Rapid Analytical Method for the Quantification of Bromoform in the Red Seaweeds Asparagopsis armata and Asparagopsis taxiformis Using Gas Chromatography–Mass Spectrometry

• Published in: ACS agricultural science & technology Vol. 1; no. 5; pp. 436 - 442
• Main Authors: Romanazzi, Donato, Sanchez-Garcia, Cristina, Svenson, Johan, Mata, Leonardo, Pes, Katia, Hayman, Colin M, Wheeler, Thomas T, Magnusson, Marie
• Format: Journal Article
• Language: English
• Published: American Chemical Society 18.10.2021
• Subjects: biomass quality; ruminant; analysis; interlab comparison; optimization; methane inhibition
• ISSN: 2692-1952; 2692-1952
• DOI: 10.1021/acsagscitech.1c00161

The red seaweed Asparagopsis is rich in bromoform (CHBr3) which effectively inhibits the production of methane in ruminants, and ongoing global research is investigating the potential to utilize Asparagopsis as a feed additive to mitigate livestock methane emissions. Due to its volatility, the concentration of bromoform in the harvested seaweed is affected by processing and storage conditions, and its quantification is thus not trivial. The accurate determination of bromoform in biomass is required for correct inclusion-response calculations and minimum effective feed inclusion rates, for interstudy comparisons, and for optimizing processing protocols. However, no such standardized protocol, with appropriate quality control and quality assurance in place, exists. Here, we present a single-laboratory validation of a simple and rapid GC-MS method for quantifying the concentration of bromoform in seaweeds with a lower limit of quantitation of 0.26 mg/g in freeze-dried material. The method is employed to assess the concentrations of bromoform in frozen and dried Asparagopsis armata and Asparagopsis taxiformis biomass. The linearity, sensitivity, precision, accuracy, and robustness of the assay are presented. In addition, the assay was implemented in two independent laboratories, and the results were compared. The assay has been accredited by the International Accreditation New Zealand (IANZ) as suitable for assessing the concentration of bromoform of frozen and freeze-dried seaweed. Furthermore, the effects of sample storage conditions and freeze-drying of seaweed were investigated, with results highlighting the need of controlled seaweed handling with implications for downstream processing into a potential commercial feed additive.