Many thanks to all who responded. There was almost unanimity that the factor for the molecular weight of angiotensin I (the product of the reaction) is 1296 and that you then need to divide by 1000 to get to pg/ml. Some of you also commented on order of the concentration and time terms. There does seem to be a difference between North American and UK usage, but I don't think it makes any difference to the results. Nice to see that the mailbase works well. I had answers within an hour. Best wishes, Brian Shine