I want to calculate CEC of clay soil. I want to estimate CEC without the use of AAS or flame photometer. In the case of methylene blue method, the endpoint is doubtful.
I seem to recall (its been >30 years) that the soil extract was titrated (complexometric titration) with Eriochrome T Black and EDTA. Check old volumes of the AOAC in the library.
Another experimental method was proposed by Michael Peech: "Determination of exchangeable bases in soils", Ind. Eng. Chem. Anal. Ed., 1941, 13(6), 436-441: http://pubs.acs.org/doi/abs/10.1021/i560094a024
The CIC is determinate by titration and the result is highly dependent on the conditions of the test. I suggest you to employ a normalized procedure such as UNE-EN ISO 11260:2011.
There is an error of 10 times on UNE-EN ISO 11260:2011. It seems they forgot to split by 10 to convert mmolc/L to cmolc/L.
Edited: It is right. I got it!!
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