Pantothenic acid, also known as vitamin B5, is a water-soluble vitamin with a chemical formula of C9H17NO5. It is one of the essential vitamins for the human body. It exists in all living tissues and is widely distributed in nature, hence the name pantothenic acid. Pantothenic acid is widely used, and pantothenic acid is present in most foods and health care products. However, the matrix of food and health care products is complex, and interference often occurs.
It can be seen that the structure of pantothenic acid contains an amino group, and sulfonic acid ion-pairing reagents can be used to enhance its retention, so as to achieve the purpose of separation from the interfering matrix.
The sample is a full-nutrition special medical food containing protein, fat, carbohydrates, trace elements, multivitamins, spices, etc. The ingredients are very complex. According to the national standard GB5009.210-2016 standard for pantothenic acid in food, the results showed that the unknown impurities interfered seriously and could not be detected.
Original mobile phase: 0.02mol/L potassium dihydrogen phosphate solution/acetonitrile=95/5.
Analysis: Black is the pantothenic acid reference substance, blue is the sample, the matrix interference is serious, and there are many interference components before and after the pantothenic acid peak. Quantitative detection is not possible. However, there is no room for optimization in the organic phase ratio in the original condition.
Method development ideas: use sodium octane sulfonate as the ion-pair reagent to combine with the amino group on the structural formula of pantothenic acid to increase the retention of pantothenic acid, and then increase the proportion of organic phase, so that other impurities appear first, so as to achieve the purpose of removing matrix interference.
New chromatographic conditions
Mobile phase A: 0.01mol/L phosphate buffer (containing 1g/L sodium octane sulfonate, adjusted to pH 2.5 with phosphoric acid)
|Mobile phase A (%)
Analysis: As expected, the retention time of most interfering impurities was shortened. Before 7.5 minutes, most of the interfering impurities had been washed out, and a few impurities with strong retention were also well separated from pantothenic acid. Due to the complex composition of the sample, in order to prevent the presence of strong retained substances, gradient elution is used, and the organic phase ratio is up to 50% and maintained for 15 minutes to wash out the remaining strong retained substances as much as possible. At the same time, it is recommended to increase the guard column to reduce the sample. Contamination of the chromatographic column to increase the life of the chromatographic column.