High−Speed Analyses using Rapid Resolution Liquid Chromatography on ZORBAX column packed 1.8 μm Particles

Over the years, separation resolution and reduction of analysis time has continually improved in High Performance Liquid Chromatography (HPLC). For further improvement, column efficiency must be increased. The relationship among separation efficiency, the mobile phase linear velocity and particle size was investigated in detail in the early 1970 s [1]. This and other systematic investigations have led to high−throughput and high−resolution HPLC that we know today. The major advantages of high−throughput HPLC are the increase in throughput and the reduction in the analysis cost. The shortening in analysis time is due to the use of a shorter column length. However, a shorter column may lead to a loss of theoretical plates, hence a decrease in chromatographic resolution that may be required for a complex mixture of compounds. To offset the potential loss of resolution, the use of smaller size particles has resulted in more efficient columns. Further, ultra high−pressure liquid chromatography using a capillary column packed 1−1.5 μm non−porous silica particles was introduced in 1997 [2]. Since then, HPLC using smaller particles has become more popular. In this paper, the technique of the use of small particles (sub− 2 micron) packed into short columns run at a high flow rate has been termed Rapid Resolution Liquid Chromatography (RRLC). Recently, RRLC analysis has become a routine method in the pharmaceutical industry. However, such a fast analysis technique is not only for the pharmaceutical field. In this study, we apply to the fast RRLC technique to a more general field in the analysis of chemical compounds. Today, the multi−residue screening method of pesticides established by the Japanese Food Hygiene Law method [3, 4] use a 250 mm×4.6 mm i.d. column packed with 5 μm octadecyl (C 18) silica gel used in the isocratic elution mode. These columns typically produce an analysis time of 30 min. However, with new Technical Review