Retention Time Windows: Why ±0.05 Minutes Is the Sweet Spot for Background Hit Filtering
Virscidian's analysis of a high-throughput AS-MS screen revealed that setting retention time windows to ±0.05 minutes optimally balances filtering true background cross-hits—capturing over 99% of them—while minimizing false positives from isomeric peaks, making this the recommended threshold for automated cross-hit filtering in workflows like Analytical Studio.
Retention Time Windows: Why ±0.05 Minutes Is the Sweet Spot for Tech Background Hit Filtering
When identifying true binding events in AS-MS workflows, background noise is a significant challenge. The retention time (Rt) windows are crucial in determining what counts as “similar” between an original hit and a potential cross-hit.
Experiment
Using data from a high-throughput screen of 250,000 compounds across 96 samples, Virscidian conducted an in-depth analysis to determine the typical retention time window between cross-hits.
Key Finding
Virscidian found that over 99% of background peaks that were true cross-hits occur within 0.05 minutes of the retention time of the original peak. When the retention time window was reduced below 0.05 minutes, real cross-hits were missed, potentially leading to inflated hit counts. Conversely, using retention time windows greater than 0.05 minutes risked including isomeric peaks without providing any meaningful gain in finding cross-hits.
Recommended Practice
Use an automated cross-hit filter, such as the one in Analytical Studio, and set its retention time filter to ±0.05 minutes. This setting maximizes cross-hit detection without increasing isomer-related misclassification.
Further analysis found that 99% of background ions identified as cross-hits fall within ±0.05 minutes of the retention time of the original hit.
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