Effect of collision gas pressure and collision energy on reactions between oxygen and the negative molecular ion of tetrachlorodibenzo-p-dioxins in the collision cell of a triple -quadrupole mass spectrometer

✍ Scribed by R. Kostiainen; S. Auriola

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 380 KB
• Volume: 25
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210250502

✦ Synopsis

Low

-energy reactive collisions between the negative molecular ion of a tetrachlorodibenzo-pdioxin (TCDD) and oxygen inside the collision cell of a triple-stage quadrupole mass spectrometer produce a substitution ion IM -C1+ 01-, a phenoxide ion [C6H4-n02Clnl-', [M -HCIJ-', and CI-by which 1,2,3,4, 1,2,3,6/1,2,3,7-and2,3,7,&TCDD isomers can be distinguished either directly or on the basis of intensity ratios. The collision conditions have an important effect on the relative abundances. Energy-and pressure-resolved curves show that the ions formed by a collisionally activated reaction (CAR) process, i.e. [M -CI + 01-and [C6H4-n02CIn]-', are favoured by a high pressure of oxygen (3-6 mTorr) (1 Torr = 133.3 Pa) and a low collision energy (0.1-7 eV), whereas the ions formed by a collisionally activated dissociation (CAD) process, i.e. [M -HCII-' and C1-, are favoured by high pressure and high energy. By choosing a relatively low collision energy (5 eV) and high pressure (4 mTorr), the CAR and CAD ions can be clearly detected.