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*   RCD Algorithm
Rapid Components Detection (RCD) is based on a model ion that represents a characteristic ion (m/z value in MS1 spectra) for every detected component. The algorithm starts with component candidate detection and model ion selection and continues with the correlation of model ion profiles to confirm or reject a candidate.
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To run the Rapid Components Detection algorithm
1.
Click the Components Detection & Spectra Deconvolution button, , and choose RCD.
The R-Component Detection Algorithm dialog box opens. This dialog box includes the following pages:
2.
3.
Click Calculate.
4.
Deconvolution page of the R-Component Detection Algorithm dialog box
The program uses a different threshold level from the one specified in the data file. In especially noisy chromatograms, setting the threshold higher can reduce the number of false positive results. However, if you feel the algorithm is too restrictive and is missing some chromatographic peaks, you can lower the default value.
Minimum Model Ion Abundance
The algorithms search for spectral peaks (model ions) that have the most rapid rise and fall of a signal in a peak region. To eliminate spikes and random fluctuations, a model ion should exhibit a minimum abundance value.
Use this option when you must analyze noisy data. The program automatically determines the smoothing factor according to the signal-to-noise ratio. You can change this value or switch off the smoothing. The system uses an exponential filter similar to the analog RC filter.
To eliminate false positive component detection, the adjacent components must show some degree of spectral dissimilarity that is represented as the match factor used in library searching. The spectra Difference Factor value is the minimal match factor between spectra that detected components should exhibit.
Background Subtraction
When you select the Automatic option, the program attempts to find a region of relatively constant signal intensity before and after every peak and sets two background scans there. To use the Manual option, set the background scans by clicking the Chromatogram Processor Utilities button and choosing Background Subtraction before starting the detection and deconvolution process (see Background Subtraction). You can set two manual background scans anywhere in the chromatogram. When you select the None option, background subtraction is not performed.
Precursor Ion Subtraction
When a product ion chromatogram is being deconvoluted, you can subtract the selected precursor ion from all scans to improve component detection. However, if a component does not fragment and you can only observe a precursor ion, you should not apply the subtraction because you can overlook this component. Note that this application does not support scan events that are often used in connection with product ion scanning.
Where you specify only a part of a chromatogram to be analyzed (time range), which can speed up your work. In this case, the algorithm ignores regions outside of the specified range.
m/z Range
Determines the m/z value range to be analyzed and ignores other spectral regions. This feature is useful when processing large chromatograms.
You can apply two extraction algorithms, the choice depending on the intended use for the component spectra. When components are intended for a library search (see Spectrum Search), use Sharp spectra deconvolution. When the purpose of component detection is target analysis, use Soft deconvolution. Generally, Sharp deconvolution subtracts peaks from coeluting components with a higher multiplication factor, and so it produces spectra with fewer peaks and lower intensities of isobaric peaks than Soft deconvolution.
Opens the Save RCD Parameters File dialog box where you can save your current parameters to a RCD parameters file (.rcd.par).
Opens the Open RCD Parameters File dialog box where you can choose a RCD parameters file (.rcd.par) to load.
More page of the R-Component Detection Algorithm dialog box


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Related Topics:
  JCD Algorithm
  TECD Algorithm
  Direct Infusion Algorithm
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