Chromatography Forum

Dear all chromatographers and regulatory people,

Can you help me with the query as mentioned below:

Query: In one of the product monograph in USP, Assay method (HPLC) does not mention the flow rate to be kept during analysis. At what flow rate the analysis should be performed. Is it mentioned in USP that if the flow rate is not mentioned we have to run the chromatography at 1.0 ml/min.

Pl reply.

Regards,

If flow is not specified, then it is not specified. You may adjust as necessary to meet any retention time specifications.

Like many of us who actually work in the lab, you've found that USP is not as thorough in some areas as management or QA thinks.

Hi Surabhi

As mentioned above, it’s obviously up to you to specify the flow rate.
So if the column is specified I’d go for the optimal flow rate in order to achieve the best performance. F. ex. if the column diameter is, let’s say, 4.6 mm and the particle size is 5 µm, I’d set the flow rate to 1 mL/min.

Best Regards

To : Surbhi

I understand from your problem that in USP monograph , Retention Time of product or Relative Retention Time of the product is also not mentioned .

Hence You may keep 1 ml / min. Flow rate if it is not mentioned in USP monograph of your desire product for 250 lengthed column & inject your product & Standard 6 times & check the repeatability . See that your desire peak R.T. should be more than dead volume of the column too .


Hope this will solve your problem.

Wouldn´t one be inclined to find the optimum flow rate if it was not specified?

Wouldn´t one be inclined to find the optimum flow rate if it was not specified?

Depends on your definition of "optimum" (my personal choice would be "the highest flow rate which gives me acceptable results and doesn't over-stress the system").

That´s just fine also, I was thinking more of optimiziing resolution. As long as you do something (like using gray substance) and then state somewhere what you did and why.