Calibration - Elementar Analysensysteme GmbH vario EL cube Operating Instructions Manual

10 - CHN determination with the liquid autosampler vario LS

Switch the main instrument switch on.

The instrument performs a reference run of the VLS.

Launch the operating software.

Set the intake pressure at the delivery point so that He flow at the PC displays approx. 200
ml/min.

Change the operating mode.

Open the "Instrument parameters" dialog in the operating software by selecting Options >
Settings > Parameters.

Check whether the parameter set corresponds to the operating mode. Click OK to confirm your
settings. The furnaces are heated.

Flush the instrument with helium during the heating phase.

After reaching the required temperatures wait for the required conditioning time for the reaction
tubes. For CHN mode the conditioning time for the combustion tube and the reduction tube is 1.5
hours.

Close all open ends of the reaction tubes again.

Set the Helium intake pressure at the delivery point to show approx. 1200 mbar at the PC
pressure display.
Phase 5: Performing follow-up work
Proceed as follows:

Perform a leak test. If a leak test was passed, the instrument is ready for operation.

Test the proper operation of the instrument with conditioning samples, blanks and standard
samples.

Calibration

General
The vario EL cube has a calibrated set of coefficients which can be used. This is already calibrated in
solids mode or may be generated here. If a different procedure is requested, Elementar suggests the
following calibration for CHN in liquid operation.
Please make sure to have the necessary standards available prior to the calibration.
The correlation between CHN content and CHN measuring values [Integrals] must be obtained by
means of a calibration. Factory set test substances with a known CHN content and different sample
weights will be analyzed.
Note:
The density of a sample has to be known in order to obtain a calibration in mg absolute vs. the peak
area.
The software automatically calculates the calibration functions (three polynomes 4th order).
A proper calibration in the selected operation mode which includes the required working range for
each element, is vital for the accuracy of the results. Calibrations therefore have to be performed with
special diligence.
The knowledge of the vario EL cube operating instructions and the technical possibilities of the
instrument are prerequisite for a successful calibration.
Experience has shown that the calibration of the vario EL cube elemental analyzer remains stable for
at least 6 months. Recalibration is recommended if the dailiy correction factor lies outside a range of
0.9 - 1.1 or if components which may influence the results have been exchanged (e.g. detector).
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
161