Figure 1

An overview of methods for retention time correction in hyphenated mass spectrometry profiling experiments. A technique often used in retention time correction involves spiking internal standards prior to data acquisition, and then linear time correction is applied manually, based on user selected markers [24, 25]. This approach has significant limitations, as discussed in [21]. The automated approaches for retention time correction in hyphenated mass spectrometry are based on two schools of thought: one is to align the entire chromatographic profiles prior to peak detection (profile alignment), and the other is to perform peak detection first, and then match extracted signal peaks across samples to correct for retention time drifts (peak matching). In either approach one can rely on the time domain data only, or include the information from the m/z data domain (mass spectra). Examples of peak matching algorithms that use retention time only (branch 1) include [18, 19, 22]; examples of peak matching algorithms that use both time domain and m/z data (branch 2) include [20, 21, 23]; algorithms for profile alignment that rely on time domain data only (branch 3) were first proposed in 1979 [39], and include [17, 26, 28, 29]; finally, examples of algorithms for profile alignment that use the entire chromatogram data matrices include [27, 30, 37]. The algorithm proposed here is a peak matching approach, and relies on both time domain data and peak mass spectra (branch 2).