The optimization of the instrumental parameters of flame atomic absorption including effect of burner height, flame stoichiometry of fuel to oxidant were studied.  The presence of highly interfering matrix such as sodium chloride on the absorption signals of cadmium,  chromium, manganese and nickel were also investigated in order to examine the effect of matrix concentration on the absorption signal and then the reality of the absorbance values given by the instrument, hence the sensitivity and reproducibility of the instrument readings and then sensitivity and reproducibility of the analysis were tested . Improvements of analysis in presence of highly interfering matrices using some releasing agent were also studied.