Food Chemistry

9.6 Polychlorinated Biphenyls (PCBs) 489

Fig. 9.3.(Continued)

The analysis starts with screening. Antibi-
otics can be detected with the help of the
bacteria whose growth they inhibit. Their
differentiation can be further improved by
means of an electrophoretic preliminary separa-
tion.
In principle, the same isolation and separation
methods and mass spectrometric techniques are
used for the unambiguous identification of veteri-
nary medicines as for pesticides (cf. 9.4.3). En-
zyme immunoassays are also used (cf. 2.6.3).

9.6 Polychlorinated Biphenyls

(PCBs)

The PCBs are complex mixtures of substances

which have been on the market since 1950.

They are widely used, e. g., as transformer

oil, hydraulic fluid, heat exchange medium,

dielectric fluid in condensers, plasticizer and

additive for printing ink. Formula 9.3 shows

2,2′,5,5′-tetrachlorobiphenyl (I) and 2,2′,4,5,5′-

pentachlorobiphenyl (II) as examples.