Determination of Retrorsine in Thyme Via Molecularly Imprinted Electrochemical Sensor: Validation and Comparison With Chromatographic Technique

Abstract

Pyrrolizidine alkaloid (PA) toxicity is a growing public health concern, especially with rising herbal product use during the pandemic, highlighting the need for accurate exposure data. Retrorsine (RTS), a retronecine-based PA, is highly toxic, causing liver damage, mutagenicity, and DNA cross-linking through metabolic activation. In the light of the need for a practical alternative to monitor pyrrolizidine alkaloid contamination in herbal products, a molecularly-imprinted-polymer sensor (MIPs-GCE) was used for exploring the electrochemical behavior of RTS electrochemical behavior using cyclic voltammetry and the selective detection of RTS using square wave voltammetry. The sensor demonstrated a linear-detection range of 0.05-2 nM, with a LOD of 0.02869 nM. The sensor's accuracy was validated by analyzing thyme samples, detecting RTS concentrations of 0.5168 and0.5345 nM with RSD of 2.4 % and 1.9 %. These results closely aligned LC-MS/MS values of 0.5142 and 0.5267 nM, confirming the sensor's precision. The sensor demonstrated high selectivity, low detection limits, and practical applicability, ensuring reliable and efficient RTS detection in the presence of twenty-eight different PA compounds. This study introduces a novel, reliable, and straightforward method for detecting PAs, with a specific focus on RTS, offering an enhancement to existing analytical techniques and presenting a complementary alternative in chromatographic applications such as LC-MS/MS, HPLC and GC-MS.