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USP and Ph. Eur. Allowable adjustments calculator

Harmonized Pharmacopeia Allowable Adjustments of Chromatographic Conditions - Isocratic Elution

ComponentCondition as per monographAdjustable fromAdjustable toLimit
Stationary Phase No change of the identity of the substituent (e.g. no replacement of C18 by C8); the other physico-chemical characteristics of the stationary phase (i.e. chromatographic support, surface modification and extent of chemical modification) must be similar; a change from totally porous particle (TPP) columns to superficially porous particle (SPP) columns is allowed provided the above-mentioned requirements are met.
Mobile phase minor component (<50%) 35.3255.32± 30 % (relative) for minor components, but no component is altered by more than ± 10 % absolute. A minor component comprises less or equal than (100/n) %, where n being the total number of components.
Cannot be reduced to zero
pH of aqueous component of mobile phase0.801.20± 0.2 pH units, unless otherwise prescribed.
Concentration of salts in buffer component of mobile phase (mM)19.8024.20±10 %
Column Temperature (°C)1232±10 °C, where the operating temperature is specified, unless otherwise prescribed
ComponentCondition as per monographAdjusted conditionsRemarks
Column Length (mm)The particle size and/or length of the column may be modified provided that the ratio of the column length (L) to the particle size (dp) remains constant or in the range − 25 % to + 50 % of the prescribed L/dp ratio.
Column Diameter (mm)In the absence of a change in particle size and/or length of the column, the internal diameter of the column may be adjusted
Particle Size (µm)Alternatively (as for the application of particle size adjustment to superficially porous particles), other L/dp combinations can be used provided that the number of theoretical plates (N) is within -25% to +50%
The column with desired dimensionCan be used.
L/dp deviation0.00%
Flow Rate (mL/min)The New flow rate as per the desired column dimension is 1.322 mL/minAfter an adjustment due to a change in column dimensions, an additional change in flow rate of ± 50 % is permitted
Injection Volume (µL)The injection volume for the desired column dimension is 33 µL When the column dimensions are changed, the injection volume may be adjusted accordingly.

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Description according to Pharm. Eur. Pharm. Eur. 11, 4.1.1. Reagents 2023 Number Recommended Phenomenex Column
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