How to test the sensitivity of HPLC?

1. Sensitivity testing method

The sensitivity of HPLC can be defined as: 1. When a quantitative substance passes through the detector of HPLC, the signal size given by the instrument is called the sensitivity of the HPLC, sometimes also known as the response value. For users, they always hope that HPLC instruments have high sensitivity, because high sensitivity means that when detecting the same amount of sample, the instrument has a larger output signal. However, the level of sensitivity does not necessarily indicate the detection capability of HPLC instruments. Only the detection limit can indicate the maximum detection capability of the instrument.

The testing method for HPLC sensitivity is mainly based on the definition of signal-to-noise ratio. Generally, the detection amount or concentration (signal intensity) when the signal is equal to or greater than twice the noise is taken as the signal size of HPLC. The division of signal and noise is the signal-to-noise ratio of the instrument (sensitivity, but S/N ≥ 2 is required).

2. Detection limit testing method

When discussing the indicators of HPLC and providing the spectrum of HPLC, one should truthfully provide the sensitivity range used (usually the most sensitive range) and the sample concentration (usually about three times the noise) in order to demonstrate the detection limit or sensitivity of the instrument.

3. Test method for noise in optical detectors

The noise of HPLC is a random output signal that is independent of the measured sample. The definition and testing methods of noise vary internationally. For example, the testing standards (ASTM) developed by the American Society for Materials and Materials stipulate that noise is divided into three types: long noise, short noise, and ultra short noise. Long noise refers to noise with 6 to 60 cycles of variation per hour, so the measurement time should be tested for at least one hour; Short noise refers to noise with 1 to 10 variation cycles per hour, so the measurement time should be tested for at least 10 to 60 minutes; Ultra short noise refers to noise with more than 10 variation cycles per minute, so the measurement time should be greater than 1 minute.