Recording Absorbance Spectra: Program ExampleDetector Control
Recording Absorbance Spectra: Program Example
The Dionex Ultimate3000 VWD-3x00 detectors allow you to record the absorbance spectra of substances used in an analysis, and thus to identify optimum wavelengths or to detect peak impurities. Spectrum scans can be triggered manually by executing a command (for more information, refer to 
Recording Absorbance Spectra) or in a sample program.
The program example below contains a trigger to trigger the scan on the trailing side of the peak when the signal has reached a value greater than 20 mAU. As long as the scan settings remain constant, the baseline scan must only be performed once.
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Trigger conditions: Retention time > 0.1 min (prevents that the injection peak is scanned) UV_VIS_1.signal > 20 (minimum height of signal) UV_VIS_1.delta<0 (signal slope must be negative, scan recorded on the trailing side of the peak) True=0.50 (minimum time within which the conditions must be fulfilled to trigger the scan) Hysteresis=0 (sets the trigger condition to "false" with a delay to prevent repeated triggers when signal is instable) |
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Trigger ScanPeak UV_VIS_1.signal > 20 and uv_vis_1.delta<0 and system.retention >0.1 , True=0.50, Hysteresis=0.0 Scan |
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EndTrigger |
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Pressure.LowerLimit = |
10 [bar] |
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ColumnOven.TempCtrl = |
On |
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ColumnOven.Temperature.Nominal = |
40.0 [°C] |
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Pressure.UpperLimit = |
400 [bar] |
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%A.Equate = |
"Water" |
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%B.Equate = |
"Acetonitril" |
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Data_Collection_Rate = |
2.0 [Hz] |
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UV_Lamp = |
On |
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Visible_Lamp = |
On |
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UV_VIS_1.Wavelength = |
254 [nm] |
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UV_VIS_2.Wavelength = |
240 [nm] |
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UV_VIS_3.Wavelength = |
310 [nm] |
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UV_VIS_4.Wavelength = |
400 [nm] |
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Sampler.InjectMode = |
Normal |
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UpSpeed = |
10.00 [mm/s] |
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DownSpeed = |
10.00 [mm/s] |
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SampleHeight = |
0.50 [mm] |
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DispSpeed = |
50.00 [µl/s] |
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DrawSpeed = |
25.00 [µl/s] |
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0.000 |
Flow = |
1.000 [ml/min] |
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%B = |
75.0 [%] |
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;lower limit for wavelength scan |
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ScanStartWavelength = |
210.0 [nm] |
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;upper limit for wavelength scan |
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ScanEndWavelength = |
400.0 [nm] |
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;Scan speed setting |
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ScanSpeed = |
Max |
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;record a baseline |
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Scanbaseline |
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;Wait UV.Ready required to prevent conflict between Autozero and Scanbaseline |
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Wait UV.Ready |
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Autozero |
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Wait UV.Ready and ColumnOven.Ready and Sampler.Ready |
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Inject |
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Pump_Pressure.AcqOn |
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UV_VIS_1.AcqOn |
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UV_VIS_2.AcqOn |
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UV_VIS_3.AcqOn |
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UV_VIS_4.AcqOn |
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0.050 |
%B = |
75.0 [%] |
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2.500 |
%B = |
95.0 [%] |
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UV_VIS_1.AcqOff |
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UV_VIS_2.AcqOff |
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UV_VIS_3.AcqOff |
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UV_VIS_4.AcqOff |
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3.000 |
%B = |
75.0 [%] |
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7.000 |
%B = |
75.0 [%] |
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Pump_Pressure.AcqOff |
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End |
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