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

Peak shape improvement of basic analytes in capillary liquid chromatography

“…A similar effect was also observed with amitriptyline, another strong base, employing the capillary LC system (Figure 4). The tailing was not caused by packing material characteristics or poor quality of the instrumentation or column packing as these parameters are controlled [3,4]. Thus, an interaction of the basic compounds with the column hardware including the preinstalled connecting capillaries can be assumed as origin of peak deformation.…”

“…Recent work focused on nonionic standard substances and illustrated that a commercially available capillary LC system with some modifications [3] and capillary columns from various suppliers [4] can almost attain as high a performance as is known from conventional size HPLC equipment. In this investigation the separation performance of the miniaturized technique is examined in comparison with conventional size HPLC for the impurity determination of nonpolar (levonorgestrel) and basic drugs (MS-275; pK a 2.94 and 3.35).…”

Capillary liquid chromatography with diode array and mass spectrometry detection for heterocyclic aromatic amine determination in ready-to-eat food treated with electron-beam irradiation

“…Moreover, in reversedphase mode, sensitivity can be increased making use of focusing techniques by injection of large solution volumes with very low elution strength (low organic solvent composition). These techniques allow the analyte preconcentration in a small plug on the head of the capillary column, thus minimizing the broadening of chromatographic peak [17,18]. Although gradient cLC has been used in combination with UV detection for HA determination in cooked ham [8], isocratic elution is preferred with MS detection.…”

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].…”