How to do recovery test?
by preparing solution of product A with a known concentration then spray it on surface of the coupon with same machine material (let it 5*5 cm SS 316) leave to dry then swap it with the same swap used in actual sampling with the same method or rinse it with the same method you rinse during actual sampling, then analyse the swap or rinse by the valid method.then from the result of analysis we can get the recovery % related to the actual known prepared solution used in the test