Comprehensive two-dimensional GC (GC × GC) qMS analysis of tetrachloronaphthalenes in Halowax formulations

Abstract

A combination of non-polar and shape selective columns in a comprehensive two-dimensional GC (GC × GC) system consisting of DB-5MS and LC-50 as the 1st and 2nd dimension columns was used to separate 22 tetrachloronaphthalene isomers. These columns enabled separation of all possible isomers of tetraCN found in the technical chloronaphthalene Halowax formulations into 18 peaks covering 15 single separated isomers and 7 co-eluting in triplicate (1,2,4,6-/1,2,4,7-/1,2,5,7-tetraCN; nos. 33/34/37) and in pairs (1,2,3,7-/1,2,4,5-tetraCN; nos. 30/32 as well as 1,3,5,8-/1,3,6,8-tetraCN; nos. 43/45). Twelve isomers of tetraCN resolved as single compounds by the GC x GC system used were found in Halowax 1001, 1013, 1014 and 1099 as well as in Equi-Halowax mixture. Three other tetraCNs that could be also resolved as single compounds were not detected in these materials, while the remaining 7 tetraCNs, which co-eluted, waits a further separation. The majority of constituents of the tetraCN homologue group of the Halowax formulations are isomers such as 1,4,5,8- (no. 46), 1,2,5,8- (no. 38), 1,2,4,8-tetraCN (no. 35), co-eluting 1,3,5,8-tetraCN (no. 43 in a pair nos. 43/45) and also co-eluting 1,2,4,6-/1,2,4,7-/1,2,5,7-tetraCN (nos. 33/34/37). The less abundant by amongst of tetraCNs in these mixtures are 1,4,6,7- (no. 47) and 1,3,5,7-tetraCN (no. 42). The remaining seven isomers, i.e., 1,2,3,4- (no. 27), 1,2,3,5- (no. 28), 1,2,3,6- (no. 29), 1,2,5,6- (no. 36), 1,2,6,7- (no. 39), 1,2,6,8- (no. 40) and 1,2,7,8-tetraCN (no. 41) are usually minor by quantity, while 1,2,3,7-/1,2,4,5-tetraCN (nos. 30/32) are also minor, or one of them is absent. Three tetraCNs not found in the Halowax formulations are isomers such as 1,2,3,8-tetraCN (no. 31), 1,3,6,7-tetraCN (no. 44) and 2,3,6,7-tetraCN (no. 48).