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.

GC-APLI-MS as a powerful tool for the analysis of BaP-tetraol in human urine.

For the first time gas chromatography (GC) coupled to atmospheric pressure laser ionization-mass spectrometry (APLI-MS) has been applied to the analysis of trans-anti-benzo[a]pyrene-tetraol (BaP-tetraol) formed from anti-benzo[a]pyrene diolepoxide (BPDE), the ultimate carcinogen of benzo[a]pyrene. This tetraol is considered to be an ideal urinary biomarker for polycyclic aromatic hydrocarbon (PAH) exposure as it reflects internal body burden and potentially adverse health effects. Optimization of the derivatization and the instrumental set-up led to an instrumental LOD of 0.5 fg, an improvement of the lowest instrumental LOD reported in literature of 6.4 fg by a factor of 10. The optimized procedure includes derivatization of hydroxyl groups using methyl iodide and cool on-column injection to prevent degradation of the analyte. First measurements of urine samples demonstrate that the method is capable of detecting BaP-tetraol in human urine collected from both smokers and non-smokers. Although results of analysis indicate a certain underestimation compared with literature data, this method can be expected to serve as an excellent method for the analysis of the biomarker BaP-tetraol in the future if an adequate internal standard such as 13C-labeled BaP-tetraol is applied.

Carbocyclic L-nucleoside analogs as potential antiviral agents.

The syntheses of several carbocyclic L-nucleoside analogs starting from enantiomerically pure (1R,2S)-2-benzyloxymethylcyclopent-3-enol are described. The key step is the coupling of a protected nucleobase with different cyclopentane derivatives following a modified Mitsunobu protocol.