Flow injection systems applications

K. Kusube, K. Abe, O. Hiroshima, Y. Ishiguro, S. Ishikawa, and H. Ho-shida. Electrochemical Derivatization of Thiamine in a Flow Injection System—Application to Thiamine Analysis. Chem. Pharm. Bull., 31 (1983) 3589. 

Santos, J. R. and A. O. S. S. Rangel. 2012. Development of a chromatographic low pressure flow injection system Application to the analysis of methylxanthines in coffee. 

Becker, T., W. Schuhmann, R. Betken, H. L. Schmidt, M. Leible, and A. Albrecht. 1993. An automatic dehydrogenase-based flow-injection system Application for the continuous determination of glucose and lactate in mammalian cell-cultures. J. Chem. Technol. Biotechnol. 58 183-190. 

Fang and co-workers [115] have reported a flow injection chemiluminescence assay for the detection of maleic hydrazide (MH). The imprinted poly(MAA-co-EDMA) polymer selectively retained the herbicide that was further treated with alkaline luminol-potassium periodate to produce a strong CL signal. Upon reaction, the absorbed MH was destroyed and removed by the flowing solution. The polymer was reused up to ten times and the linear response was between 3.5 x 10 and 5.0 x 10 2 mg mL-1 with a detection limit of 6.0 x 10 5 mg mL-1. The CILA flow injection system was used for the analysis of potato and onion samples spiked with 1.0, 2.0, and 4.0 x 10-3 mg mL-1 of MH. Recoveries ranged from 98% to 103% (RSD 2.3%), demonstrating the successful application of the method. 

One of the most successful applications of microsystem technology is the use of pTAS in diagnostics [332-335]. Microreactors have been integrated into automated analytical systems, which eliminate errors associated with manual protocols. Furthermore microreactors can be coupled with numerous detection techniques and pretreatment of samples can be carried out on the chip. In addition, analytical systems that comprise microreactors are expected to display outstanding reproducibility by replacing batch iterative steps and discrete sample treatment by flow injection systems. The possibility of performing similar analyses in parallel is an attractive feature for screening and routine use. 

Less wide-spread than the enzymatic determination of these amino acids is the application of enzyme sensor systems for precursors or other amino acids. Collins et al. [116] described a flow injection system for the determination of a-ketoglutarate during an industrial fermentation. The system was based on glutamate dehydrogenase (Eq. (11.5)) and glutamate oxidase (Eq. (11.4))... 

Tungsten-coil atomizers have to some extent been used in connection with atomic techniques in general and ETA-AAS in particular, and their popularity continues to rise. Their high simplicity and low cost make them attractive alternatives to graphite furnaces for many applications. However, they are much more interference-prone than their graphite counterparts. The interferences experienced by W-coil atomizers have been overcome in various ways, however. Thus, Barbosa et al. [25] avoid the interference from a salt matrix and implement a preconcentration step by electrochemically reducing Pb onto the coil surface. They use a flow injection system to deliver the sample through an anode inserted in the tip of the autosampler and the W-coil itself as cathode. The use of a W-coil as a platform inside a Massmann-type furnace provides no appreciable improvement over wall atomization [26]. 

Another current trend that is well underway is the use of more specific analytical instrumentation that allows less extensive sample preparation. The development of mass spectrometric techniques, particularly tandem MS linked to a HPLC or flow injection system, has allowed the specific and sensitive analysis of simple extracts of biological samples (68,70-72). A similar HPLC with UV detection would require significantly more extensive sample preparation effort and, importantly, more method development time. Currently, the bulk of the HPLC-MS efforts have been applied to the analysis of drugs and metabolites in biological samples. Kristiansen et al. (73) have also applied flow-injection tandem mass spectrometry to measure sulfonamide antibiotics in meat and blood using a very simple ethyl acetate extraction step. This important technique will surely find many more applications in the future. 

The bead injection system was designed to operate in the sequential injection mode. It is possible to carry out bead injection analysis in a low-cost flow injection system with a unidirectional pump and without a computer, mainly for applications where samples and reagents are abundant and when there is no need for micro-volume control. To this end, it is necessary to use a flow cell able to achieve bead retention, accommodation of chemical reactions and detection [87,88]. 

C. Thommen, A. Fromageat, P. Obergfell, H.M. Widmer, Application of a capillary flow cell to sophisticated flow-injection systems, Anal. Chim. Acta 234 (1990) 141. 

From a practical point of view, temperature control is generally not required in analytical applications, unless the physico-chemical processes involved are temperature dependent. A common practice is therefore to operate the flow injection system at ambient temperature, but a temperature-controlled laboratory environment is desirable. 

The spectrophotometric determination of cadmium in natural waters involving in-line formation of an aqueous dithizone suspension [121] illustrates another application of in-line suspension addition. Solid dithizone reagent was packed in a mini-column through which a surfactant (Triton X-100) stream was allowed to flow. The emerging suspension formed was added by confluence to the main analytical channel of a flow-injection system. With this innovation, good sensitivity was achieved without the need for an analyte separation/concentration LLE step and the entire procedure was carried out in the aqueous phase. 

M.J. Almendral-Parra, A. Alonso-Mateos, M.S. Fuentes-Prieto, A gas diffusion technique coupled with flow injection systems. Optimization of the process in its application to the fluorimetric determination of ammonium in water samples, J. Fluoresc. 20 (2010) 55. 

The analytical applications of chemiluminescence fall into three broad categories. First, there are some chemiluminescent reactions that are catalyzed by specific compounds and that can, therefore, be diagnostic for the presence or quantitation of those compounds. For example, the hydrogen peroxide oxidation of the cyclic luminescent hydrazide luminol is catalyzed by transition metal ions such as Co(II), which can thereby be detected at a 10 pM concentration in a flow injection system (B33) and even down to 1 pM when the chemiluminescence is induced ultrasonically (K19). Other transition metal ions that have been similarly detected (in the 1-10 nM range) are Cr(III) (C13), Cu(II), and Ni(II) (S26). Other... 

Ogbomo I, Kittsteiner-Eberle R, Engelbrecht U, Prinizing U, Danzer J and Schmidt H-L 1991 Flow-injection systems for the determination of oxidoreductase substrates applications in food quality control and process monitoring Anal. Chim. Acta 249 137-43... 

Optical detection of an antibiotic, chloramphenicol, based on competitive displacement of a chloramphenicol-methyl red conjugate bound to a chloramphenicol-imprinted polymer with free chloramphenicol has been demonstrated [40]. A flow injection system in conjunction with a 10 cm stainless steel column packed with the imprinted polymer and acetonitrile as a carrier solution containing chloramphenicol-methyl red conjugate was constructed. The dye conjugate released by displacement by free chloramphenicol was monitored at 460 nm. The signals were proportional to the concentration of free chloramphenicol injected, and the calibration range of this system included the therapeutic range of a chloramphenicol. This concept of flow displacement systems could be applicable not only for chloramphenicol determination but also for other template molecules. 

R. A. Leach and J. M. Harris, Real-Time Thermal Lens Absorption Measurements with Application to Flow-Injection Systems. Anal. Chim. Acta, 164 (1984) 91. 

A. T. Faizullah and A. Townshend, Applications of Ion-Exchange Minicolumns in a Flow-Injection System for the Spectrophotometric Determination of Anions. Anal. Chim. Acta, 179 (1986) 233. 

F. P. Bigley, R. L. Grob, and G. S. Brenner, Pharmaceutical Applications of a High-Performance Flow Injection System. Anal. Chim. Acta, 181... 

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