DEVELOPMENT AND VALIDATION OF AN ANALYTICAL METHOD FOR THE DETERMINATION OF METHYLISOTHIAZOLINONE AND METHYLCHLOROISOTHIAZOLINONE IN COSMETIC PRODUCTS USING MATRIX SOLID-PHASE DISPERSION COUPLED TO GAS CHROMATOGRAPHY - MASS SPECTROMETRY
Objective: The regulation amendment regarding the permitted limit for methylisothiazolinone (MI) and methyhlchloroisothiazolinone (MCI) preservative in cosmetic formula has been promulgated by Indonesian FDA. This amendment is to ensure consumer safety and product quality in order to prevent allergic contact dermatitis case in Indonesia. This study was to develop the first simultaneous method for quantification of MI and MCI by using matrix solid-phase dispersion (MSPD) as extraction technique followed by gas chromatography tandem mass spectrometry in cosmetic products to support that law enforcement.
Methods: The MI and MCI were extracted from cosmetic sample by using matrix solid-phase dispersion technique with alumina as solid sorbent and ethyl acetate as eluent. After being isolated, MI and MCI from the samples were analyzed using gas chromatography tandem mass spectrometry (GC-MS) equipped with DB-5MS capillary column.
Results: The validated method for both leave-on and rinse-off cosmetic showed that MI and MCI recoveries were between 97.87-103.15 %, relative standard deviation (RSD) values were lower than 11%, and limit of quantitation (LOQ) values for leave-on product were 0.96 µg/ml and 1.95 µg/ml and for rinse-off products were 0.56 µg/ml and 1.49 µg/ml for MI and MCI, respectively.
Conclusion: This purposed analytical method for determining MI and MCI in cosmetic products using MSPD-GC-MS complies with the validation acceptance criteria
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