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The five standards are plotted out in the USP
format, showing repeatable response for
each standard. The x-axis, A REF, is from the
initial observation (during IPV Setup). The y-
axis, A OBS, is the current observation.
The slope must be 1.0, +/- 0.05. The zero
intercept must be 0.0 +/_0.05. The box
shows the results for this observation.
Tabs allow the user to check at three
wavelengths: 1200, 1600, and 2000 nm.
Click on the Photometric Linearity Test
Results tab to see the tabular information.
This shows tabulated results, at each of the
three wavelengths.
USP dropped this test requirement from General Chapter <1119> as of December 1, 2008. Metrohm
does not recommend that this test be run unless company policies require it.
The user should be aware that USP tolerances for Photometric Linearity are quite relaxed, compared
to FOSS NIRSystems specifications for IPV testing. Therefore, there may be times when the USP test
passes, and IPV does not meet manufacturer’s specifications. This may be due to instrument changes
such as dirty windows, failing lamp, or placement errors. In such cases, Vision advises that Reference
Standardization may be required.
7.2.4 Gain Test
The Gain Adjust feature can be a useful diagnostic tool, though it is not required for normal
operation. Technically, gain is never adjusted on the XDS MultiVial Analyzer. The name of the test
comes from an adjustment capability that was required with older systems. With XDS, this program
reports gain information for the NIR and visible regions. No adjustment is performed.
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