Combined SPE and HPTLC as a Screening Assay of Urinary Cotinine from Male Adolescents Exposed to Environmental Tobacco Smoke**

Cotinine, as the main metabolite of nicotine, has been determined in urine using solid-phase extraction and the high-performance thin-layer chromatographic (SPE-HPTLC) method. The urine samples were collected from a group of 35 male adolescents which were moderate or significantly exposed to home environmental tobacco smoke (ETS). l-methyl-2-pyrrolidinone was used as the internal standard in the proposed screening procedure. The thin-layer chromatograms were evaluated densitometrically after visualization of cotinine spots with ninhydrin and cadmium acetate solution. The described SPE-HPTLC procedure indicated good selectivity, sensitivity and reproducibility, enabling reliable verification of interview collected questionnaire data in families exhibiting a diversified level of ETS. The results of cotinine measurements by the proposed method were applied for assessment of hazards from home ETS on the health status of elementary schoolboys, especially an increased risk for infectious respiratory tract diseases and exercise-induced bronchospasm.