固相基底电喷雾电离质谱分析固状与粘稠状药物的基质效应

固状与粘稠状辅剂常用于制造颗粒、片剂、胶囊或膏状药品,并能有效地保持药效成分活性的稳定性。基于固相基底的敞开式电喷雾电离质谱技术已被发展用于药品的直接分析。然而,固状与粘稠状基质对药物分子直接质谱检测的影响规律还不明确。该研究构建了不同黏度和不同溶解度的基质体系,采用木签(牙签)为代表的固相基底电喷雾电离质谱考察了几种模式药物分子在固状与粘稠状基质中的质谱响应规律。结果发现,易溶解的基质电离产生显著的离子干扰和抑制效应,而难溶的基质尽管不产生离子干扰,但在溶剂作用下可变成粘稠状从而抑制药物的离子化。进一步研究表明,药物分子的质谱信号随着基质的黏度增加(1~500 cP)呈幂函数降低(r 2>0.95)。该研究将增进理解固体与粘稠样品直接质谱分析的基质效应与信号响应规律。     

Impurity effect on surface states of Bi(111) ultrathin films

The surface impurity effect on the surface-state conductivity and weak antilocalization(WAL) effect has been investigated in epitaxial Bi(111) films by magnetotransport measurements at low temperatures. The surface-state conductivity is significantly reduced by the surface impurities of Cu, Fe, and Co. The magnetotransport data demonstrate that the observed WAL is robust against deposition of nonmagnetic impurities, but it is quenched by the deposition of magnetic impurities which break the time reversal symmetry. Our results help to shed light on the effect of surface impurities on the electron and spin transport properties of a 2D surface electron systems.