Purpose: The aim of the present study was to develop a simple and accurate way to measure vitamin D levels. Vitamin D
nowadays is measured by a variety of methods which their common drawbacks are expensive equipment and the need for
high trained technical staff. In this research we measured vitamin D levels by means of Fourier transform infra red method
in conjugation with the evanescent wave spectroscopy technique, in order to develop a simpler vitamin D measurement
method. Methods: Blood samples were collected from patients with vitamin D deficiency at five intervals before and up to
16 days after they took a dose of 200,000 IU vitamin D3. Samples were measured by the conventional bio-chemical method
and by the evanescent wave spectroscopy means. Results: Correlation was found between the vitamin D levels measured
by the traditional method and by the evanescent wave spectroscopy technique. The absorption lines occurred prominently
in the IR spectral regions of the Amide I (≈1650 cm−1),Amide II (≈1530 cm−1) and the (≈3400 cm−1) absorption band which
is attributed to the hydroxyl group indicated by the O-H stretch. In addition, the examination of the blood samples using the
evanescent wave spectroscopy with clustering techniques facilitated the discrimination between vitamin D deficiency and
normal vitamin D levels. Practical relevance: This study demonstrates the potential of using the Fourier transform infra
red method in conjugation with the evanescent wave spectroscopy techniquecoupled with multivariate analysis as a nonexpensive,
rapid and accurate alternative to the routine methodologies.