Ketoprofen-d3 has been used as a surrogate analytical standard for the determination of ketoprofen in sewage sludge samples by QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction with on-line solid-phase extract purification and pre-concentration, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). It may be used as an analytical standard for the determination of ketoprofen in compost from sewage sludge by ultrasound-assisted extraction (UAE) and salt-assisted liquid–liquid extraction (SALLE), followed by ultrahigh performance liquid chromatography (UHPLC) coupled to MS/MS.