The Feature Mapper node performs retention-time alignment and feature linking across data sets. Its retention-time alignment step chromatographically aligns two or more input files and calculates the aligned retention times for features (for information, see Retention-time alignment and feature mapping). It compensates for small differences in the retention times of the components in a sequence of sample runs. It is designed to align files that were acquired using the same chromatographic method.
This node aligns only files having the same fraction number for multi-dimensional data and uses the grouping information on the Grouping & Quantification page to align them.
The following table describes the parameters for the Feature Mapper node.
Parameter | Definition |
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Perform RT Alignment | Determines whether to perform retention-time alignment.
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Parameter Tuning | Determines how to tune the parameters for non-linear regression.
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Maximum RT Shift [min] | Specifies the maximum retention-time shift allowed for mapping features from different files. Range: 2–50; default: 10 |
Mass Tolerance | Specifies the maximum mass tolerance allowed for mapping features from different files, in ppm. Range: 0.01 ppm–5000 ppm; default: 10 ppm |
RT Tolerance [min] | Specifies the maximum retention-time tolerance used for mapping features from different files, in minutes. If the value is 0, the application automatically determines the tolerance. Range: 0–4; default: 0 |
Mass Tolerance | Specifies the maximum mass tolerance allowed for mapping features from different files. If the value is 0, the application automatically determines the mass tolerance. Range: 0–100.0 ppm; default: 0 ppm |
Min. S/N Threshold | Specifies the minimum signal to noise (S/N) for a consensus feature to be used. The S/N value of a consensus feature is defined by the largest S/N value of all related features and single peaks. Minimum: 0; Maximum: (unchecked) |