1H NMR determination of β-N-methylamino-l-alanine (l-BMAA) in environmental and biological samples

A nuclear magnetic resonance (1H NMR) method for the determination of β-N-methylamino-l-alanine (l-BMAA) in environmental aqueous samples was developed and validated. l-BMAA is a neurotoxic modified amino acid that can be produced by cyanobacteria in aqueous environments. This toxin was extracted from samples by means of solid-phase extraction (SPE) and identified and quantified by 1H NMR without further derivatization steps. The lower limit of quantification (LLOQ) was 5 μg/mL. Good inter and intra-assay precision was also observed (relative standard deviation <8.5%) with the use of 4-nitro-dl-phenylalanine as an internal standard (IS). This method of 1H NMR analysis is not time consuming and can be readily utilized to monitor l-BMAA and confirm its presence in environmental and biological samples.