New Portable LIBS Device for On-Site Water Hardness Testing

A recent study published in Chemosensors explored contamination in drinking water. In this study, lead author Shixiang Ma, who is from the Beijing Academy of Agriculture and Forestry Sciences and the Key Laboratory of Agricultural Sensors, and coauthors presented a new portable method that can conduct on-site detection of calcium and magnesium in surface water (1).

Water quality is an important issue worldwide, as it is a necessary ingredient for living organisms to grow and thrive. Calcium (Ca) and magnesium (Mg) are essential elements in surface water. These two elements are crucial in both environmental health and water quality assessment (1–3). These elements are key indicators of water hardness, which can impact industrial applications, drinking water standards, and aquatic ecosystems (2,3). Current methods for detecting calcium and magnesium are often time-consuming, making real-time monitoring in remote or field settings impractical (1).

Water | Image Credit: © robert - stock.adobe.com

In this study, the authors propose a new laser-induced breakdown spectroscopy (LIBS) system that can conduct rapid, in situ analysis of water. In this system, a miniaturized spectrometer integrated with a liquid jet device is used for sample introduction (1). This approach allows the LIBS system to achieve real-time, direct analysis of water samples without requiring extensive pre-treatment or laboratory conditions (1).

One of the major advancements in this study is the optimization of critical factors that influence LIBS spectral readings. Researchers determined that the ideal jet stream diameter for stable signal acquisition is 0.64 mm, with the laser ablation point positioned 5 mm from the jet outlet (1). The team enhanced signal stability by averaging the 20 individual spectra, which helped reduce the relative standard deviation (RSD) from approximately 16% to just 2% (1).

As a result, the system was able to achieve optimal detection limits for both calcium and magnesium. For calcium, the detection limit was 11.58 mg/L, and for magnesium it was 2.57 mg/L (1). Taking water from rivers and ponds, the researchers used the device to record the recovery rates of both elements. For calcium, the recovery rates hovered between 90.83% to 101.74%, whereas for magnesium, the recovery rates were between 93.43% and 108.74% (1). These high percentages demonstrate the potential of this method for testing water samples.

The portable LIBS system proposed by the authors may offer a new way to assess water quality. Its efficiency is designed to be a better alternative to traditional laboratory techniques. This method eliminates the need for complex sample preparation and transportation; as a result, it quickens the monitoring process (1). Furthermore, its portability and ease of use make it ideal for widespread deployment in field studies and remote areas where access to laboratory facilities is limited (1).

Although this study successfully demonstrates the feasibility and effectiveness of a miniaturized LIBS system for Ca and Mg detection in surface water, the researchers acknowledge the limitations of the study, which could spearhead future investigations. As an example, the research team suggests that future studies can use their method to evaluate additional water quality parameters such as heavy metals, nutrients, and organic pollutants (1). They also mentioned that enhancements in signal processing and spectral analysis techniques could further improve detection limits and analytical accuracy (1).

As water quality continues to be a global concern, the development of innovative and accessible monitoring technologies like this portable LIBS system will be critical in ensuring sustainable water management and environmental protection.

References

1. Wan, Y.; Ma, S.; Zheng, P.; et al. On-Site Detection of Ca and Mg in Surface Water Using Portable Laser-Induced Breakdown Spectroscopy. Chemosensors 2025, 13 (1), 16. DOI: 10.3390/chemosensors13010016
2. Helte, E.; Save-Soderbergh, M.; Larsson, S. C.; et al. Calcium and Magnesium in Drinking Water and Risk of Myocardial Infarction and Stroke—A Population-based Cohort Study. Am. J. Clin. Nutr. 2022, 116 (4), 1091–1100. DOI: 10.1093/ajcn/nqac186
3. McVean, A. Is Hard Water Dangerous to Drink? McGill University. Available at: https://www.mcgill.ca/oss/article/health-you-asked/you-asked-hard-water-dangerous-drink#:~:text=Several%20studies%20have%20reported%20that%20calcium%20and,help%20protect%20against%20esophageal%20and%20ovarian%20cancer. (accessed 2025-03-25).