Application of an assay for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in urine for the assessment of tobacco-related harm

Liquid-liquid extraction with UPLC-MS/MS is a convenient approach to measure low levels of NNAL in urine as a marker of biological NNK exposure, which can be used to assess the effectiveness of smoking reduction harm minimisation strategies. Enzymatic hydrolysis of NNAL-glucuronide and measuring the aglycone is not recommended.