Being that the HPT test will not work with glycerin pre treated wvo, does the methanol skew the results in the weigh-heat-weigh method?

Yes.

If the weight goes down after heating, you never know if it was the methanol that was driven off, or the water, or both.

troy

If you want to quantify the water content, you could do it in two steps. Weight a sample, heat it to below 100 C but over 65 C to boil off the methanol, then re-weigh the sample, then heat to over 100 C to boil the water off, and re-weigh.

I personally heat the WVO to about 120 C after I have done the glycerol pre-rinse and drained the glycerol. I hold it at this temperature until there are no bubbles rising from the heating element. I then do my reaction as the temperature drops to 55 C.

quote:

If you want to quantify the water content, you could do it in two steps. Weight a sample, heat it to below 100 C but over 65 C to boil off the methanol, then re-weigh the sample, then heat to over 100 C to boil the water off, and re-weigh.

Some water will be lost in step one.

quote:

Originally posted by Andrew M:

quote:

If you want to quantify the water content, you could do it in two steps. Weight a sample, heat it to below 100 C but over 65 C to boil off the methanol, then re-weigh the sample, then heat to over 100 C to boil the water off, and re-weigh.

Some water will be lost in step one.

Quite a lot actually. Making the test pointless in two steps. The WHW test will only test for moisture and volatiles combined, it can't really separate them.