N‐Nitrosodimethylamine content of aqueous dimet hylamine and phenoxy herbicide/dimethylamine formulations during storage

Abstract

N‐Nitrosodimethylamine (NDMA) levels in samples of 600 g litre−1 aqueous dimethylamine (DMA) solution stored at 4, 25 and 40°C, in formulations of the DMA salt of 2, 4‐dichlorophenoxyacetic acid (2, 4‐D) and of the DMA salt of 4‐chloro‐2‐methylphenoxyacetic acid (MCPA) at 40°C were monitored using a gas‐liquid chromatograph coupled with a thermal energy analyser (g.l.c./t.e.a.). The NDMA content of aqueous DMA at 4°C increased from 0.32μgg−1 to 8.6μgg−1 in 156 days. At 25°C it increased from 0.20μgg−1 to 10.5 μgg−1 in 156 days and at 40°C from 0.76μgg−1 to 7.12μgg−1 in 54 h. At 40°C, the NDMA in the 2, 4‐D/DMAsalt increased from 0–53μgg−1 to 2.79μgg−1 in 96 days and in the MCPA/DMA salt from 0.48μgg−1 to 5.51 μgg−1 in 21 days.