A biologist by education, I am muddling my way through "A New Standardized Method for Quantification of Humic and Fulvic Acids in Humic Ores and Commercial Products", Lamar et al.: Journal of AOAC International Vol. 97, No. 3, 2014.
I want to quantify the fulvic and humic acids in our products. I believe I understand the majority of the method. However, my point of difficulty is Step 5, when two different resins and column chromatography are involved.
Since I'm inexperienced in chromatography, my main question is what materials are required for this step. Is it just the resin? Or is there sand and glass wool involved? And should the resins ever be dry at the top?
I'm pretty sure I understand correctly that the DAX-8 resin adsorbs the FA, and conversely, the IR120 allows the FA to pass through.
Any guidance or even a link to a relevant tutorial would be greatly appreciated. I want to be certain I understand how to use DAX-8 resin and IR120 cation exchange resin before I try this method start to finish in earnest (and ask the finance department for the rotary evaporator and muffle oven).
Thank you!
Tyler,
The Lamar et al., 2014 was the basis for developing the International standard ISO 19822. During that development, step 5 of the Lamar procedure could not be repeated by the twelve laboratories participating in the ISO inter-laboratory study. As a result, numerous minor changes were made (such as quantity of resins, flow rates for elution), which may be contributing to your confusion.
Briefly, the XAD-8 resin is capable of isolating the acidic hydrophobic fulvic acids fractions from non-humic substances (especially carbohydrates), but it has to be prepared before use and regenerated after use. The ion exchange resin is intended to protonate the hydrophobic fulvic acids, particularly displacing the sodium from the initial NaOH extraction.
You have to purchase ISO 19822 because it is protected by copyright. I strongly suggest you obtain a copy, if you have any questions after reviewing it, please feel free to contact me. I was the person in charge of developing the ISO 19822.
Lawrence Mayhew
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