The chelating Agent that I'm using is thioglycolic acid.The absorbance given was:
so I've thought that maybe during the preparation the Person wrote "500µG" in the 1000µG Flask, so for the calibration curve I've considered that:
destilated H2O: 0,000
But now if I measure the standard it Shows me that the 100µG standard has 277,01µG Tungsten
Could be also a Problem from the Spectrofotometer?