Comment Menu

6.5.1 Comment...

Enter any pertinent comments about the Method (using up to 255 characters), as well as a description of the column and the name of the analyst, in the spaces provided.

6.6 View Menu

6.6.1 MainMenu

Data Acquisition parameters include all controls related to the operation of the analytical system and to data collection.

6.7.1 System

The System Assignment box shows the interface and system currently associated with an ACI Method, along with the system description stored in the configuration file(s). The list box shows all of the interfaces for which configurations are currently stored on disk. Tying the ACI Method to a specific system configuration prevents it from being used with an incorrect configuration. When creating a new ACI Method file, remember that none of the other controls in the main window are active until the system is specified. The File menu’s Save and Print commands are also inactive.

To specify the system for an ACI Method, click on the desired interface/system in the list box and then on the OK button. The selected interface and system, along with the system description, will appear to the right of the System command button.

If you have not yet configured the interface, an error message will appear when you click on the System command button. You must configure the interface, using the Configuration Editor, before you can continue.

The System command button may also be used to change the system specification for an existing ACI Method, as long as the new system has the same configuration as the one originally specified for the ACI Method. If it does not, differences in the configuration may cause errors in the Instrument Control portion of the ACI Method.

6.7.2 Detectors

Detector Selection

Number of Detectors specifies whether the analysis uses 1 or 2 detectors.

Plot Min and Plot Max are the minimum and maximum for the Y-axis of the real-time plot of the data as it is collected. The units depend on the detector selection. An inappropriate plot setting can make peaks too small to see, or else so large that the top of the peak goes off scale on the display. This setting also affects the printed output when the Autoscale options are not selected for the report.

NOTE The plot scale setting affects only the display of the data, not the collection of raw data from the detector.

Clicking on the Detector 1 or Detector 2 command button opens a Select Detector dialog box displaying the name of the currently selected detector. If this is the correct detector, click the mouse cursor on the OK button.

To select a different detector, click on either Configured Dionex Detector or Other Detector. Then click on the arrow at the right side of the drop-down combo box and select a name from the list of available detectors:

• If you select Configured Dionex Detector, this list will comprise detectors specified in the configuration file for the system. • If you select Other Detector, several non-Dionex analog output

detectors will be listed.

When you click on a detector name, the name immediately appears in the selected detector area in the middle of the dialog box. Click on OK to accept the selection.

If you select an analog detector (i.e., any detector except a Dionex Conductivity Detector Module, Variable Wavelength Detector Module-II, Pulsed Electrochemical Detector, or Capillary

Electrophoresis System), the Analog Detector Connection dialog box appears.

The Analog Detector Connection dialog box lets you enter a formula that PeakNet uses to convert detector voltage output directly to detector units. For example, suppose you are using an absorbance detector set to 1 AU (absorbance unit) full scale, where full scale is 1000 mV. Type 1 in the “(number)” edit box and AU in the “(units)” edit box. When you click on OK, PeakNet will convert the detector output directly to AU.

ACI Analog Input Connection If you use an analog detector, you must connect the Recorder output terminal on the rear of the detector to a DET connector on the ACI rear panel. Indicate which ACI connector you used by clicking on either the DET1 or DET2 button.

Time

Enter the total period of time (0.0 to 999.9 minutes) during which data will be collected, starting with the Start Sampling command from the timed events file. This is typically the time required for all peaks in the sample to elute. The Run Time parameter also

determines the range of the Time scroll bars in the Gradient and Timed Events editors.

Rate

The data collection rate determines how many data points per second (i.e., samples/second) are collected and stored in ACI memory. The data collection rate can be set to 1, 2, 5, 10, 20, or 50 Hz.

Five samples/second is adequate for most applications.

NOTE In a dual-detector system, both detectors must operate at the same sampling rate.

In general, the data collection rate should be set so that each peak is defined by 20-30 data points. If you expect all peaks to be relatively wide at the baseline, use a slow rate; if the peaks are less than a few seconds wide, use a fast rate. Selecting a faster rate than necessary does not improve accuracy; it simply slows down data processing and wastes memory and disk space.

See Appendix B for more information about the relationship between the data collection rate and the amount of data that can be stored. If your ACI was shipped before June 1, 1992, you may want to order a RAM upgrade kit (P/N 043592) to expand the ACI memory from 64K to 256K per system.