Ultra-high sensitive analysis of 3-hydroxybenzo[a]pyrene in human urine using GC-APLI-MS

Urinary 3-hydroxybenzo[a]pyrene (3-OH-BaP) is a known biomarker for human exposure to carcinogenic polycyclic aromatic hydrocarbons (PAH). In this work, a new method for the ultra-sensitive quantification of this biomarker has been developed using the hyphenation of gas chromatography and atmospheric pressure laser ionization-mass spectrometry (GC-APLI-MS). In combination with an advanced sample preparation, a limit of detection (LOD) of 0.6 pg/L was achieved which is an improvement by a factor of at least 28 compared with existing methods. The limit of quantification (LOQ) is 1.8 pg/L. With this set-up 3-OH-BaP could be analyzed in urine samples of 7 smokers and 7 non-smokers. Concentrations ranged from 37 to 270 pg/L for non-smokers and from 374 to 1171 pg/L for smokers. For the first time, 3-OH-BaP was quantifiable in all non-smoker samples as no value was below the LOQ. Correlation of the urinary 3-OH-BaP values with the number of daily smoked cigarettes and with urinary cotinine values shows a clear relationship between 3-OH-BaP content and smoking habits. This innovative analytical method enables monitoring of low levels of the biomarker 3-OH-BaP in urine of non-occupationally exposed individuals including smokers, the general population with background PAH exposure and cohorts of low exposition such as newborns and children.