Roche Diagnostics
A-4 Operator’s Manual · Version 1.0
1 Introduction to the system URISYS 2400
Description of the URISYS 2400 analyzer
The photometric reflectance measurement for all of the test parameters is
performed after an incubation time of 60 seconds. As with previous urine
analyzers from Roche Diagnostics, compensation for intrinsic urinary color,
which is a recognized interfering factor, is made through the measurement of
a blank compensation pad on the test strip. The compensation pad assists in
the prevention of false positives when a urine sample is strongly colored.
The URISYS 2400 determines the urine color by evaluating the reflectance
values of all three measuring wavelengths (470 nm, 555 nm, and 620 nm) on
the compensation pad. Color results are reported as PALE YELLOW,
YELLOW, AMBER, BROWN, ORANGE, RED, GREEN, or OTHERS.
The measurement of specific gravity (SG) is performed in a flow cell that is
filled with a urine sample during aspiration of the sample. An LED (650 nm)
transmits light to the flow cell. A charge-coupled device (CCD) determines
the angle of total reflection. The refractive index of the sample is calculated
from the angle of total reflection using a calibration curve. Transformation
into the SG value is performed by a nomogram stored in the analyzer.
The flow cell that is used to measure specific gravity also determines the
clarity of the sample. However, light of a different LED is used to measure
clarity. This LED (660 nm) transmits light to the flow cell, and the amount of
light that passes through the flow cell is measured.
The system is blanked (zeroed) during the washing process, between sample
measurements, by setting the water transmission to 100%. The transmission
values of samples are transformed to clarity results (CLEAR, LIGHT TURBID
or TURBID), by using the clarity range table that is programmed in the
software of the URISYS 2400.
Test parameter Measuring wavelength (nm)
pH 555, 620
Leukocytes 555
Nitrite 555
Protein 555
Glucose 555
Ketones 555
Urobilinogen 555
Bilirubin 555
Erythrocytes 555, 620
Color 470, 555, 620
Table A-1 Wavelengths used to measure the reflectance values
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