Optimizing the Analysis of Volatile Organic Compounds

4
Drinking Water Disinfection Byproducts
1996 amendments to the SDWA require the
EPA to review and revise existing National
Primary Drinking Water Regulations
(NPDWR) at least once every six years. Much
of this renewed interest in changes to drinking
water regulation standards stems from
studies suggesting negative reproductive
effects, such as spontaneous abortions,
resulting from trihalomethanes (THMs) in
water. Current studies using compliant levels
of THMs in water have revealed adverse
reproductive effects, therefore method detection
limits (MDLs) will continue to be lowered
in methods that address THMs. 1
1. S. Richardson, Anal. Chem. 73 (2001)
2719-2734.
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Hazardous Waste Methods (8000 Series)
The Resource Conservation and Recovery Act (RCRA) of 1976 was enforced shortly after
front-page headlines revealed the presence of serious hazardous waste sites like Love Canal,
NY and Times Beach, MO. The analytical methods for determining hazardous waste, known
as the 8000 series methods, fall under US EPA SW-846. These methods were designed for
monitoring organic pollutants in waste samples prior to disposal at hazardous waste facilities.
They also can be used for monitoring groundwater at these facilities.
Method 8010B: This packed column GC method is used to monitor 50 halogenated volatile
pollutants in hazardous waste samples. It employs purge and trap concentration and an
ELCD.
Method 8011: This capillary column GC method is used to monitor 1,2-dibromoethane
(EDB) and 1,2-dibromo-3-chloropropane (DBCP) in hazardous waste samples. It employs
microextraction, using hexane, and analysis using an ECD.
Method 8015A: This packed column GC method is used to monitor non-halogenated
volatile pollutants in hazardous waste samples. It employs purge and trap concentration and
an FID. Total petroleum hydrocarbon analysis, commonly refered to as 8015-TPH, also falls
under this method. Method 8015-TPH uses an FID to match a known pattern of gasoline
with an unknown sample containing peaks that fall within the gasoline pattern range. If a
pattern falls within the gasoline window it may be reported as gasoline.
Method 8020A: This packed column GC method is used to monitor ten aromatic volatile
pollutants in hazardous waste samples. It employs purge and trap concentration and a PID. It
is common for analysts to combine Methods 8010 and 8020, by using a PID and an ELCD
in series.
Method 8021A: This capillary column GC method is used to monitor 60 volatile contaminants
in hazardous waste samples. It employs purge and trap concentration, combined with a
PID and an ELCD in series. The PID detects aromatic compounds and double-bond compounds,
and the ELCD detects halogenated compounds.
Method 8021B: Using the same analytical technique as Method 8021A, the compound list
for Method 8021B includes ten additional compounds but does not require the analysis of
several branched aromatics and halogenated compounds.
Method 8240B: This packed column GC/MS method is used to monitor 79 volatile pollutants
in hazardous waste samples. It employs purge and trap concentration for most analytes,
but direct injection can be used for some limited applications.
Method 8260B: This capillary column GC/MS method is used to monitor 98 volatile pollutants
in hazardous waste samples. It employs purge and trap concentration for most analytes,
but direct injection can be used for some limited applications.
State GRO Methods
Leaking underground storage tanks (LUST) pose significant environmental risks throughout the
country. States have the responsibility to develop LUST testing methods. State gasoline range
organics (GRO) methods are based on EPA methods such as 602, 8020 and 8015. The most
common EPA method used is 8015, which relies on baseline-integrating the total area of the
gasoline fingerprint, using marker compounds such as hexane (C6) and dodecane (C12). The
8015-TPH Method analysis uses an FID and pattern recognition—the specific ratio of peaks
that make up a particular fuel—to identify the type of fuel. If a pattern falls within the window
markers it may be reported as gasoline, then quantified. Difficult matrices can result in misidentification
or poor quantitation of the sample, and deterioration in the environment (weathering)
further complicates the analysis. Therefore, many states have combined EPA methods, using a
PID/FID in series (e.g., Methods 8020/8015-TPH). Specific aromatic compounds are analyzed
using PID (Methods 602, 8020), which is connected to the FID (Method 8015-TPH). The common
target compounds are benzene, toluene, ethylbenzene, and m-, o-, and p-xylene (BTEX),
however many states also have added other compounds to their methods (Table I).