Cotton Yarn Sorbent Tested for HPLC-UV Detection of Anti-Inflammatory Drugs

Researchers from the University of Mazandaran in Iran developed a thin-film coating based on Fe₃O₄@SiO₂-polyoxometalate (POM) and integrated it with high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) to analyze ibuprofen, paracetamol, and diclofenac in human plasma and urine samples. The study was published in the Journal of Chromatography A (1).

Various chromatographic methods are used for analyzing drugs from samples. Ultraviolet–visible (UV–Vis) spectroscopy is also commonly used for the analysis of pharmaceutical analytes because of its simple operation and quantitative analytical capabilities. However, this method comes with limitations, including the possibility of interference from contaminants, the scientists wrote, and a limited sensitivity for lower concentrations. As such, directly quantifying pharmaceuticals is difficult. Before determination, extraction, and pre-concentration is required before determination.

Sample preparation is essential for a successful determination. This step typically serves to purify samples, enrich target analytes, and ensure compatibility with analytical instruments.

POM is a polyatomic ion made up of transition metal oxyanions linked together by shared oxygen atoms to form closed 3-dimensional frameworks. It has distinctive features, such as negative charge, high thermal stability, and the presence of organic bonds. It can also be used as a solvent. However, POMs are recorded as having low surface area and tendencies for accumulation. According to the scientists, immobilizing POMs on substrates with high surface area increases the contact surfaces and the appropriate POM, increasing extraction performance.

HPLC and UV spectroscopy, when combined, enable a mixture of molecules to be separated, with relative proportions determined by calculating concentration following elution from the HPLC column (2). This method was used to selectively determine ibuprofen, paracetamol and diclofenac, which are medications typically used to treat pain, from human plasma and urine samples. To prepare the extracting device, the prepared magnetic POM was coated on the pores and surface of cotton yarn. Cotton fiber is a natural material that is environmentally friendly, mostly consisting of cellulose. Cotton yarn (CY), created from many cotton fibers, has many notable characteristics, including cost-effectiveness, flexibility, and considerable surface area. The experimental design specifically the Box-Behnken Design (BBD) combined with Response Surface Methodology (RSM), was used to optimize experimental factors, influencing extraction efficiency. With this approach, target analytes were identified in various plasma and urine samples.

Yarn, raw materials for cotton | Image Credit: © Yannasakamon - stock.adobe.com

The optimal conditions were found to be as follows: pH = 4, extraction time = 23 min, desorption time = 3 min, desorption volume = 400 µL, and Na2SO4 concentration = 0.8%. In optimal conditions, the method’s linearity ranged from 0.5–200 µg l^-1. The limits of detection (LODs), limits of quantification (LOQs), and intra-day/inter-day relative standard deviations (RSDs) were <0.24 µg L⁻¹, 0.81 µg L⁻¹, and 4.1 %, respectively.

The method successfully detected target analytes in biological fluids, achieving high recoveries. Additionally, only 400 µL of organic solvent was required, indicating that the method had no impact on the environment. The current study only used 20 mg of sorbent and 400 µL of methanol, which the scientists claim is much cheaper than other methods (1). Each extracting device was found to be usable 32 times.

Overall, the scientists deemed their method to be simple, ecofriendly, and time-efficient with minimal solvent usage. Further, the extraction being performed under ambient condition underscored the method’s potential in laboratory settings. The novel approach, as shown by their results, was deemed well-suited for field applications.

References

(1) Aljboory, Z. H. A.; Ghani, M.; Raoof, J. B. Magnetic Polyoxometalate Composite Stabilized on the Woven Cotton Yarn as a Sorbent for Thin Film Microextraction of Some Selected Nonsteroidal Anti-Inflammatory Drugs Followed by High-Performance Liquid Chromatography-Ultraviolet Detection. DOI: 10.1016/j.chroma.2024.465615

(2) Greenwood, M. What is High-Performance Liquid Chromatography-Ultraviolet (HPLC-UV)? News Medical & Life Sciences 2022. https://www.news-medical.net/life-sciences/What-is-High-Performance-Liquid-Chromatography-Ultraviolet-(HPLC-UV).aspx (accessed 2025-4-8)