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kuanghua

铜虫 (著名写手)

[求助] 看不懂的系统适用性案例-EP8.0 头孢他啶已有2人参与

EP8.0 头孢他啶原料药质量标准中杂质F(即吡啶)的含量测定方法如下:
Impurity F. Liquid chromatography (2.2.29). Prepare the solutions immediately before use.
Phosphate buffer solution. Prepare a 10 per cent V/V solution of phosphate buffer solution pH 7.0 R4.
Test solution. Dissolve 0.500 g of the substance to be examined in phosphate buffer solution and dilute to 100.0 mL with the same solution.(供试品浓度为5mg/ml)
Reference solution (a). Dissolve 1.00 g of pyridine R in water R and dilute to 100.0 mL with the same solvent. Dilute 5.0 mL of the solution to 200.0 mL with water R. Dilute 1.0 mL of this solution to 100.0 mL with phosphate buffer solution.(对照品浓度为2.5ug/ml,限度为500ppm)
Reference solution (b). Dilute 1 mL of the test solution to 200 mL with phosphate buffer solution. To 1 mL of this solution add 20 mL of reference solution (a) and dilute to 200 mL with phosphate buffer solution.(原料药浓度为0.125ug/ml(相当于供试品浓度的0.0025%),吡啶浓度为0.25ug/ml(相当于限度浓度的10%)。为什么溶液B中原料药的浓度不是供试品一样,即供试品为5mg/ml,吡啶为2.5ug/ml?这样设计是出于什么考虑?)
Column:
– size: l = 0.25 m, Ø = 4.6 mm;
– stationary phase: octadecylsilyl silica gel for
chromatography R (5 μm).
Mobile phase: mix 8 volumes of a 28.8 g/L solution of ammonium dihydrogen phosphate R previously adjusted to
pH 7.0 with ammonia R, 24 volumes of acetonitrile R and 68 volumes of water R.
Flow rate: 1.0 mL/min.
Detection: spectrophotometer at 255 nm.
Injection: 20 μL.
Run time: 10 min.
System suitability: reference solution (b):
– resolution: minimum 7.0 between the peaks due to
ceftazidime and impurity F.
Limit:
– impurity F: not more than the area of the principal peak
in the chromatogram obtained with reference solution (a)
(500 ppm).
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veritas_xmu

铁杆木虫 (著名写手)

【答案】应助回帖

感谢参与,应助指数 +1
兼任灵敏度测试溶液  再规定下信噪比就好了

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上苍不语,时以我想
2楼2016-01-11 21:44:05
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zongyuan

捐助贵宾 (知名作家)

分离度是在这个浓度级别的,供试品溶液峰型难道是正常的?

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3楼2016-01-11 21:47:19
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kuanghua

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引用回帖:
2楼: Originally posted by veritas_xmu at 2016-01-11 21:44:05
兼任灵敏度测试溶液  再规定下信噪比就好了

这个方法单独测定一个杂质,而且是杂质对照品外标法,是否还有必要配制一个灵敏度溶液?而且与欧洲药典灵敏度溶液在标准中的说法也不同
4楼2016-01-12 08:05:28
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kuanghua

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引用回帖:
3楼: Originally posted by zongyuan at 2016-01-11 21:47:19
分离度是在这个浓度级别的,供试品溶液峰型难道是正常的?

供试品溶液峰形正常啊
5楼2016-01-12 08:05:47
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kuanghua

铜虫 (著名写手)

上面说错了,主峰是超载,但不影响杂质的测定
6楼2016-01-12 10:05:38
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yan1984

铁虫 (正式写手)

【答案】应助回帖

感谢参与,应助指数 +1
低浓度溶液看分离度,很多人不怕麻烦,做一些没有必要的事情的。
7楼2016-01-13 17:22:20
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