How to choose volumetric method and coulomb method for trace moisture test?

When the water content of the sample to be measured is relatively low, the Karl Fischer Coulometric moisture meter is used, the detection speed is not only fast, but also the data parallelism is very good; The result is ideal; so when the water content of the sample to be measured is below 1000ppm, use the Karl Fischer Coulomb moisture meter, and when the sample to be measured contains more than 1000 ppm moisture, use the Karl Fischer volumetric method moisture meter.