Table 3b. Molecular Weights Associated With the Monoterpenes Detected by PTR-MS			
Compound	m/z (mass + 1)	Structure	Description
Terpinolene	81a, 82, 137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
	65, 71, 73, 75, 77, 83, 85, 86d, 87b, 89, 93, 97, 98d, 99, 101, 103, 107, 109, 111c*, 113*, 115, 123, 125, 126,127,129, 135, 141*, 143, 149, 159, 167,169, 183		unidentified oxidation products
beta-pinene	81, 82, 137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
	83, 93, 97, 103, 121, 122, 139, 140, 141*	C9H14OH+, C9H12H+	calibrated oxidation product: nopinone, isotopes and fragments
	69, 71, 73, 79, 83, 85, 89, 93, 99, 101, 107, 108d, 109, 111*, 113*, 115, 123*, 125, 127, 129, 135, 142, 149, 151*, 153, 155*, 157, 165, 167, 169*, 171, 183, 184d, 185, 198d		unidentified oxidation products
gamma-terpinene	81, 82, 137, 138	C9H14OH+, C9H12H+	monoterpene, fragments and isotopes
	107, 123*, 124, 151*, 152, 169*,170	C10H16O2H+	uncalibrated oxidation product:
 gamma-terpinaldehyde, fragments, and isotopes			
	57, 69, 71, 73, 74, 75, 77, 83, 85, 87, 89, 93, 97, 99, 101, 102, 103, 105, 107, 109, 111*, 113*, 115, 125, 127, 129, 131, 133, 135, 139, 141*, 143, 149, 153, 155*, 157, 159*, 165, 167, 171, 181, 183, 185, 199, 230d		unidentified oxidation products
gamma-terpinene	93, 95, 81, 82, 135,  137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
	107, 123*, 124, 151*, 152, 169*,170	C10H16O2H+	uncalibrated oxidation product:
 alpha-terpinaldehyde, fragments, and isotopes			
	65, 69, 71, 73, 75, 77, 87, 89, 97, 99, 101, 103, 109, 111*, 113*, 115, 125, 127, 129, 131, 135, 139, 141*, 143, 145, 153, 155*, 157, 158, 159*, 165, 167, 171, 178d, 181, 183, 184d, 185, 199, 201,202d, 229, 230d  		unidentified oxidation products
aIons associated with parent terpenes listed in bold font represent ions > 20% of the unfragmented parent terpene.			
bUnidentified oxidation products in bold font are ions with > 5% yield (on a mole basis) from the parent terpene.  
cUnidentified oxidation products with asterisks represent ions that were observed in the canopy air of a coniferous forest in California by PTR-MS [Holzinger et al., 2005]. 
dEven mass-to-charge ratio oxidation products that are not carbon isotopes of other oxidation products are likely gas-phase nitrogen containing products, e.g., organic nitrates.