Saving analysis time without the loss of resolution

New market opportunities create a push for faster sample turnaround in research and development as well as quality control laboratories.   Bringing a pharmaceutical product to market or shipping an active ingredient to a customer are some of the reasons why analysts are asked to produce chromatographic results quicker. Accordingly, scientists have an increased interest in saving analysis time while keeping the quality of the information.  As a result, laboratory users actively investigate the potential for shorter analytical runs without the loss of resolution.

Reversed phase chromatography (RPLC) is the most common technique for analysis of small compound mixtures and columns based on C18 derivatisations are the workhorse for the analysis of drugs. Kromasil EternityXT family of columns are RPLC columns, packed for UHPLC standards in 1.8 µm and 2.5 µm particles; and for HPLC purposes in 5 and 10 µm particles. This article illustrates the separation and scale-down analysis of sulpha drugs using Kromasil EternityXT UHPLC/HPLC C18 columns to increase efficiency in the laboratory. 

Three chromatographic results for the separation of the sulpha drugs, sulfathiazole, sulfamerazin and sulfamethoxazole, are shown in Figure 1. As seen in the figure, while the columns’ internal diameter remains constant at 4.6 mm, particle size and column length is scaled accordingly so as to maintain the efficiency level between columns.  In order to keep this column efficiency, as the particle size decreases, the column becomes shorter. Both UHPLC instruments and Kromasil EternityXT UHPLC columns can tolerate higher pressure limits, so it is possible to increase the run’s flow rate while still maintaining the quality of the separation. It should be noted that the more retained compound, sulfamethoxazole, elutes at 7 minutes when using the column packed with larger particles, and the same compound elutes at just 1.1 minutes when eluting from the UHPLC column packed with 1.8 µm particles. This example shows that it is therefore possible to run several samples in duplicate in the shorter column packed with 1.8 µm particles during the time it takes to carry out one experiment with the column packed with 5 µm particles. In fact, in this example we show that it is possible to run seven times faster with the UHPLC column packed with 1.8 µm particles. These results illustrate the increase of efficiency a laboratory can achieve when using columns packed with smaller particles contributing to the overall times savings in a project and in production.