Flow-through chemical sensors

In 1991, Simon et al. [9] reported a flow-through chemical sensor for the determination of ammonium ion in water samples using a sensing... 

Figure 5.6 — Flow-through chemical sensor for the determination of ammonia. For details, see text. (Adapted from [9] with permission of the American Chemical Society).

The main important details of these procedures for AA determination are contained in Table 18.8. As can be seen in Table 18.8, among these flow analysis techniques, stopped-flow procedures are the most applied to AA determination, being mostly kinetic enzymatic determinations. BI methodologies for AA determination use spectrophotometric detection and a commercial flow cell, which is filled with appropriate solid beads, works as a flow-through chemical sensor integrating online reaction, retention, and detection on the solid-phase disposable beads. 

Fig. 7.18. Low-pressure interfaces to detectors based on flow injection. (A) Interface to a photometric detector across a membrane. (Reproduced with permission of the American Chemical Society.) (B) Interface to a flow-through photometric sensor with prior derivatization by the modified Griess reaction. (Reproduced with permission of the American Chemical Society.) (C) Interface to a piezoelectric detector. P peristaltic pump, C collector, CUC clean-up column, DB debubbler, SA sulfamic acid, NEDD /V-( 1-naphthyl)ethylenediamine dihydrochloride, SV switching valve, W waste, DF displacement flask, IV injection valve, FC-PZ flow-cell-piezoelectric crystal, OC oscillator circuitry, F frequency counter, PC personal computer. (Reproduced with permission of Elsevier.)...

Pij anowska, D. G, et al., A flow-through potentiometiic sensor for an integrated microdialysis system. Sensors and Actuators, B Chemical, B103, 350, 2004. 

Fig. 10.9 Photograph of the sensor chip and the flow through cuvette. The chip contains 11 four channel YI sensors. The light is coupled into the chip by means of an optical fiber at the top right hand side. The light is transported to the sensing area by means of a curved channel waveguide, visible as a white curved line. Ruler indicates the dimensions in centimeters. Reprinted from Ref. 28 with permission. 2008 American Chemical Society...

Fig. 10.17 Specific detection of HSV 1. Phase changes A

Volume14 Analytical Applications of Circular Dichroism edited by N. Purdie and H.G. Brittain VolumelS Trace Element Analysis in Biological Specimens edited by R.F.M. Herber and M. Stoeppler VolumelS Flow-through (Bio)Chemical Sensors... 

Bio)chemical sensors can be used in both the batch and the continuous mode. While this is also true of probe-type sensors, flow-through sensors can only be used in a continuous regime coupled on-line to a continuous-flow configuration. 

In broad terms, a flow-through sensor is an analytical device consisting of an active microzone where one or more chemical or biochemical reactions, in addition to a separation process, can take place. The microzone is connected to or incorporated into an optical, electric, thermal or mass transducer and must respond in a direct, reversible, continuous, expeditious and accurate manner to changes in the concentrations of chemical or biochemical species in the liquid or gaseous sample that is passed over it, whether forcefully (by aspiration or injection) or otherwise (gases). 

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