Colorimetric paper-based test strip for detection of methylparaben in nonconforming health care products

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Methylparaben (MPB) is a widely used preservative in pharmaceuticals and food.
• MPB is also recognized as an endocrine-disrupting compound, necessitating monitoring.
• Existing detection methods may be complex or unsuitable for point-of-use applications.

Purpose of the Study:

• To develop a simple, low-cost, and reliable colorimetric paper-based analytical device (PAD) for the on-site detection of MPB.
• To utilize smartphone imaging for quantitative analysis of MPB in healthcare products.
• To validate the accuracy and precision of the developed PAD method.

Main Methods:

• Immobilization of Fe³⁺ on a chitosan-modified paper substrate to create the test strip.
• Detection of MPB based on the coordination interaction with immobilized Fe³⁺, resulting in a violet color change.
• Quantitative analysis using smartphone image capture and an RGB color detector mobile application to measure magenta intensity.

Main Results:

• A strong correlation (R² = 0.989) was observed between magenta intensity and MPB concentration (10-50 mg mL⁻¹).
• The PAD demonstrated high accuracy (% recovery: 97.8-101.5%) and precision (RSD < 2%).
• The method was successfully applied directly to healthcare products without sample preparation, showing no significant difference from conventional methods.

Conclusions:

• The developed smartphone-based PAD offers a rapid, practical, and cost-effective solution for on-site detection of MPB.
• This technology enables the identification of nonconforming healthcare products containing MPB.
• The method holds potential for quality control and regulatory compliance in the pharmaceutical and healthcare industries.