Avoiding False Identification of 7-Hydroxymitragynine in Kratom Products Using a Multicriteria LC-MS Confirmation

Area of Science:

• Pharmacognosy
• Analytical Chemistry
• Forensic Science

Background:

• Kratom (Mitragyna speciosa) products are widely available, containing potent alkaloids like mitragynine (MG), 7-hydroxymitragynine (7-OH), and mitragynine pseudoindoxyl (MGP).
• Accurate identification of these kratom alkaloids is analytically challenging due to complex matrices with structurally similar compounds and isomers.
• Regulatory and analytical interest in kratom product composition is increasing.

Purpose of the Study:

• To develop and validate an ultrahigh-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) workflow for characterizing kratom alkaloids.
• To differentiate key kratom alkaloids (MG, 7-OH, MGP) and related isomers in authentic leaf materials and commercial products.
• To assess the alkaloid variability in diverse commercial kratom formulations.

Main Methods:

• Development of a UHPLC-HRMS workflow for kratom alkaloid analysis.
• Utilizing accurate mass measurement and diagnostic MS/MS fragmentation for compound identification.
• Employing a multicriteria confirmation strategy and untargeted metabolomic profiling.

Main Results:

• Reliable differentiation of mitragynine, 7-hydroxymitragynine, and mitragynine pseudoindoxyl and their isomers was achieved.
• Reliance solely on accurate mass or common transitions can lead to false positives for 7-OH in kratom matrices.
• Significant variability in alkaloid composition was observed across 38 commercial kratom products, with 7-OH and MGP found in tablets and capsules.
• Metabolomic profiling distinguished plant extracts from processed products enriched in specific alkaloids.

Conclusions:

• Integrating chromatographic resolution with orthogonal MS/MS criteria is crucial for reliable kratom alkaloid identification.
• The developed analytical framework enables robust characterization of complex botanical products like kratom.
• Findings highlight the need for stringent analytical methods to ensure accurate labeling and regulation of kratom products.