Characterization of lubricity improver additive in diesel by gas chromatography-mass spectrometry.

The characterization of lubricity improver additives by GC-MS-SIM is an important tool for the development and monitoring of new formulations as well as for quality control of additives in diesel. A simple method for the quantification of a linoleic oil additive derivative in diesel has been developed. Calibration is performed by analysis of standard solutions containing 2-hydroxy-ethyl linoleate with pentadecanoyl propanoate as the internal standard. The proposed method permitted the quantification of the linoleate ester at a concentration of 300 microg/mL in the additived diesel. The recovery of additive and the repeatability of the quantitative results are evaluated.

Enzymatic synthesis of medium chain monoglycerides in a solvent-free system.

The synthesis of monocaprin, monolaurin, and monomyristin in a solvent-free system was conducted by mixing a commercial immobilized lipase with the organic reactants (glycerol and fatty acids) in a 20-mL batch reactor with constant stirring. The effects of temperature, fatty acid/glycerol molar ratio, and enzyme concentration on the reaction conversion were determined. The addition of molecular sieves in the assays of monomyristin synthesis was also evaluated. The reactions were carried out for 5 to 6 h and the nonpolar phase was analyzed by gas chromatography. The best results in terms of selectivity and conversion (defined as the percentage of fatty acid consumed) were achieved when the stoichiometric amount of reagents (molar ratio = 1) and 9% (w/w) commercial enzyme were used and the reaction was performed at 60 degrees C. The addition of molecular sieves did not improve the synthesis of monomyristin. Conversions as high as 80%, with monoglycerides being the major products, were attained. After 5 h of reaction, the concentration of monoglyceride was about twice that of diglyceride, and only trace amounts of triglyceride were found. The results illustrate the technical possibility of producing medium chain monoglycerides in a solvent-free medium using a simple batch reactor.