Detector Control
Optimizing the Sensitivity (FLD-3x00(RS))

If the peak heights of the individual peaks in a chromatogram differ, you can improve the signal-to-noise ratio of the smaller peaks by switching the sensitivity during the run.

To determine the optimum sensitivity value for the Dionex FLD-3x00(RS) detectors, Chromeleon provides the MaxPMTSaturation parameter. It indicates the highest saturation of the PMT signal that was measured since the last reset. The ClearMaxPMTSaturation command is used to reset the value to 0% before the run. For details, refer to  MaxPMTSaturation or to the operating instructions of the detector.

The program example below shows how MaxPMTSaturation can be used to monitor the sensitivity for each peak while several signal parameters, including the sensitivity, are switched between peaks.

                LampMode =              Standard
                ResponseTime =          0.1
                FLD_FlowCell.TempCtrl =         Off
                FLD_FlowCell.ReadyTempDelta =   0.10 [°C]
                BaselineBehavior =      Append
                FLD.Data_Collection_Rate.Nominal =      50
                Emission_1.ExWavelength =       250.0 [nm]
                Emission_1.EmWavelength =       350.0 [nm]
                Emission_1.Sensitivity =        4
                Emission_1.PMT =                Pmt1
                Emission_1.FilterWheel =        Auto
 
 
0.000           FLD.AutoZero
                Wait    UV.Ready and ColumnOven.Ready and Sampler.Ready and FLD.Ready 
                and PumpRight.Ready and PumpLeft.Ready
                Inject
                Emission_1.AcqOn
        
                ClearMaxPMTSaturation

; First Peak is expected between 0 min and 4.90 min 
 
 4.90              Log     MaxPMTSaturation ; Log MaxPMTSaturation for first peak
 4.95              ClearMaxPMTSaturation
 

 5.000             Emission_1.ExWavelength =                       300.0 [nm]
                Emission_1.EmWavelength =                       450.0 [nm]
                Emission_1.Sensitivity =                        7
                Emission_1.PMT =                                Auto
                Emission_1.FilterWheel =                        Auto
 
; Second Peak is expected between 5 min and 9.90 min 

 
 9.90            Log     MaxPMTSaturation ; Log MaxPMTSaturation for second peak
 9.95              ClearMaxPMTSaturation
 

10.000          Emission_1.ExWavelength =                       220.0 [nm]
                Emission_1.EmWavelength =                       280.0 [nm]
                Emission_1.Sensitivity =                        2
                Emission_1.PMT =                                Pmt1
                Emission_1.FilterWheel =                        Auto
 
; Third and fourth Peak are expected between 10 min and 14.90 min 

 
14.90         Log     MaxPMTSaturation ; Log MaxPMTSaturation for third and fourth peak
14.95           ClearMaxPMTSaturation
 

15.000          Emission_1.ExWavelength =                       400.0 [nm]
                Emission_1.EmWavelength =                       750.0 [nm]
                Emission_1.Sensitivity =                        7
                Emission_1.PMT =                                Pmt2
                Emission_1.FilterWheel =                        Auto

; Fifth Peak is expected between 15 min and 29.90 min 
29.90            Log     MaxPMTSaturation ; Log MaxPMTSaturation for fifth peak


30.000          Emission_1.AcqOff
                End