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GC-MS Analysis of Phthalates: Comparison of GC Stationary Phase Performance

Dan Li, Rebecca Stevens, and Chris English

Abstract

Phthalates are ubiquitous in the environment and have attracted attention due to their potential adverse impact on human health. For this reason, detection and separation of phthalates has become a necessity. Gas chromatography is an effective approach for separating phthalates, and it can be paired with several detection techniques, including electron capture (ECD), flame ionization (FID), and mass spectrometry (MS). In this study, Pro EZGC gas chromatographic modeling software was employed to determine the optimal stationary phases and conditions for phthalate GC-MS analysis. The separation of phthalates was compared on seven different stationary phases: Rtx-440, Rxi-XLB, Rxi-5ms, Rtx-50, Rxi-35Sil MS, Rtx-CLPesticides, and Rtx-CLPesticides2 phases. In all cases, 18 EPA- and EU-listed phthalates were analyzed in less than 6 minutes. In addition, an extended list of 37 phthalates was analyzed in less than 40 minutes using an optimized method. Both Rtx-440, which is unique to Restek, and Rxi-XLB columns showed the best resolution of the complex phthalate mixture.

Introduction

Phthalates are widely used as plasticizers in a variety of industry products. However, some phthalates are considered to be endocrine disruptors [1] and are associated with a number of problems, including birth defects [2]; high blood pressure in children [3]; pregnancy-induced hypertensive heart diseases [4]; respiratory problems [5]; and obesity [6]. The European Union (EU) and United States Environmental Protection Agency (U.S. EPA) have restricted the use of the most harmful phthalates (Table I).

GC-MS is a commonly used technique for phthalate analysis because it is simple, fast, and inexpensive. GC-MS also provides mass spectral information, making it a powerful instrumental platform for phthalate determination. Using a GC column that provides good chromatographic separations is important because structural similarities among phthalates can make MS identification and quantification challenging. For instance, many phthalates share a common base peak ion (m/z 149), which makes identification and quantification of coeluting phthalates difficult. Technical grade mixtures and isomers further complicate the problem.

A recently published review summarized the most used GC and LC columns for phthalate analysis [7]. According to the literature, GC-MS has better chromatographic resolution compared to LC-MS for phthalate determination. The most commonly employed GC columns in descending order of popularity are 5-type, XLB-type, 35-type, 17-type, 50-type, and 1-type. The separation achieved on any stationary phase can be refined by adjusting instrument conditions, but this can be a time-consuming process when done in the laboratory. Pro EZGC modeling software can quickly optimize GC parameters (e.g., carrier gas type, flow rate, temperature program, column dimensions, and guard column) to produce the shortest analysis time on a given stationary phase. In this study, libraries of 37 phthalates (Table II) were built into the Pro EZGC program for seven stationary phases: Rtx-440, Rxi-XLB, Rxi-5ms, Rtx-50, Rxi-35Sil MS, Rtx-CLPesticides, and Rtx-CLPesticides2 phases. These stationary phases were evaluated for the analysis of both regulated and unregulated phthalates.

Experimental Chemicals

Restek’s EPA Method 8061A phthalates esters mixture (cat.# 33227), which contains 15 of the target analytes, each at a concentration of 1,000 μg/mL, was used as a primary reference standard. Benzyl benzoate (cat.# 31847) was used as the internal standard. All other phthalate standards were purchased from Chem Service.

Instrument

GC-MS analysis was performed on a Shimadzu QP2010 Plus GC-MS. The instrument was equipped with one of seven Restek columns using 30 m × 0.25 mm × 0.25 µm dimensions (0.20 µm for the Rtx-CLPesticides2 column). Windows-based Pro EZGC ROM software was used to determine optimized conditions for each column and then all columns were directly compared by analyzing samples under the single set of conditions that had produced the best overall separation. This direct comparison provides a better understanding of the differences in selectivity among the columns. Detailed column descriptions and GC-MS experimental parameters are given in Table I and Table III, respectively.

Sample Preparation

Standards were dissolved and diluted in methylene chloride. Standard solutions were prepared at 50 μg/mL (80 μg/mL for the internal standard benzyl benzoate). During sample preparation, plastics were strictly avoided; all preparation work was performed using glassware (volumetric flasks, syringes, vials, etc.).

Results and Discussion

A direct comparison of column performance for the separation of EPA- and EU-regulated phthalates was performed. Phthalate retention times on seven different phases were predicted by the Pro EZGC ROM program under the same GC conditions. These conditions, shown in Table I, were the conditions that produced the best overall chromatographic results among the separate sets of conditions that had been optimized for each column. Coelutions were defined as compound pairs with a resolution value of less than 1.5. The total analysis time was less than 6 minutes. In order to confirm the retention time predictions made by the Pro EZGC ROM software, chromatograms were collected on each stationary phase under the same conditions used by the software (Figure 1). Because the column lengths were not exactly 30 meters long, as they were in the simulation, the absolute retention times were slightly different from the predicted values; however, the elution orders and coeluting pairs were exactly the same as predicted. Rtx-440, Rxi-XLB, Rtx-CLPesticides, and Rxi-35Sil MS columns provided baseline separation for all EPA- and EU-listed phthalates. The two isomers of bis[4-methyl-2-pentyl] phthalate were not resolved on any of the seven phases. The elution order was comparable on the Rtx-440, Rxi-XLB, Rtx-CLPesticides, and Rxi-5ms columns.

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Table I: Predicted Elution Times for Regulated Phthalates on Various Restek GC Columns

Column: 30 m x 0.25 mm x 0.25 μm (0.20 μm for Rtx-CLPesticides2 column)
Constant linear velocity: 66.7 cm/sec
Oven: 200 °C (hold 0.5 min) to 330 °C (320 °C for Rtx-50 column) at 30 °C/min (hold 1 min)

Retention Time (min)

Peak #

Name

Listed

Rtx-440
(cat. 12923)

Rxi-XLB
(cat. 13723)

Rtx-
CLPesticides
(cat. 11123)

Rxi-35Sil MS (cat. 13823)

Rtx-50
(cat. 10523)

Rxi-5ms
(cat. 13423)

Rtx-
CLPesticides2
(cat. 11323)

CAS #

Purity

1

Dimethyl phthalate*

EPA 8061A, EPA Priority

1.28

1.16

1.14

1.29

1.46

1.10

1.23

131-11-3

Neat

2

Diethyl phthalate*

EPA 8061A, EPA Priority, EU

1.54

1.39

1.33

1.55

1.73

1.30

1.47

84-66-2

Neat

3

Benzyl benzoate

Internal Standard

2.11

1.87

1.56

2.17

2.31

1.70

1.88

120-51-4

Neat

4

Diisobutyl phthalate*

EPA 8061A

2.25

2.04

1.88

2.21

2.34

1.91

2.10

84-69-5

Neat

5

Di-n-butyl phthalate*

EPA 8061A, EPA Priority

2.58

2.33

2.10

2.53

2.69

2.17

2.38

84-74-2

Neat

6

Bis(2-methoxyethyl) phthalate*

EPA 8061A

2.74

2.48

2.26

2.86

3.10

2.27

2.63

117-82-8

Neat

7

Bis(4-methyl-2-pentyl) phthalate isomer 1*

EPA 8061A

2.85

2.62

2.37

2.71

2.83

2.50

2.64

84-63-9

Neat

8

Bis(4-methyl-2-pentyl) phthalate isomer 2*

EPA 8061A

2.86

2.63

2.37

2.72

2.84

2.51

2.65

84-63-9

Neat

9

Bis(2-ethoxyethyl) phthalate*

EPA 8061A

3.08

2.80

2.51

3.13

3.33

2.59

2.90

605-54-9

Neat

10

Di-n-pentyl phthalate*

EPA 8061A

3.16

2.91

2.58

3.08

3.21

2.71

2.89

131-18-0

Neat

11

Di-n-hexyl phthalate*

EPA 8061A

3.73

3.46

3.07

3.61

3.69

3.25

3.42

84-75-3

Neat

12

Butyl benzyl phthalate*

EPA 8061A, EPA Priority, EU

3.85

3.56

3.12

3.93

4.13

3.30

3.63

85-68-7

Neat

13

Hexyl 2-ethylhexyl phthalate

EPA 8061A

3.98

3.72

3.29

3.83

3.92

3.52

3.66

75673-16-4

Technical

14

Bis(2-butoxyethyl) phthalate*

EPA 8061A

4.12

3.82

3.39

4.08

4.21

3.60

3.85

117-83-9

Neat

15

Bis(2-ethylhexyl) phthalate*

EPA 8061A

4.21

3.95

3.52

4.05

4.12

3.82

3.91

117-81-7

Neat

16

Dicyclohexyl phthalate*

EPA 8061A, EPA Priority, EU

4.33

4.04

3.55

4.42

4.58

3.78

4.08

84-61-7

Neat

17

Di-n-octyl phthalate*

EPA 8061A, EPA Priority, EU

4.76

4.50

3.97

4.59

4.62

4.24

4.39

117-84-0

Neat

18

Diisononyl phthalate

EU

5.10

4.84

4.23

4.84

4.84

4.50

4.64

68515-48-0

Isomer mix

19

Diisodecyl phthalate

EU

5.20

4.95**

4.42

5.01

5.18

4.71

4.90

26761-40-0

Isomer mix

20

Dinonyl phthalate*

EPA 8061A

5.24

4.95**

4.39

5.04

5.10

4.72

4.83

84-76-4

Neat

Note: Shading indicates coeluting peaks (Rs<1.5). For each column, different colors of shading indicate different coelution pairs.
*These compounds are contained in Restek’s EPA Method 8061A phthalates esters mixture (cat.# 33227).
**Peaks 19 and 20 are non-isobaric and can be separated using selected ion monitoring.


Differences in the elution orders were observed on Rxi-35Sil MS and Rtx-50 phases. Notably, the elution orders of four pairs of phthalates changed on the Rxi-35Sil MS phase, including bis(2-methoxyethyl) phthalate/bis(4-methyl-2-pentyl) phthalate isomers (peaks 6 and 7/8), bis(2-ethoxyethyl) phthalate/di-n-pentyl phthalate (peaks 9 and 10), butyl benzyl phthalate/hexyl-2-ethylhexyl phthalate (peaks 12 and 13), and bis(2-butoxyethyl) phthalate/bis(2-ethylhexyl) phthalate (peaks 14 and 15).

Rtx-440 and Rtx-XLB columns had the best overall separations under these conditions. Peaks that coeluted on other phases were well resolved on Rtx-440 and Rtx-XLB columns. Pairs that were not resolved on other phases include bis(2-ethylhexyl) phthalate and dicyclohexyl phthalate (peaks 15 and 16) on the Rxi-5ms column; bis(2-ethylhexyl) phthalate and butyl benzyl phthalate (peaks 15 and 12) on the Rtx-50 column; and bis(2-methoxyethyl) and bis[4-methyl-2-pentyl] phthalate (peaks 6 and 7,8) as well as bis(2-ethoxyethyl) phthalate and di-n-pentyl phthalate (peaks 9 and 10) on the Rtx-CLPesticides2 column. In technical grade isomer mixtures, it is possible to identify isomer groups, such as diisononyl phthalate and diisodecyl phthalate (peaks 18 and 19), but it is impossible to completely resolve each individual isomer within a group. Fortunately, unique extracted ions are available for identification and quantification, e.g., m/z 293 for diisononyl phthalate, and m/z 307 for diisodecyl phthalate (Figure 1).

A more comprehensive comparison of the seven stationary phases was also conducted for the separation of 37 phthalates (a total number of 40 peaks, including three isomers) using the retention times predicted by the Pro EZGC ROM program (Table II). The GC parameters specified in Table III provided separation of 34 out of 40 peaks on both Rtx-440 and Rxi-XLB columns in less than 40 minutes and the two phases produced different coelutions. The chromatogram on the Rtx-440 column was collected and shown in Figure 2. For some pairs that were not baseline-resolved, the resolution is still adequate for qualitative analysis. There is no single set of conditions that is optimal for all phases. The program with the best overall results in terms of speed and the most peaks resolved was selected for this direct column comparison. Analysts can optimize conditions for their specific target lists using the Pro EZGC ROM program. Based on the overall analysis speed and high degree of target analyte separation, the Rtx-440 and Rtx-XLB columns are recommended for phthalate GC-MS analysis.

Table II: Predicted Elution Times for Phthalates (Extended List) on Various Restek GC Columns

Column: 30 m x 0.25 mm x 0.25 μm (0.20 μm for Rtx-CLPesticides2 column)
Constant linear velocity: 48 cm/sec
Oven: 150 °C (hold 0.8 min) to 200 °C at 5 °C/min to 275 °C at 3 °C/min (hold 2 min)

Retention Time (min)

Peak #

Name

Listed

Rtx-440
(cat. 12923)

Rxi-XLB
(cat. 13723)

Rxi-5ms (cat. 13423)

Rtx-50 (cat. 10523)

Rxi-35Sil MS (cat. 13823)

Rtx-
CLPesticides
(cat. 11123)

Rtx-
CLPesticides2
(cat. 11323)

CAS #

Purity

1

Dimethyl phthalate*

EPA 8061A, EPA Priority

4.606

3.924

3.294

5.912

4.902

3.75

4.334

131-11-3

Neat

2

Dimethyl isophthalate

5.491

4.690

3.85

6.35

5.498

4.174

4.793

1459-93-4

Neat

3

Diethyl phthalate*

EPA 8061A, EPA Priority, EU

6.537

5.642

4.762

7.809

6.785

5.24

6.106

84-66-2

Neat

4

Benzyl benzoate

Internal Standard

9.931

8.667

N/A

11.099

N/A

6.725

8.583

120-51-4

Neat

5

Diisobutyl phthalate*

EPA 8061A

11.185

10.029

8.817

11.817

11.008

9.101

10.333

84-69-5

Neat

6

Di-n-butyl phthalate*

EPA 8061A, EPA Priority

13.152

11.850

10.405

14.031

13.094

10.481

12.029

84-74-2

Neat

7

Bis(2-methoxyethyl) phthalate*

EPA 8061A

14.343

12.784

11.045

17.095

15.424

11.54

13.725

117-82-8

Neat

8

Bis(4-methyl-2-pentyl) phthalate isomer 1*

EPA 8061A

15.192

13.754

12.47

15.184

14.454

12.166

13.825

84-63-9

Neat

9

Bis(4-methyl-2-pentyl) phthalate isomer-2*

EPA 8061A

15.350

13.828

12.55

15.277

14.542

12.233

13.906

84-63-9

Neat

10

Bis(2-ethoxyethyl) phthalate*

EPA 8061A

16.910

15.132

13.199

19.063

17.59

13.186

15.875

605-54-9

Neat

11

Di-n-pentyl phthalate*

EPA 8061A

17.454

15.880

13.856

17.974

17.128

13.588

15.768

131-18-0

Neat

12

Butyl cyclohexyl phthalate

19.452

17.689

15.478

21.19

19.843

14.979

17.96

84-64-0

Technical

13

Butyl 2-ethylhexyl phthalate

19.823

18.172

16.174

20.062

19.238

15.566

17.958

85-69-8

Technical

14

Di-n-hexyl phthalate*

EPA 8061A

22.138

20.279

17.984

22.152

21.469

17.215

19.829

84-75-3

Neat

15

Butyl octyl phthalate

22.338

20.557

18.136

22.37

21.668

17.344

20.009

84-78-6

Technical

16

Butyl benzyl phthalate*

EPA 8061A, EPA Priority, EU

22.799

20.783

18.029

25.365

23.782

17.384

21.128

85-68-7

Neat

17

Hexyl 2-ethylhexyl phthalate

EPA 8061A

24.404

22.668

20.266

24.110

23.500

19.126

22.049

75673-16-4

Technical

18

Butyl isodecyl phthalate

24.632

22.793

20.392

24.220

23.685

19.424

22.22

42343-36-2

Technical

19

Bis(2-ethylhexyl)hexahydro phthalate

25.066

23.389

21.254

23.089

23.063

19.142

21.961

84-71-9

Neat

20

Bis(2-n-butoxyethyl) phthalate*

EPA 8061A

25.601

23.563

20.930

26.746

25.647

19.849

23.533

117-83-9

Neat

21

Dicyclohexyl phthalate*

EPA 8061A, EPA Priority, EU

26.651

24.495

21.771

28.989

27.671

20.530

24.792

84-61-7

Neat

22

Bis(2-ethylhexyl) phthalate*

EPA 8061A

26.692

24.845

22.585

25.903

25.458

21.135

24.048

117-81-7

Neat

23

Butyl-n-decyl phthalate

27.362

25.268

22.657

26.888

26.410

21.404

24.471

89-19-0

Technical

24

Diphenyl phthalate

27.987

25.712

22.372

32.277

30.170

21.614

26.473

84-62-8

Neat

25

Bis(4-methylcyclohexyl) phthalate isomer 1

28.003

25.922

23.016

29.547

28.476

21.677

25.923

59-43-8

Isomer mix

26

Bis(4-methylcyclohexyl) phthalate isomer 2

29.002

26.993

23.816

30.345

29.400

22.604

26.739

59-43-8

Isomer mix

27

Hexyl isodecyl phthalate

29.176

27.271

24.523

28.189

27.965

23.224

26.336

61702-81-6

Technical

28

Benzyl 2-ethylhexyl phthalate

29.791

27.781

24.747

31.498

30.216

23.219

27.594

27215-22-1

Technical

29

Bis(4-methylcyclohexyl) phthalate isomer-3

29.964

28.034

24.617

31.189

30.285

23.498

27.559

59-43-8

Isomer mix

30

Bis(2-ethylhexyl) isophthalate

30.132

28.037

25.684

28.133

28.243

23.907

26.648

137-89-3

Neat

31

Bis(2-(ethoxyethoxy)ethyl) phthalate

30.233

28.434

24.879

32.942

31.252

23.995

28.681

117-85-1

Technical

32

Di-n-octyl phthalate*

EPA 8061A, EPA Priority, EU

31.562

29.626

26.796

30.475

30.328

24.915

28.455

117-84-0

Neat

33

n-Hexyl decyl phthalate

31.680

29.748

26.878

30.788

30.450

24.994

28.566

25724-58-7

Technical

34

Diphenyl isophthalate

32.362

29.850

N/A

34.707

32.396

25.114

29.437

744-45-6

Neat

35

Dibenzyl phthalate

33.234

30.725

27.141

37.396

35.372

25.501

31.359

523-31-9

Neat

36

Diisononyl phthalate

EU

33.684

31.802

28.779

32.500

32.708

27.391

30.811

68515-48-0

Isomer mix

37

Di-n-octyl isophthalate

34.483

32.463

29.168

32.035

N/A

27.223

30.388

4654-18-6

Neat

38

Diisodecyl phthalate

EU

35.775

33.792

30.876

35.041

N/A

29.11

32.169

26761-40-0

Isomer mix

39

Dinonyl phthalate*

EPA 8061A

36.159

34.103

30.994

34.609

34.705

28.867

32.604

84-76-4

Neat

40

n-Octyl-n-decyl phthalate

36.182

34.170

30.961

34.664

34.7

28.861

32.628

119-07-3

Technical

Note: Shading indicates coeluting peaks (Rs<1.5). For each column, different colors of shading indicate different coelution pairs.
*These compounds are contained in Restek’s EPA Method 8061A phthalates esters mixture (cat.# 33227).


Table III: GC-MS Parameters

Parameters

Values for EPA EU List

Values for Extended List

Inlet temperature (°C)

280

280

Injection volume (µL)

1.0

1.0

Liner

Restek Premium 3.5 mm Precision liner w/ wool (cat.# 23320.1)

Restek Premium 3.5 mm Precision liner w/ wool (cat.# 23320.1)

Oven temperature program

200 °C (hold 0.5 min) to 330 °C* at 30 °C/min
(hold 1 min)

150 °C (hold 0.8 min) to 200 °C at 5 °C/min to 275 °C at 3 °C/min
(hold 2 min)

Carrier gas: He control mode

Constant linear velocity: 66.7 cm/sec @ 200 °C
(3 mL/min**)

Constant linear velocity: 48 cm/sec @ 150 °C
(1.6 mL/min)

Split ratio

20:1

20:1

Detector

MS

MS

Mode:

Full Scan (59–400)

Full Scan (59–400)

Transfer line temp.:

300 °C

300 °C

Scan event time

0.1 sec

0.1 sec

Analyzer type:

Quadrupole

Quadrupole

Source temp.:

280 °C

280 °C

Solvent delay time:

0.9 min

2.5 min

Tune type:

PFTBA

PFTBA

Ionization mode:

EI

EI

*320 °C for Rtx-50 column
**3 mL/min may be too high for some instruments. Consult your instrument operations manual prior to programming.


Although GC-MS is generally preferred because it provides more definitive information, phthalate analysis can also be successfully accomplished by GC-ECD. EPA 8061A is a method used to identify and quantify phthalates in aqueous and solid matrices using a parallel column configuration and dual electron capture detectors [8]. Rtx-440 and Rxi35Sil MS columns are ideal as a parallel dual column set. The Pro EZGC software provided rapid analysis conditions using the Rtx-440 column, and the Rxi-35Sil MS column served as an excellent confirmation column, due to the elution order changes that were observed. GC-ECD conditions can be easily translated from the GC-MS methods shown in Table III using Restek’s free online EZGC method translator; alternatively, optimized GC-ECD instrument parameters and example chromatograms are available at http://blog.restek.com/?p=17388 [9].

Conclusion

The seven GC columns most commonly used for phthalate analysis were directly compared using the Pro EZGC program, which provided flexibility and ease in GC optimization. The superior selectivity and high efficiency of the Rtx-440 and Rxi-XLB columns resulted in fast analysis times for both the regulated phthalates and the extended list. With good resolution, high maximum operating temperatures (340 °C for Rtx-440 and 360 °C for Rxi-XLB [Table IV]), and minimum phase bleed, the Rtx-440 and Rxi-XLB columns are the preferred choices for phthalate GC-MS analysis. A dual column set of Rtx-440 and Rxi-35Sil MS columns is recommended if GC-ECD is used instead of GC-MS.

Table IV: Maximum Temperatures

Rtx-440
(cat. 12923)

Rxi-XLB
(cat. 13723)

Rxi-5ms
(cat. 13423)

Rtx-50
(cat. 10523)

Rxi-35Sil MS
(cat. 13823)

Rtx-CLPesticides
(cat. 11123)

Rtx-CLPesticides2
(cat. 11323)

Maximum Temperature (°C)

340

360

350

320

360

340

340


Acknowledgements

The authors would like to thank Shimadzu Corporation for their consultation.

References

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[3] L. Trasande, S. Sathyanarayana, A.J. Spanier, H. Trachtman, T.M. Attina, E.M. Urbina, Urinary phthalates are associated with higher blood pressure in childhood. J. Pediatr. 163 (3) (2013) 747–753e1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4074773/
[4] E.F. Werner, J.M. Braun, K. Yolton, J.C. Khoury, B.P. Lanphear, The association between maternal urinary phthalate concentrations and blood pressure in pregnancy: The HOME Study. Environ. Health 14 (2015) 75. http://www.ehjournal.net/content/14/1/75
[5] J.J. Jaakkola, T.L. Knight, The role of exposure to phthalates from polyvinyl chloride products in the development of asthma and allergies: A systematic review and meta-analysis. Environ. Health Perspect. 116 (7) (2008) 845–853.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2453150/
[6] E.E. Hatch, J.W. Nelson, R.W. Stahlhut, T.F. Webster, Association of endocrine disruptors and obesity: Perspectives from epidemiological studies. Int. J. Androl. 33 (2) (2010) 324–332. http://www.ncbi.nlm.nih.gov/pubmed/20113374
[7] S. Net, A. Delmont, R. Sempere, A. Paluselli, B. Ouddane, Reliable quantification of phthalates in environmental matrices (air, water, sludge, sediment and soil): A review. Sci. Total Environ. 515-516 (2015) 162–180. http://www.ncbi.nlm.nih.gov/pubmed/25723871
[8] U.S. Environmental Protection Agency, Method 8061A, Phthalate Esters by Gas Chromatography with Electron Capture Detection (GC/ECD), Rev. 1, December 1996. https://www.epa.gov/sites/production/files/2015-12/documents/8061a.pdf
[9] D. Li, Phthalate determination by dual column set in eight minutes, ChromaBLOGraphy, Restek Corporation, 2015. http://blog.restek.com/?p=17388

Figure 1: EPA- and EU-listed phthalates and internal standard (benzyl benzoate) are shown under full scan mode and selected ion scan mode (m/z 293 and m/z 307) on seven different GC stationary phases (see Table III for conditions).

Rtx-440
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Peaks
1.Dimethyl phthalate
2.Diethyl phthalate
3.Benzyl benzoate
4.Diisobutyl phthalate
5.Di-n-butyl phthalate
6.Bis(2-methoxyethyl) phthalate
7.Bis[4-methyl-2-pentyl] phthalate isomer 1
8.Bis[4-methyl-2-pentyl] phthalate isomer 2
9.Bis(2-ethoxyethyl) phthalate
10.Di-n-pentyl phthalate
Peaks
11.Di-n-hexyl phthalate
12.Butyl benzyl phthalate
13.Hexyl-2-ethylhexyl phthalate
14.Bis(2-butoxyethyl) phthalate
15.Bis(2-ethylhexyl) phthalate
16.Dicyclohexyl phthalate
17.Di-n-octyl phthalate
18.Diisononyl phthalate
19.Diisodecyl phthalate
20.Dinonyl phthalate
EPA and EU Phthalates on Rtx-440
GC_EV1408

Rxi-XLB
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EPA and EU Phthalates on Rxi-XLB
GC_EV1409

Rtx-CLPesticides
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EPA and EU Phthalates on Rtx-CLPesticides
GC_EV1414

Rxi-35Sil MS
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EPA and EU Phthalates on Rxi-35Sil MS
GC_EV1413

Rtx-50
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EPA and EU Phthalates on Rtx-50
GC_EV1415

Rxi-5ms
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EPA and EU Phthalates on Rxi5ms
GC_EV1412

Rtx-CLPesticides2
(View larger)

EPA and EU Phthalates on Rtx-CLPesticides2
GC_EV1416

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Figure 2: Target compounds on the extended phthalate list (50 µg/mL) are separated under full scan mode on an Rtx-440 column (see Table III for conditions). (View larger)

Peaks
1.Dimethyl phthalate
2.Dimethyl isophthalate
3.Diethyl phthalate
4.Benzyl benzoate
5.Diisobutyl phthalate
6.Di-n-butyl phthalate
7.Bis(2-methoxyethyl) phthalate
8.Bis[4-methyl-2-pentyl] phthalate isomer 1
9.Bis[4-methyl-2-pentyl] phthalate isomer 2
10.Bis(2-ethoxyethyl) phthalate
11.Di-n-pentyl phthalate
12.Butyl cyclohexyl phthalate
13.Butyl 2-ethylhexyl phthalate
14.Di-n-hexyl phthalate
15.Butyl octyl phthalate
16.Butyl benzyl phthalate
17.Hexyl-2-ethylhexyl phthalate
18.Butyl isodecyl phthalate
19.Bis(2-ethylhexyl)hexahydro phthalate
20.Bis(2-n-butoxyethyl) phthalate
Peaks
21.Dicyclohexyl phthalate
22.Bis(2-ethylhexyl) phthalate
23.Butyl-n-decyl phthalate
24.Diphenyl phthalate
25.Bis(4-methylcyclohexyl) phthalate isomer 1
26.Bis(4-methylcyclohexyl) phthalate isomer 2
27.Hexyl isodecyl phthalate
28.Benzyl 2-ethylhexyl phthalate
29.Bis(4-methylcyclohexyl) phthalate isomer 3
30.Bis(2-ethylhexyl) isophthalate
31.Bis(2-(ethoxyethoxy)ethyl) phthalate
32.Di-n-octyl phthalate
33.n-Hexyl decyl phthalate
34.Diphenyl isophthalate
35.Dibenzyl phthalate
36.Diisononyl phthalate
37.Di-n-octyl isophthalate
38.Diisodecyl phthalate
39.Dinonyl phthalate
40.n-Octyl n-decyl phthalate
Phthalates (50 µg/mL) on Rtx-440 (Extended List, Full Scan Mode)
GC_EV1407

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