Calibration Options

This section contains commands for selecting the (re)calibration mode. Invoking the command or using the icon opens the Calibration Options dialog. Settings performed here are then stored in the calibration file. When a new calibration file is created, default values for all of its options are loaded from here.

Calibration Options - Calibration Options

Calibration Options - Calibration Options

Calibration Description

Contains a brief description of the calibration file. When a calibration file is loaded, this text is displayed in the Description field of the Open dialog; it is also shown in the Description field of the Method Setup - Calculation dialog when a calibration is loaded there.

Display Mode

Sets the method of the calibration curve display (suitable for different types of calibration curve use):

ESTD

Displays the dependence of a compound’s response to its quantity.

ISTD

Relative calibration curve:

  • If the amount of the internal standard has not been entered, displays the dependence of compound/internal standard response ratio to amount of compound.
  • If the amount of the internal standard has been entered, displays the dependence of compound/internal standard response ratio to the compound/internal standard amount ratio.

NORM

Displays the dependence of a compound's response to its quantity, just like for the ESTD type, but with added checks on calibration and chromatogram validity. Namely, the chromatogram must have empty Amount value and all peaks found in the chromatogram must have Amounts calculated, either through the calibration or through Unidentified Peak Response parameter.

STDADD

Displays the dependence of a compound's response to its quantity, but the graph is shifted so that the calibration curve crosses the x-axis.

Caution:

This parameter only indicates the display method. The actual type of calculation upon evaluation of unknown compounds can be selected in the Chromatogram window in the Result tab using the Calculation parameter.

Number of Signals

Selects the number of displayed signals when a multi-detector calibration is used. The implicit value is 1. The change is manifested in the number of commands in the Calibration - Set Signal menu and in the number of colored squares on the Overlay toolbar. If a calibration standard chromatogram is opened, the Number of Signals matches the number of signals from the calibration standard chromatogram and cannot be changed, i.e. the field is disabled.

Note:

You do not risk deleting the calibration values when you reduce the number of signals, since the file always remembers the values for all 32 possible signals.

Calibration

Sets the calibration or recalibration method for the Add All, Add Peak and Add Group commands. Possible options are:

Automatic

Automatically transfers all data related to compounds from a chromatogram to the calibration file. The data can be modified and supplemented later on.

Manual

Enables to enter the amount of the component or to modify or add the remaining data for each compound by opening one of the Manual Calibration and Recalibration or (Re)Calibrate Group dialogs.

Mode

Sets the mode of the calibration process, unless in the Standard Addition calibrations, where it is disabled.

Calibrate

Calibration mode. Data from the calibration standard will be transferred into the first empty calibration level. Changing the opened standard or closing and reopening the Calibration window starts checking for a new empty calibration level again. After all 20 calibration levels have been filled in, Clarity will rewrite the responses in the last (20th) calibration level.

Recalibrate

Recalibration mode. Unlocks the Recalibration section for setting up recalibration conditions.

Caution:

The Calibrate mode applies only while manually working from the Calibration window. In the Single Analysis or Sequence with calibration level filled in the calibration always recalibrates applying the setting from Recalibration options.

Curve Check

Enables to check the linearity of the calibration curve based on the two following parameters. The result of the linearity check is displayed on the tabs of each individual compound in the Calibration window and in case the Curve Check test is failed also in the Peak Type column of the Result Table in the Chromatogram window. Fail in any Curve Check test part that is switched on fails the whole Curve Check.

Deviation

Sets the value for the maximal allowed standard deviation of each point in the calibration curve of the given compound.

Correlation

Sets the value for the minimal allowed correlation factor as calculated on the tab of the individual compounds of the Calibration window.

Apply On

Specifies where the (re)calibration will be performed. It can be also changed in the toolbar of the Calibration window.

On All Signals

Calibration or recalibration is performed on all signals. With this option selected, clicking the Add All icon adds all peaks from the currently active signal into the Calibration Summary Table, existing peaks are then added from all the subsequent signals. This option is default when creating a new calibration.

All added peaks have the Used checkbox on all the signals checked.

On Active Signal

Calibration or recalibration is performed on the currently active signal. With this option selected, clicking the Add All icon adds all peaks from the currently active signal into the Calibration Summary Table.

All added peaks have the Used checkbox checked only on the active signal, rest of the signals have it cleared.

Recalibration

Specifies the recalibration mode conditions:

Replace

The original response is replaced by the new one and the number of recalibrations is set to one.

Average

The resulting value is calculated as the arithmetic mean of the new value and all previous values (their number is taken over from the Rec. No. column of the Compound Summary Table).

No. of Points

Sets the number of recalibrations used for the Averaging. When the number of recalibrations exceeds this number, averaging calculates floating average.

Available range is 0 - 100, default value is 10.

Note:

Change in the number of recalibrations will not immediately affect the calculation of Average. Changes will affect future recalibrations.

Compound Units

Specifies the units for compound quantities. Units are stated for all displayed amounts in calibration tables and graphs as well as in the table of integration results in the Results tab, unless other units are specified by Scale Factor and Units after Scaling fields.

Recalibration Search Criteria

The maximum percent deviation (departure) of the new values for the recalibration to be effected. In the event it has been exceeded in manual recalibration the inscription Over replacing the numerical value of the deviation will notify you. When using automatic recalibration components whose deviation in height or area exceeds the pre-set value are not recalibrated. The allowed range is 1 to 50 %.

Enable Manual Response Value Change

Enables the manual modification of responses (in the Response or Area and Height fields).

Update Retention Time

Enables the automatic update of retention time after each calibration or recalibration. The retention time is replaced using the value from the last used standard, regardless of its level.

Default Injected Volume

The value is used to perform automatic correction for differences in injected volume. In calibration, recalibration and calibration calculations the value of Inj. Volume from the chromatogram header is compared with Default Injected Volume and a new response is calculated from their ratio.

This correction method is only applicable to small deviations since it assumes that the amount is proportional to the response.

If the checkbox is left unchecked, the last recalculated values remain in effect regardless of potential changes effected in Injected Volume and Default Injected Volume fields. In this instance the last two parameters serve only for information.

Checking the checkbox and filling a value for Default Injected Volume will be recorded in Calibration Audit Trail and Details of Calibration Point - detail of the changes are recorded in the following format: Corrected by Injection Volume (Default X mL, Actual X mL).

Retention Indexes use Log. Interpolation with Unretained Peak

Use Unretained Time value (set on the Method Setup - Advanced tab) for retention index calculation (for more details see also chapter Calculation).

Caution:

When this option is unchecked, then the retention indexes are calculated using the linear interpolation and when it is checked, then the logarithmic interpolation with unretained peak time is used.

Equation used for the linear calculation of the Retention Indexes:

Where:

  • I = Kováts retention index,
  • n = the number of carbon atoms in the smaller n-alkane,
  • N = the number of carbon atoms in the larger n-alkane,
  • z = the difference of the number of carbon atoms in the smaller and larger alkane,
  • tr = the retention time.

Equation used for the logarithmic calculation of the Retention Indexes:

Where:

  • I = Kováts retention index,
  • n = the number of carbon atoms in the smaller n-alkane,
  • N = the number of carbon atoms in the larger n-alkane,
  • tr' = the adjusted retention time (tr'=tr-t0').

Response Factor as Response / Amount

Enables calculating Response Factor as RF = Response / Amount (on default : RF = Amount / Response). This setting changes the format of RF in Calibration window as well as on Results tab of the Chromatogram window.