Abstract: Green Analytical Chemistry (GAC) is a research field that seeks for more sustainable analytical approaches to minimize the toxicity and amounts of wastes without hindering the analytical performance. This is a trend in Analytical Chemistry worldwide and because of the diversity of innovations on this subject, Brazil stands out as the third in the list of the main contributors to GAC, with ca. 11.2% of the published articles. Significant innovations and interesting applications in several fields have been presented and Brazil is continuously moving from Chemistry to Green Chemistry also in the Analytical Chemistry field. Selected contributions for sample preparation, spectro- and electroanalysis, separation techniques, chemometrics, and also procedures for point-of-care measurements are critically reviewed.

ABSTRACT Coupling solid-phase extraction (SPE) to flow systems has promoted a synergistic development. Whereas SPE mechanization leads to improved precision and higher sample throughput, as well as diminishes systematic errors and contamination risks, analyte concentration and separation from the sample matrix provides a remarkable impact on detectability and selectivity in flow analysis. Historical aspects, main cornerstones, tips for system design, and recent applications are critically reviewed, in the context of analyte(s) separation/concentration, sample clean-up, and release of sorbed chemical species involving both packed (e.g. mini-columns, cartridges, and disks) or fluidized (e.g. beads and magnetic materials) particles. Novel (bio)sorbents, selective synthetic materials, and stationary phases for low-pressure chromatography are also discussed. Moreover, the feasibility of SPE for sample treatment before chromatographic separation, as well as the exploitation of direct measurements on the solid phase (optosensing) are emphasized.

Um sistema de análise por injeção em fluxo com detecção espectrofotométrica é proposto para determinação de cloreto em eletrólito de bateria chumbo-ácido, utilizando a reação com tiocianato de mercúrio(II) em meio contendo ferro(III). A formação de gradientes de índice de refração no centro da zona de amostra foi evitada utilizando um elevado volume de amostra. Interferência devida a sulfato foi investigada e a correlação entre os equilíbrios químicos envolvidos e os sinais transientes gerados foi utilizada para desenvolver uma estratégia para a quantificação de cloreto. Amostras contendo de 2,2 a 3,7 mol L-1 de ácido sulfúrico podem ser determinadas utilizando a mesma curva analítica, sem efeitos matriciais ou qualquer tratamento prévio. O limite de detecção e o desvio padrão relativo das medidas foram estimados em 0,37 mg Cl- L-1 (nível de confiança de 99,7 %) e 1,6%(n = 10), respectivamente. A frequência de amostragem foi 45 h-1. Porcentagens de recuperação entre 95,9 e 108% foram obtidas para adições de cloreto (2,00 a 8,00 mg L-1) nas amostras.

A flow injection spectrophotometric system is proposed for determining chloride in lead-acid battery electrolyte by using the displacement reaction between mercury(II) thiocyanate and chloride in a medium containing iron(III). The employment of a large sample volume was effective to avoid refractive index gradients in the central part of the sample zone. Sulfate interference was studied and the correlation between the chemical equilibria involved and the transient signals was used to develop a strategy for chloride quantification. Samples containing from 2.2 to 3.7 mol L-1 of sulfuric acid can be determined by using the same analytical curve, without matrix interference or any previous treatment. The detection limit and the relative standard deviation were estimated in 0.37 mg Cl- L-1 (99.7% confidence level) and 1.6% (n = 10), respectively. The sampling rate was 45 h-1. Recoveries between 95.9 and 108% were obtained for additions of chloride (2.00 to 8.00 mg L-1) in the samples.