Sutthinee Chanatippakorn.. Method development for the determination of hydroxylamine in rubber samples. Master's Degree(Applied Analytical and Inorganic Chemistry). Mahidol University. Mahidol University Library and Knowledge Center. : Mahidol University, 2016.
Method development for the determination of hydroxylamine in rubber samples
Abstract:
Hydroxylamine (NH2OH) is an additive compound in natural rubber (NR) used to prevent the storage hardening of NR. The amount of NH2OH in NR needed to be measured before use because of the effect to viscosity of NR. This research developed three analytical methods for the determination of NH2OH in NR samples, i.e., high performance liquid chromatography (HPLC) with cation-exchange column, HPLC with reversed-phase column, and colorimetry using Fe(II)-o-phenanthroline complex. NR samples used in this work were obtained from Michelin company and Rubber Technology Research Centre (RTEC). NH2OH was extracted from rubber by two extraction methods, i.e., solid-liquid extraction (SLE) and reflux. The developed and optimized processes of the analysis were carried out by using NH2OH standard. First, HPLC method with cation-exchange column; Synchrom S300 (250 mm × 4.6 mm); flowed with the mobile phase of ammonium acetate buffer:acetonitrile showed poor repeatability response and unacceptable recovery value. It was resulted from the side reaction of NH2OH with acetonitrile in the mobile phase. Second, the method of HPLC with reversed-phase column was carried out by forming acetone oxime derivatives between NH2OH and acetone. The separation was achieved on LiChroCART® (250 mm × 4 mm, RP-18 (5 μm)) column using 10:90 (%v/v) methanol:DI water as the mobile phase and the UV detector was set at 230 nm. The method gave linearity in the range of 0.5-50.0 mg/L with good precision (< 1.4%RSD). Detection limit (DL) was 0.16 mg/L. Third, the colorimetric method was an indirect analysis of NH2OH by reducing Fe(III) to Fe(II) and then forming red color complex of Fe(II)-o-phenanthroline. The absorbance of the complex was measured by spectrophotometer at 510 nm. The method showed linearity in the range of 0.05-2 mg/L and DL was 0.003 mg/L. Finally, these developed methods were applied for determining quantity of NH2OH in the rubber samples. For Michelin samples, the recovery was obtained at lower than 2.9% when it was extracted by SLE and lower than 13.5% by reflux. For RTEC samples, it showed higher recovery value than Michelin samples. The recoveries were in the range of 41.2-82.8% by SLE and 31.3-56.0% by reflux.
Mahidol University. Mahidol University Library and Knowledge Center