Description General description 4-Methyl-2-pentanone (Methyl isobutyl ketone (MBK)) is an organic solvent widely used in various industrial applications, and exists as a clear colorless liquid with a pleasant odor. It is occasionally found as a volatile component of urine making it a biological marker of occupational exposure to this solvent. It is used as is used as a solvent for gums, resins, paints, varnishes, lacquers, and nitrocellulose. Application MBK may have been used as internal standard in GC/MS analysis for determining off-flavors in milk extracted using solid-phase microextraction, mass spectrometry, and multivariate analysis (SPME-MS-MVA). 4-Methyl-2-pentanone may be used as an analytical reference standard for the quantification of the analyte in hydro-alcoholic matrices using high-performance liquid chromatography with diode array detection.