Introducing surface-modified ordered mesoporous carbon as a promising sorbent for extraction of N-nitrosamines.

The extraction and pre-concentration of N-nitrosamines (NAs) before their determination are mainly achieved by carbonaceous sorbents. However, the non-polar or relatively less polar NAs are strongly absorbed on the carbonaceous surface of the sorbent, leading to low extraction recoveries. In the present study, for the first time, CMK-3 and surfacemodified CMK-3 (O-CMK-3) were used to extract NAs from water. The CMK-3 surface was modified by oxidative treatment and different carboxylic groups were attached to create a hydrophilic/hydrophobic balance on the inert surface of the carbonaceous sorbent. The proposed sorbents were compared with 10 different kinds of commercial carbonaceous sorbents for the micro-solid phase extraction of eight NAs possessing a wide range of polarities. The best extraction results for both polar and non-polar NAs were obtained using O-CMK-3. Specifically, significant enhancements in the extraction of the nonpolar NAs were observed. For instance, extraction of up to 27.67 and 2.32 times greater were observed for N-nitrosodiphenylamine, and N-nitrosodimethylamine respectively, when O-CMK-3 was used instead of coconut charcoal sorbent.