Flow Analysis: Looking Back and Forward

Abstract

Flow analysis changed significantly the way of performing chemical analysis by (i) mechanization of analytical procedures in a continuous flowing stream with minimal sample intercontamination; (ii) analytical measurements without attaining chemical equilibria, thus increasing the applicability of kinetic methods and allowing the exploitation of non-quantitative processes; (iii) exploitation of concentration gradients and (iv) use of unstable reagents or measurement of unstable products. Flow-based procedures are generally characterized by high sample throughput, improved precision, minimized waste generation, and often better selectivity. The performance of detection systems is usually improved because of the in-line sample conditioning and measurements under reproductive dynamic conditions and timing. However, after achieving several innovations, perspectives for further developments have been questioned mainly because of the recent decrease in the number of publications on flow analysis. The aim of this review is then to discuss the impact of flow-based methods on chemical analysis, emphasizing recent applications and developments, including miniaturization, bioanalysis, microextractions, green analytical chemistry and synergic hyphenation with other techniques and processes. The author's personal view about research perspectives in the field is also presented.

Chemical Derivatization in Flow Analysis

“…As a recent application, the in-line microwave-assisted analyte derivatization with methyl- N -(trimethylsilyl) trifluoroacetamide to yield volatile derivatives for the determinations of atenolol and propranolol in human plasma by GC-MS [ 42 ] can be mentioned. Recently, the hyphenation of flow systems with gas or liquid chromatography was pointed out as a trend in flow analysis [ 43 ].…”

“…As chemiluminescence [ 15 ] relies on the characteristic radiation emitted during the transient formation of a reaction product or intermediary, fast reagent mixing and strict time control are mandatory to attain reliable results. In fact, the development of flow analysis has stimulated applications involving chemiluminescence [ 43 ].…”

Rapid Quantification of Antioxidant Capacity in Tea Using Laser-Induced Graphene Electrodes

“…The consumption of quinoneimine decreases the magnitude of the quinoneimine reduction signal, thus allowing for indirect detection of EGCG and/or EGC. Also, electrochemical detection is easily adapted to flow analysis, which provides additional features to analytical methods, such as sample throughput (from 100 to 200 analyses per hour), the possibility of automation (for instance, flow-injection analysis can be operated by injectors and automated pumps), 14,15 and portability (compact batchinjection cells combined with portable electronic injectors). 16 Batch-injection analysis with amperometric detection (BIA-AD) of DPPH was reported at a glassy-carbon electrode (GCE) to evaluate the antioxidant capacity of plant and tea samples.…”

Poly glycidyl methacrylate‐co‐ethylene dimethacrylate porous monolith as a versatile platform for the development of separations and solid‐phase extractions in sequential injection analyzers

“…Despite their extensive use in HPLC, the high permeability of monolithic columns is yet underexplored in low‐to‐moderate‐pressure instrumentation of flow injection or sequential injection analysis (SIA) . Sequential injection analyzers are low‐cost and portable instruments used to perform chemical derivatization, in‐line dilution, preconcentration, matrix exchange, chromatographic separations, etc.…”