Cleaning verification assays for highly potent compounds by high performance liquid chromatography mass spectrometry: Strategy, validation, and long-term performance

A cleaning-verification assay was validated for a highly potent family of compounds utilizing a swab-sampling procedure and high performance liquid chromatography mass spectrometry (LC-MS) for separation and detection of the analytes. Due to the high potency of the compound, the LC-MS method was validated at a level of 50 ng/25 cm2 and 50 ng/100 cm2 (which equates to 10 ng/ml after extraction in 5 ml of sample solvent, and 3 ng/ml after correction for sampling losses). This validation exercise included recovery estimates from all drug product contact surfaces within the clinical trial manufacturing equipment, namely, stainless steel, anodized aluminum, Rilsan® coated aluminum, bronze, polyvinylchloride, and Oilon®. The limit of detection for the LC-MS method was determined to be less than 0.5 ng/ml, or less than 0.1 ng/cm2, of the analyte. This method does not employ an internal standard. Long-term performance of the validated method is also reported. The precision on replicate injections of the standard prepared in the range of 3–6 ng/ml was typically better than 8.0% relative standard deviation (R.S.D.) over the course of 1 year, which resulted from 10 cleaning-verification submissions. Those results were consistent with the data obtained during method validation.