yongzhbenq
第80楼2010/07/27
在做多肽类样品的时候,300A孔径的填料相对100A孔径肯定要选择性好点,也就是分离度相对比较好点
流动相加入TFA,我从网上找了一些资料,看看能不能解释一下:
在反相色谱分离多肽和蛋白质的实验中,使用三氟乙酸 (TFA) 作为离子对试剂是常见的手段。流动相中的三氟乙酸通过与疏水键合相和残留的极性表面以多种模式相互作用,来改善峰形、克服峰展宽和拖尾问题。
三氟乙酸优于其他离子修饰剂的原因是它容易挥发,可以方便地从制备样品中除去。另一方面,三氟乙酸的紫外最大吸收峰低于 200nm ,对多肽在低波长处的检测干扰很小。
Applications for Trifluoroacetic Acid
plexu
第81楼2010/07/27
反相柱都可以用下面通用的方法清洗维护:
流动相中不含缓冲盐 | 分析完成后,用甲醇(或乙腈):水=90:10反向冲洗色谱柱45min |
流动相中含有缓冲盐 | 分析完成后,先用甲醇(或乙腈):水=10:90反向冲洗45min,然后再用甲醇(或乙腈):水=90:10反向冲洗色谱柱45min;(注意:甲醇(或乙腈):水=10:90容易长菌,使用时间不可超过3天); |
yongzhbenq
第84楼2010/07/27
欧洲药典虽然规定了填料的粒径、柱长、直径等等参数,但并不是要求很死,可以在一定范围内调整
比如:
Method Parameter | Acceptable Modification | Monograph 0703 Atenolol | Kinetex 2.6 µm Fast Method | Modification |
Mobile phase pH | ±0.2 units | 3 | No change | -- |
Concentration of salts in buffer | ±10% | As specified | No change | -- |
Ratio of components in mobile phase | ±30% of the minor component(s), or 2% absolute of that component, whichever is greater, but a change in any component can not exceed ±10% absolute | As specified | No change | -- |
Wavelength of UV detector | no deviations permitted | 226 nm | No change | -- |
Injection volume | Increased to as much as twice the volume specified, provided no adverse effects—must be within stated linearity range of the method | 10 µL | No change | -- |
Column temperature | ±10° | Ambient | No change | -- |
Column length | ±70% | 125 mm | 100 mm | -20% |
Column inner diameter | ±25% | 4.0 mm | 4.6 mm | +15% |
Particle size | -50% | 5 µm | 2.6 µm | -48% |
Flow rate | ±50% | 0.6 mL/min | 0.9 mL/min | +50% |
Table 1: Acceptable modifications for meeting system suitability (Source: European Pharmacopoeia guidelines) |
Fully porous 5 µm | Kinetex 2.6 µm C18 0.9 mL/min | Kinetex 2.6 µm C18 1.3 mL/min | ||
Column dimensions | 125 × 4.0 mm | 100 × 4.6 mm | 100 × 4.6 mm | |
Particle size | 5 µm fully porous | 2.6 µm core shell | 2.6 µm core shell | |
Flow rate | 0.6 mL/min | 0.9 mL/min | 1.3 mL/min | |
Backpressure | 168 bar | 270 bar | 380 bar | |
Resolution of impurities J & I | 1.95 | 3.72 | 3.65 | |
S/N ratio for Impurity J | 40 | 78.1 | 78.7 | |
S/N ratio for Impurity I | 12.3 | 30.2 | 28.7 | |
S/N ratio for Impurity G | 3.31 | 9.38 | 9.33 | |
N of Impurity J | 8,206 | 21,118 | 19,473 | |
Elution time of last peak | 33.3 min | 11.9 min | 8.0 min | |
Table 2: Improvements to EP Monograph 0703 for Atenolol and related substances using core-shell particle technology results in a three- to four-fold reduction in analysis time and organic solvent usage. (Source: Phenomenex) |