ZIMBA, PAUL V.1* and STEVE BOUE2. 1U.S.D.A./A.R.S., PO Box 38, Stoneville, MS 38776; 2U.S.D.A./A.R.S., 1100 Robert E. Lee Blvd., New Orleans, LA 70124. - Mycosporine-like amino acid intercalibration effort using replicate samples.
The measurement of mycosporine-like amino acids (MAAs) has several
inherent problems, including the lack of commercial standards for
identification and quantification. This symposium provided the
opportunity to coordinate analyses with six laboratories actively
involved in MAA research. Two samples were provided to each laboratory
and included freeze-dried nori (Porphyra sp.) and a
freeze-dried (filtered) sample of the cyanobacteria Microcystis
aeruginosa Kützing. Each laboratory provided extraction
methodologies, chromatograms of the identified peaks, as well as
estimates of the concentration of each analyte. All laboratories were
able to identify major chromatographic components of the samples
(Porphyra: shinorine, porphyra, mycosporine 2-glycine,
asterina, palythine; Microcystis: shinorine, porphyra).
Sequential cold (4C for 18 hrs) and hot (45C for 2 hrs) extractions of
the same sample resulted in differing analyte recovery. Several
currently unidentified compounds were observed in freshwater samples.
Key words: intercalibration, Microcystis, mycosporine, Porphyra