Improved sample preparation for β-N-Methylamino-L-Alanine (BMAA) Analysis by hydrophilic interaction liquid chromatography–tandem mass spectrometry and assessment of freshwater cyanobacterial cultures from Aotearoa New Zealand

Abstract

β-N-Methylamino-L-alanine (BMAA), aneurotoxic nonproteinogenic amino acid implicated in the development of neurodegenerative diseases, has been broadly associated with cyanobacteria and bioaccumulation through the food web. Early high-level detections, from poorly selective high-performance liquid chromatography-fluorescence detection (HPLC−FLD) methods, have never been repeated using modern, selective tandem mass spectrometry methods. We developed a hydrophilic interaction liquid chromatography−tandem mass spectrometry (HILIC−MS/MS) method for total BMAA analysis, using an improved solid phase extraction sample cleanup to reduce suppression. We identified oxidative degradation products of BMAA, formed during strong acid hydrolysis, due to residual nitrate in culture media and implemented a dewatering step to resolve this problem. The method was validated using Spirulina powder, environmental, and two cultured cyanobacterial samples, achieving a reporting limit of 0.3mg/kg in dry cyanobacterial samples. The validated method was then applied to an additional 30 cyanobacteria cultures from Aotearoa New Zealand. BMAA was only detected in one strain, Planktothrix sp. CAWBG-35, at 2.3mg/kg. These results indicate that BMAA is not produced at the high levels originally reported (e.g.,g/kg) in fresh water cyanobacteria and suggest that BMAA production is not widespread among freshwater cyanobacteria from Aotearoa New Zealand. These results have broad implications for future risk-based environmental and public health monitoring.