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218 result(s) for "Salvador, Amparo"
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Analysis of Cosmetic Products
This book advises the reader from an analytical chemistry perspective on the choice of suitable analytical methods for production monitoring and quality control of cosmetic products. This book will enable people working in the cosmetic industry or in research laboratories to become familiar with the main legislative and analytical literature on this subject and learn about and choose suitable analytical procedures for production monitoring and control of cosmetic products, according to their composition. The first section of the book covers various definitions and concepts relating to cosmetic products, current legislation in different countries and specific legislation on ingredients. The central body of the book addresses analytical methods for monitoring and quality control of cosmetic products with the fundamental objective being to enable reader's access to scientific reviews carried out by experts in analytical chemistry. The final section contains a small review of the alternative methods to using animals for cosmetic product evaluation. This book will benefit scientists, technologists, students, practitioners, consultants, etc.
Sunscreen Products as Emerging Pollutants to Coastal Waters
A growing awareness of the risks associated with skin exposure to ultraviolet (UV) radiation over the past decades has led to increased use of sunscreen cosmetic products leading the introduction of new chemical compounds in the marine environment. Although coastal tourism and recreation are the largest and most rapidly growing activities in the world, the evaluation of sunscreen as source of chemicals to the coastal marine system has not been addressed. Concentrations of chemical UV filters included in the formulation of sunscreens, such as benzophehone 3 (BZ-3), 4-methylbenzylidene camphor (4-MBC), TiO₂ and ZnO, are detected in nearshore waters with variable concentrations along the day and mainly concentrated in the surface microlayer (i.e. 53.6-577.5 ng L⁻¹ BZ-3; 51.4-113.4 ng L⁻¹ 4-MBC; 6.9-37.6 µg L⁻¹ Ti; 1.0-3.3 µg L⁻¹ Zn). The presence of these compounds in seawater suggests relevant effects on phytoplankton. Indeed, we provide evidences of the negative effect of sunblocks on the growth of the commonly found marine diatom Chaetoceros gracilis (mean EC₅₀ = 125±71 mg L⁻¹). Dissolution of sunscreens in seawater also releases inorganic nutrients (N, P and Si forms) that can fuel algal growth. In particular, PO₄³⁻ is released by these products in notable amounts (up to 17 µmol PO₄³⁻g⁻¹). We conservatively estimate an increase of up to 100% background PO₄³⁻ concentrations (0.12 µmol L⁻¹ over a background level of 0.06 µmol L⁻¹) in nearshore waters during low water renewal conditions in a populated beach in Majorca island. Our results show that sunscreen products are a significant source of organic and inorganic chemicals that reach the sea with potential ecological consequences on the coastal marine ecosystem.
Stir bar sorptive-dispersive microextraction by a poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent for the determination of tricyclic antidepressants and their main active metabolites in human urine
A poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent was used for the rapid and sensitive determination of tricyclic antidepressants and their main active metabolites in human urine. This material was characterized by magnetism measurements, zeta potential, scanning electron microscopy, nitrogen adsorption–desorption isotherms, and thermogravimetric analysis. The proposed analytical method is based on stir bar sorptive-dispersive microextraction (SBSDME) followed by liquid chromatography–tandem mass spectrometry. The main parameters involved in the extraction step were optimized by using the response surface methodology as a multivariate optimization method, whereas a univariate approach was employed to study the desorption parameters. Under the optimized conditions, the proposed method was properly validated showing good linearity (at least up to 50 ng mL −1 ) and enrichment factors (13–22), limits of detection and quantification in the low ng L −1 range (1.4–7.0 ng L −1 ), and good intra- and inter-day repeatability (relative standard deviations below 15%). Matrix effects were observed for the direct analysis of urine samples, but they were negligible when a 1:1 v/v dilution with deionized water was performed. Finally, the method was successfully applied to human urine samples from three volunteers, one of them consuming a prescribed drug for depression that tested positive for clomipramine and its main active metabolite. Quantitative relative recoveries (80–113%) were obtained by external calibration. The present work expands the applicability of the SBSDME to new analytes and new types of magnetic sorbents. Graphical abstract
Comparison of the energetic stress associated with experimental Nosema ceranae and Nosema apis infection of honeybees (Apis mellifera)
Nosema ceranae is a relatively new and widespread parasite of the western honeybee Apis mellifera that provokes a new form of nosemosis. In comparison to Nosema apis, which has been infecting the honeybee for much longer, N. ceranae seems to have co-evolved less with this host, causing a more virulent disease. Given that N. apis and N. ceranae are obligate intracellular microsporidian parasites, needing host energy to reproduce, energetic stress may be an important factor contributing to the increased virulence observed. Through feeding experiments on caged bees, we show that both mortality and sugar syrup consumption were higher in N. ceranae-infected bees than in N. apis-infected and control bees. The mortality and sugar syrup consumption are also higher in N. apis-infected bees than in controls, but are less than in N. ceranae-infected bees. With both microsporidia, mortality and sugar syrup consumption increased in function of the increasing spore counts administered for infection. The differences in energetic requirements between both Nosema spp. confirm that their metabolic patterns are not the same, which may depend critically on host–parasite interactions and, ultimately, on host pathology. The repercussions of this increased energetic stress may even explain the changes in host behavior due to starvation, lack of thermoregulatory capacity, or higher rates of trophallaxis, which might enhance transmission and bee death.
The prevalence of the honeybee brood pathogens Ascosphaera apis, Paenibacillus larvae and Melissococcus plutonius in Spanish apiaries determined with a new multiplex PCR assay
Summary The microorganisms Ascosphaera apis, Paenibacillus larvae and Melissococcus plutonius are the three most important pathogens that affect honeybee brood. The aim of the present study was to evaluate the prevalence of these pathogens in honeybee colonies and to elucidate their role in the honeybee colony losses in Spain. In order to get it, a multiplex polymerase chain reaction (PCR) assay was developed to simultaneously amplify the16S ribosomal ribonucleic acid (rRNA) gene of P. larvae and M. plutonius, and the 5.8S rRNA gene of A. apis. The multiplex PCR assay provides a quick and specific tool that successfully detected the three infectious pathogens (P. larvae, M. plutonius and A. apis) in brood and adult honeybee samples without the need for microbiological culture. This technique was then used to evaluate the prevalence of these pathogens in Spanish honeybee colonies in 2006 and 2007, revealing our results a low prevalence of these pathogens in most of the geographic areas studied. A multiplex polymerase chain reaction (PCR) assay was developed to simultaneously amplify the16S rRNA gene of Paenibacillus larvae and Melissococus plutonius, and the 5.8S rRNA gene of Ascosphaera apis, the main honey bee brood pathogens. The results of our transverse study revealed a low prevalence of honeybee brood pathogens in Spain in 2006 and 2007. The detection of infectious pathogens in honey bee brood samples without symptoms clearly demonstrates that they are not exclusively present in larvae that exhibit clinical signs of infection.
A Rapid and Sensitive Method for the Determination of Cannabidiol in Cosmetic Products by Liquid Chromatography–Tandem Mass Spectrometry
Cannabidiol is a phytocannabinoid with proven pharmacological properties that is also used in the cosmetic industry for its sebostatic and antioxidant activities, being considered a new anti-aging ally. An analytical method is proposed for the determination of CBD in cosmetic products by liquid chromatography with tandem mass spectrometry, after leaching the CBD from the cosmetic matrix with ethanol. Low instrumental limits of detection (0.22 ng mL−1) and quantification (0.74 ng mL−1) allow the determination of CBD at trace levels without needing preconcentration, whereas the wide linearity of the method allows the determination of CBD in more concentrated samples without high dilution. The method was successfully applied to the analysis of six cosmetic products and a raw material. The proposed method is suitable for the quality control of cosmetic products containing CBD, being able to quickly and easily determine this compound, ensuring that its concentration in the finished product is the desired one.
Simultaneous Quantification of Vitamin A and Derivatives in Cosmetic Products by Liquid Chromatography with Ultraviolet Detection
Vitamin A (retinol) and some of its derivatives are a group of fat-soluble compounds used in cosmetic products as bioactive ingredients. Therefore, it is necessary to perform the quality control of final product to ensure their efficacy and safety. A simple and rapid method to determine retinol, retinal, retinyl acetate, retinyl propionate and retinyl palmitate in cosmetics is presented here. The method is based on vortex and/or ultrasound-assisted leaching of the analytes in ethanol followed by liquid chromatography with ultraviolet detection. The analytical performance of the method was evaluated. It has shown high levels of linearity, at least up to 100 µg mL−1; high precision with RSD values below 14% and high sensitivity with low MLODs ranging between 0.3 × 10−4 and 5.9 × 10−4 % w/w, which are enough to monitor these compounds in cosmetic products. The proposed method was successfully applied to seven commercial cosmetic samples to detect and quantify the target analytes, showing the method is suitable for its employment for quality control in cosmetic industries. Cosmetic samples were spiked at two levels of concentration and recovery values around 100% were obtained, showing no significant matrix effects and, therefore, external calibration was adequate for this determination.
A Green and Rapid Analytical Method for the Determination of Hydroxyethoxyphenyl Butanone in Cosmetic Products by Liquid Chromatography
An analytical method for the determination of hydroxyethoxyphenyl butanone, which is used as an alternative preservative in cosmetic products, has been developed and validated for the first time. The method is based on a simple ultrasound-assisted lixiviation of the analyte from the cosmetic matrix followed by liquid chromatography with UV spectrophotometric detection. Under optimized conditions, the method limit of detection and limit of quantification values were 30 and 90 µg·g−1, respectively. The method was validated with good recovery values (86–103%) and precision values (RSD 0.2–4.7%). Finally, the proposed analytical method was successfully applied to 7 commercially available cosmetic samples including both lipophilic and hydrophilic matrices, such as moisturizing cream, sunscreen, shampoo, liquid hand soap, and make-up. Additionally, a laboratory-made cosmetic cream containing the target analyte was prepared and analyzed. The good analytical figures of merit of the proposed method, in addition to its environmentally-friendly characteristics, demonstrate its usefulness to perform the quality control of cosmetic products to ensure the safety of consumers.
Entry with two correlated signals: the case of industrial espionage and its positive competitive effects
Recent advances in information and communication technologies have increased the incentives for firms to acquire information about rivals. These advances may have major implications for market entry because they make it easier for potential entrants to gather valuable information about, for example, an incumbent’s cost structure. However, little theoretical research has actually analyzed this question. This paper advances the literature by extending a one-sided asymmetric information version of Milgrom and Roberts’ (1982) limit pricing model. Here, the entrant is allowed access to an intelligence system (IS) of a certain precision that generates a noisy signal on the incumbent’s cost structure. The entrant thus decides whether to enter the market based on two signals: the price charged by the incumbent and the signal sent by the IS. Crucially, for intermediate values of IS precision, the set of pooling equilibria with ex-ante profitable market entry is non-empty. Moreover, the probability of ex-ante non-profitable entry is strictly positive. In classical limit pricing models, an entrant never enters in a pooling equilibrium, so this result suggests that the use of an IS may potentially increase competition.
Solid-phase extraction liquid chromatography-tandem mass spectrometry analytical method for the determination of 2-hydroxy-4-methoxybenzophenone and its metabolites in both human urine and semen
2-Hydroxy-4-methoxybenzophenone (HMB), which is one of the most commonly used UV filters in sunscreen cosmetics to protect skin from the deleterious effects of the sun, can be percutaneously absorbed, further metabolized, and finally excreted or bioaccumulated. An analytical method for the sensitive determination of HMB and its three metabolites in both human urine and semen is developed. The presented analytical method is based on a solid-phase extraction (SPE) procedure to clean-up and preconcentrate the target analytes from the urine and semen samples followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. The methodology was fully validated and the standard addition calibration method was used to quantify the target analytes in order to correct the matrix effects observed. Considering this approach, the accuracy of the method was evaluated and the recoveries ranged from 98% to 115% and from 86% to 111% in urine and semen samples, respectively, depending on the analyte. For urine samples, the limits of detection ranged between 0.027 and 0.103 ng mL⁻¹ and the repeatability of the method, expressed as relative standard deviation, was in the range of 7.2-9.2%, depending on the analyte. In the case of semen samples, the limits of detection ranged between 1 and 3 ng mL⁻¹ whereas the repeatability was in the range of 2.2-6.4%, depending on the analyte. The described SPE-LC-MS/MS method was satisfactorily applied to both urine and semen samples from a male volunteer who applied a sunscreen cosmetic product containing HMB. HMB and its metabolites were found and quantified in the low ng mL⁻¹ range in both urine and semen samples, although at a different extent.