Preparation of aqueous reference materials for cholesterol and glycerol.

Study on reference materials. The certified reference materials GBW09203b and GBW09149 were weighed accurately and dissolved into 20% of methyl cyclodextrin aqueous solution to prepare six kinds of candidate reference materials of cholesterol and glycerol according to the concentration. The materials were tested for homogeneity and stability using routine methods. The reference methods of isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) were used to determine the concentration of cholesterol and glycerol to evaluate the accuracy of the certified values.Meanwhile, the blank verification test was carried out.The expanded uncertainty was the combination of standard uncertainty of measurement, unhomogeneity and instability.

It showed that the six candidate reference materials were homogeneous and stable for at least 1 year at -70 ℃ and -20 ℃.The certified values (reference value ± expanded uncertainty, mmol/L) were as follows, for cholesterol: 0.65±0.01, 1.31 ±0.01, 2.57±0.02, 5.21±0.06, 7.71±0.08, 10.24±0.06; for glycerol: 0.29±0.01, 0.58±0.01, 1.22±0.02, 2.24±0.02, 3.46±0.04, 4.52 ±0.04. The results of reference methods were consistent with the certified values. Blank validation tests showed that the concentration of the analytes would not be affected by the reagent and the blank matrix.

Certified reference materials for cholesterol and glycerol in aqueous solution have been prepared successfully. These materials are homogeneous and stable, and the certified values are reliable. Therefore the materials have been approved to be the Certificate Reference Materials of GBW 09823, GBW 09824, GBW 09825, GBW09826, GBW09827 and GBW 09828.(Chin J Lab Med, 2017, 40: 520-525)

Cholesterol; Triglycerides; Cyclodextrins; Solutions; Indicators and reagents; Reference standards; Tandem mass spectrometry