Cosméticos capilares: tintes

Quantifying the effects of repeated dyeing: Morphological, mechanical, and chemical changes in human hair fibers

As hair dyeing gains popularity across all age groups, concerns about the potential damage caused by chemical treatments are also on the rise. Chemical dyes have a multifaceted impact on hair fibers, affecting their morphology, physical structure, and protein composition. In a comprehensive study, we investigated the alterations in morphological and mechanical properties, as well as the chemical composition of hair fibers following continuous dyeing. Our analysis employed various techniques, including atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy, and tensile strength measurements. To assess the cumulative damage resulting from repeated dyeing, we progressively increased the number of dyeing up to 10. Surprisingly, even a single dyeing session inflicted noticeable harm on the hair. However, the detrimental effects escalated significantly when hair underwent three or more consecutive dye treatments. While the mechanical properties and protein composition exhibited non-linear changes with increasing the number of dyeing, we observed that nanoscale damage to the cuticle surface intensified proportionally with the number of dyeing. These results highlight the critical need to consider the impacts of hair dyeing practices on both the health and the structural integrity of hair.

Quantification of p-Phenylenediamine in Hair Dyes and Health Risk Implications in the UAE: Describing Discordances Between Regulations and Real-Life Practices

BACKGROUND

p-Phenylenediamine (PPD) has been used over the past five decades as a primary precursor in the production of oxidative hair dyes. Numerous health dangers are associated with the short- and long-term use of PPD, raising concerns about its safety. For instance, mounting data suggests that PPD is linked to dermatitis and allergy cases.

OBJECTIVE

To quantify the PPD content in hair dyes by measuring the PPD concentration after mixing the ingredients of commercial hair dyes.

METHODS

A total of 290 permanent hair dyes were tested. RP-HPLC-DAD analysis was performed to determine and quantify the PPD content.

RESULTS

The estimated mean of the PPD limit was 0.89 (95% CI [0.81-0.96]). Of the 290 tested hair dyes, 7.2% (n = 21) exceeded the recommended PPD concentration after mixing. Significantly more hair dyes manufactured in India and China had a PPD content exceeding 2% after mixing compared to dyes from other regions (P = 0.001). Moreover, hair dyes manufactured in India and the UAE were more likely to have incomplete descriptions of the conditions of use and warnings on the label (P = 0.002).

CONCLUSION

The effectiveness of the current regulations relevant to these products should be reevaluated. Moreover, through the use of good manufacturing procedures (GMPs), research, and the reporting of adverse reactions, hair dyes should be subjected to better control and monitoring in terms of their safety and quality.

Exposure estimates of parabens from personal care products compared with biomonitoring data in human hair from Northeast China

Parabens (PBs), a class of endocrine-disrupting chemicals (EDCs), are extensively used as additives in personal care products (PCPs); however, distinguishing between endogenous and exogenous contamination from PCPs in hair remains a challenge. We conducted a comprehensive analysis of the levels, distribution patterns, impact factors, and sources of PBs in 119 human hair samples collected from Changchun, northeast China. The detection rates of methylparaben (MeP), propylparaben (PrP), and ethylparaben (EtP) in hair samples were found to be 100%. The concentration of PBs in hair followed the order of MeP (57.48 ng/g) > PrP (46.40 ng/g) > EtP (6.80 ng/g). The concentration of PrP in female hair was significantly higher (65.38 ng/g) than that observed in male hair (7.82 ng/g) (p < 0.05). The levels of excretion rates of MeP (ERMeP) and excretion rates of PrP (ERPrP) in the hair-dying samples (ERMeP: 17.89 ng/day; ERPrP: 14.15 ng/day) were found to be 2.52 and 2.40 times higher, respectively, compared to the non-hair-dying samples (ERMeP: 7.09 ng/day; ERPrP: 6.05 ng/day). However, the system exposure dosage (SED) results revealed that although hair dyes exhibited higher PBs, human exposure was found to be lower than certain PCPs. The results of the correlation analysis revealed that toner, face cream, body lotion, and hair conditioner were identified as the primary sources of PBs in male hair. Furthermore, the human exposure resulting from the utilization of female hair dye and serum exhibited a positive correlation with hair ERMeP and ERPrP levels, indicating in the screening of samples, excluding hair samples using hair dye and haircare essential oil can effectively avoid the interference caused by exogenous contamination from PCPs.

Green synthesis of nickel-doped magnesium ferrite nanoparticles via combustion for facile microwave-assisted optical and photocatalytic applications

NixMg1-xFe2O4(x = 0, 0.2, 0.4, 0.6) nanoparticles were symphonized via combustion with microwave assistance in the presence of Tamarindus indica seeds extract as fuel. Nanoparticles nature, size, morphology, oxidation state, elemental composition, and optical and luminescence properties were analysed using PXRD, FTIR, SEM, EDX, and HRTEM with SAED, XPS, UV-Visible and photoluminescence spectroscopy. PXRD analysis confirms that synthesized nanoparticles are spinel cubic and have a 17-18 nm average crystalline size. Tetrahedral and octahedral sites regarding stretching vibrations were confirmed by FTIR analysis. SEM and HRTEM data it is disclosed that the morphology of synthesized nanoparticles has nano flakes-like structure with sponge-like agglomeration. Elemental compositions of prepared nanoparticles were confirmed through EDX spectroscopy. XPS Spectroscopy confirmed and revealed transition, oxidation states, and elemental composition. The band gap and absorption phenomenon were disclosed using UV-visible spectroscopy, where the band gap declines (2.1, 2, 1.6, 1.8 eV), with increase in nickel NixMg1-xFe2O4(x = 0, 0.2, 0.4, 0.6) doping. Photoluminescence intensity reduces with an incline in nickel doping, was confirmed and disclosed using photoluminescence spectroscopy. Dyes (Methylene blue and Rhodamine B) degradation activity was performed in the presence of NDMF nanoparticles as a photocatalyst, which disclosed that 98.1% of MB dye and 97.9% of RB dye were degraded in 0-120 min. Regarding initial dye concentration and catalyst load, 5 ppm was initiated as the ideal initial concentration for both RB and MB dyes. 50 mg catalyst dosage was found to be most effective for the degradation of MB and RB dyes. In comparison, pH studies revealed that photodegradation efficiency was higher in neutral (MB-98.1%, RB-97.9%) and basic (MB-99.6%, RB-99.3%) conditions than in acidic (MB-61.8%, RB-60.4%) conditions.

Advances in testing for sample manipulation in clinical and forensic toxicology-part B: hair samples

As a continuation of part A, focusing on advances in testing for sample manipulation of urine samples in clinical and forensic toxicology, part B of the review article relates to hair, another commonly used matrix for abstinence control testing. Similar to urine manipulation, relevant strategies to manipulate a hair test are lowering drug concentrations in hair to undercut the limits of detection/cut-offs, for instance, by forced washout effects or adulteration. However, distinguishing between usual, common cosmetic hair treatment and deliberate manipulation to circumvent a positive drug test is often impossible. Nevertheless, the identification of cosmetic hair treatment is very relevant in the context of hair testing and interpretation of hair analysis results. Newly evaluated techniques or elucidation of specific biomarkers to unravel adulteration or cosmetic treatment often focused on specific structures of the hair matrix with promising strategies recently proposed for daily routine work. Identification of other approaches, e.g., forced hair-washing procedures, still remains a challenge in clinical and forensic toxicology.

Considering the risk of a coloring shampoo with the function of gray hair cover cosmetology and skin barrier: A systematic review

Background and Aims

As the number of demanders who want to easily cover gray hair increases, the demand market is rapidly expanding along with the demand for coloring shampoos that can be dyed while shampooing. Among these coloring shampoo ingredients, it is necessary to differentiate products that are safe and harmless to the human body in consideration of hair loss or skin barrier problems caused by trihydroxybenzene (THB) ingredients. The correct selection criteria were presented by examining the problems, effectiveness, and side effects when used in relation to the skin barrier through previous studies by consideration of the ingredients of the coloring shampoo and the skin barrier of the scalp.

Methods

The analysis of this study looked at previous studies through a systematic literature review through related keywords for coloring shampoo. After reviewing 150-200 related prior papers, a total of 39 review papers were finally selected using the PRISMA flow diagram.

Results

It was confirmed through a literature review that the coloring shampoo containing THB, which is harmful to the human body, has a detrimental effect on the scalp-skin barrier.

Conclusion

This study examined the harmfulness of coloring shampoo on the scalp skin barrier. It was confirmed that frequent coloring shampoo procedures can have various harmful effects on the scalp. Therefore, it is important to reduce side effects caused by the use of harmful ingredients and maintain a healthy scalp condition through analysis of sufficient scalp conditions and consultation with experts. In addition, various studies on the standard standards and age for harmful ingredients are suggested.

Study of P-Phenylenediamine (PPD) Concentrations after Hair Dye Mixing: A Call for Safety Reassessment

Para-phenylenediamine (PPD) is a chemical that is widely used in hair dyes. Multiple safety and regulatory agencies have categorized PPD as a potent sensitizer. In addition, PPD has carcinogenicity and genotoxicity attributes and, consequently, it is regulated at a maximal concentration of 2.0%. The aim of this study was to test whether the limit for PPD is surplus, and hence whether the consumer may be exposed to unnecessarily PPD levels. Experimentally, the analysis of PPD was performed using HPLC, where method validation and an inter-laboratory comparison test (ILC) were conducted to evaluate method performance. Thirty-three commercial products were analyzed, and five products were chosen to study the unconsumed PPD. Successfully, the implemented method confirmed its suitability and validity for the determination of PPD. For ILC results, PPD levels were 0.97 ± 0.04% and 0.92 ± 0.02%, quantified by our laboratory and an accredited laboratory, respectively. For all products, the initial concentration (T0) of PPD was lower than the regulatory limit. After 45 min, the content of PPD significantly reduced compared to T0. One product showed unconsumed PPD to be as high as 96% following the recommended dyeing time. In conclusion, the existence of high levels of unreacted PPD increases the likelihood of allergic events and elevates the risk of PPD-related chemicals. Collaborative efforts between industries, regulatory bodies, and health-related decision makers are deemed necessary to establish safe concentrations for PPD.

An Electroanalytical Solution for the Determination of Pb2+ in Progressive Hair Dyes Using the Cork-Graphite Sensor

Lead is one of the most toxic metals for living organisms: once absorbed by soft tissues, it is capable of triggering various pathologies, subsequently bioaccumulating in the bones. In consideration of this, its detection and quantification in products for human consumption and use is of great interest, especially if the procedure can be carried out in an easy, reproducible and economical way. This work presents the results of the electroanalytical determination of lead in three different commercial products used as progressive hair dyes. Analyses were performed by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) using a composite cork–graphite sensor in 0.5M H₂SO₄ solution or 0.1M acetate buffer (pH 4.5), in the presence and absence of hair dye samples. The H₂SO₄ solution gave better results in terms of analyte sensitivity than the acetate buffer electrolyte. In both cases, well-defined signals for lead were obtained by DPSV analyses, enabling the calibration curve and figures of merit to be determined. The limits of detection (LOD) were found to be approximately 1.06 µM and 1.26 µM in H₂SO₄ and acetate buffer, respectively. The DPSV standard addition method was successfully applied to quantify the lead in hair dye samples, yielding values below 0.45% in Pb. All three analyzed samples were shown to comply with the limit set by the Brazilian Health Regulatory Agency, i.e., 0.6% lead in this type of product. The comparison of the electroanalytical results with those obtained by the reference method, based on the use of inductively coupled plasma optical emission spectrometry (ICP–OES), confirmed that the electroanalytical detection approach is potentially applicable as a strategy for quality control.

Polyelectrolyte-Dye Interactions: An Overview

Polyelectrolytes are polymers with repeating units of ionizable groups coupled with counterions. Recently, polyelectrolytes have drawn significant attention as highly promising macromolecular materials with potential for applications in almost every sector of our daily lives. Dyes are another class of chemical compounds that can interact with substrates and subsequently impart color through the selective absorption of electromagnetic radiation in the visible range. This overview begins with an introduction to polyelectrolytes and dyes with their respective definitions, classifications (based on origin, molecular architecture, etc.), and applications in diverse fields. Thereafter, it explores the different possible interactions between polyelectrolytes and dyes, which is the main focus of this study. The various mechanisms involved in dye-polyelectrolyte interactions and the factors that influence them are also surveyed. Finally, these discussions are summarized, and their future perspectives are presented.

Thermostable bacterial laccase for sustainable dyeing using plant phenols

Laccase is regarded as an efficacious eco-friendly enzyme in various industries. Thus, various laccases have been explored to mitigate the environmental effects of conventional industrial processing; however, the prospects of laccase in hair dyeing have not been thoroughly explored to date. On account of the adverse environmental and health-related issues posed by chemical hair dyeing, laccase as a natural alternative in dyeing hair has recently gained attention. In this study, we executed hair dyeing with different colours and shades of hair dyes developed from natural plant phenols, including ferulic acid, gallic acid, catechol, and syringaldehyde, catalysed by a novel thermostable bacterial laccase (LacT) from Brevibacillus agri. The dyed hair was characterised in terms of its colourimetric parameters (L*, a*, and b*), colour strength (K/S), reflectance (R) and colour durability. L* means luminosity and is defined by L* values from 0 (black) to 100 (white). A positive value of a* means red shades and a negative value indicates green shades. A positive value of b* shows yellow shades and a negative value indicates blue shades. Optical microscopy of circular and longitudinal sections of the dyed hair revealed that the laccase-catalysed dyes did not merely stick to the surface; instead, they well-penetrated the hair. Furthermore, the dyeing process did not affect the surface morphology of the dyed hair. The dyed hair also exhibited a desirable range of colour diversity in terms of market-driven demands and showed considerable resistance to fading during shampooing and pH alterations. Post-dyeing, the texture and tensile strength of the dyed hair remained nearly unchanged. Overall, the outcomes suggest that LacT holds high potential to be exploited extensively in the hair dyeing industry as an alternative to chemical hair dyes.

Laccase is regarded as an efficacious eco-friendly enzyme in various industries.

Assessment of the compounds formed by oxidative reaction between p-toluenediamine and p-aminophenol in hair dyeing processes: Detection, mutagenic and toxicological properties

Previous studies have demonstrated the presence of precursors and coupling agents in wastewater from hair dyeing processes. The complex reaction involved in the oxidation of these compounds can generate extremely hazardous sub-products, leading to an increase in the mutagenicity and toxicity of wastewater. Without proper treatment, this highly toxic wastewater may find its way into the drinking water treatment plant. The present work aimed to investigate the main products generated after the oxidation reaction involving p-toluenediamine (PTD) and p-aminophenol (PAP) - precursors that widely used in the composition of commercial permanent hair dyes, under experimental conditions close to the routine hair dyeing process (in the presence and absence of hydrogen peroxide in ammoniacal medium), using spectroscopic techniques. The study also investigated the mutagenicity and toxicity of the products formed in the hairdressing wash water and conducted detection analysis to determine the presence of the precursors and Bandrowski's Base Derivative (BBD) in samples of wastewater, surface and drinking water using HPLC-DAD and linear voltammetry techniques. Based on this investigation, we identified several PTD and PAP self-oxidation products and eleven sub-products derived from the reaction between PTD and PAP. Assays conducted using Salmonella typhimurium YG1041, with and without activation-induced rat liver metabolism (S9), indicated mutagenicity of the reaction products in concentrations above 10.0 μg μL^-1. The concentrations of PTD, PAP, and several reactions and oxidation products of these precursors were detected in wastewater and water samples.

Influence of cosmetic hair treatments on hair of methamphetamine abuser: Bleaching, perming and coloring

Various cosmetic hair manipulations are known to interfere with the drug of abuse concentrations in hair. It is important to know the effects of cosmetic hair treatments as they may cause false-positive or false-negative results. The article aimed to investigate the effect of bleaching, perming, and dyeing treatment on the hair of methamphetamine（MA）abusers. The research results show that during the bleaching treatment, the content of MA in the hair is positively correlated with the degree of the treatment. Bleaching caused strong chemical degradation on MA, while perming exerted more a leaching out effect. Temporary dyes in single applications had only little effects on MA, Semi-permanent dyes can penetrate into the hair and exert a stronger matrix effect. The effect of permanent hair dye on the content of MA in hair mainly depends on the concentration of hydrogen peroxide.

Cheating on forensic hair testing? Detection of potential biomarkers for cosmetically altered hair samples using untargeted hair metabolomics

Hair analysis has become an integral part in forensic toxicological laboratories for e.g. assessment of drug or alcohol abstinence. However, hair samples can be manipulated by cosmetic treatments, altering drug concentrations which eventually leads to false negative hair test results. In particular oxidative bleaching of hair samples under alkaline conditions significantly affects incorporated drug concentrations. To date, current techniques to detect cosmetic hair adulterations bear limitations such as the implementation of cut-off values or the requirement of specialized instrumentations. As a new approach, untargeted hair metabolomics analysis was applied to detect altered, endogenous biomolecules that could be used as biomarkers for oxidative cosmetic hair treatments. For this, genuine hair samples were treated in vitro with 9% hydrogen peroxide (H2O2) for 30 minutes. Untreated and treated hair samples were analyzed using liquid-chromatography high-resolution time-of-flight mass spectrometry. In total, 69 metabolites could be identified as significantly altered after hair bleaching. The majority of metabolites decreased after bleaching, yet totally degraded metabolites were most promising as suitable biomarkers. The formation of biomarker ratios of metabolites decreasing and increasing in concentrations improved the discrimination of untreated and treated hair samples. With the results of this study, the high variety of identified biomarkers now offers the possibility to include single biomarkers or biomarker selections into routine screening methods for improved data interpretation of hair test results.

Cocrystal hydrate of Bandrowski's base and clotrimazole: a prospective ingredient for hair dye formulations

When crystallized with the antifungal medication clotrimazole, p-phenylenediamine, the most prominent hair developer used in the hair dye industry today, is oxidized to its trimeric product Bandrowski's base, and forms a cocrystal.

Effect of Phyllanthus emblica Linn. on Tensile Strength of Virgin and Bleached Hairs

In Ayurveda medicine, Phyllanthus emblica Linn. (emblica) has been used as a hair nourisher for more than a decade by soaking it overnight, but no study has proved the effect of emblica on hair. This research aims to determine the effect of emblica solution on the tensile strength of three types of hair: virgin hair (VH), bleached hair (BH), and twice bleached hair (TH). The investigated active substances were deionized water (DI water) as a control, 3% emblica extract solution (3% EXS), 6% emblica extract solution (6% EXS), and 9% emblica extract solution (9% EXS). Black Virgin Asian hair was measured and analyzed before bleaching with a 12% bleaching agent once (BH) and twice (TH). Three treatments and the control were applied to each type of hair under a controlled condition. The tensile characteristics and surface morphology of all treated hairs were measured and analyzed by texture analysis (TA.XT Plus Texture Analyzer, Stable Micro Systems), Aramo (Aramo-SG Skin & Hair analysis system), and scanning electron microscopy (SEM model JSM-5410LV JEOL). The results of the nanoindentation test proved that the tensile strength and extensibility of all three types of hair increased in all concentrations (DI water, 3% EXS, 6% EXS, and 9% EXS). High magnification SEM images were taken from the cuticle surfaces and cross-sections. Emblica extracted solution (EXS) formed a coating around the hair, especially cuticle damaged by bleaching (BH and TH). The breaking pattern from the cross-section images showed that emblica extract solution reinforced all hair types. In conclusion, the emblica extract solution has a significant positive effect on the tensile strength and extensibility of VH, BH, and TH. The result has proved the ancient intelligence that the emblica nourishes the hair. In addition, our results show additional benefit by strengthening virgin hair and bleached hair.

Mimicking Natural Human Hair Pigmentation with Synthetic Melanin

Human hair is naturally colored by melanin pigments, which afford myriad colors from black, to brown, to red depending on the chemical structures and specific blends. In recent decades, synthetic efforts have centered on dopamine oxidation to polydopamine, an effective eumelanin similar to the one found in humans. To date, only a few attempts at polydopamine deposition on human hair have been reported, and their translation to widespread usage and potential commercialization is still hampered by the harsh conditions employed. We reasoned that novel, mild, biocompatible approaches could be developed to establish a metal-free route to tunable, nature-inspired, long-lasting coloration of human hair. Herein, we describe synthetic and formulation routes to achieving this goal and show efficacy on a variety of human hair samples via multiple spectroscopic and imaging techniques. Owing to the mild and inexpensive conditions employed, this novel approach has the potential to replace classical harsh hair dyeing conditions that have raised concerns for several decades due to their potential toxicity.

Assessment of p-aminophenol oxidation by simulating the process of hair dyeing and occurrence in hair salon wastewater and drinking water from treatment plant

This work reports the study of oxidation reaction of p-aminophenol (PAP) in ammoniacal medium in dissolved atmospheric oxygen and hydrogen peroxide, simulating the process of hair dyeing with permanent dyes. The products formed, which included semi-quinoneimine radical, quinoneimine, dimers, trimers and tetramers, were identified by mass spectrometry, infrared spectroscopy, UV-vis spectrophotometry, and nuclear magnetic resonance of hydrogen. The process was found to involve an autoxidation mechanism. The mutagenicity of the products was carried out by Salmonella Typhimurium YG1041 assay, and the results indicated no mutagenic properties. The presence of PAP and its oxidative products in samples of wastewater collected from hairdressing salon effluent (WW), raw river water (RRW), and water inlet and outlet of drinking water treatment plant (DWTP) was analyzed by HPLC-DAD. PAP was detected in the collected samples of WW, water samples from DWTP (before and after treatment), at concentrations of 2.1 ± 0.5 mg L^-1, 1.9 ± 0.3 × 10^-3 mg L^-1 and 1.3 ± 0.2 × 10^-3 mg L^-1, respectively. The reaction products, including dimers, trimers and tetramers were identified only in the WW sample; this shows that both the precursor in the sample and its derivatives were released into the wastewater.

A possible new oxidation marker for hair adulteration: Detection of PTeCA (1H-pyrrole-2,3,4,5-tetracarboxylic acid) in bleached hair

Hair analysis has become a valuable tool in forensic toxicology to assess drug or alcohol abstinence. Yet, hair adulteration by cosmetic products presents a major challenge for forensic hair analysis. Oxidative treatments, e.g. bleaching, may lead to analyte loss and thereby to false negative results. Currently, the eumelanin degradation product 1H-pyrrole-2,3,5-tricarboxylic acid (PTCA) serves as a marker for oxidative hair treatment, but requires the definition of cut-off values. To investigate further eumelanin degradation products as markers for oxidative hair treatment, hair samples with and without in vitro bleaching (hydrogen peroxide (H₂ O₂ ) concentrations 1.9% up to 12%; incubation times 15 min, 30 min, 60 min) were analyzed by liquid chromatography coupled to high-resolution time of flight mass spectrometry (HPLC-HRMS). The distribution of eumelanin degradation products along the hair shaft was investigated for routine applicability after segmentation of cosmetically untreated hair samples and authentically treated hair samples. The signals of the eumelanin degradation products PTCA, 1H-pyrrole-2,3,4-tricarboxylic acid (isoPTCA), and 1H-pyrrole-2,3,4,5-tetracarboxylic acid (PTeCA) were found to be significantly elevated after in vitro bleaching already with low H₂ O₂ concentrations and after short incubation times. In contrast to PTCA and isoPTCA, PTeCA was not detectable in cosmetically untreated segments up to 12 cm from hair root and was only formed through the oxidation process. The results of the study show that the detection of PTeCA within the proximal 3 to 6 cm segment can be applied to reliably detect hair adulteration attempts through hair bleaching.

Assessment of the autoxidation mechanism of p-toluenediamine by air and hydrogen peroxide and determination of mutagenic environmental contaminant in beauty salon effluent

The present work investigated the autoxidation reaction of p-toluenediamine (PTD) - a precursor - widely used in permanent hair dyeing formulation, under experimental conditions close to the hair dyeing process (oxygen and/or peroxide in ammoniacal medium), by chromatographic and spectroscopic techniques. In additional, evaluated the mutagenicity of the PTD oxidation products and the presence of PTD and this products in wastewater from beauty salon, as well as in surface water and drinking water using HPLC coupled to a diode array detector and linear scan voltammetry. Through this study, it was possible the identification of semi-quinonediimine, quinonediimine, dimers (derived from toluenediamine), and trimer radical identified as Bandrowski's Base derivative (BBD) formed during autoxidation of PTD. Salmonella Typhimurium YG1041 assay with and without metabolic activation induced rat-liver (S9) indicated mutagenic activity for BBD. Levels of PTD were determined by the standard addition method in samples collected from the wastewater of a beauty salon, as well as from the water before and after treatment in a drinking water treatment plant (DWTP) reached concentrations of 2.08 ± 0.21, 2.36 ± 0.10 × 10^-3, and 1.77 ± 0.13 × 10^-3 mg L^-1, respectively. In addition, linear sweep voltammetry was used to monitor the BBD found at the concentration of 1.59 ± 0.35 mg L^-1 in wastewater collected from the beauty salon.

Protective effect of conditioner agents on hair treated with oxidative hair dye

BACKGROUND

Hair coloring is broadly used by women and men either to change their natural hair color or to delay the onset of gray hair. Oxidative dyes may damage the hair, as chemical and physical processes are required to convert the fiber structure and, consequently, alterations in its mechanical and surface properties.

OBJECTIVES

The aim of this study was to evaluate the protective effect of silanetriol (and) Panthenol, PEG-12 dimethicone, and hydrolyzed silk (and) hydrolyzed milk protein (and) lactose as conditioner agents on hair treated with oxidative hair dye by protein loss, combability, and breaking strength.

METHODS

In this research, we analyzed the untreated hair (sample I) and the effect of oxidative hair dye emulsions, with or without conditioner agents (sample II) silanetriol (and) Panthenol (sample III), PEG-12 dimethicone (sample IV), and hydrolyzed silk (and) hydrolyzed milk protein (and) lactose (sample V) on Caucasian hair. The hair samples were submitted to protein loss quantification, breaking strength, and combing analysis.

RESULTS

For protein loss, the results were: II^a  = V^a  > IV^b  > III^c  > I^d . For the breaking strength: I^e  = II^e  = III^e  = IV^e  = V^e . For the combing analysis for wet and dry hair, the results were, respectively: II^a  > III^b  = IV^b  > V^c  > I^d and II^A  > III^b  = V^b  > IV ^c = I^c . Data classified by different letters presented statistically significant alterations, α = 5, P ≤ . 05, n = 15.

CONCLUSIONS

Based on these results, the incorporation of conditioner agents into emulsion blond color decreased the damage caused by the coloring process.

Analysis of the Maillard reaction in human hair using Fourier transform infrared spectroscopic imaging and a focal-plane array detector

The Maillard reaction has been well researched and used in the food industry and the fields of environmental science and organic chemistry. Here, we induced the Maillard reaction inside human hair and analyzed its effects by using Fourier transform infrared spectroscopy with a focal-plane array (FTIR-FPA) detector. We used arginine (A), glycine (G), and D-xylose (X) to generate the Maillard reaction by dissolving them in purified water and heating it to 150 °C. This label-free process generated a complex compound (named AGX after its ingredients) with a monomer structure, which was determined by using nuclear magnetic resonance (NMR) and FTIR-FPA. This compound was stable in hair and substantially increased its tensile strength. To our knowledge, we are the first to report the formation of this monomer in human hair, and our study provides insights into a new method that could be used to improve the condition of damaged or aging hair.