# Comparing three groups for one variable when two of the groups' values are zero

I'm trying to compare three groups but the fact that two of theml only show values of zero is giving me a hard time. Specifically, I'm comparing the production of a metabolite (M3G) by three cell lines. the results are as follow :

Line 1 : mean = 0 SEM = 0, n=10
Line 2 mean = 0, SEM = 0, n=10
Line 3 : mean = 2.89, SEM = 0.23, n=10

Here are the values for cell line 3 :

> 3,52 4,37 2,51 2,71 2,48 2,09 2,73 2,92 2,80 2,66

All the values for cell lines 1 and 2 are 0.

What test should I use to compare these cell lines ? I've been trying to find an answer and came up with a thread recommending a one-sample t-test, but I have three groups... I'm not sure what to do as I'm no expert in statistics ! For my other analyses (comparing groups with means different from zero), I usually use Mann-Whitney : is this applicable here ?