Development of a new spectrophotometric method for the determination of hydrogen peroxide

This thesis proposes a spectrophotometric method for the determination of hydrogen peroxide in real water samples. The method is based on the complexation of hydrogen peroxide with the Fe(III)-EDTA complex in the alkaline medium. A purple color of low stable peroxo-iron(III)-EDTAcomplex was formed, with maximum absorbance at 525 nm. Variety of parameters such as type of stylizer reagent and concentration, Fe(III), EDTA and NH3concentration were optimized as S2O32-, 0.003 mol/L, 0.05 mol/L and 0.05 mol/L, respectively at 525 nm.Reagent addition order and measurement time were also optimized. Determination of hydrogen peroxide method based on the formation of the purpledcolor of peroxo Fe(III)-EDTA complex was obeyed toBeer's law in the range 5.0 x10-6 - 4.08x10-3mol/L, with a molar absorption coefficient (at 525 nm) of 267.36 L mol−1 cm−1.Sandel's sensitivity of the proposed method was also calculated as 0.188ug/cm2. Limit of detection and limit of quantification was found as 2.5x10-6 and 8.5x10-6mol/L. Intraday and interday relative standard deviation of the proposed method for 2.0x10-4mol/L of H2O2 were found as 1.5% and 6.1% respectively. The effect of interfering ions that is common in real water samples were also studied. Nearly none of common ions except Fe(II) showed interfering effect to proposed method so, the method can be easily acceptable to real water samples without any sample preparation step. The proposed method was successfully applied to real water samples namely drinking water, tap water and seawater with acceptable recovery value between 90% and 118%. Keywords:determination of hydrogen peroxide, iron(III) peroxo complex, spectrophotometry, water analysis