The national standards of biofuels specify the technique specification and analytical methods. A water content certified reference material based on the water saturated octanol was developed in order to satisfy the needs of the instrument calibration and the methods validation, assure the accuracy and consistency of results in water content measurements of biofuels. Three analytical methods based on different theories were employed to certify the water content of the reference material, including Karl Fischer coulometric titration, Karl Fischer volumetric titration and quantitative nuclear magnetic resonance. The consistency of coulometric and volumetric titration was achieved through the improvement of methods. The accuracy of the certified result was improved by the introduction of the new method of quantitative nuclear magnetic resonance. Finally, the certified value of reference material is 4.76% with an expanded uncertainty of 0.09%.
Biofuels ; standards ; Magnetic Resonance Spectroscopy ; methods ; Octanols ; chemistry ; Reference Values ; Water ; analysis

Objective To investigate DNA methylation markers in the whole blood of patients with systemic lupus erythematosus(SLE),in hope to facilitate the evaluation of SLE severity.Methods Whole blood samples were obtained from 58 patients with SLE(including 14 cases of severe SLE,25 moderate SLE,19 inactive SLE)and 50 healthy controls.Bisulphite sequencing was performed to determine the methylation status of interleukin-2 common receptor gamma chain(IL-2RG)promoter region,and real-time reverse transcriptionPCR to quantify the expression level of IL-2RG mRNA,in these subjects.Results The methylation level of IL2RG promoter region was 0.217 ± 0.140,0.325 ± 0.230,0.342 ± 0.085 and 0.175 ± 0.036 in the patients withsevere,moderate and inactive SLE and healthy controls,respectively.A significant increase was observed in the methylation level of IL-2RG promoter region in the patients with inactive SLE compared with the patients with severe SLE and healthy controls(both P ＜ 0.01),and in the patients with SLE compared with the healthy controls(0.263 ± 0.047 vs.0.175 ± 0.036,P ＜ 0.05).The expression level of IL-2RG mRNA was significantly lower in the patients with SLE than in the healthy controls(2.550 ± 0.823 vs.4.293 ± 1.283,P ＜ 0.05).A negative correlation was observed between the expression level of IL-2RG mRNA and methylation level of IL2RG promoter region in 20 patients with SLE(r =-0.44,P ＜ 0.05).Conclusion The methylation status of IL2RG promoter region is statistically higher in patients with SLE than in healthy controls,and significantly different between patients with active SLE and those with stable SLE.