A straightforward method for measuring the range of apparent density of microplastics

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microplastic density is crucial for understanding their distribution and bioavailability in aquatic environments.
• Accurate measurement of microplastic density is essential for environmental monitoring and risk assessment.

Purpose of the Study:

• To develop a simple, rapid, and reliable method for measuring microplastic density.
• To evaluate the suitability of different density gradient solutions for microplastic density determination.

Main Methods:

• Development of a density gradient method using ethanol, ultrapure water, sodium iodide, and zinc chloride solutions.
• Measurement of microplastic density by observing their float or sink behavior in prepared density gradient solutions.
• Comparison of density results obtained from different solvent-based density gradient solutions.

Main Results:

• Density gradient solutions prepared with ethanol (0.8 g/cm³), ultrapure water (1.0 g/cm³), and saturated sodium iodide (1.8 g/cm³) yielded consistent and reliable microplastic density measurements.
• Zinc chloride solutions exhibited higher uncertainty in density measurements, likely due to increased surface tension.
• The developed method is suitable for measuring microplastics within a density range of 0.8-1.8 g/cm³.

Conclusions:

• The density gradient method using ethanol, ultrapure water, and sodium iodide is a practical approach for determining microplastic density.
• Sodium iodide is a preferred solvent over zinc chloride for creating stable density gradient solutions.
• This method offers a valuable tool for environmental studies focusing on microplastic contamination.