Triglycerides and Glycerol Concentration Determinations Using Plasma FT-IR Spectra

Abstract

FT-IR spectrometry was used for plasma triglyceride and glycerol concentration measurements, based on their most characteristic IR absorbances within the 1200–800 cm⁻¹ interval. Plasma samples from 68 sportsmen were taken at rest and after an endurance exercise that induced important lipolysis. After subtraction of glucose and lactate absorbances from exercise plasma FT-IR spectra, triglyceride concentration was accurately determined using the spectral window centered at 1106 cm⁻¹ (0.86 ± 0.19 vs. 0.84 ± 0.17 mMol/L; r = 0.97, P < 0.01; SEP = 0.14 mMol/L). Total glycerol concentration (sum of glycerol and glyceryl residue concentrations) was determined using the spectral window centered at 926 cm⁻¹, which was found common to triglycerides and glycerol (0.306 ± 0.057 vs. 0.326 ± 0.051 mMol/L; r = 0.98, P < 0.01; SEP = 0.02 mMol/L). Glycerol concentration could be determined using the spectral window centered at 852 cm⁻¹ (0.216 ± 0.039 vs. 0.231 ± 0.048 mMol/L; r = 0.95, P < 0.01; SEP = 0.03 mMol/L). However, weak glycerol concentration could be only indirectly determined by subtracting glyceryl residue concentration from total glycerol concentration that had been determined using the spectral window centered at 926 cm⁻¹ (0.191 ± 0.061 vs. 0.176 ± 0.051 mMol/L; r = 0.90, P < 0.05; SEP = 0.02 mMol/L). Indeed, FT-IR spectrometry appears to be an accurate method for multiple biomolecular concentration determination on plasma samples.