captopril tablets USP method

[sneha]

has anybody faced problem with analysis of captopril tablets using USP method

[Uwe Neue]

Don't know the method, but if you are getting strange peak shapes with captopril you are probably at the wrong pH. Can you describe the method and the problem?

[sneha]

the dissolution method invovles
media: 0.01nHcl, 900ml
basket:50rpm
detection by hplc
mobile phase: buffer: MEOH : 450: 550
buffer = (0.5ml OPA in 450ml WATER)

column :30cm c18 with 10microns
wavelength :220nm
USP suggest to inject samples immediately before 8hrs

i usually encountered problems like high Dissolution, and samples have to be injected within 2hrs.

secondaly assay with same chromatographic setup but diluent being diff
shows 100% assay if injected immediately and higher assay after even 1hr.



[/u]

[ym3142]

when you are talking about "USP suggest to inject samples immediately before 8hrs ; i usually encountered problems like high Dissolution, and samples have to be injected within 2hrs.
secondaly assay with same chromatographic setup but diluent being diff
shows 100% assay if injected immediately and higher assay after even 1hr. " are you meaing that the detected amount increases with the time of sample storage before injection such as 40% at 10:00 AM when the sample is prepared and injected, 45% at 11:00 AM if the same sample was injected again, and 50% at 12:00 AM if the same sample was injected again....?

If so, could you set up a way so you always inject the samples with the same delay or immediately? I am sorry to bother you.

[syx]

I think Captopril is unstable in aqueous media. You may store the sample in cooler, in vials those closed tightly to reduce degradation rate. Is it light sensitive too?