Multipumping flow systems

The low sample and reagent consumption of SIA by implementation of the multicommutation concept, since liquids are delivered to the system only when required and so the reagents and sample consumption are low. 

The ability to use MCFIA solenoid valves, which can be actuated without the need to stop their pistons. Switching between valves is so fast that no overpressure arises in the operation. 

which were developed in 2002 by two research groups at the Pharmacy Faculty of the University of Porto (Portugal) and the Piracicaba CENA (Brazil) [ 14], are based on the use of solenoid piston 

Solenoid piston pump. (For color version of this figure, the reader is referred to the online version of this book.) 

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In recent years, many flow systems consisting of several pumps (multipump flow systems) or several injectors (multicommuted flow systems) have been constmcted and exploited. Some of them are dedicated to calibration purposes. For instance, the standard addition method was recently implemented using a multicommuted system with an injection valve and three directive solenoid valves [7]. The system can automatically prepare a series of calibration solutions by successively merging a sample with three standards of different analyte concentrations. The approach is especially suitable for trace analysis because, according to the author s recommendation, it can be used when the analyte concentration in the sample is below the lower limit of linear response of a detector (it allows, in particular, potentiometric... 

The approach is very useful for e.g., chemi- and bioluminescence detection when the monitoring of short-lived chemical species is done as close as possible to the detector. With pulsed flows, mixing conditions are no longer a weakness [125] because manifold simplicity and very fast and effective mixing of the sample with reagent(s) are characteristics of multipumping flow systems. 

K.L. Marques, C.K. Pires, J.L.M. Santos, E.A.G. Zagatto, J.L.F.C. Lima, A multipumping flow system for chemiluminescent determination of ammonium in natural waters, Intern, J. Environ. Anal. Chem. 87 (2007) 77. 

Fajardo, Y., Ferrer, L., Gomez, E. et al. (2008). Development of an automatic method for americium and plutonium separation and preconcentration using a multisyringe flow injection analysis multipump flow system. Anal. Chem. 80, 195-202. 

We may classify flow methods in nonresolutive (SFA, flow injection analysis (FIA), sequential injection analysis (SIA), multicommutated flow injection analysis (MCFIA), multipumping flow systems (MPFS), etc.) and resolutive ones (chromatographic techniques, capillary electrophoresis, etc.). In this book we will mainly focus on nonresolutive flow methods of analysis. 

B. Horstkotte, C.M. Duarte, V. Cerda, Multipumping flow systems devoid of computer control for process and environmental monitoring, Int. J. Environ. Anal. Chem. (2011), http //dx.doi.org/10.1080/ 03067319.2010.548601. 

Beads packed in microcolumns is the most reported in literature, since users can customize the quantity of resin according to the capacity of it, to the volume of sample to be loaded, and to the minimum detectable activity (MDA) of the detector used. In general, packing is manually replaced in flow systems based on flow injection analysis G A), sequential injection analysis (SIA), multisyringe flow injection analysis (MSFIA) and multipumping flow systems (MPFS). By the contrary, lab on valve (LOV) allows the manipulation of heterogeneous solutions, i.e. bead injection, achieving the automated replacement of the resin. In Chapter 3 are described in detail the parts of the microcolumns and the way to fill them. Table 8.1 summarizes the variety of available resins from TrisKem International [4]. 

Flow techniques have aroused especial interest in relation to many other automatic methodologies of analysis. Ever since segmented flow analysis was developed by Skeggs in 1957, flow techniques have been in continuous evolution towards new developments from flow injection analysis (FIA) by J. Ruzicka and E.H. Hansen in 1975 up to multisyringe flow injection analysis by our group in 1999 and, more recently, multipumping flow systems in 2002 by Lapa et al. 

Multicommutated Flow Injection Analysis, Multisyringe Flow Injection Analysis, and Multipumping Flow Systems... 

Carneiro, J. M. T., E. A. G. Zagatto, J. L. M. Santos, and J. L. F. C. Lima. 2002. Spectrophotometric determination of phytic acid in plant extracts using a multipumping flow system. Anal. Chim. Acta 474 161-166. 

Note A amperometry BI bead injection CL chemiluminescence F fluorescence FAT flow analysis technique HPLC/DAD high-performance liquid chromatography with diode array detector LOD detection limit MCFIA multicommutated flow injection analysis MPFS multipumping flow systems MSFIA multisyringe FIA P potentiometry RSD relative standard deviation SF sampling frequency SFA stopped-flow analysis SP spectrophotometry. 

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