Insert Experiment Steps

Experiments can be customized to control the analysis reaction. When an experiment is inserted, the initial conditions are specified first, then the individual steps. On the Analysis Conditions tab, click Insert to insert an experiment. Select the experiment step in the box, then click Edit to modify settings. An analysis set is created by inserting up to 99 experiments in the sample file.

To edit steps that have not been started, the analysis must be suspended.

  • Upcoming steps - display as black or blue
  • Current step - step is highlighted and displays as light blue
  • Completed steps - display as light green
  The DDE Command step and Wait for synchronization message option in the Wait step are no longer supported.

 

Data from one experiment are not available for editing until the next experiment in the analysis has begun recording.

Experiment Fields
Selections Description
Change Valves

Sets the rotary valves as specified.

Dose

Injection Type:

  • Inject loop gas. Automatically injects the contents of the loop into the path that leads to the sample. The contents of the loop are pushed out of the loop by the carrier gas.
  • Manual injection. Prompts the user to inject a dose of gas into the septum using a syringe.
  • Get physisorption point. Provides a series of steps necessary to collect data for a physisorption point. These steps include placing a Dewar of liquid nitrogen around the sample tube, waiting for a return to baseline, then replacing the Dewar with water at room temperature. Repeated points can be taken by placing the Dose step within a Repeat Loop.

After Injection. Specify the conditions for completion of this step.

Baseline. See Baseline button in Analysis Conditions.

Experiment

Experiment description. Description of the experiment.

Type of analysis. See Analysis Types for TCD Analyzers.If Pulse Chemisorption is selected, the Stoichiometry button is enabled. When modifying the Active Metals table during the insertion of a Pulse Chemisorption experiment, changes to the Active Metals table on the Sample Description tab are not affected. This is useful when sequencing multiple experiments and Stoichiometry is different from one experiment to the next.

Initial Conditions. Description for Zones, Gas Flows, Outputs, and Peaks buttons are provided elsewhere in this table.

Stoichiometry.Opens the Active Metals table. Specify the percent of sample weight of the active metals in the sample and the stoichiometry factor. See  Active Metals for Chemisorption Analyzers.

 

Analysis condition defaults for metal stoichiometry factors can be set using the sample information metal table editor. Stoichiometry factors can also be set for each pulse chemisorption experiment using the analysis conditions experiment step editor. If required, stoichiometry factors for a completed pulse chemisorption experiment can be viewed and modified using the peak editor’s stoichiometry settings window.

See Peak Editor .

Recording Options

  • Include input signal. Allows the use of external electrical input from an auxiliary port or choose to report an analyzer specific parameter from the drop-down list. See Auxiliary Inputs and Outputs.
  • Zero the TCD signal when recording starts. Zeros the TCD signal automatically the first time recording starts in an experiment.
  • Invert the TCD signal. Inverts the TCD signal. For example, if only negative peaks are expected, this option can be used to record the peaks in the positive direction.

Peaks:

Use to control peak detection during analysis.

After analysis, peak detection can be further controlled using the Peak Editor. See Peak Editor . The TCD detects and records all deviations from baseline, but only those which satisfy the criteria established in this window are reported as peaks.

  The defaults are usually acceptable. See Peak Detection / Integration Options.
Gas Calibration

Use to calibrate the TCD so that peak area data can be converted to volume data. During a gas calibration, a series of known gas mixtures flows through the analyzer and the resultant signal readings are recorded. The analyzer can then use these data to calculate the concentrations of unknown mixtures flowing past the detector during subsequent analyses.

Description. Description of the experiment.

Calibration Gases. Select the Carrier and Loop gases to be used in this calibration. The gases available are those specified in an Adsorptive Properties [.ADP] file. See Adsorptive Properties and Gas Charts for gas combinations.

Flow rate. Specify a flow rate for the calibration gases. Typically, the same flow rate is used for both the carrier and reference gas. To use different flows, select Different reference flow.

Different reference flow. Use to specify different flows for the calibration gases. When selected, the Rate field is enabled to enter a different flow. This flow is used for the reference gas; the carrier gas uses the Flow Rate field.

The carrier gas flows through the path that contains the sample tube, and through the reference path. The reference path flows directly from the inlet over the reference detector, making it possible for the detector to detect variations in the gas that traveled through the sample tube (carrier) path.

Recording Options. See Recording Options

Gas Flow

Use to select the gases for this step, specify the flow rates, specify the percent of the carrier gas mixture which is composed of the reactive, and set the state of the rotary valves.

The listed gases are those specified in the Adsorptive Properties file. See Adsorptive Properties and Gas Charts for gas combinations. Select None when no gas is to be flowing (the flow rate is ignored).

Prep Gas, Carrier/Reference Gas, Loop Gas.  Select the gas for each set of inlet ports. The gases listed are those with defined adsorptive properties. If manual injections are to be programmed, the gas to be injected must be selected as Loop or Injection gas.

When an analysis is started, the application verifies that the selected gases are connected to the appropriate ports. If there is a discrepancy between a gas selected for the current sample file and the gases indicated in the Gas Configuration window, an error message is displayed.

Rate.The rate at which gas is to flow.

Different reference rate. The carrier gas flows through two separate paths through the analyzer — through the path that contains the sample tube, and through the reference path. The reference path flows directly from the inlet over the reference detector, making it possible for the detector to detect variations in the gas that traveled through the sample tube (carrier) path.

The same flow rate is typically used for both the carrier and reference gas. To use different flows in these two paths, select Different reference rate, then specify the flow to use for the reference gas path in the Rate field. (The Rate field determines the carrier gas flow rate.)

Blend carrier and loop gases. Select to have the carrier and loop gases blended then enter the percentage for the gases. Whichever field is modified, the other field automatically defaults to a percentage totaling 100. If this option is selected for a Physisorption experiment, set the correct blended active concentration in the peak editor after analysis completes.

Cold trap valve, Analysis valve, Loop valve, Vapor valve, Cold trap valve, Analysis valve, Loop valve, Back pressure valve. Select a status for each valve. If Vapor is selected for the status of the vapor valve and the vapor generator is not attached to the analyzer when the analysis is started, an error message is displayed.

Loop Calibration

Use to verify the volume of the loop for use in calculations on analyses that use the loop. Sample analysis data yield signal vs. temperature data and peak areas. Associating the sample file with a loop calibration file makes it possible for the application to convert sample data to volume values.

Outputs

Use to specify the state of the digital and relay outputs.

Ports are provided for connecting auxiliary inputs and outputs. For example, the digital outputs can be used to control a mass spectrometer. See Auxiliary Inputs and Outputs.

Start Recording

Specifies how frequently the signal reading is recorded. A Stop Recording step is inserted in the steps automatically when a Start Recording step is inserted. Multiple steps can be inserted between the Start Recording and Stop Recording steps.

One measurement every [n] seconds.[text box] Specify the frequency of measurements.

  If a Start Recording step is immediately followed by a step that prompts an immediate peak, peak data are recorded before any baseline readings can be collected. To collect some baseline data before the first peak, insert a Wait for [n] minutes step after the Start Recording step but before the step which causes the peak.
Start Repeat

Specifies the duration of the repeat sequence. Automatically inserts a Start Repeat and a Stop Repeat in the list of steps. Multiple experiment steps can be inserted within the Repeat loop.

Repeat until peaks are equal or [n] times. [button] Stops repeating the steps within the loop when the last two peaks are equal to within 5% of the area, or when the maximum number of repeats is reached. This option is useful when performing H2 or CO pulse chemisorption on supported metal catalysts.

Repeat until peaks are zero or [n] times. [button] Stops repeating the steps within the loop when the last two peaks are each less than 10% of the area of the first peak, or when the maximum number of repeats is reached. This option is useful when performing an N2O decomposition for characterizing copper catalysts.

Repeat [n] times. [button] Stops repeating the steps within the loop when the specified number of times is reached.

Repeat until peaks match the first peak or [n] times. [button] Stops repeating the steps within the loop when the last two peaks each match the first peak to within 10% of its area or when the maximum number of repeats is reached.

Temperature Ramp

Changes the sample temperature.

 

Temperatures above 850 °C can cause damage to a metal sample tube.

Also, sample temperatures significantly above 1100 °C will cause accelerated wear on furnace components and lead to premature failure of the furnace. Experiments should be designed with sample temperatures at or below 1100 °C or to minimize operating time above 1100 °C.

Ramp Type [group box]:

  • Furnace ramp. [button]   Ramps the furnace temperature directly to the End temperature ignoring the sample temperature.
  • Sample ramp. [button]Ramps the sample temperature to the End temperature. The actual furnace temperature is adjusted to meet this target.
  • Sample ramp and equilibrate. [buttonRamps the sample temperature to the End Temperature and waits for it to equilibrate before proceeding.
  • Return to ambient. [button] Allows the furnace temperature only (not the sample temperature) to return rapidly to a temperature to below 45 °C.

End temperature. [text box] The ending temperature for the ramping procedure. If the CryoCooler is installed, it is automatically enabled if an ending temperature below 20 °C is used.

Hold time. [text box] Temperature at which the sample is to be held while degassing.

Ramp rate. [text boxThe rate at which the temperature will change while advancing to the hold temperature.

Enable KwikCool. Select to use the KwikCool to reduce the furnace temperature more rapidly during cool down. If selected and the KwikCool is not attached to the analyzer when the analysis is started, an error message is displayed. If the CryoCooler (rather than the KwikCool) is attached, the cool down operation is performed by the CryoCooler.

Termination

Return to ambient temperature. Allows the furnace temperature only (not the sample temperature) to return rapidly to a temperature between 14 °C and 50 °C.

Enable KwikCool. See Enable KwikCool in Temperature Ramp.

Leave the detector enabled after analysis. Several hours may be required for the analyzer to reach thermal stability after the detector is enabled. This option keeps the detector enabled after analysis, allowing the analyzer to remain stable.

Gas flow through the detector is required while the detector is enabled but is not necessary if the detector is disabled. It is recommended to flow an inert gas to continuously purge the system.

Should the analysis be canceled due to an analyzer error, the detector will be left enabled if this option is enabled. Should the analysis be canceled, this option is ignored, and the detector is left enabled.

Vapor Calibration

A separate calibration of the TCD must be made when vapor is to be used during analysis. The Vapor Calibration experiment allows the calibration of the TCD so that peak area data can be converted to volume data. During a Vapor Calibration, one vapor at a series of temperatures is flowed through the analyzer and the resultant signal readings are recorded. The analyzer uses this data to calculate the unknown concentrations of vapors flowing past it during subsequent analyses.

Wait

Specify a waiting routine.

Wait [n] minutes. [button] Specify the time to wait.

Wait for operator. [button] Enter a description of the operator task. During an analysis, the entered message displays at the appropriate time. The analysis continues after the operator clicks OK.

Wait until baseline is stable. [button] Specify if the analysis should wait until the baseline becomes stable,  then click Baseline to specify the settings.

Wait for change from baseline or [n] minutes. [button] Specify the time to wait, click OK, then click Baseline to specify the settings.

Wait for return to baseline. [button] Waits for a return to baseline. If enabled, click OK, then click Baseline to specify the settings.

Wait for digital input number. [button] Enter the number of the digital input source being awaited, then specify the maximum number of minutes to wait for input. If the digital input is not received before the time elapses, the analysis will continue, and a warning message is displayed. See Auxiliary Inputs and Outputs.

Zones

Click to set the heat zone temperatures.

The Filament temperature must be set at least 20 °C higher than the Block zone temperature.

The Reflux must be at least 10 °C cooler than the Flask zone.

If the optional vapor generator is not installed when the analysis is started, the vapor generator fields are ignored by the application.

  For fields and buttons not listed in this table, see Common Fields and Buttons.