Encyclopedia of Environmental Science and Engineering, Volume I and II

928 PCBs AND ASSOCIATED AROMATICS

TABLE 49

PCB concentrations derived from different correlation

curves can produce drastically different result

Concn. of PCB as ppm Aroclor 1016

Early peaks Late peaks Total area

55.7 19.0 8.6

57.3 31.5 6.9

46.8 6.3 40.1

48.9 4.8 33.4

53.4, 62.6‡ 6.9 32.6, 19.5

63.5 26.5 46.7

62.2 27.0 51.4

82.9 58.2 85.8

TABLE 50

A high bias is obtained when residue peaks are

inappropriately calculated

PCB concentration (ppm Aroclor 1016)

Conventional Total area Peak height

30.7 18.7 12.5

59.6 13.7 0.9

51.6 56.8 19.7

60.6 22.0 N.D.

55.0 4.4 N.D.

147 37.7 33.0

73.0 44.1 11.6

65.5 23.2 N.D.

53.9 27.9 7.6

54.6 27.6 7.6

50.7 44.4 13.1

60.4 23.0 4.5

58.4 30.3 6.3

48.8 24.3 6.9

48.0 25.2 7.2

N.D.—not determinable.

TABLE 51

The apparent concentration of aroclor 1016 in the samples can vary by

several hundreds of percent depending upon

the peak chosen for quantitation

Retention time (min)/concentration

4.39 min 6.47 min 8.71 min

21.5 25.0 12.5

58.8 22.6 0.9

37.8 37.0 19.7

73.0† 21.0 N.D.

9.2 N.D. N.D.

38.3 91.7 33.0

65.0 46.7 11.6

51.8 34.6 N.D.

53.1 33.0 7.6

50.7 36.1 7.6

50.0 34.0 13.1

66.3 28.0 4.5

60.2 30.3 6.3

55.5 33.7 6.9

46.3 30.2 7.2

TABLE 52

Peak height ratios for standard aroclors remain constant but vary for the

sample under investigation

Peak height ratios relative to Rt  7.75 min

Sample 4.27 min 6.28 min 7.52 min 8.04 min 11.4 min

EPA 0.64 0.76 1 0.57 0.53

Standard 0.54 0.59 1 0.54 0.43

Oil (1) 0.48 0.54 1 0.45 0.45

Oil (2) 7.60 3.30 1 N.D. N.D.

Oil (3) 0.50 0.52 1 0.44 0.46

Oil (4) 9.8 3.36 1 N.D. N.D.

in a precisely controlled thermal environment. Temperature

and residence time relationships were established for the

conditions necessary to produce a specified destruction effi-

ciency. It was concluded that with a 1 sec. residence time,

most of the pyrolysis occurred within a narrow temperature

range between 640°C and 740°C (Mescher et al.^56 ). The

results were based on the disappearance of PCBs rather than

the accumulation of degradation products. The lower molec-

ular weight PCBs are less thermally stable than the higher

molecular weight congeners. The residence time of the mol-

ecules in the high temperature zone is therefore a critical

parameter in determining the overall efficiency of the deg-

radation. However, the destruction and removal efficiency

(DRE) of an incineration process for a given compound does

not consider the toxicity of any pyrolysis products. The DRE

is defined as

DRE

WW

W

=

−

×

()feed out

feed

100

where,

W feed  mass feed rate of a compound to the incinerator,

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