Assessing residual fragrances on skin after body washing: Optimization of an analytical method using solid-phase microextraction coupled with gas chromatography-mass spectrometry.

OBJECTIVE: The aim of this study is to develop and optimize a method for evaluating the persistence of residual fragrance after body washing, addressing a significant requirement in the development of personal care products. The main objective is to establish a reliable, sensitive and reproducible analytical technique to assess fragrance longevity on skin post-use of body wash products. METHODS: Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) is used to analyse residual fragrances. We investigate the extraction efficiencies of various SPME fibres and compare different methods for sampling skin-emitted fragrances, including tape stripping and sealed glass funnels. A controlled body-washing procedure is implemented to standardize the cleansing process. RESULTS: Our findings indicate that the relative standard deviation for measuring five distinct fragrances is within the range of 3%-14%, highlighting the precision of the method. A notable variance exists in the extraction efficiency of fragrances using different types of SPME fibres, with some exhibiting over a threefold difference. Furthermore, the glass funnel method for fragrance collection demonstrates an 11.7 times greater sensitivity to galaxolide than that of the tape-stripping method. Residual fragrances with base notes as the main components can be detected on the skin up to 24 h after body washing. CONCLUSION: The optimized method for residual fragrance evaluation developed in this study offers a robust tool for analysing fragrance components persisting on the skin for up to 24 h post-wash. This advancement facilitates a deeper understanding of fragrance longevity in personal care products, enabling comparative analyses between different products.

OBJECTIF: l'objectif de cette étude est de développer et d'optimiser une méthode d'évaluation de la persistance du parfum résiduel après la toilette du corps, répondant à une exigence significative dans le développement de produits de soins personnels. L'objectif principal est d'établir une technique analytique fiable, sensible et reproductible pour évaluer la longévité des parfums sur la peau après utilisation de produits de toilette pour le corps. METHODES: la microextraction en phase solide de l'espace de tête (HS­SPME) couplée à la chromatographie en phase gazeuse­spectrométrie de masse (GC­MS) est utilisée pour analyser les parfums résiduels. Nous étudions l'efficacité de l'extraction de diverses fibres SPME et nous comparons différentes méthodes d'échantillonnage des senteurs émises par la peau, y compris le stripping sur ruban adhésif et les entonnoirs en verre scellés. Une procédure contrôlée de lavage du corps est mise en place pour standardiser le processus de nettoyage. RÉSULTATS: nos résultats indiquent que l'écart­type relatif pour mesurer cinq parfums distincts se situe dans la plage de 3% à 14%, ce qui souligne la précision de la méthode. Une variance notable existe dans l'efficacité d'extraction des parfums utilisant différents types de fibres de SPME, certaines présentant plus d'un triplement de différence. En outre, la méthode de l'entonnoir en verre pour la collecte des parfums démontre une sensibilité au galaxolide 11,7 fois supérieure à celle de la méthode de stripping sur ruban adhésif. Les parfums résiduels avec des notes de fond comme principaux composants peuvent être détectés sur la peau jusqu'à 24 h après le lavage du corps. CONCLUSION: la méthode optimisée pour l'évaluation du parfum résiduel développée dans cette étude offre un outil fiable pour analyser les composants du parfum persistant sur la peau jusqu'à 24 heures après le lavage. Cette avancée offre une meilleure compréhension de la longévité des parfums dans les produits de soins personnels, permettant des analyses comparatives entre les différents produits.

A study on time-concentration superposition of dilatational modulus and foaming behavior of sodium alkyl sulfate.

The oscillatory dilatational flow of interfacial rheology is a useful tool to unveil the motion of molecules and the interaction between adsorbed molecules at the interfacial layers. Despite its usefulness, it is difficult to analyze the dilatational moduli because they are functions of both the frequency and concentration. In this study, we adopted superposition behavior to investigate the diffusive transport of sodium alkyl sulfate surfactant based on the interfacial rheology under oscillatory dilatational flow. We found that the time-concentration superposition is valid for dynamic dilatational moduli. The shifting factors for superposition on time-axis exponentially decrease as concentration increases due to the molecular exchange between interface and bulk. It is found that the concentration dependence of the shift factors decreases as the size of the hydrophilic and hydrophobic groups increases. It is worth noting that the concentration dependence of the shift factors is related to the foaming speed of the surfactant solutions: As the concentration-dependence of shifting factors increases, the foaming speed increases. It is expected that the time-concentration superposition can be a new tool to study the dynamic dilatational rheology.

Microfluidic device for sheathless particle focusing and separation using a viscoelastic fluid.

Continuous sheathless particle separation with high efficiency is essential for various applications such as biochemical analyses and clinical diagnosis. Here, a novel microfluidic device for highly efficient, sheathless particle separation using an elasticity-dominant non-Newtonian fluid is proposed. Our device consists of two stages: sheathless three-dimensional focusing (1 st stage) and separation (2nd stage). It is designed based on the principle of a viscoelasticity-induced particle lateral migration, which promises precise separation of particles in a microfluidic device. Particles of 5- and 10-µm diameters were all focused at the centerline of a circular channel at the 1st stage and successfully separated at the 2nd stage with an efficiency of ∼99.9% using size-based lateral migration of particles induced by the viscoelasticity of the medium. We also demonstrated the capability of our device for separation of blood cells into multiple fractions. The tunability of separable particle size could be achieved by changing the viscoelastic property of the medium and flow rate.

Quantitative detection of residual E. coli host cell DNA by real-time PCR.

E. coli has been widely used as a host system to manufacture recombinant proteins for human therapeutic use. Among impurities to be eliminated during the downstream process, residual host cell DNA is a major interest for safety. Residual E. coli host cell DNA in the final products are usually determined using conventional slot blot hybridization assay or total DNA Threshold assay, although these methods are time consuming, expensive, and relatively insensitive. Therefore a sensitive real-time PCR assay for specific detection of residual E. coli DNA was developed and compared with slot blot hybridization assay and Threshold assay to validate the overall capability of these methods. Specific primer pair for amplification of the E. coli 16S rRNA gene was selected to improve the sensitivity, and E. coli host cell DNA was quantified by use of SYBR Green 1. The detection limit of real-time PCR assay in the optimized condition was calculated to be 0.042 pg genomic DNA, which is much higher than those of slot blot hybridization assay and Threshold assay of which detection limit were 2.42 and 3.73 pg genomic DNA, respectively. The real-time PCR assay was validated to be more reproducible, accurate, and precise than slot blot hybridization assay and Threshold assay. The real-time PCR assay may be a useful tool for quantitative detection and clearance validation of residual E. coli DNA during the manufacturing process for recombinant therapeutics.

Inactivation of influenza A virus H1N1 by disinfection process.

BACKGROUND: Because any patient, health care worker, or visitor is capable of transmitting influenza to susceptible persons within hospitals, hospital-acquired influenza has been a clinical concern. Disinfection and cleaning of medical equipment, surgical instruments, and hospital environment are important measures to prevent transmission of influenza virus from hospitals to individuals. This study was conducted to evaluate the efficacy of disinfection processes, which can be easily operated at hospitals, in inactivating influenza A virus H1N1 (H1N1). METHODS: The effects of 0.1 mol/L NaOH, 70% ethanol, 70% 1-propanol, solvent/detergent (S/D) using 0.3% tri (n-butyl)-phosphate and 1.0% Triton X-100, heat, and ethylene oxide (EO) treatments in inactivating H1N1 were determined. Inactivation of H1N1 was kinetically determined by the treatment of disinfectants to virus solution. Also, a surface test method, which involved drying an amount of virus on a surface and then applying the inactivation methods for 1 minute of contact time, was used to determine the virucidal activity. RESULTS: H1N1 was completely inactivated to undetectable levels in 1 minute of 70% ethanol, 70% 1-propanol, and solvent/detergent treatments in the surface tests as well as in the suspension tests. H1N1 was completely inactivated in 1 minute of 0.1 mol/L NaOH treatment in the suspension tests and also effectively inactivated in the surface tests with the log reduction factor of 3.7. H1N1 was inactivated to undetectable levels within 5 minutes, 2.5 minutes, and 1 minute of heat treatment at 70, 80, and 90 degrees C, respectively in the suspension tests. Also, H1N1 was completely inactivated by EO treatment in the surface tests. CONCLUSION: Common disinfectants, heat, and EO tested in this study were effective at inactivating H1N1. These results would be helpful in implementing effective disinfecting measures to prevent hospital-acquired infections.