Measurement methods, peroxy radicals chemical conversion

Reiner, T., M. Hanke, and F. Arnold, Atmospheric Peroxy Radical Measurements by Ion Molecule Reaction-Mass Spectrometry A Novel Analytical Method Using Amplifying Chemical Conversion to Sulfuric Acid, J. Geophys. Res., 102, 1311-1326 (1997). 

For example, Cantrell and co-workers (1993) estimate the efficiency of conversion of simple alkyl peroxy radicals to vary from 0.93 for CH3CH202 to 0.47 for (CH3)2C02, and it may be even less for larger alkyl peroxy radicals. This may be the reason that in some intercomparison studies, the matrix isolation-ESR technique (vide infra), which measures the sum of ROz, gives some higher concentrations for some individual measurements than the chemical amplifier method (e.g., Zenker et al., 1998). 

The discussion that follows is divided into two sections. The Spectroscopic Methods section includes those measurement techniques that involve the interaction of a photon with a peroxy radical. The Chemical Conversion Methods section describes the measurement of another molecule or radical to which a peroxy radical has been converted. 

Chemical Amplification. The measurement of a small electrical signal is often accomplished by amplification to a larger, more easily measured one. This technique of amplification can also be applied to chemical systems. For peroxy radicals, Cantrell and Stedman (117) proposed, as a possible technique, the chemical conversion of peroxy radicals to N02 with amplification (i.e., more than one N02 per peroxy radical). This method has also been used for laboratory studies of H02 reactions on aqueous aerosols (21). The following chemical scheme was proposed as the basis of the instrument ... 

---