Spectroscopic Analysis of Melatonin in the Terahertz Frequency Range.

Uroš Puc,Gintaras Valušis,Andreja Abina,Irmantas Kašalynas,Anton Jeglič,Aleksander Zidanšek,Rimvydas Venckevičius

doi:10.3390/s18124098

Abstract

There is a need for fast and reliable quality and authenticity control tools of pharmaceutical ingredients. Among others, hormone containing drugs and foods are subject to scrutiny. In this study, terahertz (THz) spectroscopy and THz imaging are applied for the first time to analyze melatonin and its pharmaceutical product Circadin. Melatonin is a hormone found naturally in the human body, which is responsible for the regulation of sleep-wake cycles. In the THz frequency region between 1.5 THz and 4.5 THz, characteristic melatonin spectral features at 3.21 THz, and a weaker one at 4.20 THz, are observed allowing for a quantitative analysis within the final products. Spectroscopic THz imaging of different concentrations of Circadin and melatonin as an active pharmaceutical ingredient in prepared pellets is also performed, which permits spatial recognition of these different substances. These results indicate that THz spectroscopy and imaging can be an indispensable tool, complementing Raman and Fourier transform infrared spectroscopies, in order to provide quality control of dietary supplements and other pharmaceutical products.

Highlights

Hormones are crucial for the control and regulation of many different human body processes and everyday life activities
1010wt%, left—melatonin wt%,bottom bottomright—Circadin right—Circadin 10. These results show that THz spectroscopy and THz spectroscopic imaging can become an indispensable analytical tool in the recognition and identification of active pharmaceutical ingredient (API) in pharmaceutical products and counterfeits, complementing other known methods such as Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), vibrational spectroscopy, Raman spectroscopy, nuclear quadrupole spectroscopy, chromatography, and mass spectroscopy [20,54,55,56]
The spectroscopic THz approach is capable of detecting very small

Summary

Introduction

Hormones are crucial for the control and regulation of many different human body processes and everyday life activities. Novel rapid and accurate analytical methods for the determination of hormones in biological samples, pharmaceutical products, water and food, and to ensure product quality control are needed [2,3]. Developments in the terahertz (THz) technology show a promising potential for applications in many fields [12,13,14,15,16,17,18] with great emphasis on the pharmaceutical industry [19,20,21,22,23], as the far-infrared frequency

Methods

Results

Conclusion