Advances in the detection of emerging contaminant metformin: A critical review

Metformin is a well-known primary medicine for the treatment of type Ⅱ diabetes, which has become the most commonly found medicine with the largest amounts in aqueous environment owing to its incomplete metabolism in the human body. Metformin in water systems inevitably transforms into two toxic disinfection-derived byproducts during the chlorination process, posing a global threat to ecosystems and humans. As a result, metformin has been regarded as an emerging contaminant in the environment, and there is an urgent need to develop sensitive and accurate analytical methods for the detection of metformin in diverse matrices, such as pharmaceutical products, biological samples, and environmental samples. The aim of this review is to provide an overview of recent advances in various analytical methods for metformin detection by incorporating chromatographic, optical, and electrochemical based techniques, and to focus on the working principles of different techniques, detection mechanisms, and analytical performance. In addition, the challenges and perspectives of further development of analytical methods are discussed in this review.