Determination of naphthalene and total methylnaphthalenes in gasoline using direct injection-mass spectrometry.

A high-speed determination of naphthalene and total methylnaphthalenes using a non-separative method based on direct injection into the mass spectrometer was performed. The results obtained for total methylnaphthalenes were very similar to those provided with fast gas chromatography-mass spectrometry (GC-MS). However, the non-separative method afforded higher concentrations in the determination of naphthalene than those found when fast GC-MS was used. We propose a correction that removes this error very satisfactorily and allows the same results to be obtained with both methodologies. The non-separative method is rapid, simple and - in view of the results - highly suitable for the determination of naphthalene and total methylnaphthalenes in gasoline samples.