LAUSR

The present work describes a practical application of Green Analytical Toxicology (GAT) during the development of an eco-friendly dispersive liquid-liquid microextraction (DLLME) avoiding the use of highly toxic chlorinated solvents that are commonly used in this type of technique. The purpose was to further consolidate GAT guidelines during method development. Thus, a full method optimization using a multivariate statistical approach and validation were performed. To that end, synthetic cathinones (SC), one of the major classes of new psychoactive substances, were the target analytes due to their relevance and chemical diversity. Furthermore, whole blood and urine samples were the matrices of choice due to their clinical relevance. The sample preparation step prior to DLLME consisted of protein precipitation of whole blood samples, while urine specimens were centrifuged and diluted with ultrapure water. Then, borate buffer, NaCl, and ethyl acetate:acetonitrile were added and vortexed. Finally, vials were centrifuged and the organic layer was transferred to autosampler vials, evaporated to dryness and resuspended with mobile phase prior to injection into the ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) system. Once optimized, the proposed DLLME was fully validated: 0.2 and 1 ng/mL as LOD; and 1 and 10 ng/mL as LOQ for urine and blood samples, respectively. Linear range was established as 1-100 and 10-1000 ng/mL for urine and blood samples, respectively (r2 > 0.99), while bias and precision were within acceptable limits (≥ 80%). The matrix effect was of 1.9-260.2% and -12.3-139.6%; while recovery was of 27.4-60.0% and 13.0-55.2%; and process efficiency ranged from 45.0% to 192.0% and 17.9% to 58.4% for whole blood and urine, respectively. Finally, the method was applied to real case samples as proof of applicability. Thus, a simple, cheap, and fast eco-friendly technique to analyze SC in two biological specimens was described.