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• 3 •

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2004 vol. 3

GC/MS Analysis of Phthalate and Adipate

Esters in DrinkingWater

Using New Restek Reference Mixes and a Low-Bleed Column

Phthalate esters are of considerable interest

because their extensive use in consumer prod-

ucts, mainly as plasticizers, leads to widespread

human exposure and potential for environmen-

tal contamination. In the United States, the

Environmental Protection Agency (EPA) estab-

lished strict drinking water 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 drinking water quality, the goal is to

extract the compounds efficiently and identify

them accurately. EPA Method 506 offers a pro-

cedure for extracting, identifying, and quantify-

ing seven phthalate and adipate esters in drink-

ing water, 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 analysis by gas

chromatography/mass spectrometry.

We have developed two new reference materi-

als for analyses of the phthalate and adipate

esters targeted by Method 506. We prepare 506

Calibration Mix in isooctane at 1000µg/mL, per

method recommendation, and 506 Laboratory

Performance Check Mix in purge-and-trap grade

methanol at x10

the method 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.

EPA Method 506 suggests low levels of phtha-

late and adipate esters be evaluated using a

photoionization detector. The method allows

other approaches for detection, however, if

equivalent performance can be demonstrated.

Figure 1 shows a GC/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

esters with 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 surrogates were

used since the method 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 check mixes save preparation time and effort.

•Stable baseline with Rtx

-5Sil MS column—no interference with sensitive detection.

•Rapid analysis, excellent resolution.

by Katia May, Ph.D., Senior R&D Chemist, and Christopher English, Environmental Innovations Chemist

benzyl butyl phthalate

bis(2-ethylhexyl)adipate

bis(2-ethylhexyl)phthalate

di-

-butyl phthalate

di-

-octyl phthalate

diethyl phthalate

dimethyl phthalate

506 Calibration Mix

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-

-butyl phthalate

100

di-

-octyl phthalate

650

diethyl phthalate

100

dimethyl phthalate

100

506 Laboratory Performance Check Mix

Each

5-pk.

10-pk.

In P&T methanol, 1mL/ampul

31844

$30

31844-510

$135

—

w/data pack

31844-500

$40

31844-520

$150

31944

$270

Rtx®-5Sil MS Column (fused silica)

(Selectivity equivalent to Crossbond

5% diphenyl /

95% dimethyl polysiloxane) (temp. limits -60°C to 330°C)

Resprep

™

-C18 & Resprep

™

-C8 SPE Disks

• 47mm glass fiber disks embedded with C18 or

C8 bonded silica.

• Extract semivolatile organic compounds.

• Deep-pore design reduces clogging and allows

faster flow rates.

• Meet requirements for US EPA Methods 525.1,

506, 550.1, 549.1.

• Lower cost than Teflon

disks.

Description

qty.

cat.#

price

Resprep

™

-C18

47mm SPE Disks

20-pk.

24004

$95

Resprep

™

-C8

47mm SPE Disks

24-pk.

24048

$95

30-Meter, 0.25mm ID, 0.25µm df

cat.# 12723

, $445

new

★

Figure 1

Rapid analysis of phthalates, with excellent resolution, using an Rtx®-5Sil MS column.

GC_EV00745

1. 2-nitro-

-xylene (SS)

2. dimethyl phthalate

3. acenaphthene-d10 (IS)

4. diethyl phthalate

5. phenanthrene-d10 (IS)

6. di-

-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-

-octylphthalate

14. perylene-d12 (SS)

Column:

Rtx

-5Sil MS, 30m, 0.25mm ID, 0.25µm

(cat.# 12723)

Sample:

506 Calibration Mix, 1000µg/mL each analyte

(cat.# 31845)

Method 525.2 Internal Standard Mix (cat.# 31825)

Method 525.2 Surrogate Standard Mix (cat.# 31826)

Inj.:

1.0µL, 20ppm each analyte using a 4mm splitless

single gooseneck inlet liner (cat.# 20799) splitless

hold time 0.40 min.,

0.45 min. 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 0.5 min.) to 260°C @ 18°C/min.,

to 310°C @ 6°C/min. (hold 1 min.)

Det.:

Agilent 5973 GC/MS

Transfer

line temp.: 280°C

Scan range: 35–550 amu

Solvent delay: 3 min.

Tune:

DFTPP