The analysis of sucrose esters with long acyl chain by improved high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD) and electrospray ionization mass spectrum (ESI-MS) is investigated. The improved HPLC-ELSD method for the separation and quantitation of commercial and synthesized sucrose esters is described. Samples are analyzed by means of a reversed-phase (RP) HPLC using a Hypersil C8 column (250 mmx4.6 mm, 5 mu m particle size) with methanol-tetrahydrofuran (volume ratio of 90 : 10) and water under gradient condition as the mobile phase, in which the flow rate is 1.0 ml.min(-1) and the column temperature is set at 40 degrees C. This procedure provides a complete separation and determination of monoester, diester, triester and higher esters with different acyl chain lengths in each fraction by a single run, in combination with the ESI-MS technology. With this method, it is possible to determine the approximate compositions of mono-to polyesters in one analysis and quantitate pure positional isomers precisely using an external standard method. It is found that the method of ESI-MS coupling with HPLC system for the analysis of sucrose esters is straight forward, rapid and inexpensive, and can be readily applied in synthesis, purification and structure studies.