USP non-sense for method transfer?

[aceto_81]

Hi,

I was trying to transfer a USP method for HPLC to UPLC.
The internal diameter of the column may be adjusted as long as the flow linear velocity is kept constant.
So if I switch from a 150 x 4.6mm HPLC column with a flow rate of 1.0 ml/min to a 100 x 2.1mm UPLC column, I need to use the following formula according to the USP: 1.0 x (100 x (2.1^2))/(150 x (4.6^2)) = 0.139ml/min. Then I may adjust ±50%, so the flow is in the range: 0.07-0.21ml/min

Question 1: what has the column length to do with linear velocity? Or am I really wrong on this one?
Question 2: my maximum allowed flowrate is 0.21ml/min which is way under the optimal flowrate for 1.7µm particles, no other conversions allowed?

One reason for doing the transfer is that we can skip the selectivity part of the validation, as we know where all the impurities are in the USP monograph.
Do you do transfer, and do you revalidate selectivity/specificity?

Ace

[HPLCaddict]

Concerning question 1, you're completely right that linear velocity of the mobile phase has nothing to do with column length. AFAIK this "old" conversion formula has been designed in order to keep the ratio column volumes per time constant. Unfortunately, it doesn't take into account the shift of the van-Deemter minimum when going to smaller particle sizes.
That said, the update of USP (second supplement) which is going into action on december 1st, has a different formula: without the length of the columns included . Unfortunately, particle size change is still not considered.
So, wait until december and you will be at least allowed to go to 0.31mL/min (taking the 50% change into account).

[shaun78]

When I bought UPLCs for a pharma lab I worked in, I was also charged with the task of performing method transfers from HPLC to UPLC.

First, your detector is likely going to be different. I'd hate for an auditor to even try to think to make that an issue. So, I verified linearity on the UPLC.

Second, column chemistries are not all equal. Even if they are (ie HPLC and UPLC of the exact same column exists) I would hate for an auditor to make trouble over that as well. So, specificity was reconfirmed on a very simplistic level (blank and no coeluting peaks; impurity methods had to pass peak purity). If there was a critical pair in the separation, my requirement was that resolution between the two needed to increase when going from HPLC to UPLC.

If you want to follow the USP, you must use their equations. However, nothing states that you must follow them as long as you prove equivalency. I demonstrated that the equation which I believe HPLCaddict is referencing works better than the USP equation. My proof was again RRT matchups between the chromatography produced by the two equations and the original HPLC method. You will see that HPLCaddict's equation maintains the relative chromatography much better.

Also, again the USP is only a recommendation. Anyone can realize if you have a 5 um particle for HPLC, you can't transfer down to 1.7 or 1.8 um particle. Transferring to a 3 or 3.5 um, 2.5 um, and then a 1.7 um particle is beating around the bush and you are asking for trouble. So, I did direct transfers from 5 um to 1.7 um. My justification for ignoring the USP was to prove with each method that specificity was maintained.

One word of caution: you might notice elution order changing on you in rare cases due to differences in pressure. This will put you in a very interesting pickle.

[krickos]

Hi Below is some text cut out from <621> USP.

I get the feeling that your are reducing particle size too much ie more than 50%, which would triggger a formal validation that would likely need approval by FDA (alternativly filing of an alternative procedure to USP).

Reducing paticle size stepwise may seem neat but you would still be outside the 50% limit as the dimension in the monograph decides, not what you reduced to in a prior method.

As I see it you can go from 10 to 5µm, 5 to 3,5µm or 3,5 to 2,1µm without tempering with the 50% limit.

To my knowledge USP is thinking on a chapter on how to convert HPLC procedure to UPLC, to facilitate a shift to smaller columns/particles without excessive revalidation and regulatory approval.

My point being if you operate within what USP allows and you refer to USP in your file, you do not have to notify FDA or similar if you operate outside there is a risk you have to be aware of or additional work needed to get it approved.


Regards Chris






Adjustments to chromatographic systems performed in order to comply with system suitability requirements are not to be made in order to compensate for column failure or system malfunction.
If adjustments of operating conditions are necessary in order to meet system suitability requirements, each of the items in the following list is the maximum variation that can be considered, unless otherwise directed in the monograph; these changes may require additional validation data. To verify the suitability of the method under the new conditions, assess the relevant analytical performance characteristics potentially affected by the change. Multiple adjustments can have a cumulative effect on the performance of the system and are to be considered carefully before implementation. Adjustments to the composition of the mobile phase in gradient elution are not recommended. If adjustments are necessary, only column changes (same packing material) or dwell volume adjustments are recommended.

pH of Mobile Phase (HPLC): 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.

Concentration of Salts in Buffer (HPLC): The concentration of the salts used in the preparation of the aqueous buffer employed in the mobile phase can be adjusted to within ±10% if the permitted pH variation (see above) is met.

Ratio of Components in Mobile Phase (HPLC): The following adjustment limits apply to minor components of the mobile phase (specified at 50% or less). The amounts of these components can be adjusted by ±30% relative. However, the change in any component cannot exceed ±10% absolute (i.e., in relation to the total mobile phase). Adjustment can be made to one minor component in a ternary mixture. Examples of adjustments for binary and ternary mixtures are given below.
Binary Mixtures
specified ratio of 50:50: 30% of 50 is 15% absolute, but this exceeds the maximum permitted change of ±10% absolute in either component. Therefore, the mobile phase ratio may be adjusted only within the range of 40:60 to 60:40.
specified ratio of 2:98: 30% of 2 is 0.6% absolute. Therefore the maximum allowed adjustment is within the range of 1.4:98.6 to 2.6:97.4.
Ternary Mixtures
specified ratio of 60:35:5: For the second component, 30% of 35 is 10.5% absolute, which exceeds the maximum permitted change of ±10% absolute in any component. Therefore the second component may be adjusted only within the range of 25% to 45% absolute. For the third component, 30% of 5 is 1.5% absolute. In all cases, a sufficient quantity of the first component is used to give a total of 100%. Therefore, mixture ranges of 50:45:5 to 70:25:5 or 58.5:35:6.5 to 61.5:35:3.5 would meet the requirement.
Wavelength of UV-Visible Detector (HPLC): Deviations from the wavelengths specified in the procedure are not permitted. The procedure specified by the detector manufacturer, or another validated procedure, is used to verify that error in the detector wavelength is, at most, ±3 nm.

Stationary Phase
column length (gc, hplc): Can be adjusted by as much as ±70%.

column Inner diameter (hplc): Can be adjusted if the linear velocity is kept constant. See Flow Rate (HPLC) below.

Particle Size (HPLC): The particle size can be reduced by as much as 50%, but cannot be increased.

Flow Rate (HPLC): When column dimensions have been modified, the flow rate can be adjusted using:

"picture of formula missing"

in which F1 is the flow rate indicated in the monograph, in mL/min; F2 is the adjusted flow rate, in mL/min; 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%.

Injection Volume (HPLC): The injection volume can be reduced as far as is consistent with accepted precision and detection limits; no increase is permitted.


Column Temperature (HPLC): The column temperature can be adjusted by as much as ±10. Column thermostating is recommended to improve control and reproducibility of retention time.

[Consumer Products Guy]

Krickos - here in USA we don't "notify" the FDA of any pharmaceutical validations. We perform them and document them, that's how it works here for cGMP (GLP is different, there one submits).

Yes, with a particle size of that amount, I would do some validations, and at least show what the USP and FDA call "equivalent results". But I don't think they define what "equivalent results" actually are.

[shaun78]

But I don't think they define what "equivalent results" actually are.

That is the beauty of it all.

When I have done this, I simply stated parameters for system suitability had to be similar or improved. Peak shape, plates, resolution, rsd. If those were equivalent then it sounds like the method is performing similarly.

I actually did that on an ANDA for a company for which I worked. The original HPLC validation went to the FDA. The amendment where I changed the HPLC column from a Synergi ... to a HPLC Atlantis (5 um) went to the FDA. The amendment for a change from an HPLC to a UPLC column (HSS T3, 1.8 um) went to the FDA.

For the column (HPLC to HPLC) transfer I looked at system suitability, linearity, and specificity of a critical pair. For the UPLC transfer, I looked at system suitability, linearity, and specificity of the same critical pair.

The FDA asked zero questions and gave their blessing.

The point of bringing this up is I clearly did a USP no no several times here. I applied scientific judgment and covered my proverbial back. The FDA was happy; you do not have to follow USP; USP was setup by the government as a guidance. Nothing is written saying the USP are the law; the FDA is the law.