Recently, two papers have been published in Talanta and Analitical Chimica Acta comparing protein phosphatases (PP) from several sources (ZEU-INMUNOTEC, Millipore and GTP) and origin (recombinant or natural).
A colorimetric in vitro assay was used to compare phosphatases in solution or entrapped within either a photoploymer or an agarose. Authors showed that the phosphatase from ZEU was the most sensitive to microcystins with a detection limit of 0.0039 ug/L and an IC50 of 0.56 ug/L for MC-LR in the assay conditions.
In the case of okadaic acid toxins, phosphatase from ZEU had a detection limit of 0.012 ug/L when phosphatase was used in solution. Analysis of real samples (mussels) using the ZEU´s phosphatase showed also a very good repeatability (RSD = 1-6%).
These results show that phosphatase from ZEU is the best choice for the detection of okadaic acid and microcystin toxins.
ZEU-INMUNOTEC uses its own phosphatase to produceOKATEST (a kit for the detection of okadaic acid toxins in molluscs, recently UE-validated) and MICROCYSTEST (a kit for the detection of microcystins in water, evaluated under the ETV program in agreement with the U.S. Environmental Protection Agency).