2.4 Sensitivity

0.01-0.lppb using P&T/CGC/PID/ELCD.

0.1 ppb using P&T/CGC/MS (scan mode).

10-100ppb using static headspace/CGC/MS.

0.5-lppb for trihalomethanes using direct aqueous injection/CGC/ECD.

Volatile organic compounds 2 47

Semi-volatile organic compounds

3.1 Introduction

Semi-volatile organic compounds are an extremely heterogeneous group of priority pollutants including haloethers, halogenated hydrocarbons, nitro-samines, phthalates, polycyclic aromatic hydrocarbons (PAHs), nitroaromatics, benzidines, PCBs, organochlorine pesticides, triazines, phenols and some other industrial chemicals. In fact, the definition of a semi-volatile compound is rather arbitrary and based on gas chromatographic data. In practice, compounds are considered as volatile when they can be analysed by purge and trap techniques (see Chapter 2) and as semi-volatile when purging is less efficient due to the compounds' lower vapour pressure but their analysis by CGC is still possible. In general, semi-volatile compounds have molecular weights ranging from 100 to 300 daltons and typically elute from a standard capillary column at between 80° С (after decane) and 320° С

The US EPA protocols include methods for the monitoring of semi-volatile organic compounds in water samples using capillary gas chromatography with mass spectroscopic detection (CGC/MS). EPA method 525 involves sample preparation by solid phase extraction and is applicable to drinking water samples and targets 43 compounds including PAHs, PCBs, organochlorine pesticides, triazines, phthalates and pentachlorophenol. Alternatively, waste water samples may be analysed by liquid-liquid extraction (EPA method 625), which includes the analysis of PAHs, PCBs, semi-volatile halogenated hydro­carbons, organo-chlorine pesticides, phthalates, nitrosamines, benzidines and phenols (total of 73 compounds).

The compounds that may be analysed by either one (or both) of these methods are listed below and both sample preparation techniques are described in detail in this chapter. Since these techniques may also be applied to other medium boiling point, low to medium polarity pollutants, they are often used as general screening techniques. For some classes of compounds, more specific and selective methods with lower detection limits are described in later chapters.

Semi-volatile organic compounds 3 73

3.2 Compounds

EPA 525 EPA 625

SPE LLE

HALOETHERS

bis (2-chloroethyl) ether - +

bis (2-chloroisopropyl) ether (EC) - +

bis (2-chloroethoxy) methane - +

4-chlorophenyl phenylether - +

4-bromophenyl phenylether - +

SEMI-VOLATILE HALOGENATED COMPOUNDS

1,3-dichlorobenzene	(EC)
1,4 -dichlorobenzene	(EC)
1,2-dichlorobenzene	(EC)
hexachloroethane	(EC)
1,2,4-trichlorobenzene	(EC)
hexachlorobutadiene	(EC)
hexachlorocyclopentadiene
2 -chloronaphthalene	(EC)
hexachlorobenzene	(EC)
NITROSAMINES
N-nitroso-dimethylamine
N-nitroso-di-n.propylamine
N-nitroso-diphenylamine
PHTHALATES
dimethylphthalate
diethylphthalate
di-n.butylphthalate
butylbenzylphthalate
bis-(2 -ethylhexyl)phthalate
di-n.octylphthalate
bis-(2 -ethylhexyl)adipate

74 3 Semi-volatile organic compounds

		EPA 525	EPA 625
		SPE	LLE
POLYCYCLIC AROMATIC HYDROCARBONS
naphthalene	(EC)	-	+
acenaphthylene	(EC)	+	+
acenaphthene	(EC)	-	+
fluorene	(EC)	+	+
phenantrene	(EC)	+	+
anthracene	(EC)	+	+
fluoranthene	(EC)	-	+
pyrene	(EC)	+	+
benzo(a)anthracene	(EC)	+	+
chrysene	(EC)	+	+
benzo(b)fluoranthene	(EC)	+	+
benzo(k)fluoranthene	(EC)	+	+
benzo(a)pyrene	(EC)	+	+
indeno(l,2,3-cd)pyrene	(EC)	+	+
dibenzo(ah)anthracene	(EC)	+	+
benzo(ghi)perylene	(EC)	+	+
NITROAROMATICS
nitrobenzene		-	+
2,6 -dinitrotoluene		-	+
2,4-dinitrotoluene		-	+
BENZIDINES
benzidine	(EC)	-	+
3,3'-dichlorobenzidine	(EC)	-	+
POLYCHLORINATED BIPHENYLS
2-chlorobiphenyl	(EC)	+	-
2,3'-dichlorobiphenyl	(EC)	+	-
2,4,5-trichlorobiphenyl	(EC)	+	-
2,2',4,4'-tetrachlorobiphenyl	(EC)	+	-

Semi-volatile organic compounds3 75

		EPA 525	EPA 625
		SPE	LLE
2,2',3,4,6-pentachlorobiphenyl	(EC)	+	-
2,2',4,4',5,6-hexachlorobiphenyl	(EC)	+	-
2,2',3,3',4,4',6-heptachlorobiphenyl	(EC)	+	-
2,2',3,3', 5,5',6,6'-octachlorobiphenyl	(EC)	+	-
arochlor mixtures		-	+
ORGANOCHLORINE PESTICIDES
lindane (gamma-HCH)	(EC)	+	+
heptachlor	(EC)	+	+
alachlor		+	-
aldrin	(EC)	+	+
heptachlorepoxide		+	+
gamma-chlordane	(EC)	+	-
alpha-chlordane	(EC)	+	-
trans-nonachlor		+	-
endrin	(EC)	+	+
methoxychlor		+	-
toxaphene		+	-
alpha-HCH		-	+
beta-HCH		-	+
delta-HCH		-	+
endosulfan	(EC)	-	+
p,p'-DDE		-	+
p,p'- DDD		-	+
p,p'-DDT	(EC)	-	+
dieldrin	(EC)	-	+
endosulfan sulphate		-	+

76 3 Semi-volatile organic compounds

ЕРА 525 ЕРА 625

SPE LLE

TRIAZINES

simazine (EC) +

atrazine +

PHENOLS

phenol - +

2-chlorophenol (EC) - +

2-nitrophenol - +

2,4-dimethylphenol - +

2,4-dichlorophenol (EC) - +

chloro, 4-methyl, 3-phenol (EC) - +

2,4,6-trichlorophenol - +

2,4-dinitrophenol - +

4-nitrophenol - +

methyl, 2,4,6-dinitrophenol - +

pentachlorophenol (EC) + +

INDUSTRIAL PRODUCTS

isophorone - +

azobenzene - +

(EC) Included on the European Community Priority Pollutants list. (+/-) analysed or not analysed by above mentioned EPA methods.

Semi-volatile organic compounds 3 77