Sequential injection

Micro reactors allow the sequential injection of the reaction partners, rather than introducing them in one step. By this means, the course of the reaction, in particular concerning the dynamic evolution of the concentration of reactants, may be changed. It is hoped that this may impact on selectivity. 

However, despite having a lower yield, sequential injection is seen to have the advantage of allowing more in-depth variation of process parameters, in particular concentration changes and performing individual stages of the reaction separately [136]. 

Fang, Q., Wang, F.-R., Wang, S.-L., Liu, S.-S., Xu, S.-K., and Fang, Z.-L., Sequential injection sample introduction microfluidic-chip based capillary electrophoresis system, Anal. Chim. Acta, 390, 27, 1999. 

Cold curing permits the formation of dual density foam products. We either sequentially inject different formulations or we mold the first foam then mold the second around or on top of it. When making dual density foams, it is important that the first component develop a continuous skin prior to the injection of the second reactive mixture. 

M. Klein, D.J.W. Mous and A. Gottdang, Fast and accurate sequential injection AMS with gated Faraday cup current measurement, Radiocarbon 46, 77 82 (2004). 

Polasek M, Skala P, Opletal L and Jahodar, L. 2004. Rapid automated assay of anti-oxidation/radical-scavenging activity of natural substances by sequential injection technique (SIA) using spectrophotomet-ric detection. Anal Bioanal Chem 379(5—6) 754—758. 

Cerda et al. [ 142] have described a sequential injection sandwich technique for the simultaneous determination of nitrate and nitrite in seawater. 

Kim et al. [116] determined plutonium isotopes in seawater by an online sequential injection technique with sector field ICP-MS. 

Table 6 Examples of Sequential Injection Analysis with CL Detection...

The alternative measurement technique [5] is to select the ions of interest from the ion source and sequentially inject these into the accelerator. As only one beam is in the system at any given time, there is no possibility of inter-beam interferences. With such a system, it will be necessary to ensure that the cycle time between beams is short compared to the time-span over which any efficiency changes could occur. As well, the normal method for stabilizing the accelerator will not be available, and other methods must be developed. 

Whatever system is used, it may prove valuable in some circumstances to be able to reduce the beam intensities of the most abundant isotope to reduce accelerator loading. This can in principle be easily accomplished with sequential injection by... 

Motz SA, Klimundova J, Schaefer UF, Balbach S, Eichinger T, Solich P, Lehr C-M (2007) Automated measurement of permeation and dissolution of propranolol HC1 tablets using sequential injection analysis. Anal Chim Acta 581 174—180... 

Kansiz et al. has published a paper wherein they used MIR and sequential injections to monitor an acetone-butanol fermentation process.17 In this work, acetone, acetate, n-butanol, butyrate, and glucose were analyzed automatically, using computer-controlled sampling techniques. In this case, gas chromatography was the reference method. The SEPs for the components were acetone, 0.077 acetate, 0.063 butyrate, 0.058 -butanol, 0.301 and glucose, 0.493 g/1. The authors state that the precision and accuracy of the MIR methods were as good as the reference method. 

Gutes and coworkers presented an automated electronic tongue based on sequential injection analysis (SIA) and linear sweep voltammetry, for the simultaneous determination of glucose and ascorbic acid, by means of ANN regression. The models were evaluated with an external test set (Gutes et al., 2006). 

Cortina, M., Duran, A., Alegret, S., and Valle, M. A. (2006). Sequential injection electronic tongue employing the transient response from potentiometric sensors for anion multidetermination. Anal. Bioanal. Chem. 385(7), 1186-1194. 

Ipatov, A., Abramova, N., Bratov, A., and Dominguez, C. (2008). Integrated multisensor chip with sequential injection technique as a base for "electronic tongue" devices. Sens. Actuators B 131(1), 48-52. 

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