Molecular analytical release tags and their use in chemical analysis

A release tag compound for labeling substances for analytical purposes, said compound being represented by the formula

• Sg--CO--L--Rx
• wherein:
• each Sg is a signal group, each CO is a carbonyl group to which an Sg is bonded, each Rx is a reactivity group, L is a linking group to which each SgCO group and each Rx group are bonded, and each COL portion is a release group which is cleavable to release an Sg-containing compound;
• and wherein:
• each Sg is a C-linked organic moiety containing from 1 to 20 carbon atoms, the carbon atom of Sg which is bonded to the carbonyl carbon adjacent to linking group L being denominated as the .alpha.-position, and Sg comprises a radical selected from the group consisting of substituted alkyl, substituted keto-alkyl, substituted alkenyl, and substituted alkynyl radicals;
• said substituted alkyl, substituted keto-alkyl, and substituted alkenyl radicals bearing at least two electronegative substituents, and said substituted alkynyl radicals bearing at least one electronegative substituent;
• said electronegative substituents being selected from the group consisting of halogens, cyano, dihalomethyl and trihalomethyl;
• and further,
• 1) when Sg is keto-alkyl, alkenyl, or alkynyl, Sg comprises at least one moiety selected from the group consisting of:
• .beta.-E-alkynyl, .alpha.-E-.alpha.-alkynyl, .beta.-E-.alpha.-keto (provided that the carbonyl carbon adjacent to linking group L is connected to a nitrogen or oxygen atom of L), .alpha.-E-alkenyl, and .alpha.-E-.alpha.-alkenyl, wherein E is an electronegative substituent selected from the group consisting of halogens, cyano, dihalomethyl, and trihalomethyl;
• 2) when Sg is alkyl, the .alpha.-carbon atom bears at least two of said electronegative substituents but no more than one fluorine atom;
• each Sg being further selected such that upon cleavage of said release tag compound at said COL portion, signal group Sg is released in a volatile form suitable for electron capture determination in the gas phase;
• L is oxy or amino;
• and
• Rx comprises a phenylene moiety which is connected to L and which contains a reactive, functional group.