LC-MS determination of catecholamines and related metabolites in red deer urine and hair extracted using magnetic multi-walled carbon nanotube poly (styrene-co-divinylbenzene) composite

A novel analytical methodology for the extraction and determination of catecholamines (dopamine, epinephrine and norepinephrine) and their metabolites DL-3,4-dihydroxyphenyl glycol and DL-3,4-dihydroxymandelic acid by LC-MS is developed and validated for its application to human and animal urine and hair samples. The method is based on the preliminary extraction of the analytes by a magnetic multi-walled carbon nanotube poly (styrene-co-divinylbenzene) composite. This is followed by a < 9 min chromatographic separation of the target compounds in an Onyx Monolithic C-18 column using a mixture of 0.01% (v/v) heptafluorobutyric acid in water and methanol at 500 mu L min(-1) flow rate. Detection limits within range from 0.055 to 0.093 mu g mL(-1), and precision values of the response and retention times of analytes were > 90%. Accuracy values comprised the range 79.5-109.5% when the analytes were extracted from deer urine samples using the selected MMWCNT-poly (STY-DVS) sorbent. This methodology was applied to real red deer urine and hair samples, and concentrations within range from 0.05 to 0.5 mu g mL(-1) for norepinephrine and from 1.0 to 44.5 mu g mL(-1) for its metabolite 3,4-dihydroxyphenyl glycol were calculated. Analyses of red deer hair resulted in high amounts of 3,4-dihydroxyphenyl glycol (0.9-266.9 mu g mL(-1)).