Fundamentals of sinusoidal flow sequential injection spectrophotometry

Abstract

A rational design of the sequential injection analyzer is based on description of the mutual penetration of sample and reagent zones, which are sequentially stacked into a tubular conduit and then injected into a reactor and transported toward the detector by means of a carrier stream, flowing at a preprogrammed rate. Variables governing zone penetration have been identified by a series of dispersion experiments, for sequential injection of two and three zones, thus outlining the conditions for performing single- and double-reagent-based assays. A parallel is drawn between conventional flow injection and corresponding sequential injection colorimetric determinations of chloride and phosphate, with the aim of suggesting guidelines for the development of spectrophotometric- and fluorescence-based sequential injection methods.

Development of a fluorimetric sequential injection analysis (SIA) methodology for determination of quinine

“…7 Increase in sample volume enhances the sensitivity of the measurements only if excess of reagent is fed to the sample zone. Thus, for sample volumes as large as the ones leading to 1 < D < 2, sandwiching the sample between reagent zones is recommended.…”

“…A typical system is configured in single line by a syringe pump, coupled to a two-way valve that can communicate with the carrier or with a multiport valve through a holding coil where the reaction zone is formed prior to injection toward the detector, placed in another port of the multiport valve, immediately after the reaction coil. 7 The optimization process can be laborious and take a long time, depending on the chosen route and variables considered in the process. The whole process may be simplified by an initial evaluation of sample dispersion and mixing efficiency using a dye solution in place of either sample or reagent.…”

“…The whole process may be simplified by an initial evaluation of sample dispersion and mixing efficiency using a dye solution in place of either sample or reagent. 7,8 In SIA systems this approach is useful because the physical configuration does not change, and all the parameters can be used for development of other methods if the tubing dimensions are not altered. As a second step the chemical parameters are optimized for the specific determination, usually considering: concentration of reagents, flow rate, stopped-flow time and others.…”

A análise por injeção sequencial (SIA): vinte anos em uma perspectiva brasileira

“…Revertendo-se a direção do fluxo, as zonas são transportadas em direção ao detector através de uma bobina de reação, cuja função é garantir um percurso analítico mínimo para a sobreposição das zonas por efeitos de dispersão causados por difusão axial e radial, assim como da convecção. Um estudo sobre estes processos de dispersão e difusão foi detalhado por Gübeli et al 7 Toda a operação é controlada por um computador que disponha de programa específico para o SIA. As partes do sistema (indicadas pela linha tracejada na Figura 1) tornam-se então gerenciáveis pelo operador, exclusivamente através da interface computadorizada.…”

Advancement of Flow-based Analysis with Alternative Chemical Reactions and New Devices for Environmental and Biological Samples

“…[9][10][11] And, Economou reviewed SIA for on-line sample handling and pretreatment. 12 Figure 1(b) shows a mini-conduit module with a flow cell and a fiber optics mounted atop a multi-port valve, called SI-Lab-on-Valve.…”