Research Article | | Peer-Reviewed

Evaluation of Two Spectrometric Approaches for Measuring Metal Concentrations in Drinking Water

Received: 29 August 2025     Accepted: 11 September 2025     Published: 9 October 2025
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Abstract

This study aimed to compare the performance of photometric analysis and flame atomic absorption spectrophotometry (FAAS) in determining iron concentrations in water samples. Thirty samples were collected from wells located in the Anani and Gonzacque-ville neighborhoods and analyzed using both techniques. Photometric results indicated that 26 out of 30 samples had iron concentrations below the Ivorian regulatory limit of 0.3mg/L, while three samples exceeded this threshold. In contrast, AAS measurements showed that all samples complied with the standard, with no exceedances recorded. Statistical analysis revealed a significant difference between the two methods, with photometric readings generally yielding higher iron concentrations than those obtained via AAS. This discrepancy highlights the importance of employing more precise analytical techniques such as FAAS for routine water quality monitoring, particularly when assessing critical parameters like iron.

Published in Science Journal of Analytical Chemistry (Volume 13, Issue 3)
DOI 10.11648/j.sjac.20251303.11
Page(s) 63-67
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Photometer, Flame Atomic Absorption Spectrophotometer, Iron, Water

1. Introduction
Water is essential to life . To maintain good health, it is crucial to have access to safe drinking water in sufficient quantities for daily needs . Drinking water is defined as water that can be consumed without posing a risk to human health. Therefore, water that does not meet potability standards may present health risks and contribute to the emergence of waterborne diseases . Consequently, monitoring water quality is vital to detect the presence of pathogenic agents and ensure the safety of consumed water . Spectrometric techniques are commonly used for quality control purposes . In Côte d’Ivoire, the agency responsible for monitoring drinking water quality routinely uses portable photometers at sampling sites. To assess the reliability of this method, a comparative study was conducted with FAAS. The objective of this study was to verify iron concentration measurements in drinking water samples.
2. Materials and Methods
2.1. Equipment and Reagents
The equipment used in this study included a pH meter (HACH HQ 11d®, France), a turbidimeter (TURB 430 IR®, France), a photometer (Palintest 7100®, United Kingdom), and a flame atomic absorption spectrophotometer (FAAS Agilent®, United States). Standard laboratory glassware was employed throughout the analyses. Analytical-grade reagents were used, including iron reagent tablets (Iron HR), nitric acid, and distilled water.
2.2. Iron Determination
a. Using the Palintest® Photometer
For photometric analysis, a 10mL volume of water was collected using a macropipette and transferred into a clean test tube. A crushed and homogenized iron reagent tablet ("Iron HR") was then added to the sample. After a one-minute waiting period to allow optimal color development, the photometric measurement was performed using program Phot 19, corresponding to the iron determination protocol. Absorbance was measured at 520nm, and the iron concentration (mg/L) was directly displayed by the device .
b. Using Flame Atomic Absorption Spectrophotometry (FAAS)
A 100mL volume of water sample was collected, filtered, and acidified by adding 1mL of concentrated nitric acid. A three-point calibration curve was prepared from a 1mg/L stock iron solution, diluted with nitric acid-acidified water to obtain standard solutions of 1, 3, and 6mg/L. Iron analysis in the water samples was performed under the following conditions:
Wavelength: 248.3nm - Flame type: Air-acetylene - Air flow rate: 10L/min - Acetylene flow rate: 2 L/min - Reading mode: Direct absorbance - Reading time: Average of three consecutive readings - Injection volume: 5mL per sample - Analytical blank: Distilled water acidified with 5% nitric acid - Calibration curve: Standards at 1, 3, and 6mg/L.
2.3. Statistical Tests
A statistical analysis was conducted to compare two quantitative variables corresponding to the mean iron concentrations obtained. The comparison test was performed using R software (Version 2022.07.2-576) and Microsoft Excel (Version 2021). Statistical analyses including the Shapiro-Wilk test, F-test, and the non-parametric Wilcoxon test were conducted.
3. Results
According to the results obtained (Table 1), photometer readings indicated that the majority of samples (26 out of 30) had iron concentrations below the regulatory threshold (Figure 1). One sample (Sample 24) showed an iron concentration equal to the standard (0,3mg/l), while three samples (Samples 28, 29, and 30) exceeded the permissible limit (Figure 2). In contrast, results obtained using Flame Atomic Absorption Spectroscopy (FAAS) revealed that all analyzed samples had iron concentrations below the regulatory threshold (Figure 1).
Figure 1. The histogram of iron concentrations measured by photometer (a) and FAAS (b).
Figure 2. Trend curve of iron concentrations obtained by photometry and FAAS.
The Shapiro-Wilk test indicated that the data were not normally distributed (p-value < 0.05). The F-test revealed significantly different variances between the two groups (p-value < 0.05), justifying the use of a non-parametric approach. The Wilcoxon test showed a statistically significant difference between M1 and M2 (p-value < 0.05), with values obtained using the photometer being significantly higher than those obtained via FAAS. These results confirm that the data are non-normally distributed, the group variances are unequal, and there is a significant difference between the two analytical methods.
Table 1. Iron contents by photometer and FAAS per sample.

Sample number

Photometer assay (mg/l)

FAAS assay (mg/l)

E1

0.03

< at the detection limit

E2

0.14

< at the detection limit

E3

0.11

0.0105

E4

0.29

0.0034

E5

0.06

0.0237

E6

0.05

0.0345

E7

0.04

0.0141

E8

0.04

0.0312

E9

0.08

0. 0245

E10

0.02

0.0502

E11

0.08

0.0520

E12

0.10

0,0044

E13

0.05

0,0319

E14

0.19

0,0094

E15

0.05

0,0043

E16

0.12

0,0318

E17

0.12

0,0424

E18

0.06

0,0223

E19

0.03

0,0550

E20

0.29

0,1435

E21

0.28

0,0851

E22

0.12

0,0409

E23

0.08

0,0308

E24

0.30

0,0588

E25

0.08

0,0378

E26

0.10

0,0425

E27

0.18

0,0596

E28

0.38

0,0781

E29

1.02

0,0596

E30

0.74

0,0592

Average

0.174

0.038

Standard deviation

0.217

0.030

Mean standard error

0.039

0.005

4. Discussion
The comparative analysis of iron concentrations in groundwater using photometry and FAAS reveals notable discrepancies between the two methods. While photometric analysis identified three samples exceeding the recommended iron threshold, FAAS results indicated that all samples remained within acceptable limits. This divergence underscores the importance of methodological choice in environmental monitoring, particularly when assessing trace metal concentrations. Photometry, although operationally simple and suitable for field use, is susceptible to matrix interferences and lacks the specificity required for accurate quantification in complex samples. The elevated values observed may stem from colorimetric interferences.
Or insufficient sample preparation, as the method does not typically involve acid digestion a step that enhances analytical reliability by minimizing the influence of organic and inorganic contaminants .
In contrast, FAAS offers superior sensitivity and selectivity by directly measuring the absorption of light by vaporized atoms. Its robustness against interferences, especially when corrective techniques are applied, makes it a more reliable tool for trace metal analysis . The statistical comparison of results confirms that photometric readings tend to overestimate iron concentrations, potentially leading to false-positive assessments of water quality risks.
From a public health perspective, accurate determination of iron levels is essential. Excess iron not only affects organoleptic properties of water such as taste and color but also poses health risks, particularly in vulnerable populations like children .
The findings also highlight the limitations of portable photometers like the Palintest® device, which, despite their accessibility and ease of use, may not be suitable for rigorous environmental assessments. For research and regulatory purposes, especially in contexts where water quality directly impacts public health, FAAS remains the reference method .
Future studies should explore hybrid approaches, combining the accessibility of field photometry with confirmatory laboratory techniques such as FAAS. Additionally, capacity-building efforts in regions relying on simplified methods should prioritize training in sample preparation and interpretation of results to ensure data reliability and informed decision-making.
5. Conclusion
This study was initiated to evaluate and compare the analytical performance of photometry and FAAS in the determination of iron concentrations in drinking water. The results indicate that iron levels measured by photometry are, in most cases, below regulatory thresholds but consistently higher than those obtained via FAAS. This discrepancy was statistically validated. FAAS stands out for its enhanced sensitivity, superior precision, and reduced susceptibility to analytical interferences, although its implementation is more time-consuming. These findings strongly support the integration of FAAS into the equipment of laboratories responsible for water quality monitoring, in order to ensure the reliability and rigor of analytical results.
Abbreviations

FAAS

Flame Atomic Absorption Spectrophotometry

Author Contributions
Kpaibé Sawa André: Conceptualization, Methodology, Writing – original draft, Supervision
Yao Marcelle: Formal Analysis
Ablé Nina: Methodology
Yao Jean Simon: Methodology
Amin N’cho Christophe: Methodology, Supervision
Conflicts of Interest
The authors declare no conflicts of interest.
References
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[2] Odoulami L. Problématique de l’eau potable et de la santé humaine dans la ville de Cotonou (République du Bénin) [thèse de doctorat]. Cotonou: Université d’Abomey-Calavi, 2009, 230 p.
[3] Umvie. L’eau non potable: explication, conséquences et solutions. [consulté le 20 mai 2024]. Disponible sur:
[4] DÉGBEY, Cyriaque, MAKOUTODE, Michel, OUENDO, Edgard-Marius, et al. La qualité de l’eau de puits dans la commune d’Abomey-Calavi au Bénin. Environnement, Risques & Santé, 2008, 4(7), p. 279-83.
[5] Amin NC, N’kousse, Kpaibe SAP, Seki TO, Degny GS, Gbagbo TAG, Perception des ménages de la qualité de l’eau d’adduction publique en Côte d’Ivoire. Bulletin de Santé Publique de Côte d'Ivoire. 2024, 03(02), p 30-34.
[6] Douglas A, Skoog F, James H, Stanley R. Principles of Instrumental Analysis. 7th ed. Cengage Learning, 27 janvier 2017, 992 p.
[7] Makoutode M, Assani AK, Ouendo EM, et al. Qualité et mode de gestion de l’eau de puits en milieu rural au Bénin: Cas de la sous-préfecture de Grand-Popo. Médecine D’Afrique Noire. 1999, 46(11), p 528‑34.
[8] Seki TO, Yapo TW, Kpaibe SAP, et al. Caractérisation physicochimique et microbiologique des eaux de puits à usage de boisson à Aboisso (sud-est de la Côte d’Ivoire). Int J Biol Chem Sci. 2024; 18(1), p 311-25.
[9] WHO. Guidelines for drinking-water quality. WHO Chron. 2011; 38(4): 104 8.
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  • APA Style

    André, K. S., Marcelle, Y., Nina, A., Simon, Y. J., Chimelle, O., et al. (2025). Evaluation of Two Spectrometric Approaches for Measuring Metal Concentrations in Drinking Water. Science Journal of Analytical Chemistry, 13(3), 63-67. https://doi.org/10.11648/j.sjac.20251303.11

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    ACS Style

    André, K. S.; Marcelle, Y.; Nina, A.; Simon, Y. J.; Chimelle, O., et al. Evaluation of Two Spectrometric Approaches for Measuring Metal Concentrations in Drinking Water. Sci. J. Anal. Chem. 2025, 13(3), 63-67. doi: 10.11648/j.sjac.20251303.11

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    AMA Style

    André KS, Marcelle Y, Nina A, Simon YJ, Chimelle O, et al. Evaluation of Two Spectrometric Approaches for Measuring Metal Concentrations in Drinking Water. Sci J Anal Chem. 2025;13(3):63-67. doi: 10.11648/j.sjac.20251303.11

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  • @article{10.11648/j.sjac.20251303.11,
      author = {Kpaibé Sawa André and Yao Marcelle and Ablé Nina and Yao Jean Simon and Ogré Chimelle and Amin N’cho Christophe},
      title = {Evaluation of Two Spectrometric Approaches for Measuring Metal Concentrations in Drinking Water
    },
      journal = {Science Journal of Analytical Chemistry},
      volume = {13},
      number = {3},
      pages = {63-67},
      doi = {10.11648/j.sjac.20251303.11},
      url = {https://doi.org/10.11648/j.sjac.20251303.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sjac.20251303.11},
      abstract = {This study aimed to compare the performance of photometric analysis and flame atomic absorption spectrophotometry (FAAS) in determining iron concentrations in water samples. Thirty samples were collected from wells located in the Anani and Gonzacque-ville neighborhoods and analyzed using both techniques. Photometric results indicated that 26 out of 30 samples had iron concentrations below the Ivorian regulatory limit of 0.3mg/L, while three samples exceeded this threshold. In contrast, AAS measurements showed that all samples complied with the standard, with no exceedances recorded. Statistical analysis revealed a significant difference between the two methods, with photometric readings generally yielding higher iron concentrations than those obtained via AAS. This discrepancy highlights the importance of employing more precise analytical techniques such as FAAS for routine water quality monitoring, particularly when assessing critical parameters like iron.
    },
     year = {2025}
    }
    

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    AB  - This study aimed to compare the performance of photometric analysis and flame atomic absorption spectrophotometry (FAAS) in determining iron concentrations in water samples. Thirty samples were collected from wells located in the Anani and Gonzacque-ville neighborhoods and analyzed using both techniques. Photometric results indicated that 26 out of 30 samples had iron concentrations below the Ivorian regulatory limit of 0.3mg/L, while three samples exceeded this threshold. In contrast, AAS measurements showed that all samples complied with the standard, with no exceedances recorded. Statistical analysis revealed a significant difference between the two methods, with photometric readings generally yielding higher iron concentrations than those obtained via AAS. This discrepancy highlights the importance of employing more precise analytical techniques such as FAAS for routine water quality monitoring, particularly when assessing critical parameters like iron.
    
    VL  - 13
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