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Research Article

Argentometric determination of chloride content in tap water at Gimba city administration, South wollo, Ethiopia

[version 1; peer review: 1 not approved]
PUBLISHED 17 Jan 2025
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Abstract

Background

This study investigates chloride concentrations in tap water samples from Gimba city administration, using the argentometric method to assess water quality. Chloride levels are a key indicator of water treatment effectiveness, particularly the adequacy of chlorination, which is critical for preventing waterborne diseases.

Methods

Chloride concentrations in tap water samples from various locations in Gimba city administration, were determined using the argentometric titration method. Silver nitrate (AgNO₃) was employed as the titrant to precisely quantify chloride ions. The water samples were collected from different sites in Gimba, and chloride levels were measured to evaluate the adequacy of water treatment processes.

Results

The chloride concentrations across all samples ranged from 52.8 mg/L to 71.9 mg/L, well below the World Health Organization’s recommended limit for drinking water. Significant variation in chloride levels was observed, with Dembesh exhibiting the highest concentration and Medera the lowest.

Conclusion

The low chloride concentrations suggest insufficient chlorination at the sampling sites, which may compromise the effectiveness of water disinfection and contribute to the prevalence of waterborne diseases in the region. The study underscores the need for enhanced water treatment and disinfection practices in Gimba city to ensure safe drinking water and reduce health risks.

Keywords

Argentometric method, Chloride content, Drinking water, Gimba city administration

1. Introduction

1.1 Background of the study

Water is a vital natural resource, essential for life and human development. Its quality directly impacts public health, economic stability, and environmental sustainability. In many urban areas, ensuring safe and clean drinking water has become increasingly important due to rising population growth, industrialization, and agricultural expansion.1,2 Chlorides are naturally occurring ions in water that, while not typically harmful in small quantities but have an effect if its concentration exceeds 250 ppm.3 Elevated chloride levels in drinking water can affect its taste, corrosiveness, and, in certain cases, pose health risks, especially to people with pre-existing conditions like hypertension.46

Gimba City Administration, located in Legmbo Woreda, South wollo, Ethiopia, has been grappling with water quality concerns due to a combination of natural factors and human activities, including urbanization and municipal discharge. As the city continues to grow, monitoring the quality of drinking water has become crucial to safeguarding public health. Chloride contamination, often a consequence of sewage infiltration, industrial activities, or saltwater intrusion, is one of the parameters that needs consistent monitoring.6 The determination of chloride content in drinking water sources, therefore, is a fundamental aspect of ensuring safe and potable water for the population.

The argentometric method, a widely used titrimetric technique, provides an accurate and reliable means of determining chloride ions in water. This method involves the titration of chloride ions with silver nitrate, forming a precipitate of silver chloride. The endpoint of the titration is detected by the use of a suitable indicator, and the concentration of chloride is calculated based on the volume of silver nitrate used. Its simplicity, precision, and cost-effectiveness make it an ideal choice for evaluating the chloride content in water.7,8

This study focuses on assessing the chloride content in drinking water sourced from various locations within Gimba City Administration, employing the argentometric method. By evaluating chloride concentrations in different water sources, the study aims to provide a comprehensive understanding of the water quality in the city, compare the results with established international standards, and highlight potential risks to public health. The findings of this research was contribute to water quality monitoring programs and support decision-making for improved water management in the town.

Methods

Description of study area

Gimba is a town located in the pastoral area of the Ethiopian Highlands, within the Legambo district of South Wollo. It is situated approximately 79 km southwest of Dessie, 22 km northeast of Akesta, and 52 km south of the town of Tenta. The town is positioned at geographical coordinates 10°59′8″N latitude and 39°16′17″E longitude, with an elevation of 3,224 meters (10,577 feet) above sea level. Gimba is characterized by a cold climate, typical of the highland regions, and experiences the Belg season, a short rainy period that usually occurs between March and May. http://wikimapia.org›Tulu-Awlia

Sample collection

Drinking water samples were collected from five sites in Gimba city administration, namely Dembesh, Chiro, Medera, Segno, and Yerma, during December 2024 (dry season). The samples were gathered in plastic polyethylene bottles and transported to the laboratory, ensuring that they were kept in cool conditions to prevent any alteration in water quality parameters. Prior to sampling, the polyethylene bottles were thoroughly washed, cleaned, and rinsed with distilled water. The collection and preservation of the samples followed standard methods.9

The aim of the sampling process was to obtain samples that accurately represented the water quality parameters at each site. The sample sizes were kept as small as possible while still being sufficient for analysis. Efforts were made to handle the samples carefully, ensuring that their characteristics remained unchanged. Grab samples were taken from each site following the procedures outlined in the Standard Methods.9 Only one sample was collected from each sampling sites during the study period.

Chemicals

The reagents chemicals used in the experiment were 8.4935 g of Silver Nitrate was purchased from Merck, Darmstadt, Germany; 5 g of Potassium Chromate from Sigma-Aldrich (St. Louis, MO, USA); and 0.584 g of Sodium Chloride from Merck, Darmstadt, Germany, along with distilled water. All chemicals used were laboratory-grade and were used without further purification.

Apparatus

Beakers, graduated cylinder, Conical flask, burette, filter paper, pipette, pipette filler, volumetric flask, digital balance, Titration setup (stand, clamp, and funnel) and Stirring Rod were taken from our chemistry laboratories for this experiment.

Solutions and reagents

Standard sodium chloride solution (0.1 M): Dissolve 0.584 g of AR grade NaCl (Equivalent weight = 58.44 g/mol) in distilled water in a 100 mL standard measuring flask, make up the solution to the mark with distilled water and homogenize.

Silver nitrate solution (0.05 M): Dissolve 8.4935 g of AR grade silver nitrate (Equivalent weight = 169.87 g/mol) in 1000 mL conical flask with distilled water and homogenize.

Potassium chromate solution (5% solution): Dissolve 5 g of AR grade potassium chromate in 100 mL of distilled water in a conical flask.

Standardization of silver nitrate

All the glass apparatus first washed with tap water and then rinse thoroughly with distilled water. Rinse the burette with silver nitrate solution and fill it with the same solution up to zero mark. Pipette out 20 ml of standard sodium chloride solution into a clean 250 mL conical flask and add 1 mL of potassium chromate indicator. Titration of the above solution with silver nitrate solution taken in the burette until the first appearance of permanent red brown colour is formed. The faint reddish brown colour should persist permanently. Repeat the titrations for concordant values. From the titration values calculate the strength of silver nitrate solution.10

Determination of chloride concentration in the water samples

In this experiment, 200 mL of a collected water sample is pipetted into a clean 250 mL conical flask. To this, 1 mL (approximately 4-5 drops) of potassium chromate indicator is added. The solution is then titrated with a silver nitrate solution, which is placed in the burette, according to the procedure outlined in Part 1. After completing the titration, the concentration of chloride ions in the water sample is calculated using the formula provided by,10 based on the titration results. This process is repeated in triplicate for each site to ensure accuracy.

ChlorideIonConcentration(mg/L)=N×V×35.5×1000Volume of sample(mL)

Where:

N = normality of silver nitrate

V = Volume of titrant used

35.5 = Molar mass of chloride ion

1000 = Conversion factor

Statistical data analysis

The results were subjected to an analysis of variance (ANOVA), which was performed using an online ANOVA calculator with some modifications. Mean comparisons were carried out using the Least Significant Difference (LSD) method at a significance level of P<0.05. Descriptive statistics, including the mean, standard deviation (SD), minimum, and maximum values, were used to evaluate the water quality parameters. https://goodcalculators.com/one-way-anova-calculator/.

Result and discussion

In this study, chloride concentration in the sample was determined using argentometric titration. The titration was performed at a pH range of 7 to 10, as chromate ions are the conjugate base of weak chromic acid. at pH values below 7, the chromate ion becomes protonated, and chromic acid predominates in the solution. As a result, in more acidic solutions, the concentration of chromate ions is too low to form a precipitate at the equivalence point. Conversely, when the pH exceeds 10, silver hydroxide forms, resulting in a brownish precipitate that interferes with detecting the endpoint. A suitable pH was maintained by saturating the analyte solution with sodium bicarbonate.11

The most familiar Mohr’s method in which alkaline or alkaline earth chlorides react with silver nitrate in presence of indicator potassium chromate solution as indicator a simple and accurate method for chloride ion determination. The significance of chloride (Cl-) ion present in the water is known to everyone. But the presence of higher concentration (> 250 ppm) leads to unwanted toxic problem, corrosion in the industry and etc. In the present investigation, the water samples were we collected from Gimba city administration and analysed for chloride ion concentration. The amount of chloride (Cl-) ion determined in the collected water sample was reported in Table 1.

Table 1. Concentration of chloride ion in drinking water samples.

Sampling sitesConcentration (mg/L)WHO StandardES Standard EPA Standard
Medera52.8±3.7250 mg/mL250 mg/mL250 mg/mL
Dmbesh71.9±7.1
Chiro61.8±6.4
Segno59.2±6.4
Yerma58.9±6.3
LSD, α = 0.0511.1

In the present study, laboratory analysis of chloride concentrations in drinking water samples revealed a range from a minimum value of 52.8 mg/L to a maximum of 71.9 mg/L, with a median value of 59.2 mg/L, indicating significant variation in chloride levels across the different sampling sites. The chloride concentration trends followed the order: Dembesh > Chiro > Segno > Yerma > Medera ( Table 1). Dembesh had the highest chloride concentration, possibly due to higher levels of contamination or natural sources in the region, while Medera recorded the lowest levels, suggesting either better water quality or less human impact. Chiro’s chloride concentration was similar to that of Dembesh, pointing to comparable environmental influences, while Segno and Yerma showed intermediate levels, possibly reflecting a mix of natural and anthropogenic factors. These findings highlight the considerable variation in chloride levels across the sites, emphasizing the need for site-specific water quality management and further investigation into the factors influencing chloride concentrations. The levels of chloride in water can fluctuate due to various factors such as the source of water and the existence of either natural or human-induced sources of contamination.12

Additionally, the table showed that the mean chloride concentrations between Dembesh and Medera, Dembesh and Segno, and Dembesh and Yerma were statistically different (p<0.05). This suggests that the disinfection or chlorination mechanism at the Dembesh site may be more effective than at the other four sites. But there is no significant mean difference between the other sites.

A similar trend was observed in a study conducted by Tadesse et al.,13 who evaluated drinking water quality in various regions of Ethiopia. They reported chloride concentrations ranging from 28 to 115 mg/L, with an average value of 52.7±15.2 mg/L., which aligns closely with the findings in the present study. Chloride in drinking water primarily results from the dissolution of salts such as sodium chloride (NaCl), as well as from anthropogenic sources including industrial waste, sewage, and seawater. Lower chloride concentrations typically indicate minimal pollution influx, suggesting that areas with lower chloride levels, such as Medera, may experience less environmental contamination.

The estimated daily chloride intake for adults is 2,300 mg, with approximately 530 mg lost per day through perspiration. This loss is recommended to be compensated through both diet and daily water intake.14 However, in Gimba city administration, the chloride levels in the potable water are significantly lower than the WHO recommended standard of 250 mg/L. All water samples from the city contained chloride levels below 72 mg/L, indicating that the water may not be adequately disinfected. Chlorine, the most commonly used water disinfectant, is essential for ensuring safe drinking water, but its low concentration in Gimba’s potable water suggests that proper disinfection processes are not being effectively implemented. This lack of adequate chlorination likely contributes to the prevalence of waterborne diseases in the area. Results are expressed as mean ± SD of three replicates (n = 3, p < 0.05).

In general, all the values are well below the 250 mg/L threshold, meaning the chloride concentrations in these sources are within the acceptable range for drinking water. Chloride at high levels can lead to unpleasant taste and, in extreme cases, can have adverse health effects, particularly for people with certain conditions like hypertension. However, since the chloride levels in all these water sources are much lower than the maximum acceptable limit, they are generally considered safe for consumption and domestic use in terms of chloride content. This indicates that the water from these sources does not pose a significant risk regarding chloride contamination and is safe for drinking, cooking, and other household activities.

Conclusion

The study revealed significant variation in chloride concentrations across different sampling sites in Gimba city administration, with Dembesh exhibiting the highest chloride levels and Medera the lowest. The observed chloride concentrations were well below the ES, EPA and WHO recommended limits, with all sites having concentrations below 72 mg/L. This indicates potential issues with water disinfection and the need for improved chlorination practices. Chlorine, as a key disinfectant, is essential for ensuring water safety, and the low levels found in Gimba’s potable water suggest that the disinfection process may be inadequate, which could contribute to the prevalence of waterborne diseases in the region.

Author contributions

All the authors are contributed equally in this manuscript and also both authors read and approved the final manuscript.

Ethics and consent

Ethics and consent were not required.

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Asfaw MD and Belete AB. Argentometric determination of chloride content in tap water at Gimba city administration, South wollo, Ethiopia [version 1; peer review: 1 not approved]. F1000Research 2025, 14:104 (https://doi.org/10.12688/f1000research.160681.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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Approved with reservations A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approvedFundamental flaws in the paper seriously undermine the findings and conclusions
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Reviewer Report 14 Feb 2025
Yang Song, Virginia Tech, Blacksburg, USA 
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Title: Argentometric determination of chloride content in tap water at Gimba city administration, South wollo, Ethiopia
The authors brought an interesting case study to examine the chloride levels in tap water samples at Gimba city administration. The average concentration ... Continue reading
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Song Y. Reviewer Report For: Argentometric determination of chloride content in tap water at Gimba city administration, South wollo, Ethiopia [version 1; peer review: 1 not approved]. F1000Research 2025, 14:104 (https://doi.org/10.5256/f1000research.176612.r362671)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.

Comments on this article Comments (0)

Version 1
VERSION 1 PUBLISHED 17 Jan 2025
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Alongside their report, reviewers assign a status to the article:
Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions
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