Solid-phase extractions in flow analysis

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.

Optimization of solid‐phase extraction of parabens and benzophenones in water samples using a combination of Plakett‐Burman and Box‐Behnken designs

“…Preliminary preconcentration experiments were performed to determine the effect of sorbent material type (C18, HLB, and Strata X). This factor was evaluated in a univariate experiment because sorbent materials with different particle sizes and breakthrough capacities were used . The C18 sorbent was selected to evaluate its preconcentration capacity for PCPs due to its better retention capacity for most analytes in the mixture (see Supporting Information Figure S2).…”

Use of dimethylglyoxime for the spectrophotometric flow-based determination of nickel in natural waters

“…One of the strategies, very often used in analytical chemistry, is solid phase extraction (SPE). This is considered a very versatile technique for sample preparation and the main objective is the sample matrix removal and/or enrichment of the target analyte, enabling the increase of sensitivity and selectivity [7][8][9][10]. However, some drawbacks are associated with the use of this technique in a flow-based approach, such as the decrease on sample analysis throughput, the preferential pathways and the increased backpressure [10].…”

“…This is considered a very versatile technique for sample preparation and the main objective is the sample matrix removal and/or enrichment of the target analyte, enabling the increase of sensitivity and selectivity [7][8][9][10]. However, some drawbacks are associated with the use of this technique in a flow-based approach, such as the decrease on sample analysis throughput, the preferential pathways and the increased backpressure [10]. Another potential strategy, that aims the increase of the sensitivity of a spectrophotometric method in flow analysis, is the use of cells with increased pathlength such as the liquid waveguide capillary cell (LWCC) [11].…”

Desenvolvimento de colunas monolíticas poliméricas para extração em fase sólida de metais e separação de neurotransmissores por nanocromatografia de interação hidrofílica

“…Tal conformação resulta em alta eficiência de separação devido à rápida difusão dos analitos que se estabelece na fase estacionária, diminuindo a contribuição do termo C da equação de van Deemter. Além disso, colunas empacotadas com partículas core-shell geram pressão muito menor do que as colunas (de mesmo diâmetro e comprimento) empacotadas com partículas totalmente porosas de mesmo diâmetro[61,52]. Mesmo assim, colunas monolíticas são mais apropriadas aos sistemas SIC, pois permitem análises mais rápidas (maiores vazões) sem perda de eficiência, como demonstrado por Urio e Masini para separação de herbicidas triazínicos usando colunas monolíticas e core-shell[114].O fluxo bidirecional e descontínuo característico do SIA é usado para aspirar e injetar volume bem definido de uma suspensão de partículas esféricas com propriedades adsorventes e formar colunas renováveis e bastante reprodutíveis em cada ciclo de SPE, numa abordagem chamada de SPE por injeção de esferas, ou do termo em inglês, Bead Injection -Solid Phase Extraction (BI-SPE).…”

“…solução de lavagem é enviada pela coluna e remove o que restou dos componentes não retidos da amostra; (iv) Eluição: o eluente passa pelo sorvente liberando o analito[52].A SPE é mais fácil e rápida de ser realizada do que a LLE por não ocorrer a formação de emulsão. Também expõe menos o operador a amostras perigosas e a solventes orgânicos tóxicos, tem maiores fatores de pré-concentração e polui menos o ambiente, já que reduz o consumo de solventes orgânicos tóxicos.…”