ANALYSIS OF SOLUTION AND GAS PHASE MOLECULAR STATES OF FORMALDEHYDE BY GAS CHROMATOGRAPHY AND CHEMICAL IONIZATION MASS SPECTROMETRY.

摘要

Formaldehyde is a highly reactive compound that exists at equilibrium in hydrated oligomeric forms, polyoxymethylene glycols, in aqueous solution. Methanol is added to formaldehyde solution to prevent precipitation of longer chain oligomers through formation of more soluble monomethyl ethers of the polyoxymethylene glycols. Each of these condensates of formaldehyde exerts its vapor pressure independently so that a complex mixture of compounds is emitted from formalin. But hydrated species of formaldehyde have yet to be detected in the gas phase. Trimethylsilylation of the oligomeric formaldehyde hydroxyl groups by N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) prevents interconversion of the oligomers, allowing the formaldehyde derivatives to be separated by gas chromatography. Development of a gas phase derivation technique with BSTFA coupled with chemical ionization (CI) mass spectrometry with ammonia as the reactant gas was used to characterize the TMS derivatized oligomers present in the headspace above reagent grade formalin solution. Application of the fundamental flame ionization detector principle of equal per carbon response, verified for TMS derivatizes with a series of trimethylsilylated alcohols and glycols, allowed quantitations of the individual derivatized oligomers in formalin solution and the solution headspace.