The Investigation of a New Recording Mode for Capillary Zone Electrophoresis
ZHANG Hong-Yi, LI Qian-Feng, LIU Hui-Tao, CHEN Xing-Guo-HU Zhi-De, WANG Rui
2000, 21(12):
1832-1836.
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Since capillary zone electrophoresis emerged as a powerful separation tool, it has been a common practice to record the electropherogram in terms of the time domain.In this recording mode, the migration time often has a considerable change as the potential gradient and temperature inside the capillary do not remain constant in different runs.In this paper, attempt is made to solve the problem in a new way.The electric flux, defined as the amount of electric charge following a cross section of the capillary in a time interval, takes the place of the time as the domain in an electropherogram.At first, it is theoretically demonstrated that as regards to the reproducibility of separation result the use of the electric flux domain is superior to that of the time domain.Then the performances of electric flux domain and time domain are compared in two typical background electrolyte systems, 20 mmol/L Na2B4O7(pH=9.18) and 10mmol/Lphosphate (pH=8.28).When 10mmol/Lphosphate is used as the background electrolyte and applied voltage varies from10to25 kV(the corresponding temperatures at different voltages are also calculated from our method.), the reproducibility in migration time for berberine hydrochloride, antipyrine, sulfadimidine and sulfadiazine is41.7%, 41.8%, 41.5% and42.2%, respectively.In contrast, the reproducibility in electric flux for the above analytes is1.05%, 0.89%, 0.55% and0.84%, respectively.The reproducibilities in peak areas obtained from the two recording modes under the same experimental conditions are also compared.The relative standard deviation in area obtained from time mode for berberine hydrochloride, antipyrine, sulfadimidine and sulfadiazine is 42.5%, 44.5%, 42.9%, 45.0%, respectively.In contrast, the reproducibility in electric flux for the above analytes is3.79%, 2.83%, 3.02% and5.19%, respectively.Besides, the relative standard deviations in migration time and electric flux are compared in 12runs made consecutively at a fixed voltage.The relative standard deviation in electric flux (<0.7%) is lower than that in migration time (>1.8%)
