Hyphenation of atmospheric pressure chemical ionisation mass spectrometry to supercritical fluid chromatography for polar car lubricant additives analysis.
Car lubricant additives are added to mineral or synthetic base stocks to improve viscosity and resistance to oxidation of the lubricant and to limit wear of engines. As they belong to various chemical classes and are added to a very complex medium, the base stock, their detailed chromatographic analysis is very difficult and time consuming. In a previous paper, it was demonstrated that supercritical fluid chromatography (SFC) allows the elution of common low-molecular-weight additives. Since their total resolution could not be achieved owing to the limited peak capacity of packed columns, the hyphenation of selective and informative detection methods such as atomic emission detection (AED) was required. Further to results obtained in SFC-AED, this work describes the hyphenation of SFC to atmospheric pressure chemical ionisation ion trap mass spectrometry (MS). SFC-MS hyphenation is detailed: temperature, flow rates of gas and mobile phase introduced in the source, position of the restrictor, ionisation additives and conditions of autotune are studied. Car lubricant monitoring requires negative and positive ionisation modes with or without the addition of ionisation auxiliary solvent according to the nature of additives. Moreover, when sensitivity is of major concern for a selected additive, the autotuning routine of the MS has to be performed in conditions as close as possible to analytical conditions, i.e. under subcritical conditions. Unambiguous identification and structure elucidation of several additives in formulated car lubricants are also presented.
Lavison-Bompard
Gwenaelle
G
Laboratoire Environnement et Chimie Analytique (UMR CNRS 7121), Ecole Supérieure de Physique et de Chimie Industrielles de Paris, Paris cedex 05, France.
Thiébaut
Didier
D
Beziau
Jean-François
JF
Carrazé
Bernadette
B
Valette
Pascale
P
Duteurtre
Xavier
X
Tabet
Jean-Claude
JC
D001274:Atmospheric Pressure; D001336:Automobiles; D002245:Carbon Dioxide / Q000737:chemistry; D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D004867:Equipment Design; D054327:Lubricants / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D015203:Reproducibility of Results; D013696:Temperature
D054327:Lubricants; D002245:Carbon Dioxide