Analytical Concordance of EDTA Complexometry and Atomic Absorption Spectrometry in Assessing Alkaline Earth Metal Profiles of Commercial Table Water Sold in Okigwe Town

 

Eberendu, Kizito O.1*, Nlemchukwu Benedict N.C.1, Ejezie, Michael U.1,

Ukachukwu Veronica I.1, Eberendu Stella U.2, Emele Hyacinth C.1

1Department of Chemistry, University of Agriculture and Environmental Sciences, Umuagwo, Nigeria.

2Department of Mass Communication, Abia State University, Uturu, Nigeria.

*Corresponding Author E-mail: kizito.onyedikachi@uaes.edu.ng

 

ABSTRACT:

This study presents a comparative evaluation of titrimetric and atomic absorption spectrophotometric (AAS) technique for the determination of calcium (Ca) and magnesium (Mg concentrations in table water sold in Okigwe own, Imo State, Nigeria. Calcium and magnesium are essential minerals that influence water hardness and have significant implications for human health and water quality. Samples of commercially packaged table water were collected from different locations within Okigwe town and analyzed using complexometric titration with ethylenediaminetetraacetic acid (EDTA) and atomic absorption spectrophotometry. The accuracy, sensitivity, and dependability of the outcomes from the two approaches were evaluated. The amounts of Ca and Mg observed in the water samples were assessed against World Health Organization (WHO) drinking water standards. Findings revealed variations in mineral content among the samples, reflecting differences in water sources and treatment processes. While the titrimetric method proved to be simple and cost-effective, the AAS technique demonstrated higher sensitivity and precision. The study concludes that although both methods are suitable for routine water abalysis, atomic absorption spectrophotometry offers superior analytical performance for trace metal determination. The results provide valuable information for water monitoring, public health assessment, and regulatory compliance in the packaged water industry.

 

KEYWORDS: Calcium determination, Magnesium determination, Atomic absorption spectrophotometry, EDTA titration, Packaged drinking water.

 

 

INTRODUCTION:

Both economical progress and human health depend on having access to clean, safe drinking water1. In many regions, including Nigeria, packaged drinking water has become a major source of potable water due to inadequate municipal water supply systems. The quality of packaged drinking water is therefore of significant public health concern.

 

Calcium and magnesium are naturally occuring alkaline earth metals commonly found in groundwater and surface water sources. These metals are the principal contributors to water hardness and play vital roles in human physiology, including bone mineralization, enzymatic activity, cardiovascular regulation, and neuromuscular function6,7. Epidemiological studies have shown that moderate intake of calcium and magnesium through drinking water is associated with beneficial health outcomes, particularly reduced risks of cardiovascular diseases, whereas extremely low or excessive concentrations may lead to adverse health effects8,9.

 

Analytical determination of calcium and magnesium in water is essential for quality assessment and regulatory compliance. Complexometric titration using ethylenediaaminetetraacetic acid (EDTA) is a classical analytical technique widely employed due to its simplicity and cost-effectiveness3,10. However, this method is susceptible to endpoint detection errors. Atomic absorption spectrophotometry (AAS) is an instrumental technique known for its high sensitivity, selectivity, and precision in metal analysis4,11,12.

 

Comparative evaluation of classical and instrumental analytical methods is important for selecting appropriate techniques for routine water quality monitoring. This study therefore aims to determine calcium and magnesium concentrations in packaged drinking water sold in Okigwe Town using EDTA titration and AAS, and to compare the analytical performance of both methods with reference to international drinking water standards.

 

MATERIALS AND METHODS:

Sample Collection:

Commercially packaged drinking water samples were randomly purchased from retail outlets within Okigwe Town, Imo State, Nigeria. To avoid contamination, all samples were brought to the lab in their original, sealed containers and kept at room temperature until analysis.

 

Reagents and Apparatus:

All reagents used were of analytical grade. Standard solutions of EDTA, calcium, and magnesium were prepared using distilled water. Apparatus used included burettes, pipettes, volumetric flasks, conical flasks, a pH meter, and an atomic absorption spectrophotometer equipped with calcium and magnesium hollow cathode lamps.

 

Estimation of Calcium and Magnesium concentrations by EDTA Titration:

Standard complexometric titration techniques were used to measure the amounts of calcium and magnesium. The water samples were buffered to the required pH and titrated against standardized EDTA solution using appropriate indicators. The endpoint was identified by a distinct colour change, and concentrations were calculated from the volume of EDTA consumed.

 

Estimation of Calcium and Magnesium by Atomic Absorption Spectrophotometry:

Atomic absorption spectrophotometric analysis was carried out after calibrating the instrument with standard solutions of calcium and magnesium. Absorbance measurements were taken at the distinctive wavelengths for each metal after samples were sucked straight into the flames. Concentrations were obtained from calibration curves.

 

Data Analysis:

Results obtained from both analytical methods were compared, and measured concentrations were evaluated against World Health Organization drinking water standards.

 

Results:

The concentrations of calcium and magnesium in the packaged drinking water samples were successfully determined using both EDTA complexometric titration and atomic absorption spectrophotometry (Tables 1 and 2).

 

Calcium concentrations varied among the sampled water brands. EDTA titration produced consistent values across samples, while AAS generally yielded slightly higher concentrations, indicating greater sensitivity. All calcium concentrations obtained were within WHO permissible limits for drinking water.

 

Magnesium concentrations also showed variations among the samples. Results obtained using EDTA titration were reproducible; however, AAS analysis provided more precise measurements, particularly for samples with lower magnesium content. All magnesium concentrations were within WHO recommended limits.

 

 

Table 1: Calcium and Magnesium of water determined by AAS analysis (mg/L)

Element

Water sample (mg/L)

BLANK

COF

BEN

MAK

IVO

MAT

JON

ALK

DOO

SMAR

NIC

Sample No.:

1

2

3

4

5

6

7

8

9

10

11

Calcium

0.90

2.80

2.05

2.14

2.44

0.98

1.44

2.22

3.00

2.40

1.10

Magnesium

0.75

0.98

1.54

1.11

1.15

1.00

1.19

0.99

1.14

1.20

1.35

 

Table 2: Calcium and Magnesium of water determined by Complexometric Method (mg/L)

Element

Water sample          (mg/L)

BLANK

COF

BEN

MAK

IVO

MAT

JON

ALK

DOO

SMAR

NIC

Sample No.:

1

2

3

4

5

6

7

8

9

10

11

Calcium

1.85

3.31

3.35

3.62

2.95

2.76

2.62

3.00

2.82

3.12

3.11

Magnesium

1.00

2.80

1.68

2.13

2.11

2.30

1.65

1.73

1.62

1.78

1.20

* COFO = COF, BENOBLE = BEN, MAKAGINUS = MAK, IVON = IVO, MATRIX = MAT, JONUK = JON, ALKALINE = ALK, DOOM = DOO, SMART ICE = SMA, and DE NICE = NIC

Overall, both methods exhibited similar trends in calcium and magnesium distribution across the samples, with AAS demonstrating superior analytical performance.

 

DISCUSSION:

The variations in calcium and magnesium concentrations observed among the packaged drinking water samples may be attributed to differences in water sources, geological formations, and treatment processes employed by manufacturers5,12. The presence of these minerals confirms their natural occurrence in drinking water and their contribution to water hardness.

 

The EDTA titration method proved suitable for routine analysis due to its simplicity and affordability, consistent with previous studies2,13,14. However, the reliance on visual endpoint detection may introduce minor errors. Atomic absorption spectrophotometry minimized subjective errors and provided improved sensitivity and precision, particularly for low-level metal determination4.

 

The findings of this study are in agreement with earlier reports highlighting the advantages of instrumental methods over classical titrimetric techniques for trace metal analysis in water5,15. Nevertheless, both methods were adequate for assessing compliance with drinking water quality standards.

 

CONCLUSION:

This study demonstrates that both EDTA complexmetric titration and atomic absorption spectrophotometry are effective for the determination of calcium and magnesium in packaged drinking water. While EDTA titration is cost-effective and suitable for routine monitoring, atomic absorption spectrophotometry offers superior sensitivity and precision. All water samples analyzed complied with World Health Organization standards for calcium and magnesium, indicating that they are safe for human consumption with respect to these parameters.

 

ACKNOWLEDGEMENTS:

The authors acknowledge the Department of Chemistry laboratories for providing the facilities and technical assistance required for this research.

 

REFERENCES:

1.      Kulinkina AV, Kosinski KC, Liss A, Adjei MN, Ayamgah GA, Webb P, et al. Piped water consumption in Ghana: A case study of temporal and spatial patterns of clean water demand relative to alternative water sources in rural small towns. Science of the Total Environment. 2016 Jul 15; 559: 291–301. doi: 10.1016/j.scitotenv.2016.03.148.

2.      Singh AK. Acid catalised solvolysis of amyl methanoate in binary aqueous solvent system and solvent effect on kinetics of activation parameters. Asian Journal of Research in Chemistry. 2020; 13(6): 485–488. doi:10.5958/0974-4150.2020.00085.1.

3.      Al-Ogaili NA, Osama S, Jazme D, Saad S. In vitro antibacterial investigation and synergistic effect of Ficus carica and Olea europaea aqueous extracts. Research Journal of Pharmacy and Technology. 2020; 13(3): 1198–1203. doi:10.5958/0974-360X.2020.00221.8.

4.      Stacey GL, Keen NT. Plant–microbe interactions. Chapman and Hall; New York: 1996.

5.      Mandell GL, Petri WA. Antimicrobial agents: penicillin, cephalosporins, and other β-lactam antibiotics. In: Hardman JG, Limbird LE, editors. Goodman and Gilman’s The Pharmacological Basis of Therapeutics. 9th ed. New York: McGraw-Hill; 1996. p. 1073–1101.

6.      Mallika AG, Tulasi Das V. Impact of stress on working performance of nurses and organizational effectiveness in hospitals. Asian Journal of Management. 2020; 11(3): 225–232. doi:10.5958/2321-5763.2020.00035.9.

7.      Catling LA, Abubakar I, Lake IR, Swift L, Hunter PR. A systematic review of analytical observational studies investigating the association between cardiovascular disease and drinking water hardness. BMJ. 2008; 336: 860–863. doi:10.1136/bmj.39404.633125.25.

8.      Rylander R. Drinking water constituents and disease. J Nutr. 2008 Feb; 138(2): 423S–425S. doi:10.1093/jn/138.2.423S.

9.      Monarca S, Donato F, Zerbini I, Calderon RL, Craun GF. Review of epidemiological studies on drinking water hardness and cardiovascular diseases. Eur J Cardiovasc Prev Rehabil. 2006 Aug; 13(4): 495–506. doi: 10.1097/01.hjr.0000216545.05723.3e.

10.   World Health Organization. Hardness in drinking-water: background document for development of WHO guidelines for drinking-water quality. Geneva: WHO Press; 2011.

11.   Nerbrand C, Agréus L, Arvidsson Lenner R, Nyberg P, Svärdsudd K. The influence of calcium and magnesium in drinking water and diet on cardiovascular risk factors in individuals living in hard and soft water areas with differences in cardiovascular mortality. BMC Public Health. 2003; 3: 21. doi:10.1186/1471-2458-3-21.

12.   Rosenlund M, Berglind N, Hallqvist J, Bellander T, Bluhm G. Daily intake of magnesium and calcium from drinking water in relation to myocardial infarction. Epidemiology. 2005 Jul; 16(4): 570–576.  doi: 10.1097/01.ede.0000165390.18798.62.

13.   Rylander R, Bonevik H, Rubenowitz E. Magnesium and calcium in drinking water and cardiovascular mortality. Scand J Work Environ Health. 1991 Apr; 17(2): 91–94. doi:10.5271/sjweh.1722.

14.   Yang CY. Calcium and magnesium in drinking water and risk of death from cerebrovascular disease. Stroke. 1998 Feb; 29(2): 411–414. doi: 10.1161/01.STR.29.2.411.

15.   Kozisek F. Regulations for calcium, magnesium, or hardness in drinking water in the European Union member states. Regul Toxicol Pharmacol. 2020 May; 112: 104589. doi: 10.1016/j.yrtph.2020.104589.

 

 

 

 

Received on 02.02.2026      Revised on 13.04.2026

Accepted on 15.05.2026      Published on 04.07.2026

Available online from July 30, 2026

Asian J. Research Chem.2026; 19(4):287-289.

DOI: 10.52711/0974-4150.2026.00044

©A and V Publications All Right Reserved

 

This work is licensed under a Creative Commons Attribution-Non Commercial-Share Alike 4.0 International License. Creative Commons License.