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Improve Retention and Peak Shape for Early-Eluting Pesticides in LC-MS/MS

13 May 2009

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How important is the HPLC column in a comprehensive LC-MS/MS screening method? LC-MS/MS is quickly gaining acceptance for residue testing, and can simultaneously monitor hundreds of pesticides, including those difficult to detect by GC. With such a powerful detector, hasn’t the column become simply a sample inlet device? While the MS/MS detector allows for specific, sensitive detection of pesticides, the LC separation is still very important! For the highest quality data, we need to move the pesticides away from non-retained matrix components, as well as ‘spread’ the pesticides throughout the retention time window. Standard C18 columns often give poor retention and distorted peak shape for more polar species. Ultra Aqueous C18 columns show significantly better peak shape for early-eluting pesticides (see figure), as well as an even distribution of pesticides in the retention time window. A C18 is a useful all-purpose column; for pesticides, an Aqueous C18 column is better.