Development and validation of an HPLC-MS-MS method for quantitating bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin 770) and a related substance in aqueous extracts of plastic materials.

Tinuvin 770 is a light stabilizer present in numerous polymers utilized in medical or pharmaceutical applications (e.g., manufacturing, packaging, delivery systems and devices). Under conditions of use, Tinuvin 770 and its related substances may leach from the polymers and accumulate in pharmaceutical products that are administered to subjects to produce a therapeutic benefit. In order to establish the amounts of Tinuvin 770 that may be extracted from such systems and devices, sensitive and selective analytical methodologies are required. A liquid chromatographic method with tandem mass spectrometric detection (LC-MS-MS; API-ES, positive ion mode) has been developed for the purpose of quantitating Tinuvin 770 and a related substance at low concentrations [200 ng/mL (ppb) or less] in aqueous extracting media. Issues related to injection-to-injection carryover and sample matrix effects were mitigated by the addition of potassium chloride to the test samples, where the potassium ion increases Tinuvin solubility via a "salting in" effect. The developed method was validated for this application by assessing performance characteristics including accuracy, response linearity, precision, specificity, and solution stability. The validated method is suitable for the quantitation of these analytes in the concentration range of 1-200 ng/mL.