Gamma radiolytic eradication of methoxychlor in aqueous media. The degradation pathways using HPLC and SPME-GC-MS

The gamma radiation-induced degradation of environmental pollutant methoxychlor in water was investigated. A 60Co gamma radiation source with a dose rate of 372 Gy h-1 was used for gamma irradiation of 1 mg L-1 and 10 mg L-1 methoxychlor in water with a varied absorbed dose of 1-5 kGy. A single step clean up and pre-concentration procedure based on solid phase micro-extraction was optimized. The extent of radiolytic degradation was monitored by reversed phase HPLC-UV and GC-ECD. The trace and ultra trace level degradation products were identified using GC-MS-SPME by comparing their mass spectra with the NIST 98 m mass spectral library. Most of the generated products for 4 kGy dose are substituted chlorophenols. The reaction pathways of these substituted chlorophenols and benzophenone formation are also proposed. However, generated chlorophenols disappeared along with methoxychlor for an absorbed dose of 5 kGy. The attained degradation of methoxychlor is ∝ 95% that reflects the potential use of ionization radiation for wastewater treatment. (orig.)