[Determination of immunoglobulin G in mare colostrum by high-performance gel permeation chromatography]

A direct high-performance gel permeation chromatographic (HPGPC) method for the determination of immunoglobulin G in mare colostrum was established. HPGPC separation was performed on a TOSOH TSK-G4000PW(XL) column (300 mm x 7.8 mm, 5 microm) with 0.05 mol/L phosphate buffer solution (pH 6.9) as the mobile phase at a flow rate of 0.8 mL/min, and the column temperature was maintained at 25 degrees C. The injection volume was 20 microL. At the detection wavelength of 280 nm, the linear range was from 0.2 to 3.0 g/L (r2 = 0.999 5) with a detection limit of 0.08 mg/L (S/N = 10). The recovery was 97.47% with a relative standard deviation (RSD) of 1.22%. The RSDs of the peak area of stability, accuracy and reproducibility for the established method were 2.86%, 1.62% and 1.82%, respectively. Mare milk was collected from Zhaosu (China), a complete collection was stored in an ice box, then sent to a laboratory and stored in a low temperature refrigerator. The whey milk was prepared by centrifugation two times at 12 000 r/min and 4 degrees C for 30 min. The whey protein was obtained from the middle layer. A 2 mL volume of the whey milk was mixed with 23 mL of mobile phase. The average contents of IgG were from 35.0 g/L to 50.0 g/L at the first lactation (2 h), and the average contents of IgG were from 2.0 g/L to 4.0 g/L after 72 h. The relatively simple analytical method was proved to be accurate and precise in its application to mare colostrum.