For analysis of phthalic acid monoesters in the filtered
water samples, 5 µL of 10 mg L MBP-d and MEHP-d in
4 4
g of potassium hydroxide granule. A total of 0.25 mL of
diazomethane in diethyl ether solution was added to the
concentrated extracts obtained from the filtered water and
SS samples, and the mixture was allowed to stand for 30 min
at room temperature. The solution was concentrated to 0.5
-
1
acetone were spiked into 500 mL of the filtered water samples.
Phthalic acid monoesters in the water samples were extracted
by passing the water samples through the solid-phase
extraction cartridge, PS-2 or C18 with Sep-pack concentrator
mL under a stream of N
2
. The resulting solutions which were
-
1
(
Waters), at a flow rate of 15 mL min after acidifying the
spiked with internal standard fluoranthene-d10 (IS) at a final
-
1
water samples to pH 2 with 1 N HCl. In the case of SDB-XD,
the monoesters were extracted with the disk set to disk-
concentration of 0.1 µg L were injected into the GC-MS.
GC-MS Conditions. GC-MS conditions for phthalic acid
mono- and diesters were as follows: GC model, HP-5890
series II (Hewlett-Packard, Palo Ato, CA); injector temper-
ature, 220 °C; column head pressure, 80 kPa; carrier gas,
helium; auto sampler, HP-7673 (Hewlett-Packard); sample
size, 1 µL (split-less injection, purge on time for 1 min; glass
wool was not stuffed in the split-less insert); analytical
column, HP5-MS, 0.25 mm i.d. × 30 m, film thickness 0.25
µm (J&W Scientific, Folsom, CA). The GC oven temperature
was programmed as follows: held at 50 °C for 1 min, increased
-
1
holder (3M) at a flow rate of about 100 mL min . The
cartridges and the disk were dehydrated by passing air
through them for 30 and 5 min, respectively, and then the
monoesters were eluted with 5 mL and then 2 mL of CH
The CH Cl solution was dehydrated by passing the solutions
through the small glass column packed with sodium sulfate
anhydrous (Na SO ), which was washed by CH Cl , and then
concentrated to 0.5 mL under the stream of nitrogen (N ).
2 2
Cl .
2
2
2
4
2
2
2
The blank sample of the filtered river water was prepared
without water-sample loading to the solid-phase cartridge
or the disk SDB-XD and was subjected to the same procedures
as the filtered river samples. The monoesters in the filtered
river water samples were analyzed in duplicate samples at
one sampling site.
-
1
from 50 to 200 °C at 10 °C min and from 200 to 300 °C at
-1
6 °C min ; MS model, Automass II mass spectrometer (JEOL,
Akishima, Tokyo); ionization potential, 70 eV; ionization
current, 300 µA; ion source temperature, 220 °C; temperature
of transfer line between GC and MS, 250 °C. For the
fragmentation study, methylated phthalic acid monoesters
were measured by scanning at ranges from 50 to 500 m/ z.
For the measurement of phthalic acid mono- and diesters
in water sample, single ion monitoring (SIM) using the
fragment ions listed in Table 1 was performed. The base
peak, m/ z 163 or 167, was used for quantification of the
monoesters. The concentrations of MBP and MEHP in the
For the phthalic acid monoesters in SS trapped on the
glass filter AP-40, the filter was put into a 100-mL flask, and
-1
5
4 4
µLof10 mg L MBP-d and MEHP-d in acetone was spiked
on the filter. After addition of 100 µL of 5 N HCl to the filter,
the monoesters were extracted twice by sonication for 5 min
with 5 mL of methanol. About 10 mL of the combined solution
was added to 500 mL of the water made using PURIC-MX
and acidified to pH 2 with HCl, and then the monoesters
were analyzed in accordance with the methods for the filtered
water samples. The blank sample of SS was prepared without
water-sample loading to AP-40 and was subjected to the same
procedures as SS. To measure the content of SS in river water,
the same river water (500-1000 mL) was passed through the
AP-40, and then the weights of AP-40 were measured after
drying for 4 h at 105 °C. The analysis of the monoesters in
SS and measurement of SS content were performed in
duplicate samples at one sampling site.
filtered water and SS samples were corrected with MBP-d
and MEHP-d , and the other monoesters were determined
4
4
with IS. The ion used for quantification of the phthalic acid
diesters was m/ z 149, except for DMP, in which m/ z 163 was
used, and each molecular ion peak was used for confirmation.
The concentrations of each diester in river water samples
were corrected with a corresponding surrogate compound.
Results and Discussion
Analytical Conditions of Phthalic Acid Monoesters in Water
Sam ple. The mass spectra of some phthalic acid monoesters
methylated with diazomethane are presented in Figure 2. A
weak molecular ion peak of less than 0.1% and an ion at m/ z
149 were observed for each methylated monoester, except
for DMP. The fragment ions at m/ z 163 and 181 were common
ions in the methylated monoesters that have alkyl chain
lengths beyond 2 and may be due to the cleavage of long
chain alkyl groups. The fragment ions at m/ z 167 and 185,
and the molecular ion at m/ z 240 of methylated MBP-d4,
correspond to the fragment ions at m/ z 163 and 181 and the
molecular ion at m/ z 236, respectively, of methylated MBP.
In the case of methyl-benzyl phthalate, the intensity of the
fragment ions at m/ z 164 is relatively higher than the other
compounds, and the fragment ion at m/ z 181 is less than
0.1%. DMP and methylethyl phthalates appeared as ions at
M-32, which may be due to cleavage of the methyl group,
but did not appear at m/ z 181 or appeared at less than 0.1%.
Phthalic acid diesters generally appeared as the fragment
ions of M-R, M-2R, M-COOR, and M-2COOR (25), and the
fragment ion at m/ z 149 is well-known as a characteristic ion
for these compounds. Phthalic acid diesters, except for DMP,
corresponding to the monoesters investigated in this study
did not appear as fragment ions at m/ z 163 and 181. From
these results, the monitor ions of the methylated monoesters
were defined as shown in Table 1.
Phthalic acid diesters in river water samples were extracted
by using Empore Disk SDB-XD according to the EPA methods
(
24) without filtration. Attention was also needed to prevent
contamination of DBP and DEHP during sample preparation.
The procedures described below were performed at the clean
bench with attached active carbon filter (Dalton, Los Angeles,
CA). Each surrogate compound of phthalic acid diester listed
in Table 4, with hydrogen substituted by deuterium at 2, 3,
4
9
, and 5 positions of the benzene ring (purity more than
8%, Kanto Chemical Co., Chuo-ku, Tokyo), was spiked into
-1
the river water at a final concentration of 0.1 µg L . An aliquot
of water samples (250-500 mL) was passed through the disk
at a flow rate of 50-100 mL min . The cartridge was
dehydrated by passing air through it for 5 min, and then the
-
1
phthalates were eluted with 10 mL of CH
solution was dehydrated by passing the solutions through
the small glass column packed with Na SO and then
concentrated to 1000-fold under a stream of N . The resulting
solutions spiked with the internal standard fluoranthene-d10
2 2 2 2
Cl . The CH Cl
2
4
2
-
1
(
IS) at final concentrations of 0.1 µg L were injected into
the GC-MS. The blank sample was prepared without water-
sample loading to the disk SDB-XD and was subjected to the
same procedures as the river samples. The diesters in river
water samples were analyzed in duplicate samples at one
sampling site.
Methylation of Phthalic Acid Monoesters. The diazo-
methane was prepared by adding 1 g of N-methyl-N′-nitro-
N-nitrosoguanidine to 5 N sodium hydride solution, and then
diazomethane gas was trapped to 20 mL of ice-cold diethyl
ether. The diazomethane solution was dehydrated using 0.1
Typical retention times and linearity of calibration curves
of phthalic acid monoesters under the GC-MS conditions
are listed in Table 1. The correlation coefficients for the peak
area ratios of the methylated monoesters to IS compound vs
-
1
concentrations from 0.01 to 0.2 mg L of the monoesters
VOL. 35, NO. 18, 2001 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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