Abstract
Although 2-amino-5-nitrophenol (2A5NP) is one of the ingredients of hair dye, there has been no information on the dermal absorption rate of 2A5NP. 2A5NP is managed at less than 1.5% in Korea and Japan. In this study, analytical methods were developed and validated using high-performance liquid chromatography (HPLC) in various matrices of wash, swab, stratum corneum (SC), skin (dermis + epidermis), and receptor fluid (RF). Validation results were acceptable based on Korea Ministry of Food and Drug Safety (MFDS) guideline. The HPLC analysis showed a good linearity (r2 = 0.9992–0.9999), a high accuracy (93.1–110.2%), and a good precision (1.1–8.1%) in accordance with the validation guideline. Franz diffusion cell was used to determine dermal absorption of 2A5NP using mini pig skin. 2A5NP (1.5%) was applied to skin at 10 μl/cm2. For certain cosmetic ingredients such as hair dye with short exposure time, an interim wash step (after 30 min) was added during the study. After application for 30 min and 24 h, skin was wiped off with swab and SC was collected using tape stripping. RF was sampled at 0, 1, 2, 4, 8, 12, and 24 h. Total dermal absorption rate of 2A5NP (1.5%) was determined to be 13.6 ± 2.9%.
Keywords: 2-Amino-5-nitrophenol (2A5NP), Dermal absorption, Franz diffusion cell, Hair dye, High performance liquid chromatography (HPLC)
Introduction
The perception and purpose of hair dyeing have changed a lot over time. In the old days, people dyed their hair black to cover up their gray hair, whereas today people dye their hair to express their individuality or look attractive. Nowadays, the number of people dyeing their hair themselves at home is increasing. The number of dyeing products is also increasing. According to the 2019 cosmetics industry analysis report, hair dye products had the highest annual average growth rate (2014–2018) at 88.3% in Korea [1]. Also, according to Korea's 2020 cosmetics import and export performance statistics, hair dye product was ranked the second most imported after basic cosmetic [2]. In export, it ranks third after basic cosmetics and color cosmetics [2]. Accordingly, the hair dye market is growing all over the world. Increasing market of hair dye increases exposure of people to hair dye. Thus, people have a higher possibility of experiencing adverse effects such as skin sensitization from hair dye [3]. Studies in the United States have shown that skin sensitizers are very common in hair dye products, with 99% of hair dyes studied containing potent skin sensitizers [3, 4].
Risk assessment is necessary to comprehensively evaluate harmful effects that might occur when humans are exposed to chemicals present in consumer products (medicine, cosmetics, etc.) [5]. It consists of four steps: hazard identification, dose–response assessment, exposure assessment, and risk characterization. In exposure assessment, systemic exposure dosage (SED) is calculated as the amount of exposure using daily usage, maximum use of ingredients, dermal absorption rate of ingredients, and body weight. In risk characterization, the risk can be determined by dividing the no observed adverse effect level (NOAEL) by the SED and calculating the margin of safety (MOS) [6]. Dermal absorption rate in the risk assessment determines whether the absorption of a chemical into the skin or penetration of a chemical through the skin is sufficient to cause local or systemic toxicity [7]. Through this study, the dermal absorption rate was found and the result could be used for risk assessment. Although 2-amino-5-nitrophenol (2A5NP) is not classified as a strong skin sensitizer, it is one of the ingredients used for hair colorants. 2A5NP is used as a powder form. It has a small molecular weight of 154.12 g/mol. 2A5NP has an XLogP3 value of 1.5, which is more soluble in ethanol, acetone, and benzene than in water [8]. Detailed physicochemical properties of 2A5NP are shown in Table 1. 2A5NP is produced from 2-aminophenol by reaction with acetic anhydride to form 2-methylbenzoxazole, which is nitrated and hydrolyzed to form 2A5NP [9]. It was first synthesized by Kaltwasser and Oehrn in 1920 [10]. 2A5NP is used for color synthetic resins, lacquers, inks, and wood stains [10]. 2A5NP is also used as an intermediate in the manufacture of several azo dyes [11]. Azo dyes are dyes with an azo group (–N = N–) as a chromophore. They account for more than half of synthetic dyes [12]. 2A5NP is a brown-orange dye. It is used as a hair dye component, which is managed at less than 1.5% in Korea and Japan. When 2A5NP is used in coal-tar hair dyes, it is recommended not to exceed 30 min after applying to hair [13]. In this regard, the US Federal Food, Drug and Cosmetic Act (FDCA) recommends the use of preliminary test precautions and guidance statements [14]. There have been no studies on skin toxicity or dermal absorption rate for 2A5NP. Several analytical methods have been reported for the analysis of oxidative hair dyes [15–18]. Some of these methods may only be suitable for verifying the purity of raw materials and for simultaneous analysis of multiple components. So, the first objective was to develop analytical method to quantify 2A5NP in a rapid way in biological samples. And the second purpose of this study was to determine the dermal absorption rate of 2A5NP using a Franz diffusion cell.
Table 1.
Physical and chemical properties of 2-amino-5-nitrophenol
| Properties | Value | Ref |
|---|---|---|
| IUPAC Name | 2-Amino-5-nitrophenol | [8] |
| CAS NO | 121–88-0 | |
| Empirical formula | C6H6N2O3 | |
| Structural formula |
|
|
| Molecular Weight | 154.12 g/mol | |
| XLogP3 | 1.5 | |
| Physical form | Powder | |
| Solubility | Soluble in ethanol, acetone, and benzene | |
| Solubility in water | Slightly soluble in water (< 1 mg/ml (20℃)) | |
| Synonyms | 2-Hydroxy-4-nitroaniline | |
| 5-Nitro-2-aminophenol | ||
| 3-nitro-6-aminophenol | ||
| Rodol YBA |
Materials and methods
Chemicals
Trifluoroacetic acid (TFA), 2-amino-5-nitrophenol (2A5NP, 96%), and polyethylene glycol (PEG) were purchased from Tokyo Chemical Industry Co. (Tokyo, Japan). Distilled water (DW), acetonitrile (ACN) and methanol were purchased from Honeywell Burdick & Jackson Co. (St. Harvey, MI, USA). Hydrogen peroxide solution was purchased from Sigma Aldrich Co. (St. Louis, MO, USA).
HPLC analysis of 2A5NP
High-performance liquid chromatography (HPLC) analysis of 2A5NP was performed using an Agilent 1290 infinity LC (Agilent Technology, Waldbronn, Germany). Samples were detected with a ultraviolet–visible spectroscopy (UV–Vis) detector at wavelength of 200 nm. A Luna C18 (150 × 3.00 mm i.d. 3 µm) (Phenomenex, CA, USA) column with Security Guard Cartridges RP-1 (4 × 3.0 mm; Phenomenex, CA, USA) was used. Chromatographic separation of compounds was carried out with a mobile phase composed of DW containing 0.1% (v/v) trifluoroacetic acid (TFA) as eluent A and ACN containing 0.1% (v/v) TFA as eluent B. The flow rate and injection volume were set at 0.35 ml/min and 10 μl, respectively. HPLC was proceeded with an isocratic condition. Detailed conditions of HPLC for 2A5NP are shown in Table 2
Table 2.
Analytical HPLC conditions for 2-amino-5-nitrophenol
| Item | Condition |
|---|---|
| Column | Luna 3u C18(2) 100A (150 × 3.00 mm) |
| Mobile Phase | DW (0.1% TFA): ACN (0.1% TFA) = 65: 35 |
| LC condition | Isocratic |
| Wavelength | UV–Vis (200 nm) |
| Column oven temperature | 40 ℃ |
| Autosampler temperature | 4 ℃ |
| Flow rate | 0.35 ml/min |
| Running time | 6.5 min |
| Injection volume | 10 μl |
| Retention time | 4.0 min |
Method validation of 2A5NP
Calibration standards
This study was conducted in accordance with guidelines for validation of bio-sampling methods of the Korea Ministry of Food and Drug Safety [19]. 2A5NP was poorly soluble in water. Thus, a stock concentration of 10 mg/ml was prepared with 70% ethanol. Standard solutions at 5, 10, 20, 50, 100, 200 and 500 µg/ml were prepared by diluting the stock solution. Calibration solutions were made by mixing 15 µl of standard solutions with 135 µl of a blank matrix of WASH (30 min), SWAB (24 h), stratum corneum (SC), SKIN (dermis + epidermis), and receptor fluid (RF). All the calibration samples were diluted 1/tenfold with each blank. Final concentrations of calibration solutions were 0.5, 1, 2, 5, 10, 20, and 50 µg/ml. Then 50 µl of calibration solution was mixed with 150 µl of 50% (v/v) methanol. The mixtures were vortexed and centrifuged at 13,000 rpm for 10 min. The supernatant was then filtered using a 0.2 µm polytetrafluoroethylene (PTFE) filter (ADVANTEC, Dublin, CA, USA) and then 10 μl of the supernatant was injected on to HPLC.
Quality control (QC) sample
The lower limit of quantitation (LLOQ) was determined to be 0.5 µg/ml. Limit of quantification (LOQ, 1.5 µg/ml), minimum of quantification (MOQ, 15 µg/ml) and high of quantification (HOQ, 30 µg/ml) were set differently from the concentration of calibration solutions, respectively [15]. Each sample was made using the same method used for calibration standards. Mixtures were centrifuged at 13,000 rpm for 10 min. The supernatant was then filtered using a 0.2 µm polytetrafluoroethylene (PTFE) filter (ADVANTEC, Dublin, CA, USA).
Accuracy and precision of 2A5NP
Accuracy is a measure of the proximity of an experimental value to the actual amount of a substance in a matrix [20]. Precision is a measure of how close measurements are to each other [20]. In order to verify accuracy and precision, intra-day and inter-day tests should be performed. Intra-day test was performed for accuracy and precision for five times a day. Inter-day test for accuracy and precision was done for three times in three days. The accuracy was calculated using the following formula: accuracy (%) = (measured concentration/nominal concentration) × 100. The precision was calculated as the coefficient of variation (CV) using the following formula: precision (%) = (standard deviation / mean) × 100. Results of accuracy and precision should be within 20% of the LLOQ concentration and within 15% of the remaining concentrations [19].
In vitro dermal absorption
This study was conducted in accordance with in vitro skin absorption test guidelines [21, 22]. The process was carried out using Franz diffusion cells using six mini pig skins with a thickness of 500 µm (Apures, Pyeongteak, Korea) [23]. According to the guidelines of the Ministry of Food and Drug Safety, a water–ethanol mixture (1:1) or 6% polyethylene glycol 20 oleyl ether (PEG) solution should be used as the receptor fluid for the evaluation of hydrophobic test substances [22]. Since 2A5NP is more soluble in organic solvents than water [8], 6% PEG was used as the receptor fluid. Before application to pig skin, 2A5NP (3%) and hydrogen peroxide (6%) were mixed in a 1:1 ratio to make it 1.5% 2A5NP according to the Korean dyeing standard [24]. Finally, 1.5% 2A5NP (17.7 µl) was applied to 1.77 cm2 of mini pig skin (10 µl/cm2). It is common to wash the skin 24 h after application. Although test substances such as hair dye are exposed to the skin for up to 45 min and then washed [25], in most skin absorption studies related to hair dye, washing was performed 30 min after application [13]. The skin was wiped off with a swab 30 min after application in the same manner as in the previous hair dye dermal permeation study, and the skin was wiped once more after the end of the test (24 h). After 24 h, it was wiped off with an alcohol swab (SWAB, 24 h). The stratum corneum (SC) of the skin was collected using tape stripping. The tape (Scotch ™, 3 M, Maplewood, MN, USA) was cut into 1.5 × 1.5 cm pieces and removed 15 times. The mini pig skin was then cut into 8 pieces. The WASH (30 min), SWAB (24 h), SC, and SKIN used in each step were put in 10 ml ethanol, sonicated for 1 h, and refrigerated for 24 h prior to analysis. RF was collected at 0, 1, 2, 4, 8, 12, and 24 h and stored in a refrigerator before analysis. After 50 µl of extract sample (WASH (30 min), SWAB (24 h), SC, SKIN) and RF were mixed with 150 µl of 50% methanol, the mixture was then centrifuged at 13,000 rpm for 10 min. The supernatant was then filtered using a 0.2 µm polytetrafluoroethylene (PTFE) filter (ADVANTEC, Dublin, CA, USA). Analysis was carried out using HPLC conditions as mentioned above.
Results
Linearity of calibration standards
Calibration curves were obtained at seven concentrations (0.5, 1, 2, 5, 10, 20, and 50 μg/ml). Chromatograms of blank and LLOQ (0.5 µg/ml) are presented in Fig. 1. The retention time of 2A5NP was 4.1 min. To confirm the linearity of the calibration curve, the degree of association between y and x variables was expressed as the correlation coefficient (r2) [26]. A correlation coefficient close to 1 indicates that the calibration curve is linear [27]. The r2 values of SWAB (WAHS 30 min + SWAB 24 h), SC, SKIN, and RF of 2A5NP were calculated to be 0.9992, 0.99959, 0.99948, and 0.99948, respectively (Table 3).
Fig. 1.
Chromatograms of 2-amino-5-nitrophenol at the blank, LLOQ (0.5 µg/ml) in WASH: alcohol swab (a), SKIN: dermis + epidermis (b), SC: stratum corneum (c), RF: receptor fluid (6% polyethylene glycol) (d)
Table 3.
Accuracy and precision of 2-amino-5-nitrophenol
| Sample | Concentration (μg/ml) | Linearity (r2) | Intra-day1 | Inter-day2 | ||
|---|---|---|---|---|---|---|
| Accuracy3 (%) | Precision4 (%) | Accuracy (%) | Precision (%) | |||
| SWAB5 | 0.5 | 0.9992 | 100.95 | 1.52 | 101.73 | 4.43 |
| 1.5 | 100.36 | 2.29 | 96.89 | 5.47 | ||
| 15 | 101.30 | 2.33 | 103.91 | 2.81 | ||
| 30 | 100.41 | 1.79 | 102.54 | 1.99 | ||
| SC6 | 0.5 | 0.99959 | 105.93 | 5.39 | 99.53 | 8.05 |
| 1.5 | 97.61 | 7.81 | 99.77 | 5.90 | ||
| 15 | 93.11 | 5.48 | 102.46 | 3.76 | ||
| 30 | 105.46 | 3.83 | 104.06 | 2.25 | ||
| SKIN7 | 0.5 | 0.99948 | 95.79 | 5.69 | 95.27 | 4.49 |
| 1.5 | 99.95 | 4.85 | 101.51 | 4.35 | ||
| 15 | 101.81 | 0.91 | 96.69 | 1.47 | ||
| 30 | 96.63 | 1.82 | 96.01 | 1.60 | ||
| RF8 | 0.5 | 0.99948 | 108.24 | 2.75 | 100.72 | 4.83 |
| 1.5 | 106.63 | 4.44 | 104.07 | 4.84 | ||
| 15 | 109.43 | 1.08 | 106.36 | 1.51 | ||
| 30 | 110.24 | 1.78 | 104.48 | 1.70 | ||
1Repeated 5 times a day
2Repeated 3 times another day
3(measured concentration/nominal concentration) × 100 (%)
4(standard deviation / mean) × 100 (%)
5WASH (30 min) + SWAB (24 h)
6Stratum corneum
7Dermis + epidermis
8Receptor fluid (6% Polyethylene glycol)
Accuracy and precision
The accuracy of SWAB (WASH 30 min + SWAB 24 h) was determined to be 96.9–103.9% on average. The precision was determined to be 1.5–5.5% based on the coefficient of variation (CV). The accuracy of SC was determined to be 97.6–105.9% on average. The precision was determined to be 2.3–8.1% based on CV. The accuracy of SKIN was determined to be 92.6–101.8% on average. The precision was determined to be 0.9–5.7% based on CV. The accuracy of RF was determined to be 100.7–110.2% on average. The precision was determined to be 1.1–4.8% based on CV. The accuracy and precision in intra-day and inter-day met the criteria. Detailed results are shown in Table 3. Thus, the current analytic method for 2A5NP was validated successfully.
In vitro dermal absorption of 2A5NP
In vitro dermal absorption study of 2A5NP was performed using the developed analytical method. Most of the exposed 2A5NP were found in the intermediate washing step after application (WASH, 30 min). Recovery rate of 2A5NP in hair dye was found to be 72.2 ± 2.7% for WASH (30 min), 4.6 ± 1.4% for SWAB (24 h), 1.0 ± 2.3% for SC, 4.4 ± 1.2% for SKIN and 9.1 ± 2.9% for RF. Total absorption (SKIN + RF) was 13.6 ± 2.9%. Total recovery (WASH (30 min) + SWAB (24 h) + SC + SKIN + RF) was 91.4 ± 3.9% (Table 4, Fig. 2).
Table 4.
In vitro dermal absorption of 2-amino-5-nitrophenol
| 2-Amino-5-nitrophenol content (%) (mean ± standard deviation) |
|
|---|---|
| WASH (30 min) | 72.2 ± 2.7 |
| SWAB (24 h) | 4.6 ± 1.4 |
| 1SC | 1.0 ± 2.3 |
| 2SKIN | 4.6 ± 1.3 |
| 3RF | 9.1 ± 2.9 |
| Total dermal absorption | 13.6 ± 2.9 |
| Total recovery | 91.4 ± 3.9 |
1 SC: stratum corneum
2 SKIN: dermis + epidermis
3 RF: receptor fluid (6% Polyethylene glycol)
Fig. 2.
In vitro dermal absorption rate of 2-amino-5-nitrophenol. WASH:alcohol swab, SC: stratum corneum, SKIN: dermis + epidermis, RF: receptor fluid (6% polyethylene glycol)
Permeation parameter of 2A5NP
Equilibrium flux (Js) and permeability coefficient (Kp) are key parameters evaluated in in vitro experiments in which the donor concentration of the permeabilizing agent is maintained at a constant dose condition [28]. Permeation values were calculated from receptor concentrations measured as cumulative 2A5NP of receptors at each sampling point normalized to the exposed skin surface area (1.77 cm2). The calculated Js value was 0.57 ± 0.18 µg/cm2/h (Table 5). The cumulative transmittance amount of 2A5NP reaching RF after applying 1.5% 2A5NP is shown in Fig. 3.
Table 5.
Permeation parameter of 1.5% 2-amino-5-nitrophenol through excised mini pig skin (mean ± standard deviation)
| Substance | Permeation parameter Js (Equilibrium flux, μg/cm2/h) |
|---|---|
| 2A5NP | 0.57 ± 0.18 |
Fig. 3.
Permeation profiles of 2-amino-5-nitrophenol through excised pig skin
Discussion
2A5NP is an ingredient of hair dye. It is managed at less than 1.5% in Korea and Japan. The purpose of this study was to develop a new analytic method to measure 2A5NP. Another purpose of this study was to determine the dermal absorption rate using the Franz diffusion cell and this analytical method.
The newly developed analytical method showed a good linearity (r2 = 0.9992–0.9999), a high accuracy (93.1–110.2%), and a high precision (1.1–8.1%), thus validating this method. Its accuracy and precision also met the criteria specified in the guidelines (LLOQ: within 20%, LOQ, MOQ, HOQ: within 15%) [16, 29].
When compared with papers related to HPLC conditions for oxidative hair dye analysis, the retention time (RT) of 2A5NP in the current study was faster than that in previous studies using HPLC for oxidative hair dye analysis. In previous papers, the LLOQ was set at 1 μg/ml. However, in this study, it was set at 0.5 μg/ml. Taking this into account, it showed that analysis was possible at lower concentrations [30]. Compared with previous studies, the advantage of the method developed in this study is that it does not need to adjust the pH of the mobile phase and the analysis time is short. And analysis is possible with a small injection volume. As mentioned in the introduction, previous analytical methods of hair dyes have focused on purity of raw materials and simultaneous analysis [15–18]. However, the developed analysis in this study can quantify only 2A5NP in biological samples. These could be advantages compared to previous studies. The validation of 2A5NP analytical methods demonstrated that the developed HPLC method was a useful, simple, and rapid technique for quantitating 2A5NP in biological samples.
This study showed dermal absorption rate of 2A5NP using the Franz diffusion cell on mini pig skin The dermal absorption rate of 2A5NP (1.5% final) was 13.6 ± 2.9% (36.1 ± 7.6 μg/cm2). 5-Amino-6-chloro-o-cresol is also used as a hair dye ingredient. Its chemical structure is similar to 2A5NP. The dermal absorption rate of 5-amino-6-chloro-o-cresol using the Franz diffusion cell on mini pig skin has been reported [31]. To determine dermal absorption of 5-amino-6-chloro-o-cresol, it was mixed with 6% hydrogen peroxide and applied to the skin. The dermal absorption rate of 5-amino-6-chloro-o-cresol (2%) was 30.21 ± 9.78 µg/cm2, similar to that of 2A5NP. In one study, two formulations applied the same dose to the skin. The dermal absorption rate was higher in the liquid formulation than in the cream formulation [26]. 5-amino-6-chloro-o-cresol was tested in a cream formulation, and 2A5NP material was tested in a liquid state. The treatment concentration was low at 2A5NP, but the reason for the higher absorption rate may be due to the difference in formulation. Their similar structural and physicochemical properties might have resulted in their similar skin absorption properties [32].
The dermal absorption rate of 2A5NP was 13.6 ± 2.9%. This value could be used in exposure assessment of 2A5NP. The systemic exposure dosage (SED) is calculated with the amount of exposure using daily usage, maximum use of ingredients, dermal absorption rate of ingredients, and average body weight (60 kg).
In conclusion, the validation of the 2A5NP analytical method demonstrated that the developed HPLC method was a useful and rapid technique for separation and quantitation of 2A5NP in biological samples. The dermal absorption rate of 2A5NP was determined to be 13.6 ± 2.9% (36.1 ± 7.6 µg/cm2).
Acknowledgements
This work was supported by Grants (19172MFDS221 and 22202MFDS158) from the Ministry of Food and Drug Safety, Republic of Korea in 2019 and 2022. This work was supported by the Korea Environment Industry & Technology Institute (KEITI) through the Technology Program for Establishing Biocide Safety Management, funded by the Korea Environment (MOE) (2021002970001, 1485017976).
Abbreviations
- 2A5NP
2-Amino-5-nitrophenol
- ACN
Acetonitrile
- CV
Coefficient of variation
- DW
Distilled water
- FDCA
US Federal Food, Drug and Cosmetic Act
- HOQ
High of quantification
- HPLC
High-performance liquid chromatography
- Js
Equilibrium flux
- LLOQ
Lower limit of quantitation
- LOQ
Limit of quantification
- MFDS
Ministry of Food and Drug safety
- MOQ
Minimum of quantification
- NOAEL
No observed adverse effect level
- PEG
Polyethylene glycol
- PTFE
Polytetrafluoroethylene
- RF
Receptor fluid
- SC
Stratum corneum
- SED
Systemic exposure dose
- TFA
Trifluoroacetic acid
Author contributions
All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by YJK, HYK, JEI, HYK and JDL. Writing-original draft preparation was performed YJK. And writing-review, editing and supervision were performed K-BK. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Funding
This work was supported by Grants (19172MFDS221 and 22202MFDS158) from the Ministry of Food and Drug Safety, Republic of Korea in 2019 and 2022. This work was supported by the Korea Environment Industry & Technology Institute (KEITI) through the Technology Program for Establishing Biocide Safety Management, funded by the Korea Environment (MOE) (2021002970001, 1485017976).
Data availability
All data generated or analysed during this study are included in this published article.
Declarations
Conflict of interest
The authors declare no conflict of interest.
Consent to participate
Informed consent was obtained from all participants.
Ethics approval
No ethical approval is required.
References
- 1.KHIDI (Korea Health Industry Development Institute) (2019) Cosmetic industry analysis. https://www.khidi.or.kr/board/view?linkId=48809330&menuId=MENU00085
- 2.KCA (Korea Cosmetic Association) (2021) Cosmetics market information. https://kcia.or.kr/home/industry/industry_01.php?type=view&no=13559&ss=page%3D%26skind%3D%26sword%3D%26ob%3D
- 3.Kim K, Kabir E, Jahan SA. The use of personal hair dye and its implications for human health. Environ Int. 2016;89:222–227. doi: 10.1016/j.envint.2016.01.018. [DOI] [PubMed] [Google Scholar]
- 4.Hamann D, Yazar K, Hamann CR, Thyssen JP, Lidén C. p-Phenylenediamine and other allergens in hair dye products in the U nited S tates: A consumer exposure study. Contact Dermatitis. 2014;70(4):213–218. doi: 10.1111/cod.12164. [DOI] [PubMed] [Google Scholar]
- 5.MFDS (Ministry of Food and Drug Safety) (2019) Common guidelines for risk assessment of human products. https://www.mfds.go.kr/brd/m_210/view.do?seq=14364
- 6.Lee JD, Kim J, Jang HJ, Lee B, Kim K. Percutaneous permeability of 1-phenoxy-2-propanol, a preservative in cosmetics. Regul Toxicol Pharmacol. 2019;103:56–62. doi: 10.1016/j.yrtph.2019.01.002. [DOI] [PubMed] [Google Scholar]
- 7.Poet TS, McDougal JN. Skin absorption and human risk assessment. Chem Biol Interact. 2002;140(1):19–34. doi: 10.1016/S0009-2797(02)00013-3. [DOI] [PubMed] [Google Scholar]
- 8.PubChem (2021) Chemical and physical properties of 2-amino-5-nitrrophenol. https://pubchem.ncbi.nlm.nih.gov/compound/2-Amino-5-nitrophenol
- 9.IARC (International Agency for Research on Cancer) (1993) Occupational exposures of hairdressers and barbers and personal use of hair colourants; some hair dyes, cosmetic colourants, industrial dyestuffs and aromatic amines. IARC monographs on the evaluation of carcinogenic risks to humans, p. 57 [PMC free article] [PubMed]
- 10.Society of Dyers and Colourists (1971) Colour Index, 3rd edn, Vol. 4. Bradford, Yorkshire, p. 4647.
- 11.NCATS (National Center for Advancing Translational Sciences) (2021) Properties of 2-amino-5-nitrrophenol. https://drugs.ncats.io/drug/0149H05U82#:~:text=2%2DAmino%2D5%2Dnitrophenol%20is%20used%20as%20an%20intermediate,lacquers%2C%20inks%20and%20wood%20stains.&text=It%20has%20been%20used%20(and,in%20permanent%20hair%20colouring%20products
- 12.Chung K. Azo dyes and human health: a review. J Environ Sci Health C. 2016;34(4):233–261. doi: 10.1080/10590501.2016.1236602. [DOI] [PubMed] [Google Scholar]
- 13.SCCS (Scientific Committee on Consumer Safety) (2010) Opinion on basic criteria for the In vitro assessment of dermal absorption of cosmetic ingredients. Updated 22 June 2010. SCCS/1358/10
- 14.Burnett C, Bergfeld W, Belsito D, Klaassen C, Marks J, Shank R, Andersen F. Final report on the safety assessment of amino nitrophenols as used in hair dyes. Int J Toxicol. 2009;28(3):217S. doi: 10.1177/109158180935465. [DOI] [PubMed] [Google Scholar]
- 15.Franco JH, Silva BF, Zanoni MV. Using ionic liquid combined with HPLC-DAD to analyze semi-permanent hair dyes in commercial formulations. Anal Methods. 2015;7(3):1115–1122. doi: 10.1039/C4AY02311K. [DOI] [Google Scholar]
- 16.Ahmed HAM, Maaboud RMA, Latif FFA, El-Dean AMK, El-Shaieb KM, Vilanova E, Estevan C (2013) Different analytical methods of para-phenylenediamine based hair dye. J Cosmet Dermatol Sci Appl 3:17-25. 10.4236/jcdsa.2013.33A1003
- 17.Andrisano V, Gotti R, Di Pietra AM, Cavrini V. HPLC analysis of oxidation hair dyes in permanent hair colorants. J Liq Chromatogr Relat Technol. 1994;17(13):2919–2937. doi: 10.1080/10826079408013510. [DOI] [Google Scholar]
- 18.Shao BH, Xu XZ, Yan JW, Fu XY. Quantitative determination of commercial oxidation hair dyes by reversed-phase HPLC. J Liq Chromatogr Relat Technol. 2001;24(2):241–249. doi: 10.1081/JLC-100001485. [DOI] [Google Scholar]
- 19.MFDS (Ministry of Food and Drug Safety) (2013) Guidelines for validation of bio-sampling methods. http://www.mfds.go.kr/index.do?mid=687andpageNo=2andseq=8003andcmd=v
- 20.Betz JM, Brown PN, Roman MC. Accuracy, precision, and reliability of chemical measurements in natural products research. Fitoterapia. 2011;82(1):44–52. doi: 10.1016/j.fitote.2010.09.011. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.OECD (Organisation for Economic Cooperation and Development) (2004) Guideline for the testing of chemicals skin absorption: in vitro method. 427. https://ntp.niehs.nih.gov/iccvam/suppdocs/feddocs/oecd/oecdtg428-508.pdf
- 22.MFDS (Ministry of Food and Drug Safety) (2009) Guideline for in vitro skin absorption method. B1-2009-4-001. http://www.nifds.go.kr/brd/m_15/view.do?seq=11430
- 23.Kim J, Im JE, Lee JD, Kim K. Analytical method development and percutaneous absorption of propylidene phthalide, a cosmetic ingredient. J Toxicol Environ Health A. 2021;84(20):811–820. doi: 10.1080/15287394.2021.1944941. [DOI] [PubMed] [Google Scholar]
- 24.MFDS (The Ministry of Food and Drug Safety) (2014) Regulations on cosmetic safety standards. Ministry of Food and Drug Safety 2014–118 issue. http://www.mfds.go.kr/index.do?mid=687andpageNo=2andseq=8003andcmd=v
- 25.SCCP (Scientific Committee on Consumer Products) (2009) Opinion on intermediates and reaction products of oxidative hair dye ingredients formed during hair dyeing. https://www.semanticscholar.org/paper/ON-Intermediates-and-reaction-products-of-oxidative-Dubakiene-Ja%C5%BAwiec-Kanyion/a789f24b1b9e99b2adefbb4df6c40ace1ca85162
- 26.Im J, Kim HY, Lee JD, Park J, Kang K, Kim K. Effect of application amounts on in vitro dermal absorption test using caffeine and testosterone. Pharmaceutics. 2021;13(5):641. doi: 10.3390/pharmaceutics13050641. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Moosavi SM, Ghassabian S (2018) Linearity of calibration curves for analytical methods: A review of criteria for assessment of method reliability. IntechOpen Limited London, UK
- 28.WHO (World Health Organization) (2006) Dermal absorption. World Health Organization. https://apps.who.int/iris/handle/10665/43542
- 29.Lee Y, Kim H, Pham Q, Lee J, Kim K. Pharmacokinetics and the dermal absorption of bromochlorophene, a cosmetic preservative ingredient, in rats. Toxics. 2022;10(6):329. doi: 10.3390/toxics10060329. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Pel E, Bordin G, Rodriguez AR (1998) HPLC candidate reference method for oxidative hair dye analysis. I. separation and stability testing. Journal of Liquid Chromatography & Related Technologies 21:883–901. 10.1080/10826079808000516
- 31.SCCS (Scientific Committee on Consumer Safety) (2009) Opinion on 5- amino-6-chloro-o-cresol. https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_005.pdf
- 32.EFSA (European Food Safety Authority) Buist H, Craig P, Dewhurst I, Hougaard Bennekou S, Kneuer C, et al. Guidance on dermal absorption. EFSA J. 2017;15:e04873. doi: 10.2903/j.efsa.2017.4873. [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
All data generated or analysed during this study are included in this published article.