A new instrumental method for the determination of 29 phthalate esters, including six recently banned from baby toys by the European Union, using positive chemical ion- ization and retention-time locking is described.
This document presents a new instrumental method for determining 29 phthalate esters, including six recently banned by the European Union. The method utilizes positive chemical ionization (PCI) and retention-time locking (RTL) to improve the identification and discrimination of these compounds in various matrices.
The text details the experimental setup involving an Agilent 6890Plus Gas Chromatograph, 7683 Automatic Liquid Sampler, and 5973N Mass Selective Detector (MSD) with a CI option. It compares the use of methane versus ammonia as reagent gases for PCI, demonstrating that ammonia provides a cleaner spectrum where the protonated molecule is the base peak, facilitating easier identification.
| Injection Port Temperature | 300°C |
|---|---|
| Pulse Pressure & Time | 25.0 psi 1.00 min |
| Purge Flow & Time | 20.0 mL/min 3.00 min |
| Gas Saver Flow & Time | 20.0 mL/min 3.00 min |
| Initial Flow & Mode | 1.2 mL/min Constant Flow |
| MSD Transfer Line Temp | 325°C |
Ammonia is recommended as the reagent gas to reduce chemical noise and enhance identification.
RTL allows for the creation of compound acquisition methods and quantitation databases that can be reproduced in any laboratory anywhere.
The protonated molecule is the single dominant peak in the ammonia PCI mass spectrum.