Terminating electrolyte

Capillary tube isotachophoresis using a potential gradient detector is another technique that has been applied to the analysis of alcohol sulfates, such as sodium and lithium alcohol sulfates [303]. The leading electrolyte solution is a mixture of methyl cyanate and aqueous histidine buffer containing calcium chloride. The terminating electrolyte solution is an aqueous solution of sodium octanoate. 

Milk Isotachophoresis Conductivity 2ng 40% methanol, 10 mM sodium acetate pH 4.8, 0.2% hydroxy-ceUulose (leading electrolyte), 40% methanol, 20 mM acetic acid (terminating electrolyte) Prometryne, desmetryne, terbutryne, atrazine (OH metabolites), simazine (OH metabolites) 126... 

There are three main electrophoretic methods of separation (i) zone electrophoresis, where the components are separated on a basis of relative mobilities (ii) isotachophoresis, where the separation is again based on relative mobilities but where the solutes are sandwiched between leading and terminating electrolytes ... 

Isotachophoresis is carried out using a Shimadzu IR-2A isotachopho-retic analyzer with a potential gradient detector. Conditions for the analysis comprise a leading electrolyte of 5 mM potassium acetate (pH 6.0) containing 0.2% Triton X-100 and a half volume of dioxane, and a terminating electrolyte of 10 mM p-alanine adjusted to pH 4.5. 

Capillary isotachophoresis (CITP) is an electromigration technique, which is performed using a discontinnous buffer system, formed by a leading electrolyte (LE) and a terminating electrolyte... 

FIGURE 6.12 Schematic view of the CITP separation mechanism. The sample is introduced into the capillary between two electrolyte systems a leading electrolyte (L), having electrophoretic mobility higher than any of the sample components to be separated and a terminating electrolyte (T), having electrophoretic mobility lower than any of the sample components (A). The sample components are separated according to the order of their individual mobility into distinct zones, which are sandwiched between T and L (B). The separated zones move with the same velocity toward the capillary end where they are detected as bands (C). 

Procaine and other local anesthetics were separated by Chmela et al. with a VLD isotachophoresis apparatus, equipped with coupled PTFE separatory (23 cm x 0.8 mm) and analytical columns (23 cm x 0.8 mm) [151]. In one system, the leading cation was (0.01 M) containing 0.05 poly(vinylalcohol), with acetate as the counter-ion. The pH of the leading electrolyte was 4.75. The terminating electrolyte was 0.03 M beta-alanine. Two other systems were also reported. 

Kostelecka and Haller have determined procaine in mass-produced and extemporaneous pharmaceuticals by capillary isotachophoresis [152]. The method was carried out using pH 4.85 acetate buffer solution, and 0.01 M formic acid as leading and terminating electrolytes, respectively. 

Blood chemistry. Pretest, and at least prior to termination, electrolytes and electrolyte balance, acid-base balance, glucose, urea nitrogen, serum lipids, serum proteins (albumin-globulin ratio), enzymes indicative of organ damage such as transaminases and phosphatases should be measured. Toxicant and metabolite levels should be assessed as needed. 

In one report, bidirectional FTP was achieved on a PMMA chip. A common terminating electrolyte (TE) was employed to achieve simultaneous cationic and anionic separations. Without a complex injector design, sample introduction was achieved hydrodynamically for FTP separation [638]. 

Figure 5.20 shows the separation of ephedrine, procaine, and cycloserine using cationic cITP. The leading electrolyte consisted of 10 mM potassium acetate and acetic acid (pH 4.75), and the terminating electrolyte consisted of 10 mM acetic acid no additives were used. 

System No. Parameter Leading electrolytes 1st stage 2nd stage Terminating electrolyte... 

Fig. 13.1 Separation unit in a column coupling configuration as used for the analysis of anions in river water 1, sampling block with a 30pL sampling valve 2, terminating electrolyte compartment with a cap (3) 4,...

Capillary isotachophoresis (CITP) — An electrophoretic separation technique (-> electrophoresis) in a discontinuous -> buffer system, in which the analytes migrate according to their -> electrophoretic mobilities, forming a chain of adjacent zones moving with equal velocity between two solutions, i.e., leading and terminating electrolyte, which bracket the mobility range of the analytes. Ref [i] Riekkola ML, Jonsson jA, Smith RM (2004) Pure Appl Chem 76 443... 

One explanation for the sharpening of the later-eluting impurities is a phenomenon called sample self-stacking [42,43], This is a variant of transient isotachophoresis (ITP) [44], In this case, the leading electrolyte is chloride ion, while the main component acts as the terminating electrolyte. The requirement for ITP is fulfilled since the impurity s mobility is bracketed by leader and terminator. While you may not understand all of this, accidental ITP is not rare... 

II) Isotachophoresis K separation in a discontinuity between two buffer solutions (the leading and the terminating electrolyte). The sample components are introduced in small quantities in the discontinuity, a d.c. current is applied, and the various components start to move. Consecutive zones are formed and a steady state is attained where each zone moves with equal velocity, hence the name. 

Fig.l Electrical field strength in the zones of the leading electrolyte, L, the sample consisting of A and B, and the termination electrolyte, T. For details, see the text. 

Isotachophoresis. This name derives from the fact that in this technique all sample bands ultimately migrate at the same velocityO). Sample is inserted between two electrolyte solutions, a leading and a terminating electrolyte. In a particular separation either cations or anions may be determined, but not both at once. 

A unique feature of Isotachophoresls is that after the separation process has been completed, all electrophoretic parameters remain constant with time. Assuming a uniform current density, all sample constituents between the leading-terminating electrolyte migrate at Identical speeds. Moreover, at constant current density local migration rates will be constant. In this steady state, resolution values of stac)ced constituents will be either unity or zero. The basic features of the steady-state configuration have been discussed [3.4]. 

Figure 2. Schematic diagram of an ITP-apparatus. a = PT-electrode b = terminating electrolyte c = drain d = silicone septum e = UV-detector f = conductivity (potential gradient) detector g = silicone septum h = semi-permeable membrane (e.g. cellulose acetate) i = Pt-electrode. p and q lead to a current-stabilized power supply (20 kV). The separation compartment is a PTFE-capi1lary (I.D. =...

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