Determination of Impurities in the Oligonucleotide by Solid Phase Extraction Ionchromatography

Objective An solid-phase-extraction ion chromatography was developed for determining three residual impurities such as acetic acid(MCAA),dichloroacetic acid(DCAA) and chloride ion(Cl-) in crude oligonucleotide simultaneously.Methods The final optimized conditions for testing were listed as follows by using Ionpac AS 23(4 mm×250 mm) analytical column,Ionpac AG23(4 mm×50 mm) protective column,mobile phase as 0.8 mmol·L-1 NaHCO3/4.5 mmol·L-1 Na2CO3 and suppressed conductivity detector.Results The standard curve equation of MCAA,DCAA and Cl-were Y= 5.230 7X+0.014(r=0.999 7),Y=19.762X-0.007 2(r=0.999 9) and Y=507.4X-0.746 2(r=0.999 8),respectively;MCAA,DCAA and Cl-showed a good linearity in 0.002-0.400 μg·mL-1,0.000 624-0.156 μg·mL-1,0.002 4-1.5 mg·mL-1 and detection limits were 0.02,0.312 ng·mL-1 and 0.01 μg · mL-1,respectively.Conclusion The method is simple,fast,accuracy and can be used for impurities control of crude oligonucleotide.