Retention volume, adjusted

When the mobile phase is a gas, a compressibility factor j must be applied to the adjusted retention volume to give the net retention volume ... 

Returning to equation (13), it is now possible to derive an equation for the adjusted retention volume, (V r),... 

Adjusted retention volume (V R) The retention volume for a substance (Tr) minus the retention volume of an unretained substance (Tm) W = VR- Vm. 

Adjusted retention time, 327 Adjusted retention volume, 327 Air, 139, 140... 

Figure 1.3 A schematic chromatogram-. VR, retention volume VK-, adjusted retention volume V, elution volume of peak V0, void volume W, peak width VM, holdup volume OX, volume of injector XY, volume of detector, including volume of tubing.

Adjusted retention volume Vi Concentration of solute in stationary ... 

Those characteristics of the chromatogram that have theoretical significance will be discussed later, but some common measurements that can be taken from the chromatogram are given now. The elapsed time between the dead point and the peak maximum is called the retention time, and the time between the dead point and the peak maximum the adjusted retention time. If the retention time is multiplied by the mobile phase flow-rate, the product is called the retention volume. Similarly, multiplying the adjusted retention time by the flow-rate gives the adjusted retention volume. 

Figure 1.18. Types of chromatograms, (a) Differential chromatogram (b) integral chromatogram (c) peak resolution. O, injection point OX, injector volume OY, detector volume OA, holdup volume, VM OB, total retention volume, VR AB, adjusted retention volume,...

Adjusted retention volume. V The solute retention volume minus the retention volume for an unretained peak. 

Net retention volume. VN- The adjusted retention volume multiplied by the pressure gradient correction factor. 

Relative retention. ra/b The adjusted retention volume of a substance related to that of a reference compound obtained under identical conditions. 

Retention index. I. A number relating the adjusted retention volume of a component A to the adjusted retention volumes of normal paraffins. Each n-paraffin is arbitrarily allotted, by definition, an index of one hundred times its carbon number. The index number of component A is obtained by logarithmic interpolation. 

V = adjusted retention volume. The component which is more re-tamed (greater value of Vi) is placed m the numerator. 

EFFECTIVE NUMBER OF PLATES. Desty et al. (31) introduced the term effective number of plates, N, to characterize open tubular columns. In this relationship adjusted retention volume, VR, in lieu of total retention volume Vp, is used to determine the number of plates. This equation is identical to Purnell s separation factor discussed below. 

A chromatographic peak provides valuable information, namely, the elapsed time from the injection point or the difference in elution times of two peaks (qualitative information), the peak shape (qualitative or quantitative information), and the peak size(quantitative information). The simplest qualitative tool is simply the comparison of retention data from known and unknown samples. A chromatogram illustrating the commonly used retention nomenclature is given in Figure 4.1. The retention time (tp>) is the time elapsed from injection of the sample component to the recording of the peak maximum. The retention volume (VR) is the product of the retention time and the flow rate of the carrier gas. Generally, the adjusted retention time (t ) or adjusted retention volume (V >) and the relative retention (rA/B) are used for qualitative analysis. Adjusted retention time (volume) is the difference between the retention time (volume) of the sample and an inert component (usually air). The relative retention is the ratio of the adjusted retention time (or volume) of a standard to the adjusted retention time (or volume) of the unknown, (see Chapter 2). 

Since a finite pressure drop exists over the length of the column, the adjusted retention volume is often multiplied by the pressure gradient correction factor, j, to give a net retention volume, VN. 

DISTRIBUTION CONSTANT. For elution GSC the distribution constant Kn can be obtained from the adjusted retention volume v. and the surface area of the adsorbent, A (rrr ). ... 

Evaluation and Preparative GPC Fractionation of PMMA. The baseline-adjusted retention volume curves of the preparative GPC fractions are shown in Figure 3. The characterization data are shown in Table III. 

Absorption, 6, 8, 40 Accuracy, definition of, 99 Activity coefficient, 109-110 Adjusted retention volume, 10 Adsorption, 6, 8, 40 Affinity chromatography, 224-225 Area, measurement of, 102 Area normalization, 104 Asymmetry of peaks, 14, 43... 

It is called the adjusted retention volume (or time), and it is designated with a superscript prime. It is also shown in Figure 1.4. 

Fig. 9.2.2. An HPLC chromatogram showing components eluted at Va (the interstitial volume) and VR., respectively. VR- = adjusted retention volume...

From this equation, an important parameter termed the capacity factor, k, can be calculated. This factor is a comparison of the adjusted retention volume of a particular constituent on the FIPLC column relative to the interstitial volume, V0, and is given by ... 

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