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The Golay Equation for Open Tubular Columns The corresponding equation describing dispersion in an open tubular column was developed by Golay (10) for GC columns but is equally applicable to LC columns and to dispersion in connecting tubes. The Golay equation differs from equation (10) in that, as there is no packing, there can be no multipath term. Consequently, the equation contains only three functions. One function describes dispersion from longitudinal diffusion and the other two describes dispersion from the resistance to mass transfer in the mobile and stationary phases, respectively. The Golay equation takes the following form:- (11) where (r) is the column radius, and

Figure 2. Band Dispersion Resulting from Newtonian Flow The dispersion in open tubes was examined by Golay (3) and Atwood and Golay (4) and experimentally by Scott and Kucera (5) and Lochmuller and Sumner (6). The variance per unit length of an open tube (H) according to Golay is given  by   where (Dm) is the diffusivity of the solute in the mobile phase, (u) is the linear velocity of the mobile phase, and (r) is the radius of the tube. At relatively high velocities (i.e., at velocities much greater than the

at one time and only a single peak will be represented.  The effect of viscous flow on dispersion will first be considered. Dispersion in Detector Sensors Resulting from Newtonian Flow Most sensor volumes are cylindrical in shape, are relatively short in length, and have a relatively small length-to-diameter ratio. The small length-to-diameter ratio is in conflict with the premises assumed in the development of the Golay equation for dispersion in an open tube. Atwood and Golay (11) extended the theory of dispersion in open tubes to tubes having small length-to-diameter ratio. The theory is complex and not relevant here as, if appropriate cell design is employed, the dispersion from viscous sources will be negligible. Nevertheless, the effect on solute profiles is shown in figure 5

Dispersion in Detector Sensors Due to Newtonian Flow The majority of sensor cells are cylindrical in shape, relatively short in length and have a small length-to-diameter ratio (small aspect ratio). Unfortunately, the small aspect ratio conflicts with the assumptions adopted by Golay in the development of the equation that describes the dispersion that takes place during fluid flow through an open tube. As a consequence, the Golay equation for open tubes can not be applied to cylindrical sensor cells. As a result, Atwood and Golay [12] extended the theory of dispersion in open tubes to tubes of small length-to-diameter ratios. Details of the development of the theory will not be given here because, with proper cell design, it is no longer pertinent to practical

;             (51) The equation of Horvath and Lin was very similar to that of Huber and Hulsman and, in fact, only differed in the magnitude of the power function of (u) in their (A) and (D) terms. These workers were also trying to address the problem of a zero (A) term at zero velocity and the fact that some form of "turbulence' between particles aided in the solute transfer across the voids between the particles. The Golay Equation The basic equation describing the dispersion that takes place in an open tubular column was developed by Golay (8) for GC but is equally, and directly, applicable to LC. The Golay equation differs in one important aspect from the equations for packed columns in that, as there is no packing, there can be no multipath term or coupling factor and thus, contains only two functions. One function describes the longitudinal diffusion effect and the other the combined resistance to mass

of the Giddings equation, which simplifies to the Van Deemter equation when the mobile phase velocity is close to, or around, the optimum mobile phase velocity. The form of the Van Deemter equation and, in particular, the individual functions contained in it, are well substantiated by experiment. The Knox equation is obtained from an empirical fit to experimental data and the individual functions of other pertinent variables contained in the equation are not all substantiated by experiment. The Golay equation accurately described dispersion in capillary or open tubular columns but in GC the compressibility of the mobile phase must also be taken into account (Golay in his original derivation did not accommodate gas compressibility). It would appear from the data available at this time, that the Van Deemter equation (for packed columns) or the Golay equation (for capillary or open tubular columns) would be the most appropriate to use in column design and in the interpretation of