I am perform determine accuracy in validation of method for assay. As my knowledge, there are general method in determination of accuracy: (1), by adding spiking standard solution into placebo and (2) by adding the spiking standard solution into assay preparation (prepared from the finished product according to the method).
What is advantages and disadvantages of these methods? Anyone help me to clarify this question.
Thank you very much!
The difference is, one is placebo, the other is product. One without API, other with API. When you spike, one will have only spiked amount, the other will have spiked amount and label amount. You will have to do the calculation according the the conditions. Placebo is better and mostly used because there you know exactly the true value. When you use the product, you have to depend on some uncertainity as you may not know whether it has 100% label claim or slightly off. Also your range may or may not include spiked+LC. If out of range, it will be a problem. Generally product is used when it is difficult to make placebo (lack of info, know how or material).
Are you sure that in (2) he wasn’t asking about standard addition?
What you describe in your reply is to assay plant-made or lab-made product, as another way.
the better way is to use sample that contains known concentration of API. by this method you may know the matrix effect during sample solution preparation and extraction efficiency of the analyte from the sample by the solvent.