Determination of methylisothiazolinone and methylchloroisothiazolinone in cosmetic products by ultra high performance liquid chromatography with tandem mass spectrometry

Isothiazolinone biocides are broad‐spectrum preservatives that are widely used in cosmetics, household, and industrial products. An increase in the number of cases of allergic contact dermatitis to isothiazolinone preservatives, namely, methylisothiazolinone and methylchloroisothiazolinone, have been recently noticed. The Food and Drug Administration relies on analytical methods to quantify levels of use of cosmetic ingredients and support...