Determination of formaldehyde in formaldehyde-releaser patch test preparations.

Background: Positive patch test reactions to formaldehyde-releasers in patients co-reacting to formaldehyde are often ascribed to formaldehyde allergy. However, the formaldehyde content of patch test materials has not been investigated.

Objectives: To demonstrate and quantify free formaldehyde in commercial patch test materials and in prepared aqueous solutions of formaldehyde releasers.

Quantitative 13C NMR spectroscopic studies on the equilibrium of formaldehyde with its releasing cosmetic preservatives.

The aim of our study was to show that NMR spectroscopy is an excellent method to obtain reliable information about the equilibrium between free formaldehyde and its formaldehyde releasers. For this purpose, we compared several O- and N-formal-based formaldehyde releasers used in industrial and consumer products. The underlying chemical structures as well as the release of formaldehyde were followed quantitatively as a function of the pH and dilution.

Ultrasonic velocity measurements as a method for investigating phase transitions of monoglyceride emulsifier systems in pearlescent cosmetic creams.

The phase transitions of monoglyceride emulsifier systems and pearlescent effects in cosmetic creams are investigated using ultrasonic velocity measurements. The transitions between the different phases of monoglyceride emulsifier systems--the coagel, liquid-crystalline lamellar phase, and gel phase--are detected in creams by changes in the ultrasonic velocity with variation of the temperature. The phase transition temperatures correspond to DSC results.