STRATEGIES FOR THE OPTIMUM SEPARATION OF GAMMA RADIOLYTIC DEGRADATION PRODUCTS OF METHOXYCHLOR USING RP-HPLC

Abstract

Different types of reversed phase (RP) columns have been incorporated for the separation of gamma radiolytic degradation products (DPs) of methoxychlor. The effect of carbon chain length, carbon content, surface area, pore size, pore volume, and column dimensions of RP columns on DPs separation has also been investigated. The separation of DPs has been optimized employing methanol-water mobile phase and UV-DAD. In methanol media two major and five minor DPs were detected in gamma irradiated MXC by RP-HPLC. The peaks eluting before the parent peak on reversed phase column are expected to be relatively polar compounds while peaks after MXC are assumed to be non-polar in nature corresponding to general RP behavior. From HPLC analysis it is inferred that at gamma radiation dose of 5 kGy ≥95% MXC has been degraded for a dose rate of 200 Gyh⁻¹. The chemical radiation yield (G-value) along with effect of MXC concentration on degradation has also been explored. The physico-chemical parameters of RP columns have been compared under the optimum separation conditions. It may be concluded that HPLC is an excellent tool to investigate radiolytic degradation of persistent organic pollutants.

Keywords:

• degradation products
• gamma irradiation
• G-value
• HPLC
• methoxychlor
• RP separation

Notes

*N for naphthalene for eluent 70% methanol in water at UV 254 nm with flow rate 1.0 mL min⁻¹.

**N for biphenyl for eluent 75% acetonitrile in water at UV 254 nm with flow rate 1.0 mL min ⁻¹ .

*P1-P7 is gamma radiolytic degradation products of MXC.