ESA Coulochem III Electrochemical Detector

Dionex Detectors
ESA Coulochem III Electrochemical Detector

In addition to the standard commands available for all detectors (see Dionex Detectors) and several General Device Commands, Chromeleon provides the commands and parameters from the table below (please note that the display Filter level determines which commands and properties are displayed).

If the detector is connected to Chromeleon, the REMOTE LED and SECURITY LED on the keypad are illuminated. To prevent accidental changes in the operating parameters, none of the front panel keys are active.

Detector commands

Command/Property	Description
Autozero	(Pulse Mode) Performs an autozero. (DC Mode) Sets the DC output signals (both analog and digital) to zero.
CellState	Determines if the working potential is to be applied to the cells (On), including the guard cell. Off is used to remove the working potential from the cells.
Data_Collection_Rate	Sets the rate [Hz] at which Chromeleon collects digital data from the detector.
DemoFileName	File name of the demo file.
PostCellCleanDuration	(DC Mode) Sets the time that the detector waits after cleaning the cell or cells.
SecondCell	(DC Mode) Determines whether the second cell of the dual cell is used (Used or NotUsed).

The following commands and properties are available only if a Thermal Organizer is installed:

TempCtrl	Turns temperature control of the Thermal Organizer on or off.
Temperature	Indicates the current temperature.
TemperatureNominal	Sets the nominal temperature.
WaitForTempReady	When setting this property to Yes the Ready property also checks whether the cell temperature has reached the nominal value and is stable. If No is selected, no check of the cell temperature is performed.

The following commands and properties are available only if a guard cell is installed in DC mode:

GuardCell	Indicates the current status of the guard cell (On or Off).
GuardCellClean	Determines whether the guard cell should be cleaned after the run (On or Off).
GuardCellCleanDuration	Sets the duration for cleaning the guard cell.
GuardCellCleanPotential	Sets the guard cell potential during cell cleaning.
GuardCellPotential	Sets the potential of the guard cell. The applied cell potential controls the oxidation or reduction capability potential.

ECD channel commands for DC Mode

Command/Property	Description
CellClean	Determines whether cell cleaning is performed (On or Off). This process is used to apply a very high potential (e.g. +900 mV) or a very low potential (e.g. -400 mV) to the cell for a short period of time at the end of each analytical run to recondition the cell surface. This process is recommended only under conditions where it is suspected that compounds in a complex sample matrix (for example, urine) can build up on cell surfaces. The Clean Cell procedure serves to remove these compounds from the electrode surface.
CellCleanDuration	Sets the duration of Clean cell potential (1 to 120 sec). The recommended Clean cell duration is 5 to 20 sec.
CellCleanPotential	Sets a Cell potential that will be applied at the end of each analytical run. Recommended settings are either +900 mV or –400 mV.
FilterConstant	Defines the filter constant. A lower value ensures that all peaks are visible, however, at an increased noise level. The pseudo peaks that are sometimes visible can make integration and reporting more difficult. A high value provides chromatograms that look "smooth", but very narrow or closely adjacent peaks may not be visible. As a rule of thumb, select a filter constant that is not smaller than the width of the narrowest peak. The recommended Filter time constant is 5 sec.
GainRange	Sets the sensitivity range of the detector. Enter the appropriate Full scale gain range so that peaks of interest remain on scale. Smaller values (e.g., pA) correspond to higher sensitivity settings, while larger values (e.g., mA) represent less sensitive settings. The smaller the selected range, the larger is the representation of the detected peaks.
Offset	Each signal can receive a channel offset. The entry is in percent, that is, a value of +10 means a signal increase by 10%, depending on the selected voltage range (Output Voltage). If the voltage range (OutputVoltage) is 0 to +1V, the signal offset is 10% of 1V = 0.1V.
OutputVoltage	Sets the analog signal output voltage. The recommended Signal output voltage is 1 V.
Potential	Sets the potential for the analytical cell.
Retention	Reports the signal's retention time (read-only).
Signal	Reports the current signal value (read-only).

ECD channel commands for Pulse Mode

Command/Property	Description
AcquisitionDelay	Sets the time (T1') before actual measurement starts. If T1 was set to 500 ms, T1' can vary between 60 and 495 ms (for example, 300 ms). The stabilization phase should be as small as possible to receive a measuring signal as large as possible in the following measurement phase. At the same time, it must be long enough to ensure that the majority of the capacitive load of the electrode is faded.
E1_Potential	Sets the potential (E1) used for detecting a substance. The value should reflect the optimum of the substance to be determined.
E1_PulseWidth	Sets the time (T1) during which E1 is active on the electrode (for example, 500 ms). The actual measuring phase (M) starts only after the freely selectable stabilizing phase of the electrode (Analytical Pulse Acquisition Delay T1') has passed. The longer T1 is selected, the better the observed signal-to-noise ratio will be and the fewer data points can be collected within a specific time span. There is the risk that adjacent peaks will be insufficiently resolved.
E2_Potential	Sets the increased electro-positive potential (E2) that is applied for cleaning the electrode. The value should be close to the oxidative decomposition potential of the mobile phase.
E2_PulseWidth	Sets the time (T2) for which the Cleaning Pulse Potential E2 is active.
E3_Potential	Sets the strongly reduced potential (E3) for recovering the original status of the electrode. The value should be close to the reductive decomposition potential of the mobile phase.
E3_PulseWidth	Sets the time (T3) for which the Equilibration Pulse Potential E3 is active.
E4_PulsePotential	E4 is an optional potential setting.
E4_PulseWidth	The pulse width (T4) is the period of time for which the optional potential (E4) is applied.
FilterConstantPulse	Sets the time constant used for the filter applied to the measurement data.
GainRangePulse	Sets the sensitivity range of the detector. Enter the appropriate Full scale gain range so that peaks of interest remain on scale. Smaller values (e.g., pA) correspond to higher sensitivity settings, while larger values (e.g., mA) represent less sensitive settings. The smaller the selected range, the larger is the representation of the detected peaks.
OffsetPulse	The signal can receive a channel offset. The entry is in percent, that is, a value of +10 means a signal increase by 10%, depending on the selected voltage range (Output Voltage Pulse). If the voltage range is 0 to +1V, the signal offset is 10% of 1V = 0.1V.
OutputVoltagePulse	Sets the maximum voltage range.
Retention	Reports the signal's retention time (read-only).
Signal	Reports the current signal value (read-only).

For installation details, refer to ESA Coulochem III Electrochemical Detector: Installation.