Analysis Conditions

Analysis conditions specify the parameters used to guide an analysis.

Analysis Conditions Fields and Buttons Table
Field or Button Description
Analysis Conditions [drop‑down box]

Use to browse for an Analysis Conditions file that contains analysis condition parameters to be used in the analysis.

Baseline [button]

Specifies baseline settings if a Wait step depends upon the Baseline.

Establishes the Slope or Acceleration threshold and Duration for determining what constitutes a Stable Baseline, a Change From Baseline, and a Return To Baseline. These values control whether a particular change in the signal is significant to the current experiment — such as defining a stable baseline.

Some Wait steps are contingent upon the values selected — such as if the experiment contains a Wait until Baseline is stable step, the signal is compared to these values to determine if a stable baseline has been established. Lower slope/acceleration values and longer durations create a more rigorous definition of these factors than higher values and shorter durations.

Stable Baseline. Detected when the signal slope is below the threshold for the indicated duration.

Change from Baseline. Detected when the signal acceleration exceeds the threshold for the indicated duration.

Return to Baseline. Detected when the signal acceleration falls below the threshold for the indicated duration.

Insert [button]

Insert a new step into the experiment. Steps can be inserted after the analysis has started by suspending the analysis.

See Insert Experiment Step.

To ensure safe operation and reliable results, a chemically inert gas flow should be inserted between flows of two chemically reactive gases such as hydrogen and oxygen.

Insert Analysis Conditions [button]

Click to load an entire list of steps, baseline parameters, and peaks parameters from the selected dynamic analysis conditions file.

Sample tube type [selection] Select the type of sample tube to be used.
Step Detail [group box] Displays summary information about the highlighted experiment step.
  For fields and buttons not listed in this table, see Common Fields and Buttons.

Insert Experiment Step

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 and Buttons Table
Field or Button Description
Change Pressure
  Do not use quartz sample tubes with pressures above 1034 mmHg. The O-rings will not seal and the sample tube can be released from the fitting.

Use to set target pressures for analysis or preparation, or return to atmospheric pressure.

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].

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 Chemical Adsorption.

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 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 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.

Active concentration. Specify the percent of the gas mixture which is composed of the reactive gas versus an inert filler. This value is used for pulse chemisorption data reduction.

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.

Cold trap valve, Analysis valve, Loop valve, Back pressure valve. Select a status for each valve.

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 information 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. 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. 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 chemical adsorption on supported metal catalysts.

Repeat until peaks are zero or [n] times. 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. 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. 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

Ramp Type:

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

End temperature.  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. How long the sample is to be held at the specified temperature before beginning to cool down.

Ramp rate. The 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.

Wait

Specify a waiting routine.

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

Wait for operator. 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. 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. Specify the time to wait, click OK, then click Baseline to specify the settings.

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

Wait for digital input number. 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.

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