BIBECHANA Vol. 22, No. 2, August 2025, 181-187 ISSN 2091-0762 (Print), 2382-5340 (Online) Journal homepage: http://nepjol.info/index.php/BIBECHANA Publisher:Dept. of Phys., Mahendra Morang A. M. Campus (Tribhuvan University)Biratnagar Comparative pH analysis of synthetic and natural cleaning agents: implications for eco-friendly and dermatological safety Narendra Kumar Chaudhary∗, Mandip Yadav, Sujan Budhathoki Dipak Baral, Janak Adhikari, Ajaya Bhattarai 1 Department of Chemistry, Mahendra Morang Adarsh Multiple Campus, Biratnagar, Tribhuvan University, Nepal ∗Corresponding authors. Email: chem_narendra@yahoo.com Abstract Cleaning agents are essential for maintaining hygiene in domestic and industrial settings, and their pH plays a critical role in determining their safety and efficacy. This study analyzed the pH profiles of locally available synthetic (soaps, shampoos, and detergents) and natural cleaning agents (Aloe vera and Reetha) in dilute solutions to evaluate their implications for skin health and environmental safety. The results showed Neem Kanti Patanjali (NKP) and No. 1 soaps exhibited near-neutral to mildly alkaline pH (6.88–7.95), making them suitable for skin applications. Dove and Sunsilk (SS) shampoos have slightly acidic profiles (6.35–6.85), aligning with the scalp's natural pH. Detergents like Surf Excel and Ariel were strongly alkaline (8.16–8.59) suggesting effective cleaning but possibly being harsh on sensi- tive skin. Natural cleaning agents exhibited eco-friendly properties, with Aloe vera having a mildly acidic pH of 5.40–5.79, and Reetha being near neutral to slightly alkaline, with a pH of 7.36–7.74. In all samples, dilution reduced alkalinity or acidity, emphasizing the importance of using the correct concentrations. These findings highlight the need for pH-balanced formu- lations to ensure compatibility with human skin and minimize environmental harm. Future research should focus on optimizing product formulations for skin health, biodegradability, and ecological safety while promoting sustainable cleaning practices. Keywords Cleaning agent, Shampoo, pH behavior, Soap, Skin compatibility, Dermatological safety Article information Manuscript received: May 17, 2025; Revised: May 24, 2025; Accepted: May 26, 2025 DOI https://doi.org/10.3126/bibechana.v22i2.78901 This work is licensed under the Creative Commons CC BY-NC License. https://creativecommons. org/licenses/by-nc/4.0/ 1 Introduction Cleaning refers to washing clothes and dishes and maintaining personal hygiene to ensure a healthy, safe, and pleasant environment. It involves remov- ing dirt, organic matter, salts, and visible soil from objects and surfaces using water, and various clean- ing products [1,2]. Cleaning agents play a vital role in daily life, helping prevent the spread of pathogens 181 http://nepjol.info/index.php/BIBECHANA chem_narendra@yahoo.com https://doi.org/10.3126/bibechana.v22i2.78901 https://creativecommons.org/licenses/by-nc/4.0/ https://creativecommons.org/licenses/by-nc/4.0/ Narendra Kumar Chaudhary et al./ BIBECHANA 22 (2025) 181-187 182 in homes, healthcare settings, and industrial envi- ronments [3]. These agents are generally catego- rized as synthetic or natural and are available in liquids, powders, sprays, granules, or solids [2]. Understanding their pH behavior is critical, as cleaning agents are commonly used in aqueous so- lutions. The pH of a diluted cleaning agent in- fluences its effectiveness, compatibility with human skin, and environmental impact [4]. For instance, acidic agents are effective for removing mineral de- posits but may irritate the skin or harm ecosys- tems if improperly disposed of. Alkaline agents are suitable for cleaning grease and oils but may dis- rupt the natural pH of skin and pose environmental risks [5, 6]. In contrast, neutral agents tend to be milder, offering safer options for both skin and na- ture. Since human skin has a slightly acidic pH of 4.5 to 5.5, cleaning products with extreme pH levels can lead to skin issues such as irritation, dryness, or allergic reactions [7, 8]. Environmental concerns also arise from the discharge of cleaning solutions into water bod- ies, where altered pH levels can negatively af- fect aquatic organisms and soil microbiota [9, 10]. Therefore, evaluating the pH behavior of cleaning agents is essential to ensure both personal and en- vironmental safety. Synthetic cleaning agents, such as soaps, shampoos, detergents, bleaches, and de- greasers, are widely used due to their high effi- cacy and affordability [8]. These agents typically contain synthetic surfactants, petrochemicals, dyes, and fragrances, which enhance their cleaning power but may pose risks to health and the environment over time [1,11]. Repeated exposure to such chem- icals can lead to skin problems, particularly in in- dividuals with sensitive skin. Moreover, synthetic cleaning waste can pollute water sources, disrupt aquatic ecosystems, and contribute to toxic build- up [12]. Natural cleaning agents, on the other hand, are formulated with eco-friendly ingredients such as baking soda, citric acid, vinegar, and essential oils. These products are generally safer for both human health and the environment because of their mild pH and biodegradable nature. Often mar- keted under the umbrella of "green cleaning", these agents emphasize not only safe ingredients but also sustainable manufacturing, packaging, and disposal practices [13]. As the demand for eco-conscious products increases, refining the formulation of natu- ral cleaning agents is essential to ensure they remain effective and safe. This research aims to analyze the pH behavior of nine synthetic and two natural cleaning agents in dilute solutions and assess their implications for skin health and environmental safety (Table 1). Comparing their pH profiles will help to pro- mote sustainable cleaning practices, inform con- sumer choices, and guide the development of safer and more eco-friendly products. 2 Experimental 2.1 Materials Four different types of cleaning agents such as com- mercial soaps, shampoos, detergents, and natural products, were selected in this study and purchased from local markets in Biratnagar, Nepal. The com- mercial soaps analyzed were Liril soap, Dettol soap, Neem Kanti Patanjali soap (NKP), and No. 1 soap (N1), while the shampoos included Head & Shoulders (HS), Clinic Plus (CP), Sunsilk (SS), and Dove. The detergents studied were Surf Ex- cel (SE), Clean Add (CA), 2-in-1, and Ariel. Ad- ditionally, natural agents such as Aloe Vera gel (AVG) and Indian soapberry (Reetha) (ISB) were included to provide a broader perspective on clean- ing performance and safety. Distilled water was used as the diluent to ensure consistent and un- contaminated conditions for the pH measurements. Figure 1 shows images of some commercial and natural cleaning agents studied. Analytical grade reagents and standard laboratory equipment were used throughout the study. Figure 1: Cleaning agents under study. 2.2 Preparation of Sample Solutions The preparation of different sample solutions was done using different techniques. Six different solu- tions for soaps and detergents were made by dis- solving 0.2 gm and 0.25 gm of the samples, respec- tively, in 50 mL to 100 mL volumes of distilled wa- ter. These were prepared at room temperature with gentle stirring to ensure complete dissolution. For shampoos, 1.5 mL of each was diluted with dis- tilled water to create volumes ranging from 25 to 75 mL and mixed gently to achieve a homogenous solution. Natural product sample solutions, such as Aloe Vera gel and Reetha (Indian soapberry), were made by dissolving 0.5 gm of each in 50–100 mL of distilled water while stirring to ensure uniform dispersion [14,15]. Narendra Kumar Chaudhary et al./ BIBECHANA 22 (2025) 181-187 183 Figure 2: Preparation of sample solutions. 2.3 pH Measurement A digital pH meter (MARS auto pH meter) was used to measure the pH of the prepared solutions. The meter was calibrated with standard buffer so- lutions at pH 4.0, 7.0, and 10.0 prior to each set of measurements. To prevent cross-contamination, the electrode was rinsed with distilled water and blotted dry before immersion in test solutions. The experiments were conducted at room temperature, and the pH readings were recorded after stabiliza- tion on the meter display. The pH of each sam- ple was measured in triplicate, and the average val- ues were calculated for analysis. Trends in alkalin- ity, acidity, and buffering capacity were revealed by tabulating the results, which were categorized ac- cording to sample types, including soap, shampoo, detergent, and natural products. Quality control procedures included making fresh solutions to pre- vent contamination or deterioration, cleaning glass- ware thoroughly with distilled water, and checking the accuracy pH meter on a regular basis. Table 1 lists the composition details and other pertinent data for every cleaning agent under study. 3 Results and Discussion The pH levels of various soaps, shampoos, deter- gents, and natural cleaning agents were measured in different volumes of distilled water to evaluate their pH behavior and compatibility with skin and fabric. 3.1 Soaps The pH analysis of various soaps revealed distinct trends in alkalinity and neutrality upon dilution with distilled water. The pH of Liril soap de- creased from 7.4 at 50 mL to 6.97 at 100 mL, tran- sitioning from slightly alkaline to almost neutral, suggesting its mild nature. Dettol soap showed a reduction in pH from 7.28 to 6.68 as the water volume increased, aligning with its formulation for antibacterial activity at mildly acidic to neutral pH levels. NKP soap demonstrated a comparable be- havior, with pH ranging from 7.31 to 6.88, suggest- ing its suitability for skincare due to its mild nature. No. 1 soap, initially more alkaline at 7.95, became closer to neutral at 6.78 after dilution, making it appropriate for general use. These findings demon- strate the varying degrees of alkalinity and neutral- ity of soaps, which can influence their compatibil- ity with skin health and applications, depending on their pH behavior during dilution [11, 16–18]. It is Narendra Kumar Chaudhary et al./ BIBECHANA 22 (2025) 181-187 184 therefore likely that dilution reduces the buffering capability of the solutions. The pH values for each soap with different amounts of distilled water are shown in Table 2, and Figure 3 provides a visual representation of these values. Table 2: pH of different soaps at varying volumes of distilled water. S.N. Volume of distilled water (ml) Mass of Soap (gm) Liril Dettol No. 1 NKP 1 50 0.2 7.40 7.28 7.95 7.31 2 60 0.2 7.26 7.00 7.84 7.18 3 70 0.2 7.15 6.88 7.51 7.12 4 80 0.2 7.07 6.78 7.38 7.08 5 90 0.2 7.00 6.73 7.27 7.00 6 100 0.2 6.97 6.68 6.78 6.88 Figure 3: pH of different soaps at varying volumes of distilled water. 3.2 Shampoos The pH of shampoos plays a crucial role in their effectiveness and compatibility with hair and scalp health. Head & Shoulders (HS) shampoo exhib- ited a pH range of 7.14 to 6.66, and supports its anti-dandruff properties, as slightly acidic formula- tions are kinder on the scalp. With an initial pH of 6.78 and a steady decline to 6.35, Clinic Plus exhibits mild acidity that is unlikely to be dam- aging to hair or the scalp. Sunsilk demonstrated minimal variation in pH (6.83 to 6.62), suggesting a stable formulation suitable for regular use. Dove demonstrated a steady drop in pH from 6.85 to 6.48, highlighting its standing as a mild and moisturizing product. These findings highlight the importance of pH-balanced formulations in maintaining scalp health and preventing hair damage, as excessively alkaline products can disrupt the natural structure of hair, and lead to issues like dryness and break- age [19,20]. The pH information for each shampoo with different amounts of distilled water is shown in Table 3 and is graphically depicted in Figure 4. Table 3: pH of different shampoos at varying volumes of distilled water. S.N. Volume of distilled water (ml) Volume of Shampoo (ml) HS CP SS Dove 1 25 1.5 7.14 6.78 6.83 6.85 2 35 1.5 7.10 6.65 6.80 6.78 3 45 1.5 7.05 6.60 6.75 6.69 4 55 1.5 7.00 6.54 6.72 6.63 5 65 1.5 6.85 6.48 6.70 6.54 6 75 1.5 6.66 6.35 6.62 6.48 Figure 4: pH of different shampoos at varying vol- umes of distilled water . 3.3 Detergents The pH analysis of four detergents, such as Surf Excel, Clean Add, 2-in-1, and Ariel, were found to have a uniformly alkaline pH, which makes them suitable for removing tough stains. Surf Excel and 2-in-1 detergents exhibited identical pH ranges from 8.59 to 8.19, highlighting their strong alka- Narendra Kumar Chaudhary et al./ BIBECHANA 22 (2025) 181-187 185 line properties. Similar patterns were seen in Clean Add, where pH levels marginally dropped from 8.56 to 8.20. The alkaline profile of Ariel detergent was maintained, although its range was somewhat smaller, ranging from 8.42 to 8.16. These pH val- ues align with the general characteristics of laun- dry detergents, which are formulated to be alkaline for efficient cleaning of dirt, grease, and oils. How- ever, because high-pH solutions are harsh, improper rinsing may eventually cause fabric damage, even though their alkalinity guarantees effective stain re- moval [21]. The pH values for each detergent with different amounts of distilled water are shown in Table 4 and are visually represented in Figure 5. Table 4: pH of different detergents at varying volumes of distilled water. S.N. Volume of distilled water (ml) Mass of Detergent (gm) Surf Excel Ariel 2 in 1 Clean Add 1 20 0.25 8.51 8.42 8.59 8.56 2 30 0.25 8.45 8.35 8.49 8.48 3 40 0.25 8.40 8.30 8.38 8.43 4 50 0.25 8.35 8.25 8.33 8.39 5 60 0.25 8.21 8.19 8.24 8.23 6 70 0.25 8.18 8.16 8.19 8.20 Figure 5: pH of different detergents at varying vol- umes of distilled water. 3.4 Natural Cleaning Agents The pH levels of natural agents such as Aloe Vera and Indian Soapberry (Reetha) have been studied to understand their suitability for various applica- tions. Aloe Vera exhibits a mildly acidic nature, with its pH increasing from 5.40 at 50 mL to 5.79 at 100 mL. The natural pH of human skin, which nor- mally falls between 4.5 and 5.5, is closely matched by this mild acidity, making it advantageous for skincare and calming applications. On the other hand, Indian Soapberry (Reetha) shows a near neu- tral pH profile, varying from 7.74 to 7.36. This neu- trality makes Reetha suitable for use as a natural cleaning agent for both skin and fabric, as it is less likely to cause irritation or disrupt the skin's natu- ral pH balance [22–24]. Table 5 summarizes the pH data for these natural agents in different volumes of distilled water, and Figure 6 shows the data graph- ically, giving a thorough overview of their charac- teristics. Table 5:pH of different natural agents at varying volumes of distilled water. S.N. Volume of distilled water (ml) Mass of Soap (gm) pH (Aloe vera) pH (Reetha) 1 50 0.5 5.40 7.74 2 60 0.5 5.43 7.66 3 70 0.5 5.48 7.58 4 80 0.5 5.59 7.49 5 90 0.5 5.65 7.42 6 100 0.5 5.79 7.36 Narendra Kumar Chaudhary et al./ BIBECHANA 22 (2025) 181-187 186 Figure 6: pH of different natural agents at varying volumes of distilled water. 4 General Discussion The study highlights the critical role of pH in de- termining the suitability and safety of personal care and cleaning products. The majority of soaps and shampoos have a pH that is close to neutral to slightly acidic, which is in line with the skin's nor- mal pH range of 5.4 to 5.9. This makes them ap- propriate for use on the skin and scalp [25]. In contrast, detergents are strongly alkaline, reflecting their primary purpose of cleaning fabrics but neces- sitating thorough rinsing to avoid irritation or dam- age from residual traces [26]. Dilution with distilled water consistently lowered the pH across all tested samples, likely due to the reduced concentration of acidic or alkaline ions. Among personal care prod- ucts, items like Neem Kanti Patanjali soap, Dove shampoo, and Aloe Vera demonstrated mild pH lev- els, minimizing the risk of disrupting the skin’s acid mantle. Furthermore, detergents' strong alkalinity makes them potentially harmful to sensitive skin if they are not properly rinsed out of fabrics [27]. Natural cleaning agents such as Reetha and Aloe Vera were found to have pH profiles suitable for eco- friendly and non-damaging cleaning applications, offering a sustainable alternative to synthetic prod- ucts. This research highlights the importance of understanding pH profiles to optimize product ap- plications and ensure user safety. It also emphasizes that maintaining a pH balance close to natural skin levels is essential for preventing issues such as dry- ness, irritation, or disruption of the skin's natural barrier. By tailoring formulations to appropriate pH levels, manufacturers can enhance product effi- cacy while minimizing adverse effects on users and the environment. 5 Conclusion The compatibility of soaps, shampoos, detergents, and natural products with skin and hair health is highlighted by the study of their pH levels. Most of the soaps tested ranged from neutral to mildly alkaline and were influenced by the volume of dis- tilled water used during preparation. Liril soap had a pH of 7.4 to 6.97, indicating mild alkalinity suit- able for cleaning without harsh effects. Dettol soap showed a slightly lower pH range (7.28 to 6.68), making it more skin-friendly. Neem Kanti Patan- jali and No.1 soaps also displayed mild alkalinity, supporting their cleaning efficacy while maintain- ing skin compatibility. Shampoos such as Head & Shoulders, Clinic Plus, Sunsilk, and Dove had pH values from slightly acidic to neutral, aligning with the natural scalp pH (5.4–5.9). This balance is vital for maintaining hair health and preventing dryness or irritation. In contrast, detergents like Surf Excel and Ariel exhibited higher alkaline pH values (8.59 to 8.16), reflecting their strong cleaning action but potentially harsh effects on sensitive skin. 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Skin cleansing without or with compromise: soaps and syndets. Molecules, 27, 2022. Introduction Experimental Materials Preparation of Sample Solutions pH Measurement Results and Discussion Soaps Shampoos Detergents Natural Cleaning Agents General Discussion Conclusion