How do I calculate signal-to-noise ratio in ASTRA? - WKB319058

ENVIRONMENT

• Software: ASTRA
• Instruments:
  • Light scattering detectors (LS 11, LS 5, LS 2)
  • Optilab refractometer
  • UV detector
  • Third-party RI detectors

ANSWER

To calculate the signal-to-noise (S/N) ratio in ASTRA:

1. Use the USP <621> definition: S/N = H/h, where H is the peak height and h is the peak-to-peak baseline noise.
2. Determine H by enabling Peak Height fields for LS, RI, and UV signals in the ASTRA Report Designer [1].
3. For LS detectors, apply a diagnostic method from \\System\\Methods\\Light Scattering\\Diagnostics, draw a baseline peak, and record the Noise Peak-to-Peak value from the QC Report.
4. For Optilab RI detectors, apply a method from \\System\\Methods\\RI Measurement\\Diagnostics, define a baseline region, and retrieve the noise value from the RI Noise procedure.
5. For UV and third-party RI detectors, manually estimate h by measuring the difference between max and min signal values in a baseline region of roughly five minutes.

A minimum S/N of 100:1 is recommended, with higher ratios required for sensitive applications [1].

ADDITIONAL INFORMATION