HPLC-FLU detection of cortisol distribution in human hair

Recently cortisol level in hair is supposed to be a good biomarker of chronic stress. We had developed a new method based on HPLC-FLU for identification of cortisol in human hair and measured cortisol distribution of each 1-cm segment along hair shaft. Hair sample was pulverized and incubated in 0.1 M HCl and extracted with ethyl acetate. The extraction was derived with sulfuric acid. The derivative was extracted with SPE C18 column. The detection limit was 1 pg/mg, the intraday and interday precisions were 7.3% and 8.5%, and average recovery was 102.5 ± 13.0%. Cortisol concentrations of 32 humans' hair ranged from 3.28 to 24.83 pg/mg. There was a distinct decline in the cortisol of 1-cm segment along hair shaft. This method showed that the precision was matched with mass spectroscopy. The cortisol in 1-cm hair segment sensitively reflects a retrospective calendar over 1 month.