What ’ s the Most Meaningful Standard for Mass Spectrometry : Instrument Detection Limit or Signal - to - Noise Ratio ?

Terry L. Sheehan and Richard A. Yost When evaluating the performance of mass spectrometers, one needs to consider the best (or most meaningful) figure of merit to use; options include instrument detection limit (IDL) and signal-tonoise ratio (SNR). In the last 15 years, vendor specifications for SNR have increased from 10:1 to greater than 100,000:1. Does that accurately reflect improvements in mass spectrometers? Although there have been many significant changes, the change in SNR specifications has been far greater than the corresponding change in method detection limits (MDL). Under appropriate conditions, SNR is a meaningful standard, but the value of any SNR must be evaluated in context of the chromatography and sample. Factors influencing the validity of vendor SNR specifications are reviewed, and the statistical alternative of IDL is presented as a replacement that is more consistent with regulatory guidelines and a more relevant indicator of instrument performance. What’s the Most Meaningful Standard for Mass Spectrometry: Instrument Detection Limit or Signal-to-Noise Ratio?