GC-FID Method Note – Phthalates (EPA 606)

Analysis of Phthalate Esters (US EPA Method 606) in the miniGC

Introduction

Phthalates or phthalate esters are plasticizers that add flexibility to materials like PVC (polyvinylchloride). They are a very commonly occurring persistent organic pollutant (POP) that can be found in the environment and food and are a toxicity concern, therefore methods and regulations like the EPA Method 606 have been developed to monitor their presence.

Reference Method

(https://www.restek.com/en/pages/chromatogram-view/GC_CF01131)

Column	MXT-5, 30 m, 0.53 mm ID, 1.00 µm
Sample	606 Phthalate Esters Calibration Mix (Restek PN: 31031)
Conc.	50 ng per compound
Injection
Inj. Vol.:	0.5 uL split injection (split ratio 50:1)
Liner:
Inj. Temp.:	300°C
Oven
Oven Temp.:	Hold at 40°C for 6 min Ramp to 300°C @ 10°C/min Hold at 300°C for 15 min
Carrier Gas	H2, constant linear velocity
Linear Velocity:	50 cm/sec

Detector	FID @ 300°C
Instrument

Reference Standard

Reference Standard 606 Phthalate Esters Mix (Restek PN: 31031)

1. dimethyl phthalate
2. diethyl phthalate
3. di-n-butyl phthalate
4. butyl benzyl phthalate
5. bis(2-ethylhexyl)phthalate
6. di-n-octyl phthalate

2,000 ug/mL of each compound in methanol

Reference Chromatogram

Peaks:

1. dimethyl phthalate
2. diethyl phthalate
3. di-n-butyl phthalate
4. butyl benzyl phthalate
5. bis(2-ethylhexyl)phthalate
6. di-n-octyl phthalate

miniGC Method

Column	MXT-5, 30 m, 0.25 mm ID, 0.25 µm (Restek PN: 70223-LUC25)
Sample	606 Phthalate Esters Calibration Mix (Restek PN: 31031)
Injection
Inj. Vol.:	0.5 µL split injection (split ratio 50:1)
Liner:	4 mm low pressure drop precision inlet liner w/ wool (Restek PN: 23309)
Inj. Temp.:	300°C
Oven
Oven Temp.:	Hold at 40°C for 6 min Ramp to 300°C @ 10°C/min Hold at 300°C for 15 min
Carrier Gas	He, constant flow
Linear Velocity:	47.2 cm/sec, 2.50 mL/min

Detector	FID @ 300°C
Instrument	Lucidity miniGC

miniGC Chromatograms

Results

This was a very quick experiment to see how closely we could replicate the chromatogram produced on a traditional GC by injecting a standard into the miniGC and comparing the chromatogram to the same chromatogram produced on the traditional GC using the same standard and roughly the same method and column. We used a slightly different method and column for convenience sake using a different carrier gas and a smaller ID column. But overall, the chromatograms looked very similar for the two systems compared, which is a success. Further experiments are planned.

More results from the miniGC can be found here: https://luciditysystems.com/products/minigc/minigc-results/

More information on the miniGC can be found here: https://luciditysystems.com/products/minigc/

To see the miniGC in operation go here: https://luciditysystems.com/products/minigc/minigc-interface/