End-column

LIGHT ENDS COLUMN DRYING COLUMN PRODUCT COLUMN FINISHING COLUMN... 

FIGURE 3-24 Electrophoretic separation of catechols with end-column detection. Detection potential, +0.8 V separation capillary, 20 kV The peaks correspond to 4.6 fmol dopamine (1), 4.1 fmol isoproterenol (2), and 2.7 fmol catechol (3). (Reproduced with permission from reference 60.)... 

Electroosmotic flow, 195 End column detection, 89 Energy barrier, 16 Enzyme electrodes, 172, 174 Enzyme immunoassays, 185 Enzyme inhibition, 181 Enzyme reconstitution, 178 Enzyme wiring, 178 Equilibrium potential, 15 Ethanol electrodes, 87, 178 Exchange current, 14... 

REACTOR SEPARATOR AZEO COLUMN LIGHT END COLUMN... 

ATP Luciferin-luciferase Phosphate buffer (pH 7.8) End-column CL detection 5 nM 84... 

Figure 9 End-column CL detector for CE proposed by Zare s group. (From Ref. 84, with permission.)...

In the ruthenium frA-bipyridine system, an orange emission at 610 nm arises when the excited stated [Ru(bpy)32+] decays to the ground state. Ru(bpy)32+ is the stable species in the solution and the reactive species—Ru(bpy)33+—can be generated from Ru(bpy)32+ on the electrode surface by oxidation at about +1.3 V. Adding Ru(bpy)32+ to the electrolyte and using an end-column electrode to convert the Ru(bpy)32+ into the active Ru(bpy)33+ form allow a simple and sensitive ECL detection mode. The reaction lends itself to electrochemical control due to the electrochemically induced interconversion of the key oxidation states ... 

Figure 13 Electropherogram of selected amino acids with end-column addition of 1 mM Ru (bpy)32+. Separation conditions 20 kV with injection of analytes for 8 s at 20 kV. Capillary, 75 im id, 62 cm long with a 4-cm detection capillary. Buffer 15 mM borate, pH 9.5. The electrode used for in situ generation of Ru(bpy)33+ was a 35-jlm-diameter carbon fiber, 3 mm long held at 1.15 V versus a saturated calomel electrode. The PMT was biased at 900 V. Peak identification (1) 100 fmol TEA, (2) 70 fmol proline (3) 1.6 pmol valine, (4) 50 pmol serine. Injection points. (From Ref. 97, with permission.)...

Loads applied to panels on the short wall will be resisted by the three end columns. The roof panels will act as a diaphragm to distribute the loads but they must also resist vertical blast loads in bending which reduces in-plane capacity. To avoid this problem, the top of the center column will be supported by a truss in the roof of the end bay. This truss will utilize the rigid frame beams as chord members with additional angles added to form the struts Braced frames in the end bay wall will provide the support reaction for the roof truss as well as the load from the corner columns. The end bay braced frame will consist of the rigid frame columns and x bracing. Since the columns must resist loads from both directions, the axial capacity in each direction is artificially reduced for the analysis. 

Table 2-1 show the relationship between the coverage and the electric charge consumed for the COad oxidation for each voltammogram shown in Fig. 2-32. The right end column, Nico. which is defined as ... 

A dual electrochemical microchip detection system, based on the coupling of conductivity and amperometric detection schemes, was developed for simultaneous measurements of both nitroaromatic and ionic explosives [34], The microsystem relied on the combination of a contactless conductivity detector with an end-column thick-film carbon amperometric detector. Such ability to monitor both redox-active nitroaromatic and ionic explosives is demonstrated in Figure 13.7, which shows typical dual-detection electropherograms for a sample mixture containing the nitroaromatic explosives trinitrobenzene (TNB) (4), TNT (5), 2,4-DNB (6), and 2-Am-4,6-DNB (7), as well as the explosive-related ammonium... 

The second approach (end-column detection) is best suited for capillaries of 25 pm or less [49]. This mode of detection is illustrated in Figure 27.20. In this case, the electrode is placed at the end of the capillary (but not inside) and no coupler is employed. A 70-cm, 5-pm-i.d. capillary filled with a zwitterionic... 

Figure 27.20 Schematic drawing of CE with end-column amperometric detection A, capillary B, cathodic buffer reservoir and electrochemical cell C, carbon fiber electrode D, electrode assembly, E, micromanipulator RE, reference electrode. [Adapted with permission from Ref. 49.]...

J. Wang, M.P. Chatrathi, A. Ibanez and A. Escarpa, Micromachined separation chips with post-column enzymatic reactions of class enzymes and end-column electrochemical detection assays of amino acids, Electroanalysis, 14 (2002) 400-404. 

Data from Table 2.112 have been analyzed by the Yates technique and outcomes are given in Table 2.113. The interesting thing in relation to the former example is that the mechanical method, which does not require knowledge of Eq. (2.67) has been demonstrated. Column (1) is obtained by adding up the response data pairs to the column and then by subtracting the data. For example, 19=9+10, 14=8+6,...,11= 5+6, 1=10-9, -2=6-8,...,1=6-5. As shown, differences are taken from the same data pairs but in this way the second data minus the first, the fourth minus the third and so on to the column end. Column (2) is obtained from the first column in the same way. Column (3) from (2), (4) from (3) and (5) from (4). This calculation is evidently repeated k times for a full factorial experiment of 2k. Column (5) gives... 

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