Reductive amination derivatization for the quantification of garlic components by isotope dilution analysis

Area of Science:

• Analytical Chemistry
• Food Chemistry
• Biochemistry

Background:

• Garlic organosulfur compounds (OSCs) possess significant health benefits.
• Accurate quantification of OSCs in garlic is crucial for nutritional and health studies.
• Existing analytical methods may lack the precision required for absolute quantification.

Purpose of the Study:

• To synthesize novel internal standards for four major garlic OSCs: S-allylcysteine (SAC), alliin, S-methylcysteine (SMC), and S-ethylcysteine (SEC).
• To develop and validate an isotope dilution analysis (IDA) method for the accurate quantification of these OSCs in garlic.
• To establish a robust analytical approach for enhancing the reliability of OSC measurements.

Main Methods:

• Synthesis of ¹³C, D₂-labeled internal standards for SAC, alliin, SMC, and SEC via reductive amination.
• Development of an ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) method utilizing multiple reaction monitoring (MRM).
• Validation of the IDA method, assessing linearity (R²), and recovery rates.

Main Results:

• ¹³C, D₂-labeled internal standards for four garlic OSCs were successfully synthesized.
• The UHPLC-MS/MS method with IDA demonstrated high linearity (R² = 0.9989–0.9994) for the quantified OSCs.
• Average recoveries for the four OSCs ranged from 89% to 105% across different concentration levels, indicating method accuracy.

Conclusions:

• The developed reductive amination-based method provides novel internal standards for IDA of garlic OSCs.
• This IDA method significantly improves the accuracy and reliability of quantifying SAC, alliin, SMC, and SEC in garlic samples.
• The approach is extendable for the quantitative analysis of other compounds requiring precise measurement.