Development of a Modified QuEChERS Extraction for the Detection of Rosemary Extracts (E392) Expressed as Sum of Carnosol and Carnosic Acid in Food by LC-MS/MS.

Background: Rosemary extracts are derived from the leaves of Rosmarinus officinalis and commonly employed as a natural food preservative. They serve as natural antioxidants in food, preventing spoilage and extending shelf life.

Objective: This study aimed to develop a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction with liquid chromatography tandem mass spectrometry (LC-MS/MS) for the analysis of rosemary extracts in food as the sum of its markers carnosol and carnosic acid.

Method: Carnosol and carnosic acid in food were extracted by a modified QuEChERS extraction after the addition of analyte protectants during extraction and analyzed by LC-MS/MS via an internal standard calibration method. 2,2'-isopropylidienediphenol and podocarpic acid were used as internal standards for carnosol and carnosic acid, respectively.

Results: The limit of detection (LOD) of carnosol and carnosic acid were all less than 1 mg/kg, while their corresponding values of limit of quantitation (LOQ) ranged from 1.44 to 3.12 mg/kg in various matrixes. Spike recoveries at three fortification levels (10, 50, and 300 mg/kg) were all within 90-110% with RSD less than 10% in all cases.

Conclusions: A modified QuEChERS extraction with LC-MS/MS detection for the analysis of rosemary extracts in food was successfully developed, validated, and demonstrated to be fast, robust, and reliable.

Highlights: The developed modified QuEChERS extraction with LC-MS/MS detection offered a fast and efficient way to analyze rosemary extracts in various foods during a routine food surveillance program.