Understanding cenros Error

I don't have the NADA package, but I suspect that the cenros function is
doing something like dividing by zero. With that much data, it may be hard
to pinpoint where this is occurring. I would cut my data in half, run it,
cut the remainder in half, run it and so on until the error goes away.
With any luck, the last slice of data that was removed won't be too large
to work out which value is causing the problem and what the problem is.

Jim,

   That is a great idea. I'll chunk the data into smaller files and see if I
can isolate the problem. Also, there are 37 different chemicals in the data
set and I first should try them all and see if the problem is consistent; I
tried only silver and aluminum before asking for guidance.

   Another potential approach that might be worth pursuing is to subset the
data frame by chemical and working separately with each. As I'm just
beginning to learn how to analyze left-censored data I've a long way to go.

Thanks for the suggestion,

Rich