Metrohm NIRS XDS Transmission OptiProbe Analyzer - Manual (Page 65)

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7.2.5 Low Flux Test
Low Flux Test is included for users who must run this test in support of regulatory requirements, such
as mandated by the United States Pharmacopeia (USP) General Information Chapter on Near Infrared
Spectroscopy.
Low Flux Test uses a nominal 10% transmission standard in the sample position. Using the calibration
fixture, the T03 standard would be closest to 10% transmittance. A noise test is run using this
standard. Because the transmission value is less than the instrument standard, the test is considered a
good method for testing instrument noise in the range of transmission of many common sample
absorptions.
The XDS instrument has an internal 10% neutral density filter (transmittance) screen, triggered by
software, which can be used in place of an external 10% standard. This screen gives equivalent
results during the Low Flux Test, and minimizes the possibility of operator error in placing the
standard.
To initiate the Low Flux Test, follow this sequence:
From the Diagnostics menu bar, select Low Flux
Test.
Vision asks if the user wishes to use an external
sample (standard) for the test. Click “Yes” to use
an external 10% (T03) transmission standard.
Alternatively, click “No” to use the internal 10%
transmission screen for Low Flux Test.
XC-1310 Transmission Standards contain a 10%
standard (T03xxxx) which may be used for this
test.
The 10% Standard must be placed into the
calibration fixture. Verify that the cover is on
before this test.
Follow Vision screen instructions for testing.
If the user clicks “No” to the external standard, then Vision will automatically trigger the 10% internal
screen for this test. In this case, the transmission probes should be in the calibration fixture with no
standard, and with the cover closed.