Increased Ordering of Potassium Stearate/Stearic Acid/Glyceryl Stearate Confined between Swollen Cross-Linked Poly(acrylic acid).

In this paper, we investigate the phase behavior of a surfactant mixture comprising glyceryl stearate, potassium stearate, and stearic acid, in the presence of Carbopol, a commonly used thickener in personal care products. At low Carbopol concentrations (<0.03%), the surfactant mixture interacted with Carbopol electrostatically, increasing the degree of Carbopol swelling and, consequently, the overall viscosity. However, such an effect diminished as the Carbopol concentration was further increased. At a Carbopol concentration of 0.2%, two types of liquid crystalline surfactant structures, namely, multilamellar vesicles and lamellae, were observed between the swollen Carbopol domains. Although similar types of surfactant structures were present in a much more concentrated surfactant solution having a similar viscosity but without Carbopol, the lamellae in the presence of Carbopol were more ordered and with a larger d spacing. The increased ordering was probably induced by the interactions between the surfactants and Carbopol as the surfactants were confined between the swollen Carbopol domains.

Determination of iodopropynyl butylcarbamate in cosmetic formulations utilizing pulsed splitless injection, gas chromatography with electron capture detector.

Current analytical methodology for iodopropynyl butylcarbamate (IPBC) analysis focuses on the use of liquid chromatography and mass spectrometer (LC-MS), but the high instrumentation and operator investment required has resulted in the need for a cost effective alternative methodology. Past publications investigating gas chromatography with electron capture detector (GC-ECD) for IPBC quantitation proved largely unsuccessful, likely due to the preservatives limited thermal stability. The use of pulsed injection techniques commonly used for trace analysis of thermally labile pharmaceutical compounds was successfully adapted for IPBC analysis and utilizes the selectivity of GC-ECD analysis. System optimization and sample preparation improvements resulted in substantial performance and reproducibility gains. Cosmetic formulations preserved with IPBC (50-100ppm) were solvated in toluene/isopropyl alcohol and quantified over the 0.3-1.3µg/ml calibration range. The methodology was robust (relative standard deviation 4%), accurate (98% recovery), and sensitive (limit of detection 0.25ng/ml) for use in routine testing of cosmetic formulation preservation.