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Title: Isothiazolinones Quantification in Shampoo Matrices: A Matter of Method Optimization or Stability Driven by Interactions?
Authors: Tomás, Mariana 
Agonia, Ana Sofia
Borges, Lígia
Palmeira-de-Oliveira, Ana 
Oliveira, Rita Palmeira de 
Keywords: cosmetics; shampoo; cosmetic ingredients; preservatives; methylisothiazolinone; chloromethylisothiazolinone; dermatitis
Issue Date: 2020
Publisher: MDPI
Project: Health Sciences Research Center (CICS-UBI) through National Funds by FCT - Foundation for Science and Technology (UID / Multi / 00709/2019) 
Labfit HPRD, Lda 
Serial title, monograph or event: Cosmetics
Volume: 7
Issue: 1
Abstract: Methylisothiazolinone (MI) is one of the most used preservatives in shampoos and also one of the most e ective. A preservative mixture known as Kathon CG is commercially available. It contains 5-chloro-2-methyl-4-isothiazolin-3-one (CMI) and 2-methyl-4-isothiazolin-3-one (MI) (3:1) and stabilizers. The aim of this study is to evaluate the influence of formulation factors in the quantification and stability of isothiazolinones in shampoos. Two shampoo bases containing Kathon CG as a preservative were prepared. Some ingredients that are at risk of interfering with the preservative stability were added to these formulations. The preservative was quantified by HPLC-DAD (High-performance liquid chromatography with a diode-array detector) after preparation of the formulation and after storage at room temperature and at 40 C. The addition of magnesium silicate proved to be essential for the breakdown of the interaction between the matrix and the analytes in the extraction procedure. The content of CMI/MI decreased right after preparation indicating that immediate interactions between CMI/MI and the ingredients may have occurred after preparation resulting in a decrease in the preservative concentration. Detrimental interactions between the ingredients, regarding the stability of the isothiazolinones were detected immediately after preparation and over time resulting in the reduction of CMI/MI concentration in these cosmetic shampoos.
ISSN: 2079-9284
DOI: 10.3390/cosmetics7010004
Rights: openAccess
Appears in Collections:I&D CIBIT - Artigos em Revistas Internacionais

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