Estimation of the band broadening contribution of HPLC equipment to column elution profiles

UV Longitudinal cell design with enhanced sensitivity for capillary electrophoresis

“…As previously shown [1,2], the effect of extracolumn variance can be simply evaluated by calculating the decrease in plate number for the different path lengths of Ushaped cells. Since we were able to eliminate the contribution of the unions to the variance, we assume that the major contribution to the variance is due to the cell and the column volumes.…”

“…With these limitations, detectors based on the principles of the Beer-Lambert law, have been dominant in this area. Recently, ultra-sensitive UV-absorption detector cells have been described [1,2] for capillary and microbore liquid chromatography, and this type of cell could potentially be utilized in MECC. Small column dimensions and narrow solute bands demand detectors with minimal dead volumes and fast responses in order to maintain the efficiency inherent in these techniques.…”

Evaluation of packed capillary liquid chromatography columns and comparison with conventional-size columns

“…The basic assumption is that the true N-value for a column, N col , is independent of retention time. This is only correct if the conditions pointed out by Claessens et al are met [32]:…”

“…Thus their influence on overall band broadening effects each peak to the same extent, in contrast to the retention time-dependent dispersion due to the packed bed. The linear extrapolation method (LEM) offers a possibility for separate evaluation of the quality of the packed bed and of the other column parts, respectively [30][31][32][33][34][35]. The basic assumption is that the true N-value for a column, N col , is independent of retention time.…”

Measurement and Modeling of Extra-Column Effects Due to Injection and Connections in Capillary Liquid Chromatography

“…However, it has been shown that accurately calculating the variance of these extra-column peaks can sometimes prove difficult due to detection limitations [28], challenges selecting proper integration limits for peak moment analysis [31][32][33][34], and discrepancies in the pressure when either the column or ZDV fitting is being measured [35]. An alternative to this "subtraction" method to determine extra-column effects is the use of linear extrapolation [18,[36][37][38][39][40][41], where the variance of several analyte peaks with different retention factors are extrapolated back to an intercept that describes the extra-column variance. Others have reported the calculation of extra-column band broadening through graphical analysis or deconvolution of the peak shapes eluted from the column [42,43].…”