Optimization and comparison of GC-FID and HPLC-ELSD methods for determination of lauric acid, mono-, di-, and trilaurins in modified coconut oil

Abstract

Modified coconut oil (MCO) obtained from the glycerolysis of virgin coconut oil (VCO) and glycerol under various conditions should have different amounts of bioactive fatty acids (FAs) and acylglycerols (AGs). Methods were developed to analyze lauric acid (LA), monolaurin (ML), dilaurin (DL), and trilaurin (TL) in MCO samples using gas chromatography - flame ionization detector (GC-FID) and high performance liquid chromatography - evaporative light scattering detector (HPLC-ELSD). The purpose of this research is to optimize and compare GC-FID and HPLC-ELSD methods for determination of LA, ML, DL, and TL in MCO samples. All the standard curves exhibited good linearity (R2 ≥ 0.9995), except for that of LA analyzed by HPLC-ELSD (R2 = 0.9971). The limits of detection (LODs) and quantification (LOQs) were found to be in the range of 0.033–0.260 mg/ml and 0.099–0.789 mg/ml for the GC-FID method and 0.040–0.421 mg/ml and 0.122–1.277 mg/ml for the HPLC-ELSD method, respectively. The GC-FID method (LOD ≤ 0.033 mg/ml) was more sensitive than HPLC-ELSD method (LOD ≤ 0.421 mg/ml) and showed satisfactory recoveries for LA analysis while HPLC-ELSD method (LOD ≤ 0.040 mg/ml) was more sensitive than GC-FID method (LOD ≤ 0.260 mg/ml) and exhibited acceptable recoveries for TL analysis. Both methods were applied to determine the MCO samples produced under varied conditions for glycerolysis. The results revealed that the developed GC-FID method is suitable for the quantification of LA, ML, and DL while the developed HPLC-ELSD method is appropriate for the determination of ML, DL, and TL. Both developed GC–FID and HPLC–ELSD methods produced reproducible results for the determination of LA, ML, DL, and TL in MCO samples.