The most used liquid DTPA chelates are 3% and 6%. The 3% version is based on sodium and the 6% is based on ammonium. The 6% is the highest quality DTPA that is available in the market and is completely free of sodium and sulphate.
Technically, there is no problem using DTPA 3% iron chelate. DTPA 7 and 11% are fixed forms. The DTPA 7% is the fixed variant on the liquid DTPA 3%, and the STPA 11% is the fixed variant of the liquid DTPA 6%.
