Forensic Applications for 1,4-Dioxane and Solvent Stabilizers - Environmental Investigation and Remediation - page 424

TABLE 9.3 (continued)
Documented Impurities in Chlorinated Solvents and Their Potential for Enrichment
During Vapor Degreasing

Impurity
Amounts (Total)

Potential Concentration after
Vapor Degreasing Cycle References Impurities in Specifi c Chlorinated Solvents

1,1-Dichloroethylene f 398 ppm Evaporates

Trans -1,2-dichloroethylene f 50 ppm Evaporates

200 ppm Concentrates

Trichloroethylene f (b.p. = 87°C)

475 ppm Concentrates

Tetrachloroethylene f (b.p. = 121°C)

Dichloromethane technical grade (b.p. = 39.7°C)

[12] May contain methyl chloride Evaporates

Chloroform (b.p. = 61.2°C) Concentrates

1,1-Dichloroethane (b.p. = 57.2°C) Concentrates

1,2-Dichloroethane (b.p. = 83.5°C) Concentrates

Sources: [1] European Chemicals Bureau (2004); [2] Parsons et al. (1984); [3] Borror and Rowe (1981); [4] ASTM (2006);
[5] UNEP (2005); [6] Totonidis (2005); [7] Henschler et al. (1977); [8] European Chemicals Bureau (2004);
[9] Henschler et al. (1980); [10] Stewart et al. (1969); [11] Maltoni et al. (1986); and [12] IARC (1986).

NA Not available.

a Both would evaporate in PCE & TCE; ASTM test method to determine MC and DCM in TCE & PCE suggests these
impurities were present.
b Industrial grade TCE.
c Industrial grade TCE (1977).
d Trichloroethylene (Europe, pre-1995).
e

=

German technical grade.

Technical grade.

One of the attributes that producers of solvents marketed for a competitive edge is the quality and
reliability of their products. There was an inherent business interest in producing high-quality, high-
purity TCE; hence, it is likely that the purity improved over time and as end-use demands for TCE
became more specialized and sensitive to impurities, for example, in the electronics industry.
PCE may occur as a coproduct when TCE is produced by the chlorination of 1,2-dichloroethane or
the oxychlorination of ethylene (Doherty, 2000a). As noted in Section 1.2.3, typical technical or indus-
trial grade TCE has been known to include about 0.15% carbon tetrachloride as the major chlorinated
hydrocarbon impurity since the 1950s; however, PCEMI was not mentioned (Willis and Christian,
1957). PCEMI was not reported in analyses of pre-1977 American technical grade TCE (Henschler
et al., 1977) or in pre-1990 American technical grade TCE (Holt, 1990). The Japanese analysis of pre-
1983 industrial grade TCE detected several impurities, but PCE was not among them (Tsuruta et al.,
1983). TCE produced in Eu rope before 1995 had up to 0.03% PCE as a n i mpu r it y ( Eu ropea n Chem ica ls
Bureau, 2004). Indian TCE and British reagent grade TCE both contained detectable PCEMI in more
recent analyses (Totonidis, 2005). In America, a widely used grade of vapor degreasing TCE, Dow
Chemical's Neu-Tri™, had a purity of 99.4% in 1981, as indicated in Table 1.14, with stabilizers com-
posing the balance. However, a technical grade of TCE, meeting military specii cation O-T-634 and
distributed by Ashland Chemical in 1986, indicated a TCE content of 95% or more. Dow's technical
grade TCE for military specii cation O-T-634 in 1981 was the same as its Neu-Tri™ reported as 99.4%
TCE and 0.6% 1,2-butylene oxide with identical composition listed in 1991, 1994, and 1999 (Lane and
Smith, 2006). Table 9.4 lists some of the MSDS descriptions of TCE in the 1980s and 1990s.
The purity listing on an MSDS does not necessarily imply that the balance of the solvent may
include impurities; solvent stabilizers often composed the balance. It is only through the laboratory
analysis of solvents that PCEMI and other impurities are dei nitively revealed.