As of my last knowledge update today, SME refers to a sample preparation technique widely used in analytical chemistry for the extraction and concentration of analytes from complex matrices.1
References
1Rani P, Nanda BP, Narang RK, Bhatia R. Advancements in solvent microextraction: Recent developments and diverse applications in the modern era. Separation Science Plus.:2300243. doi:10.1002/sscp.202300243