By Recovery on Monday, August 25, 2003 - 11:15 pm:
Developing a HPLC method for assay/impurity of a tablet (containing mannite, Aerosil, Croscarmellose-sodium, HPMC and MgStearate) I have got problems with the accuracy: the matrix of the tablet "swallows" about 2 % of the drug substance.
What can I do to improve the recovery ? I use acetonitrile/phosphate buffer pH 4 40:60 as extraction medium.
By Anonymous on Tuesday, August 26, 2003 - 09:02 am:
Find a beter solvent for your API?
Maybe first add 40% ACN, sonicate and then add the phosphate buffer?
Check your filters ( no absorbtion by the filters, because aerosil wont dissolve in your extraction medium).
Heating?
There are lot of ways to improve the recovery, but are you sure there is 100% in the tablet?
By Recovery on Tuesday, August 26, 2003 - 11:13 pm:
It was a spiked placebo solution so I´m sure to have 100% API. Furthermore, without adding the placebo I can find 100% and I am sure about solubility of the API. I also compared centrifuging against different filters and found no difference. I guess it could be the aerosil. But how minimizing the effect?