Trace Detection of Aspartame in Beverages

Importance of the Topic

Aspartame is one of the most widely used high-intensity artificial sweeteners in the beverage industry. Its low caloric contribution and high sweetness intensity drive demand in diet and sugar-reduced products. Concerns over potential health risks, especially for individuals with phenylketonuria, and ongoing scrutiny by regulatory agencies underline the need for reliable, on-site screening methods to ensure consumer safety.

Objectives and Study Overview

The primary goal of this study was to establish a rapid, sensitive, and field-deployable protocol for trace detection of aspartame in carbonated water and diet cola. Using the Metrohm Instant SERS Analyzer (MISA) paired with gold nanoparticles, the work aimed to:

• Create a reference surface-enhanced Raman scattering (SERS) spectrum for aspartame.
• Define detection limits in simple and complex beverage matrices.
• Demonstrate a minimal-preparation, portable assay suitable for on-site beverage testing.

Methodology and Sample Preparation

Pure aspartame was dissolved at 1 mg/mL to generate a reference spectrum. Beverage samples were prepared by spiking carbonated water at concentrations from 100 µg/mL down to 100 ng/mL. Diet cola samples were diluted 1:9 with water. For each measurement, 100 µL of sample was combined with 800 µL of Au nanoparticle colloid and 100 µL of 0.5 M NaCl, shaken gently, and analyzed using the MISA vial attachment. Spectra were acquired with a 785 nm laser at 5 % power, 1 s integration, and 10 accumulations with orbital-raster-scan enabled.

Used Instrumentation

• MISA Advanced (Metrohm Instant SERS Analyzer) with ORS spectrograph
• MISA Vial Attachment (Cat. 6.07505.040)
• ID Kit – Au NP (Gold nanoparticle colloid, Cat. 6.07506.440)
• Software: Misa Cal V1.0.15
• Laser settings: 785 nm, 5 % power, 1 s integration, 10 averages

Main Results and Discussion

SERS spectra revealed clear aspartame peaks down to 100 ng/mL in spiked carbonated water, demonstrating excellent sensitivity. In 10×-diluted diet cola, aspartame was detected reliably between 10 and 50 µg/mL, aligning with typical use levels (around 350 µg/mL). The minimal dilution step effectively reduced background signals from cola ingredients while maintaining analytical performance.

Benefits and Practical Application

• Rapid analysis with total assay time under five minutes per sample.
• Simple sample preparation: one-step dilution and mixing.
• Portable, battery-powered instrument ideal for field or mobile labs.
• Cost-effective screening alternative to centralized laboratory methods.
• On-site compliance testing for food safety and quality control.

Future Trends and Opportunities

Advances in nanoparticle substrates and integration of compact Raman spectrometers could further enhance sensitivity and reduce detection limits. Combining SERS with machine-learning algorithms may enable multiplexed screening of multiple sweeteners and contaminants in a single run. Integration with smartphones or handheld devices can simplify data interpretation and reporting in low-resource or point-of-need environments.

Conclusion

The study demonstrates that the Metrohm Instant SERS Analyzer with gold nanoparticle colloid provides a fast, sensitive, and portable solution for detecting trace levels of aspartame in beverages. This approach supports on-site quality control and regulatory compliance, offering a valuable tool for food safety monitoring.