Congener Specific Analysis of 140 Chlorobiphenyls in Technical Mixtures on Five Narrow-Bore GC Columns

HRGC separation of PCB congeners

“…This group has recently demonstrated fast chromatographic separations of a technical PCB mixture (Aroclor 1248) by using a narrow-bore column with an internal diameter of 50 ym, a film thickness of 0.05 pm (polydimethylsiloxane) and a length of 7 m [21]. The chromatogram obtained with a total run time of 4 min was comparable in resolution with those obtained in our laboratory with total run times around 60 min on a 50 m long column with an internal diameter of 0.25 mm using the same phase [22]. High-speed gas chromatography is a promising technique.…”

“…However, for mono-and non-ortho chlorinated CBs the column act as polar. The high affinity of the large carborane group in the backbone of the stationary phase towards CBs with no ortho-substitution has previously been explained by a o-electron interaction between the CB moiety and the carborane caused the rotational freedom of such CBs which allows for a coplanar conformation and a strong contact with the carbordne group [22]. positions, e) chlorines vicinal to an ortho-chlorine, f) the number of two-carbon paths without substitution, g) the number of threecarbon paths without substitution, h) thenumber of four-carbon paths without substitution, i) the difference in number of chlorines between rings, and j) the number of chlorines squared.…”

“…One determining factor is the degree of ortho-substitution. Increasing the polarity of the stationary phase increases the retention time less for compounds with a high degree of ortho-substitution and vice versa [22]. This may be explained by the steric effect of substitution in the ortho-position which leads to a distortion of the biphenyl moiety with a resulting reduction in its aromaticity.…”

“…SlL-19 (14%), BPX70 (70%), and SIL-88 ( 100%) leads to considerable changes in the elution order of the CBs. Structural principles for the effect on CB retention of cyanopropyl in the stationary phase have recently been elucidated [22,39]: The determining factor is again the degree of ortho-substitution, i.e. by increasing the polarity of the stationary phase through substitutions with cyanopropyl groups into the dimethyl siloxane polymer the retention time increases more for CBs with none or a few ortho-substitutions than for CBs with many ortho- …”

Correct identification of polychlorinated biphenyls in temperature-programmed GC with ECD detection

“…Mullin et al [16] (SE-54: all 209 PCBs) and Larsen [17](SIL-5, SIL-8, and SIL-19: the 140 CBs in technical mixtures of Aroclors 1016, 1232, 1248, and 1262). 2) Injections of authentic reference compounds on each column (62 individual congeners).…”