EGTA



Ethylene glycol tetraacetic acid (EGTA) is a common buffer ingredient due to its chelating activity. It is similar to the better known EDTA, but has a much higher affinity for calcium ions than for magnesium ions. Buffers made with EGTA are used in some cases to mimic the environment inside living cells where calcium ions are usually at least a thousandfold less concentrated than magnesium ions.

Full chemical name: ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid

EGTA 0.5M stock solution
100 ml solution
 * 19g EGTA (MW 380g/mol)
 * ddH2O to 90ml
 * adjust pH 7.5/8.0 with solid NaOH (>4g)
 * adjust volume to 100ml

Note: EGTA will not go into solution without NaOH. Once the pH has been raised sufficiently it dissolves quickly. For pH 7.5 the exact amount required is slightly above 4g. Add 3.5-4g immediately, then proceed carefully not to overshoot the desired pH.

Stability & storage

 * room temperature
 * for years