This Information Applies To: Agilent Refractive Index Detectors, G1362A and G7162A/B
The ASTM Drift and Noise Test for Agilent RID modules available within Agilent Lab Advisor Software fails. This article will help you identify potential causes of the test failure and how to resolve them.
If you encounter a general RID baseline drift or a high noise that causes your ASTM Drift and Noise Test to fail, this may be due to:
An acceptable noise should look comparable to the following graph (Figure 1):
Figure 1. RI Signal during the ASTM Drift and Noise Test
The Noise is calculated according to the ASTM method as shown in Figure 2:
Figure 2: RI Signal Noise calculation
1. Noise = maximum peak - minimum peak, 2. Wander, 3. Time.
The time range for each cycle,
dt, is typically set to 0.5 minutes in the test. The noise is calculated as the difference between minimum and maximum in these time intervals. The wander value, although not appearing in the test results, is determined as the peak-to-peak noise of the mid-data values in the ASTM noise cycles. The drift is calculated as the slope of a linear regression over the whole measurement.
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