Nuclear magnetic resonance (NMR) longitudinal rotating frame relaxation time (T_1ρ), rarely used in low-field NMR, can be more effective than conventional T₁ and T₂ relaxation times to differentiate polymorphic forms of solid pharmaceuticals. This could be attributed to T_1ρ sensibility to structural and molecular dynamics that can be enhanced by changing the strength of the oscillating magnetic field (B₁) of spinlock pulses. Here, we compared the capacity of T₁, T₂, and T_1ρ to differentiate inactive (A) and active (C) crystalline forms of the World Health Organization essential drug Mebendazole. The results showed that T₁ and T₂ values of both forms were statistically identical at 0.47 T. Conversely, T_1ρ of both forms measured with weak spinlock B₁ fields, ranging from 0.08 to 0.80 mT were statistically different in the same spectrometer. The T_1ρ also has the limit of detection to detect the presence of at least 10% of inactive A form in the active C form. Therefore, T_1ρ, measured with weak spinlock B₁ fields can be an effective, streamlined, and complementary approach for characterizing not only solid active pharmaceutical ingredients but other solid-state materials as well.

中文翻译：

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具有弱自旋锁定场的 NMR 纵向旋转框架弛豫时间 (T1ρ) 作为表征固态活性药物成分的方法：概念验证


核磁共振 (NMR) 纵向旋转框架弛豫时间 (T _1ρ ) 在低场 NMR 中很少使用，但比传统的 T ₁ 和 T ₂ 对结构和分子动力学的敏感性，可以通过改变自旋锁脉冲的振荡磁场 (B ₁ ) 的强度来增强这种敏感性。在这里，我们比较了 T ₁ 、 T ₂ 和 T _1ρ 区分世界非活性 (A) 和活性 (C) 晶型的能力卫生组织基本药物甲苯咪唑。结果表明，两种形式的T ₁ 和T ₂ 值在统计上相同，均为0.47 T。相反，用弱自旋锁B测量的两种形式的T _{1ρ 1} 场，范围从 0.08 到 0.80 mT，在同一光谱仪中具有统计差异。 T _1ρ 还具有检测限，可检测活性 C 形式中是否存在至少 10% 的非活性 A 形式。因此，用弱自旋锁 B ₁ 场测量的 T _1ρ 可以是一种有效、简化和补充的方法，不仅可以表征固体活性药物成分，还可以表征其他固态材料。