• 3 •
800-356-1688 •
2004vol. 3
GC/MSAnalysisofPhthalateandAdipate
Esters inDrinkingWater
UsingNewRestek ReferenceMixes and a Low-Bleed Column
Phthalate esters are of considerable interest
because their extensive use in consumer prod-
ucts, mainly as plasticizers, leads towidespread
human exposure and potential for environmen-
tal contamination. In theUnited States, the
Environmental Protection Agency (EPA) estab-
lished strict drinkingwater standards for two of
these semivolatile compounds, bis(2-ethyl-
hexyl)phthalate and bis(2-ethylhexyl)adipate, as
potential carcinogenic agents. Because even
trace amounts of these esters can have a harm-
ful effect on drinkingwater quality, the goal is to
extract the compounds efficiently and identify
them accurately. EPAMethod 506 offers a pro-
cedure for extracting, identifying, and quantify-
ing seven phthalate and adipate esters in drink-
ingwater, using liquid/liquid extraction (methyl-
ene chloride / hexane) or liquid/solid extraction
(octadecyl (C18) disk, e.g., Restek cat.# 24004),
extract concentration to 1mL, and analysisbygas
chromatography/massspectrometry.
We have developed two new referencemateri-
als for analyses of the phthalate and adipate
esters targeted byMethod 506.We prepare 506
CalibrationMix in isooctane at 1000µg/mL, per
method recommendation, and 506 Laboratory
Performance CheckMix in purge-and-trap grade
methanol at x10
5
themethod detection limit
(MDL) for each analyte.
In our quest for superior chromatography and
improved detection limits for this and other
analyses, we have developed a series of low
bleed polymeric stationary phases, using
Crossbond
®
bonding technology. By providing
stable baselines at higher temperatures, these
phases allow higher signal-to-noise ratios, and
thus greater sensitivity.
EPAMethod 506 suggests low levels of phtha-
late and adipate esters be evaluated using a
photoionization detector.Themethod allows
other approaches for detection, however, if
equivalent performance can be demonstrated.
Figure 1 shows aGC/MS analysis of the phtha-
lates and adipates, using an Rtx
®
-5Sil MS col-
umn. Column bleed is low, even at the 310ºC
oven temperature needed to elute the phthalate
esterswith the highest boiling points. At this
temperature, column bleed from an unstable
column could have a significant effect on detec-
tion limits.The 80ºC starting temperature and
18ºC/min. temperature program ensure a fast
analysis, without inhibiting resolution. US EPA
525.2 internal standards and surrogateswere
used since themethod does not list specific
monitoring compounds.
In analyses for phthalate and adipate esters,
a low-bleed Rtx
®
-5Sil MS column can extend
detection limits and help ensure you of reliable
data from your samples.
•New calibration and quality control checkmixes save preparation time and effort.
•Stable baselinewith Rtx
®
-5Sil MS column—no interferencewith sensitive detection.
•Rapid analysis, excellent resolution.
by KatiaMay, Ph.D., Senior R&D Chemist, and Christopher English, Environmental Innovations Chemist
benzyl butyl phthalate
bis(2-ethylhexyl)adipate
bis(2-ethylhexyl)phthalate
di-
n
-butyl phthalate
di-
n
-octyl phthalate
diethyl phthalate
dimethyl phthalate
506CalibrationMix
Each
5-pk.
10-pk.
1,000µg/mL each in isooctane, 1mL/ampul
31845
$25
31845-510
$112.50
—
w/data pack
31845-500
$35
31845-520
$125
31945
$225
benzyl butyl phthalate 250µg/mL
bis(2-ethylhexyl)adipate
1200
bis(2-ethylhexyl)phthalate 250
di-
n
-butyl phthalate
100
di-
n
-octyl phthalate
650
diethyl phthalate
100
dimethyl phthalate
100
506LaboratoryPerformanceCheckMix
Each
5-pk.
10-pk.
In P&Tmethanol, 1mL/ampul
31844
$30
31844-510
$135
—
w/data pack
31844-500
$40
31844-520
$150
31944
$270
Rtx®-5SilMSColumn (fusedsilica)
(Selectivity equivalent to Crossbond
®
5% diphenyl /
95% dimethyl polysiloxane) (temp. limits -60°C to 330°C)
Resprep
™
-C18&Resprep
™
-C8SPEDisks
•47mm glass fiber disks embeddedwith C18 or
C8 bonded silica.
•Extract semivolatile organic compounds.
•Deep-pore design reduces clogging and allows
faster flow rates.
•Meet requirements for US EPAMethods 525.1,
506, 550.1, 549.1.
•Lower cost thanTeflon
®
disks.
Description
qty.
cat.#
price
Resprep
™
-C18
47mm SPEDisks
20-pk.
24004
$95
Resprep
™
-C8
47mm SPEDisks
24-pk.
24048
$95
30-Meter, 0.25mm ID, 0.25µm df
cat.# 12723
, $445
!
new
★
Figure1
Rapidanalysisof phthalates,withexcellent resolution, usinganRtx®-5SilMScolumn.
GC_EV00745
1. 2-nitro-
m
-xylene (SS)
2. dimethyl phthalate
3. acenaphthene-d10 (IS)
4. diethyl phthalate
5. phenanthrene-d10 (IS)
6. di-
n
-butyl phthalate
7. pyrene-d10 (SS)
8. benzyl butyl phthalate
9. bis(2-ethylhexyl)adipate
10. triphenyl phosphate (SS)
11. chrysene-d12 (IS)
12. bis(2-ethylhexyl)phthalate
13. di-
n
-octylphthalate
14. perylene-d12 (SS)
Column:
Rtx
®
-5Sil MS, 30m, 0.25mm ID, 0.25µm
(cat.# 12723)
Sample:
506 CalibrationMix, 1000µg/mL each analyte
(cat.# 31845)
Method 525.2 Internal StandardMix (cat.# 31825)
Method 525.2 Surrogate StandardMix (cat.# 31826)
Inj.:
1.0µL, 20ppm each analyte using a 4mm splitless
single gooseneck inlet liner (cat.# 20799) splitless
hold time 0.40min.,
0.45min. pressure pulse@ 50psi
GC:
Agilent 6890
Inj. temp.:
270°C
Carrier gas:
helium, constant flow
Flow rate:
1.0mL/min.
Oven temp.: 80°C (hold 0.5min.) to 260°C@ 18°C/min.,
to 310°C@ 6°C/min. (hold 1min.)
Det.:
Agilent 5973GC/MS
Transfer
line temp.: 280°C
Scan range: 35–550 amu
Solvent delay: 3min.
Tune:
DFTPP
