Analysis of Trace Elements in Water using Ultra Thin Film (1)

Importance of the Topic

Analysis of trace elements in water is critical for environmental monitoring, public health, and industrial quality control.
Conventional EDX methods with filter paper sample holders yield detection limits at ppm level, insufficient for many regulatory and research requirements.
Replacing filter paper with an ultra thin polymer film significantly improves signal‐to‐noise ratio, enabling ppb‐level analysis.

Objectives and Study Overview

The study aims to demonstrate quantum improvements in EDX analysis of water samples by using a 0.15 µm polyimide film sample holder.
It evaluates lower detection limits, qualitative performance, and compares results with standard NIST 1643d trace element reference material.

Methodology and Instrumentation

Sample preparation involved depositing 50 µL of water solution on a 2 mm diameter section of 0.15 µm polyimide film stretched in a plastic holder.
Drying was performed at 70 °C for 40 min, and optional CCD imaging was used to confirm uniform residue distribution.
EDX measurements were carried out on a Shimadzu EDX‐700 with the following conditions:

• X‐ray tube: Rh anode
• Filters: none, Ti, and Ni
• Acceleration voltage: 50 kV and 15 kV (automatic adjustment)
• Measurement diameter: 3 mm
• Measurement time: 1000 s
• Atmosphere: air or vacuum

Main Results and Discussion

Qualitative spectra of NIST 1643d demonstrated clear element peaks and reduced background noise when using the ultra thin film.
Detection limits calculated with L.L.D = 3 x (BG/T)1/2 x C/NET showed ppb‐level sensitivity for elements such as Na (1911 ppb), Mg (406 ppb), Si (44 ppb), K (121 ppb), Mn (12 ppb), Fe (10 ppb), Co (18 ppb), Ni (15 ppb), Zn (15 ppb), As (15 ppb), Sr (18 ppb), Mo (22 ppb), and Ba (65 ppb).
Use of Ti and Ni filters further optimized element detection by suppressing interfering peaks.

Benefits and Practical Applications

The ultra thin film method offers:

• Lower sample volume (50 µL) and minimal sample preparation
• Enhanced sensitivity and reduced detection limits to ppb range
• Rapid screening suitable for environmental, industrial, and QA/QC laboratories
• Compatibility with existing EDX instrumentation

Future Trends and Potential Applications

Integration of ultra thin film EDX with microfluidic devices for automated analyses in field settings.
Development of real‐time monitoring platforms for water quality assessment.
Expansion to nanoparticle and speciation studies by coupling with complementary techniques.

Conclusion

The ultra thin polymer film sample holder in EDX analysis enables quantum improvements in signal‐to‐noise ratio, achieving ppb‐level detection of trace elements in water.
This method streamlines sample preparation and extends the applicability of EDX for routine environmental and industrial monitoring.

Reference

• NIST Standard Reference Material 1643d, Trace Elements in Water.
• Shimadzu Application Note SCA_125_016, Analysis of Trace Elements in Water Using Ultra Thin Film.