and concurrent crystallization of conjugated materials.…”

“…To help verify this material, we separately synthesized BTTT1.5; detailed synthesis is available in the Supporting Information. Fractionation of aliphatic polymers in SCF has previously been reported, 43,44 but this result is the first to show the fractionation and concurrent crystallization of conjugated materials. Figure 3 shows photoluminescence (PL) spectra of BTTT1.5 crystals formed in scHex compared with pure BTTT1.5 (synthesized via Stille coupling) in solution and crystallized from slow evaporation of hexanes at room temperature.…”