电喷雾飞行时间质谱法研究溶液pH值对醋氨己酸锌络合结构的影响

目的　考察不同pH值条件下醋氨己酸锌络合结构的稳定性。方法　测定不同pH值醋氨己酸锌溶液的电喷雾离子化/飞行时间质谱,研究其络合结构的稳定性。结果　证明醋氨己酸锌络合结构在pH值为2.54时最稳定,且在此pH值有一定的缓冲作用。根据质谱数据,发现在此pH条件下,醋氨己酸锌较易形成(M+ZnY)⁺(Y=CH₃CONH(CH₂)₅COO^-)和(2M+Na)⁺离子。结论　醋氨己酸锌能减低胃的酸度;可进一步形成多聚体;对于胃酸分泌过多的病人,它与质子泵阻断剂、胃酸抑制剂的联合用药是合理的。

EFFECT OF SOLUTION pH VALUE ON THE CHELATION STRUCTURE OF ZINC ACEXAMATE BY ELECTROSPRAY IONIZATION MASS SPECTROMETRY

AIM: To study the effect of solution pH value on the chelation structure of zinc acexamate. METHODS: A series of samples at different solution pH values were prepared by 10% HCl or 1 mol.L-1 NH3.H2O. Then API/TOFMS with electrospray ion source was applied to assay the samples. The nitrogen curtain gas and nebulizer gas were adjusted to a constant flow rate of 0.6 microL.min-1 and 2 microL.min-1 respectively. Samples were infused into the electrospray interface using a 500 microL syringe pump at a flow rate of 5 microL.min-1. Mass spectra were acquired in positive ion modes by scanning over the range of m/z 100-1,000. RESULTS: The chelation structure of zinc acexamate is stable at pH 2.54 and it can be easy to form the ion (M + ZnY)+ (Y = CH3CONH(CH2)5COO-) and (2M + Na)+ in this condition. CONCLUSION: The drug is an effective antiulcer agent. It may decrease the acidity of stomach juice, and form a polymer to protect the ulcer.