Hi,

I don't know what your complex comprises, but could it be that oxidation occurs within the molecule? This would result in a net mass increase of 16 Da.

You state "mass 447" for the Cu complex. I suppose that you look at positive ions so you expect some protonation or adduct formation ? Do you expect m/z 447 ? or adduct with H+ (448) or Na+ (470) ? Addition of two Na+ is not possible because you get charge +2. Two Na may be added to acidic molecules by removing H+ (example RCOOH --> (RCOONa)Na+, singly charged) with mass (m/z) increase of (22+23).

It's a copper (11)acetate complex sir

I suppose that the ion you observe at m/z 493 is singly charged ? The first problem is the origin of the charge: Cu2+ with one anion in the complex ? or proton or Na+ adducts ?

I do not know if it positive or negative mode, but i Maldi can also happen a loss or adding of an electron. If the complex is neutrum and you add two Na you should have an double chargly but In maldi in general you observe single charge. Could be that the ion get one electron and become single charge?