Abstract

Saliva provides a valuable tool for assessing oral and systemic diseases, but concentrations of salivary components are very small, calling the need for precise analysis methods. In this work, Fourier transform infrared (FT-IR) spectroscopy using transmission and photoacoustic (PA) modes were compared for quantitative analysis of saliva. The performance of these techniques was compared with a calibration series. The linearity of spectrum output was verified by using albumin–thiocyanate (SCN^–) solution at different SCN^– concentrations. Saliva samples used as a comparison were obtained from healthy subjects. Saliva droplets of 15 µL were applied on the silicon sample substrate, 6 drops for each specimen, and dried at 37 ℃ overnight. The measurements were carried out using an FT-IR spectrometer in conjunction with an accessory unit for PA measurements. The findings with both transmission and PA modes mirror each other. The major bands presented were 1500–1750 cm^–1 for proteins and 1050–1200 cm^–1 for carbohydrates. In addition, the distinct spectral band at 2050 cm^–1 derives from SCN^– anions, which is converted by salivary peroxidases to hypothiocyanate (OSCN^–). The correlation between the spectroscopic data with SCN^– concentration (r > 0.990 for transmission and r = 0.967 for PA mode) was found to be significant (P < 0.01), thus promising to be utilized in future applications.

© 2016 The Author(s)

Photoacoustic phase-controlled Fourier-transform infrared spectroscopy

Santeri Larnimaa, Mikhail Roiz, and Markku Vainio
Opt. Continuum 2(3) 564-578 (2023)

Analysis of aircraft exhausts with Fourier-transform infrared emission spectroscopy

Jörg Heland and Klaus Schäfer
Appl. Opt. 36(21) 4922-4931 (1997)

High temperature Fourier transform photoacoustic spectroscopy: sample emission effects

S. McGovern, B. S. H. Royce, and J. Benziger
Appl. Opt. 24(10) 1512-1514 (1985)

Fourier transform spectroscopy of LaS in the infrared

R. J. Winkel, Sumner P. Davis, and Mark C. Abrams
Appl. Opt. 35(16) 2874-2878 (1996)

Quantitative Fourier transform IR photoacoustic spectroscopy of condensed phases

Y. C. Teng and B. S. H. Royce
Appl. Opt. 21(1) 77-80 (1982)