Flow-injection analysis system, schematic

Fig. 19. Schematic design of a flow injection analysis (FIA) system. A selection valve (top) allows a selection between sample stream and standard(s). The selected specimen is pumped through an injection loop. Repeatedly, the injection valve is switched for a short while so that the contents of the loop are transported by the carrier stream into the dispersion/reaction manifold. In this manifold, any type of chemical or physical reaction can be implemented (e.g. by addition of other chemicals, passing through an enzyme column, dilution by another injection, diffusion through a membrane, liquid-liquid extraction, etc. not shown). On its way through the manifold, the original plug undergoes axial dispersion which results in the typical shape of the finally detected signal peak...

Fig. 14 a. Schematic arrangement for Flow Injection Analysis for a simple spectrophotometric determination, b A typical experimental output from such a system, showing lack of carry over even with large samples. (Metal ion Bismuth Reagent Pyrocatechol violet, 5 x 10 3 M pH 2-4 Sample size 200 pi Analysis rate 80 hr-1)... 

Figure 3 shows a schematic of the FIA system and details the thin-layer transducer cell, which contains the poly(3-methylthiophene) anion sensor electrode(s). Electrochemical detection in the amperometric mode was employed for the FIA/EC (flow injection analysis with electrochemical detection) studies. A typical potential used was +1.00 volts vs. Ag/AgCl reference electrode. The FIA-EC system consisted of an Altex lOOA double reciprocation pump and a Rheodyne injector (Cotai, CA) with either a 20 or 50 microliter sample loop. Constant potentials were applied using the herein described DWEP, which is software controlled. The electronically transduced signals are converted from analog to digital by use of A/D and D/A converter circuits. The option exists to automatically save the data on the computer or print the results as the experiment progresses. 

FIGURE 1.3 Schematic manifolds of typical flow injection analysis (FIA) systems (a) single line manifold, (b) multiline configuration RCl, RC2—reaction coils. (Adapted from Ruzicka, J., 2009, Tutorial on Flow Injection Analysis (4th ed.). From Beaker to Micro fluidics, www.flowinjection.com.)... 

FIGURE 1.5 Schematic diagram of flow injection analysis (FIA) system with immunoassay detection RIANA (abbreviation from River ANAlyser ) based on total internal reflection fluorescence with immobilized fluorescently labeled antibodies. The source of the excitation light is a He-Ne laser, and the collected fluorescent light is filtered and detected by photodiodes (PD). (Adapted from Rodriguez-Mozaz, S. et al. 2004. Biosens. Bioelectron. 19 633-640.)... 

FIGURE 1,10 Schematic diagram of the hybrid flow-through microcolumn extraction/ multisyringe flow injection analysis (MSFIA) system for fractionation and online determination of orthophosphate. SP—syringe pump, MSP—multisyringe pump, SV— selection valve, V—solenoid valves, KR—knotted reactors, D—detector. (Adapted from Buanuam,]. et al. 2007. Talanta 71 1710-1719.)... 

FIGURE 33.4 Schematic representation of flow-based systems developed from 2003 to 2014 for the determination of antioxidant activity by the ABTS assay resorting to single (a) or double-line (b) flow injection analysis, sequential injection analysis (c), multisyringe flow injection analysis (d), and mesofluidic lab-on-valve (LOV) system (e) P, pump IV, injection valve S, sample RC, reaction coil D, detector W, waste C, carrier SV, selection valve MC, mixing chamber MS, multisyringe CV, commutation valve HC, holding coil LOV, lab-on-valve. 

Figure 14.4 Schematic diagram of the cliromatographic system used for the analysis of very low concentrations of sulfur compounds in ethene and propene CP, pressure regulator CF, flow regulator SL, sanrple loop R, restriction to replace column 2 VI, injection valve V2, tliree-way valve to direct the effluent of column 1 to either column 2 or the restriction column 1, non-polar- capillary column column 2, tliick-film capillary column SCD, sulfur chemiluminescence detector FID, flanre-ionization detector.

A schematic diagram of the automatic system is shown in Fig. 4.7a. The sample -to-gas-chromatograph interface and requirements for the injection of a hquid mixture onto a gas chromatographic column from a flowing stream present the greatest problem, in contrast to sample transfer and dilution techniques in automatic analysis, which are well documented. 

A detailed description of IC is given in reference 1 however, the basic principles of the method can best be described by an example. Figure 1 schematically represents both an anion and a cation IC analysis. In both cases, the instrumentation involves a pumping system, an eluent, an injection valve, an ion-exchange separator column, an ion-exchange suppressor column and a conductivity cell. The sample is first injected into the flow system then the well known reaction equilibrium shown in Figure 1 results in the separation of sample anions or cations on the separator column (2). 

A schematic of a commercially available system that was conflgured in our laboratory for parallel analysis and purification is shown in Figure 11-9. This four-channel parallel LC/MS purification system consists of a binary HPLC system, an autosampler configured with four injection, a multichannel UV detector, a quadrupole mass spectrometer equipped with an MUX ion source which monitors four flow streams simultaneously, and four independently... 

Distillation, as defined in this chapter, also includes direct thermal analysis techniques. These techniques involve the heating of a food sample in an in-line (i.e., in the carrier gas flow of the (jC) desorber. (jenerally, aroma compounds are thermally desorbed from the food and then cryofocused to enhance chromatographic resolution. This technique has been used for a number of years for the analysis of lipids and was later modified to include aqueous samples [32,33]. Aqueous samples were accommodated by including a water trap after the desorption cell. This general approach has been incorporated into the short path thermal desorption apparatus discussed by Hartman et al. [34] and Grimm et al. [35]. A schematic of this apparatus is shown in Figure 3.5. In the schematic shown, a sample of food is placed in the desorption tube and quickly heated. The volatiles are distilled into the gas flow that carries them into the cooled injection system where they are cryofocused prior to injection into the analytical colunm. 

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