Xylem photoLab 6600 UV-VIS - Manual (Page 130)

Operation photoLab
®
6600 UV-VIS
130 ba75848e01 08/2009
4.14.4 AQA3/MatrixCheck
The MatrixCheck is used to check if the photometric determination is
disturbed by other substances present in the sample (sample matrix). The
MatrixCheck can be carried out by spiking or diluting:
The photometer enables a simplified MatrixCheck with the aid of the
Spectroquant
®
CombiCheck R-2 addition solution. The MatrixCheck can be
carried out immediately. The volumes required for the sample and standards
are displayed on the screen. The MatrixCheck is then carried out with a single
spiking.
For the MatrixCheck with a standard or your own, however, you can enter the
number of spikings or dilutions yourself (max. 3).
Note
Settings for AQA checks are only available for users of the user group,
administrator.
The AQA check can be carried out by any user.
MatrixCheck by
spiking
For the MatrixCheck by spiking, the photometric determination is repeated
after a defined amount of analyte has been added to the test sample in the
form of standard solutions.
The nominal value for the determination is calculated from the added amount
of analyte, provided that there is no disturbance due to the sample matrix.
After the photometric determination the measured value is compared to the
nominal value and the recovery rate is calculated. A matrix disturbance is
likely if the recovery rate is less than 90 % or more than 110 %.
MatrixCheck by
diluting
For the MatrixCheck by dilution, the photometric determination is repeated
after the test sample has been diluted with distilled water.
The nominal value for the determination is calculated from the dilution,
provided that there is no disturbance due to the sample matrix. After the
photometric determination the measured value is compared to the nominal
value and the recovery rate is calculated. A matrix disturbance is
likely if the recovery rate is less than 90 % or more than 110 %.