An automatic SPME/GCMS assay to measure mono and dihydrohy naphthalenes in human urine

Due to its toxicological relevance and its large presence in working and living environments the need for a specific biological monitoring of naphthalene exposure is recognize. The traditional assay to measure naphthalene metabolites in urine employs time consuming sample preparation, typically performed by liquid-liquid or solid phase extraction, followed by chromatographic analysis. Aim of this work was to set a simple and automatic assay to measure naphthalene mono and dihydroxy metabolites in human urine and to test its applicability in biological monitoring. Solid phase microextraction (SPME) with on-fiber derivatization was chosen for sample preparation. Optimization was carried on using several fiber coatings and different silylating agents. Stability of the samples was obtained by addition of an antioxidant solution. Separation and detection of the analytes was obtained by GC/MS. The presence of naphthalene metabolites in subjects with different exposures was assayed. A novel and automatic SMPE GC/MS assay in which 1- and 2-naphthol, and 1,2-, 1,4-, 1,7- and 2,6- dihydroxynaphthols were directly sampled from urine and derivatized by immersion of a PDMS-DVB fiber in silylating agent vapours, was set. Preliminary results obtained analyzing urine samples of non-smoking and smoking not occupationally exposed subjects, and coke oven workers showed levels in the range of those obtained using a traditional approach. The developed assay is simple, and time and reagent saving. It opens interesting perspectives to enlarging biomonitoring of naphthalene exposure in humans