1. Trihalomethane Detection in Municipal Water Sources Using Solid Phase
Microextraction and GC/MS
Andrés M. Balboa Livis, Dr. Ning Gao
Department of Chemistry, St. Lawrence University, Canton, NY 13617
Abstract
Trihalomethanes (THMs) may form in municipal water supplies during the
chlorination process used to disinfect water. The 2 most common THMs in
municipal water are Chloroform (CHCl3) and Bromoform (CHBr3), which have been
found to be carcinogenic and decrease birth weights. In this project, headspace
solid-phase microextracion (SPME) coupled with a Gas Chromatography with a
Mass Spectrometer (GC-MS) was used to determine the concentration of CHBr3 in
municipal water supplies of the North Country. SPME is the sampling process by
which the analyte is heated in a capped vial with a fiber above the water level,
allowing for the adsorption of TMHs. The fiber is then injected into the inlet of a
GC/MS, allowing for the THMs to desorb and be separated from other chemical
species in the GC’s column and then be detected in the MS detector.
A standard curve of gas chromatogram integration area counts of CHBr3 vs
concentrations of CHBr3 was established. This was done by preparing standard
solutions of CHBr3 at different concentrations and obtaining an integrated GC peak
area for each known concentration of CHBr3. The resulting standard curve was then
used to calculate the concentrations of CHBr3 in municipal water samples collected
in the villages in and around the Adirondacks and analyzed by the SPME/GC-MS
method.

2. Introduction
THMs arise from the chlorination process performed on municipal water
supplies. Once in the water, disinfectant products can react with organic matter
resulting in the THMs chloroform and bromoform as described below (Olson, T.M. et
al.).
Figure 1: A possible reaction mechanism for the formation of bromoform in
municipal water supplies during the chlorination process.
The most common methods of exposure to THMs are dermal exposure and
ingestion. Dermal exposure is the most rapid means of exposure, occurring during

3. bathing or swimming in contaminated water (Caro, J.; Gallego, M.), where THMs are
absorbed through the skin and into the blood stream.
The Environmental Protection Agency (EPA) has catalogued THMs as B2
contaminants (Environmental Fact Sheet), indicating they are probable human
carcinogens. After prolonged toxicity, an increase in rectal, colon and bladder cancer
cases was observed, along with decreased in birth weight of infants, spontaneous
abortion and fetal growth retardation (Wright, JM et al.).
Method
Solid Phase Micro-extraction (SPME) is the sampling method by which the
analyte adsorbs onto a fiber (fused silica) coated with an adsorbent phase
(CAR/PDMS polymer) . Using SPME in conjunction with Gas Chromatography/Mass
Spec (GC/MS) allows for its use as an analytical tool. The SPME method is a solvent-
free, rapid and sensitive option compared to other techniques such as purge and
trap.
In our method, adapted from Allard, S. et al., a 17 mL water sample along
with 9.35g of Na2SO4 are placed in a 25 mL vial capped with a Teflon coated rubber
septum. A new rubber septum was used during every trial to ensure no THMs were
lost during the process. The vial is then allowed to incubate in a circulating water
bath at 60˚C for 15 minutes before the metal sleeve housing the SPME fiber is used
to perforate the rubber septum. The fiber is then exposed, allowing for THMs to
adsorb onto the fiber during a period of 15 minutes. The fiber is then retracted into
the sleeve and exposed once again in the GC/MS inlet.

4. The GC/MS method used involved a splitless injection with helium as the gas
carrier flowing at 2mL/min, and with the injection port at 160˚C . The initial oven
temperature was set to 40˚C for 2 minutes; the temperature was then ramped up by
20˚C/min to 80˚C and held for 4 minutes. Next, the temperature was ramped up by
10˚C/min to 220˚C and held for 1 minute. Finally, the temperature was ramped up
by 50˚C/min to 300˚C and held for 3 minutes, adding up to a total time of 27
minutes.
Results
A bromoform standard curve (Figure 2) was created by diluting a 100 ppm
stock solution into lower concentration solutions (0.5, 1, 2, 5, 10 and 20 ppm). Each
solution was then analyzed (replicating each analysis three times) using GC/MS,
resulting in a value for area counts of the bromoform peak. The average values for
the different integration areas were then plotted against their concentrations,
resulting in the standard curve for CHBr3.
y = 4E+06x - 1E+06
R² = 0.99941
0
10000000
20000000
30000000
40000000
50000000
60000000
70000000
80000000
90000000
100000000
0 5 10 15 20
IntegrationAreaCounts
Bromoform Concentration (ppm)
Standard Curve for CHBr3

5. Figure 2: Standard curve for CHBr3, reporting an R2 of 0.99941.
The R2 value that we report is 0.99941. A previous study conducted by
Murphy, R. investigating concentrations of CHCl3 used the same method as outlined
in our methods section and reported an R2 value of 0.96255. The improvement of
this value is due to two small modifications in the method: First, the use of a
circulating water bath rather than a hotplate, allowing for more a more controllable
and reproducible temperature of the sample. Secondly, the use of only one SPME
fiber. Although this has proven to be more time consuming, reproducibility is
dramatically improved. Due to differences in adsorptivity efficiency, the use of two
different fibers will innately introduce random error in data obtained.
Once the standard curve was created, water samples were then collected
from neighboring towns and analyzed according to our method. The 3-replicate
average of integration area counts was then used to solve for the “x” term in the
equation representing our standard curve, yielding the concentration of CHBr3 in
ppm. Due to downtime of the GC/MS instrument caused by a helium leak in the
instrument, only one sample could be analyzed. Our data shows that Canton
municipal water contains a negligible amount of THMs, if any at all.
Future Research
In future research, more municipal water sources in the North Country
would by tested for CHBr3. That being said, there are 9 other members of the THM
family which could be present in water supplies and have an adverse effect on the

6. population. Further research might also focus on the detection of these
contaminants, such as iodotrahalomethanes which are present in a much lower
concentration but require a lower threshold in the body to produce cell toxicity.
References
*Allard, S.; Charrois, J.W.A.; Joll, C.A.; Heitz, A. Simultaneous Analysis of 10
Trihalomethanes at Nanogram per Liter Levels Using Solid-Phase Microextraction
and Gas Chromatography Mass-Spectroscopy. Journal of Chrom. A. 2012, 1238, 15-
21.
*Caro, J.; Gallego, M. Assesment of Exposure of Workers and Swimmers to
Trihalomethanes in an Indoor Swimming Pool. Environ. Sci. Technol. 2007, 41, 4793-
4798.
*Environmental Fact Sheet. www.des.nh.gov (accessed Sept 17, 2012) New
Hampshire Department of Environmental Services, 2006.
*Olson, T.M.; Gonzalez, A.C.; Vasquez, V.R. Gas Chromatography Analyses for
Trihalomethanes: An Experiment Illustrating Important Sources of Disinfection By-
Products in Water Treatment. Journ. Chem. Ed. 2001, 78, 1231-1234.
*Wright, J.M.; Schwartz, J.; Dockery, D.W. Effect of Trihalomethane Exposure on Fetal
Development. Occup. Environ. Med. 2003, 60, 173-180.
* Murphy, R.; Gao, N.; Trihalomethane Detection in Municipal Water Sources Using
Solid Phase Microextraction and GC/MS (2013)