A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method as an alternative to a gas chromatography-thermal energy analyser (GC-TEA) method recommended by the European Committee on Standardization (CEN) was validated for the simultaneous determination of eight N-nitrosamines released into artificial saliva from rubber or elastomer teats and soothers. N-nitroso-dipropylamine-d₁₄ (NDPA-d₁₄) was used as internal standard for accurate quantification. The method was validated with relatively good analytical results, including sufficiently low limits of detection (0.1-2 µg kg⁻¹) of sample) and good linearity (r²> 0.99) throughout the studied concentration ranges. Intra- and inter-day precisions expressed with the relative standard deviation (RSD, %) were 3.4-8.0% and 4.4-11.3%, which were below the performance criteria based on one-half of the value derived from the Horwitz value. It was also found that the LC-MS/MS method is sufficiently rugged and successfully applicable to its routine analysis for the compliance test of Commission Directive 93/11/EEC.
The objective was to investigate effects on the hand of protease used in dishwashing liquids (DWL). A group of 30 Koreans (normal skin) and 24 Japanese (12 atopic and 12 normal) were employed for two different studies, respectively. The 30 Koreans were divided into three groups. Each group immersed their hands for 15 min a day for 9 days into DWL containing 0.005% protease, 0.02% protease, or non-enzyme DWL. The 24 Japanese immersed their hands for 15 min a day for 4 days into 0.005% protease-containing or a non-enzyme DWL. The hand skin was evaluated by measuring overall and dry skin grades, estimated before and after exposures to the test products. The Korean study shows that 0.005% and 0.02% protease-containing DWL are less irritating to the skin than non-enzyme control, as measured by better overall skin grades and less dry skin. The Japanese study shows that 0.005% protease-containing DWL are less irritating to the skin than non-enzyme control in both atopic and normal subjects. The 0.005% protease use did not cause any adverse dermatological effects to atopic subjects compared with non-enzyme control. Both studies indicate that 0.005% and 0.02% protease resulted in better skin mildness profile, without causing adverse dermatological complications to the subjects.
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