Combating selective ionization in the high resolution mass spectral characterization of complex mixtures.

Direct "dilute and shoot" mass spectral analysis of complex naturally-occurring mixtures has become the "standard" analysis in environmental and petrochemical science, as well as in many other areas of research. Despite recent advances in ionization methods, that approach still suffers several limitations for the comprehensive characterization of compositionally complex matrices. Foremost, the selective ionization of highly acidic (negative electrospray ionization ((-) ESI)) and/or basic (positive electrospray ionization ((+) ESI)) species limits the detection of weakly acidic/basic species, and similar issues (matrix effects) complicate atmospheric pressure photo-ionization (APPI)/atmospheric pressure chemical ionization (APCI) analyses.

Speciation of nitrogen-containing compounds in diesel fuel by comprehensive two-dimensional gas chromatography.

Nitrogen-containing compounds in diesel fuel have been speciated by comprehensive two-dimensional gas chromatography with nitrogen chemiluminescence detector (GC x GC-NCD). The speciation of nitrogen-containing compounds in diesel is difficult because of low concentration and complexity. The advantages of GC x GC are improved resolution and enhanced sensitivity.

Speciation of sulfur-containing compounds in diesel by comprehensive two-dimensional gas chromatography.

Sulfur-containing compounds in diesel have been speciated by comprehensive two-dimensional gas chromatography (GCxGC) with a sulfur chemiluminescence detector (SCD). The advantages of GCxGC technique are higher resolution and greater sensitivity. GCxGC-SCD can achieve the class separation of sulfur-containing compounds with an appropriate separation column combination.