A rapid and sensitive method is described for the detection of melatonin in
rat pineal gland and melatonin tablets. Capillary electrophoresis (CE) wit
h electrochemical detection (EC) was used. This method had high sensitivity
and good reproducibility. The detection limit of melatonin was as low as 1
.3 x 10(-9) mol/l (0.30 fg). There was a linear range of concentration from
3.9 x 10(-7) to 3.25 x 10(-5) mol/l with a correlation coefficient of 0.99
9. The linear equation was Y = 8.27 + 0.0042X with a slope of 0.0042 pA/nM.
The relative standard deviations of the peak current response and the migr
ation time for 16 continuous injections of 6.5 mu M melatonin were 4.5 and
0.48%, respectively. The proposed method was applied to detect melatonin in
the rat pineal gland and the melatonin tablets. Good results were obtained
compared with previous reports. (C) 1999 Elsevier Science B.V. All rights
reserved.