原文由 plexu(plexu) 发表:
原文由 小卢(luxw) 发表:
这个问题我考虑过!但有个担心的问题,就是由于我们的大多检测标准时欧盟或美国药典标准,因此填料、柱长、直径都固定了,如果选择保护柱的话,还需要考虑那么多吗?
美国药典欧洲药典对填料和柱长并没有规定很死,是允许在一定范围内调整的,加保护柱肯定不违反药典的规定。
前面讲了一些欧洲药典的规定,后面可以再看看美国药典的规定
Adjustments to the Chromatographic SystemAs mentioned,
<621> allows a number of adjustments to the chromatographic system in response to issues with a procedure's system suitability. These are the maximum allowable variations unless the individual monograph directs otherwise.
Ratio of components in mobile phase: Although the replacement of any solvent in the mobile phase constitutes a change and not an adjustment, the amounts of the minor components (specified as 50% or less) in the mobile phase can be adjusted up to ±30% relative to the particular component. However, the change in any component cannot exceed ±10% absolute (that is, in relation to the total mobile phase). Adjustments can be made to one minor component in a ternary mixture.
pH of mobile phase: The pH of the aqueous buffer used in the preparation of the mobile phase can be adjusted to within ±0.2 units of the value or range specified.
Column temperature: The column temperature can be adjusted by as much as ±10 °C.
Concentration of salts in buffer: The concentration of the salts used in the preparation of the aqueous buffer for the mobile phase can be adjusted up to ±10% relative to the particular component, provided the permitted pH variation (see above) is met.
Wavelength of UV–vis detector: Deviations from the wavelengths specified in the method are not permitted.
Stationary phase: - Column length: The column length can be adjusted by as much as ±70%.
- Column inner diameter: The column inner diameter can be adjusted, provided that the linear velocity is kept constant (see Flow Rate).
Flow rate: When column dimensions have been modified, the flow rate can be adjusted using the following formula:
where
F1 is the flow rate indicated in the monograph, in milliliters per minute;
F2 is the adjusted flow rate, in milliliters per minute;
l1 is the length of the column indicated in the monograph;
l2 is the length of the column used;
d1 is the column inner diameter indicated in the monograph; and
d2 is the internal diameter of the column used.
Additionally, the flow rate can be adjusted by ±50% (2).
Injection volume: The injection volume can be reduced as far as is consistent with accepted precision and detection limits, but no increase is permitted.
Particle size: Particle size can be reduced by as much as 50% but cannot be increased.
Column Dimensions: Inner Diameter, Length The chromatographic purity test included in the hydroxyzine hydrochloride monograph (8) required the use of two 10 cm × 3 mm columns coupled in series and containing packing L3 with a flow rate of 0.4 mL/min. It would be advantageous to use one column with standard dimensions of 4.6 mm i.d. and a 25-cm length. Chapter
<621> allows the simultaneous change of column inner diameter and length and recommends the flow rate be adjusted according to equation 1 given earlier.
The new flow rate calculated using the formula is 1.2 mL/min. When a flow rate of 1.0 mL/min was used with a 4.6-mm i.d. and 25-cm length column, the observed resolution was greater than 3. The current official monograph includes the revised column dimensions of 4.6-mm i.d. and 25-cm length and flow rate of 1.0 mL/min