Laboratory Glassware Cleaning Validation by Liquid Chromatographic Quantitation of Betamethasone Valerate Residues

Use of clean glassware ensures reliability of analyses that are carried out in laboratories. Glassware should be free of contaminants and residues from previous tests. It is therefore necessary to demonstrate the efficiency of glassware cleaning procedure through validation. This study aims to evaluate the cleaning efficiency of laboratory glassware by quantitation of betamethasone valerate residues in cleaned glassware. Betamethasone ointment was selected through a risk ranking process as the worst to clean product. Glassware used in analysis of this drug product was cleaned manually and residues evaluated using high performance liquid chromatography. The analysis method was validated at concentration levels of 1 - 8 µg/ml for specificity, accuracy, precision, linearity, limit of detection and limit of quantitation. The method demonstrated residue recovery of 97%. Repeatability and inter-mediate precision expressed as relative standard deviation were 1.2% and 1.4%, respectively. The calibration curve was linear over a concentration range from 2.04 to 6.13 µg/ml with a correlation coefficient of 0.9997.  The detection limit and quantitation limit were 0.11 µg/ml and 0.34 µg/ml, respectively. No residue was detected in glassware that was sampled for the cleaning validation. The results indicate that the manual cleaning method is effective as the level of betamethasone residues in cleaned glassware was below detection limit and thus will not interfere with analysis of the subsequent analyte.