ABSTRACT
The potential of high-speed analyses by rapid resolution liquid chromatography (RRLC) and RRLC/MS on 1.8-microm porous particles packed into short columns operated at high flow-rate was investigated and compared with the performance of 5-microm porous particles packed into conventional columns. Using similar chemistries, the ease of conversion from conventional HPLC to an RRLC method was demonstrated. In order to display the practicality of RRLC separations, the analysis of pesticides in crops and catechins in Japanese green tea was selected. Using the Japanese Food Hygiene Law method, which employs a conventional 5-microm RP column (250 mm x 4.6 mm) for quantification of pesticides in crops, the analysis time was 25 min under isocratic conditions. Using the RRLC method on the short (50 mm x 4.6 mm) column packed with 1.8-microm porous particles, the same separation could be performed in 0.8 min with the RRLC/MS method without a loss in resolution. At the highest flow rate, compared to the conventional method, the time could be reduced by a factor of 31. In gradient elution, the fastest separation of catechins in Japanese green tea was achieved by RRLC on 50-mm x 4.6-mm id or 50-mm x 2.1-mm id RRLC columns packed with 1.8-microm particles. The analysis time at 5 mL/min was less than 1 min. Compared to the conventional HPLC method on a 150-mm column packed with 5-microm particles, time was reduced by a factor of 15. The effect of other experimental parameters such as the column temperature, acquisition rate of the detector and the influence of cell volume on chromatographic performance was also investigated. After the optimization, the analysis precision under the fastest RRLC conditions was examined. RSDs of retention time and peak area were 0.2% and 0.47%, respectively.
