Sequential injection analysis systems

To increase the percentage of dialysis, as well as the dialysis time, multiple flow reversals with a time of 20 s between each flow reversal is selected. Similar results are obtained by using a sequential injection system with the stopped-flow period around 150 s. The advantage of utilizing the stopped-flow mode over multiple flow reversals in the sequential injection analysis systems is that it needs less programming and, also, it reduces the strain on the pump. 

P.C.A.G. Pinto, M.L.M.F.S. Saraiva, J.L.M. Santos, J.L.F.C. Lima, Fluorimetric determination of aminocaproic acid in pharmaceutical formulations using a sequential injection analysis system, Talanta 68 (2006) 857. 

C. Frank, F. Schroeder, R. Ebinghaus, W. Ruck, A fast sequential injection analysis system for the simultaneous determination of ammonia and phosphate, Microchim. Acta 154 (2006) 31. 

A.M. Pimenta, A.N. Araujo, M.C.B.S.M. Montenegro, Simultaneous potentiometric and fluorimetric determination of diclofenac in a sequential injection analysis system, Anal. Chim. Acta 470 (2002) 185. 

Edwards, K. A. and Baeumner, A. J. (2006) Sequential injection analysis system for the sandwich hybridization-based detection of nucleic acids. Anal Chem. 78, 1958-1966... 

The selectivity, enantioselectivity, and sensitivity of a method can be improved by using it as detection system in flow injection analysis and/or sequential injection analysis systems.261... 

Chough, S. H., Rhee, J. L, Sequential injection analysis system for on-line monitoring of L-cysteine concentration in biological processes. Talanta 2005, 68, 187-192. 

The Sequential Injections Analysis System of the Integrated Biosensors... 

Lopes C. M.P.V., Almeida A.A, Liicia M.M.F.S., Lima J.L.F.C. Determination of Rh, Pd and Pt in urine samples using a pre-concentration sequential injection analysis system coupled to a quadrupole-inductively coupled plasma-mass spectrometer. Analytica Chimica Acta 2007 600 226-232. 

Zarate, N., M. P. Ruiz, R. Perez-Olmos, A. N. Araujo, M. Conceiqao, and B. S. M. Montenegro. 2009. Development of a sequential injection analysis system for the potentiometric determination of nitrite in meat products by using a Gran s plot method. Microchim. Acta 165 117-122. 

Araujo, A. R. T. S., M. L. M. F. S. Saraiva, and J. L. F. C. Lima. 2008. Enzymatic determination of total and oxidized glutathione in human whole blood with a sequential injection analysis system. Talanta 74 1511-1519. 

Hartwell, S. K. 2012. Flow injection/sequential injection analysis systems Potential use as tools for rapid liver diseases biomarker study. International Journal of Hepatology 2012 1-8. 

Economou, A., Voulgaropoulos, A., 2002. LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on... 

Fig. 4. Sequential injection analysis system, a) sample and reagents aspiration, b) mixture dispense. CS, carrier solution LR, loading reactor SV, selection valve S, sample R1 and R2, reagents RR, reaction coil D, electrochemical flow cell W, waste.

Fernandez, C., A.C.L. Conceicao, R. Rial-Otero, C. Vaz, and J.L. Capelo. 2006. Sequential flow injection analysis system on-line coupled to high intensity focused ultrasound Green methodology for trace analysis applications as demonstrated for the determination of inorganic and total mercury in waters and urine by cold vapor atomic absorption spectrometry. Anal. Chem. 78 2494-2499. 

M. A. Segundo, J. L. F. C. Lima, A. O. S. S. Rangel, Automatic flow system based on sequential injection analysis for routine determinations in wines, Anal. Chim. Acta, 513 (2004), 3 -9. 

The concentration step is very easy to implement in sequential injection analysis. The system is very simple and the results are reproducible. Most of the time, this step is not necessary for HPLC. When it is necessary, it can easily be done in the same time with the extraction step. 

The utilization of sequential injection analysis coupled with HPLC systems increases the reliability of an HPLC analysis considerably because the primary factor that contributes to the increasing uncertainty is the sample preparation. It is always necessary to look to the most reliable methods for sample preparation, because only these methods will give the best results after the automation by using sequential injection analysis. The best coupling must be concerned with the selectivity and sensitivity assured by a sequential analysis system and by the selectivity and sensitivity of the HPLC technique. The introduction of bead injection considerably improves the reliability of the discussed system. 

These aspects, as well as the need for simpler systems, can be considered the driving forces for the proposal and development of sequential injection analysis. 

Here, it is interesting to mention the stepwise injection system [79], a variant of sequential injection analysis (without a holding coil), which permits the accomplishment of all the steps involved in a specific application as if they were stationary. The related instrument is very robust and amenable to gas analysis. 

The main characteristic of this system is its ability to efficiently manage functionalised beads [83,85]. The solutions involved are handled in the same way as in sequential injection analysis but the monitored species is normally adsorbed onto a solid phase, which helps to improve analytical sensitivity and /or selectivity. 

Sequential injection analysis with lab-on-valve was conceived by Ruzicka in 2000 [84] as a progression of the sequential injection system towards downscaling. All components are integrated in a single unit mounted on a multi-position valve. The detector compartment is reduced and placed very close to the sample inlet, thus minimising the required volumes of sample, reagent and wash solution. 

The system combines the advantageous characteristics of flow injection analysis, such as a high sample throughput and low detection limits, with those of sequential injection analysis such as robustness and versatility. It was initially exploited for industrial process control, with spectrophotometric detection, for the determination of highly acidic or alkaline protolytes using an ingenious titration procedure [109], free... 

There are many variants of analytical flow systems, e.g., segmented flow analysis, flow injection analysis, sequential injection analysis, multisyringe flow injection analysis, batch injection analysis, mono-segmented flow analysis, flow-batch analysis, multi-pumping flow analysis, all injection analysis and bead injection analysis, all of which have acronyms [176]. In view of the existence of several common features, however, all flow analysers can be broadly classified as either segmented or unsegmented, with the most common example of the later mode being the flow injection analyser. 

S.-H. Fan, S.-L. Wang, X.-F. Fan, F.-R. Wang, Z.-L. Fang, Studies on sequential injection spectrophotometric system using a reflective flow cell for process analysis, Spectrosc. Spectral Anal. 24 (2004) 368. 

---