| Peony seed is an ideal oil resource, it is very rich in oil content, and which contain the amount of unsaturated fatty acids is very high. In this study, peony seed oil was selected as the study object of new analysis method for fatty acid, we eventually established a set of accurate and reliable analysis determination method for fatty acid by a series of methods study, optimization, verification and comparative experiments, and then this method (UPLC-ELSD method) was used very well.Firstly, the chromatographic conditions and the working parameters of UPLC-ELSD were optimized, chromatographic condition was as follows:Welch Ultimate UHPLCXB-C18 column (2.1mm × 100mm,1.8μm); the A of the mobile phase:0.2% of acetic acid methanol solution, the B of the mobile phase:0.2% acetic acid water solution, A:B = 85:15, the flow rate was 0.40 mL/min; column temperature was set as 30℃; injection volume was 1μL. The working parameters of detector:drift tube temperature was 95 ℃; oil free air pump provided carrier gas, and the flow rate of carrier gas was 2.8 L/min; gain was set to 4.Then we conducted a series of method study experiment. The experimental results show that:the linear relationship of linolenic acid, linoleic acid, palmitic acid, oleic acid and stearic acid was very well, and the linear correlation coefficient(R) respectively was 0.9932,0.9996,0.9955,0.9952 and 0.9915. the stability of this method was very well (the RSD values of each fatty acid respectively was 1.79%,1.44%,0.76%,1.38% and 2.12%), the reproducibility of this method also was very well (the RSD values of each fatty acids respectively was 1.75%,2.38%, 1.56%,2.27% and 2.16%), the sensitivity of this method was well (minimum detection limit of each fatty acid respectively was 0.01,0.01,0.02,0.02,0.02 mg/mL), it had high recovery rate(the average recovery of each fatty acid was 98.8%、98.6%、98.6%、 97.1% and 98.2%).Saponification conditions after being optimized:KOH- methanol solution concentration was 0.70 mol/L, saponification time was 70min, saponification temper- ature was 62.2 ℃; the content of total fatty acid was 700.26 mg/g through the final verification test, and the theoretical value was 693.82 mg/g, the error was only 0.93%, less than 1%.After measuring the remaining triglycerides in saponification sample, we found that the triglycerides chromatographic peak in saponification sample of peony seed oil was completely disappeared, it also proved that the best saponification process parameters was indeed very reliable. In addition, this method was indeed a feasible new analysis technique by comparing with gas chromatography.By comparing peony seed oil with several other edible oil through the UPLC-ELSD method, we found that the amount of linolenic acid (336.04 mg/g) in peony seed oil was high, second only to linseed oil (490.01 mg/g), far more than the common tea oil (126.18 mg/g), rice bran oil (95.76 mg/g) and our daily consump-tion arowana cooking oil (192.83 mg/g); secondly, the peony seed oil was rich in oleic acid (148.75 mg/g) and linoleic acid (163.21 mg/g), and the quantity of saturated fatty acid (palmitic acid and stearic acid) was minimum, in other word, The proportion of unsaturated fatty acids was highest in peony seed oil. In addition, the total amount of fatty acid in peony seed oil was also very high (total 700.26 mg/g), which more adequately explained that peony seed oil had great value and broad application prospect. |
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