Minimizing Carryover Using a Four Solvent Wash Station
App Note 10/2008
When analytes from a sample injection into an LC system are not completely flushed from the sample introduction
hardware, valve and connections following the injection, a carryover effect can be seen in subsequent injections of blank samples. Minimizing this carryover effect during an analytical run is important for providing reproducible and reliable data. Typically, limiting carryover to less than 20% of the lower limit of quantitation is desired. As today’s detection systems become increasingly sensitive, reduction
of carryover becomes increasingly important.
In this work, we present a wash station that allows the user access to up to four independent wash solvents that can be used following an LC injection to minimize the carryover effect for compounds with particularly strong retention properties. Using a GERSTEL MPS 3 autosampler with MAESTRO software enables the analyst to control the Four Solvent Active Wash Station, toggle the injection valve to clean the sample loop, and to control valve switching used for offline column conditioning when multiplexing analytical runs.
Techniques used to minimize the carryover effect are discussed and examples of HPLC injection cycle control options available within the MAESTRO software are illustrated. LC-MS/MS data are presented showing a reduction of the carryover effect when using a Four Solvent Active Wash Station for a compound having particularly strong retention properties.