Both these terms are a sign of weak and passive constructions:
The tests were carried out on the samples
The pond sampling was performed at 6.00 am
The pond sampling was performed at 6.00 am
Avoid these constructions and improve your writing by activating the verbs that are hiding as nouns:
We tested the samples or The samples were tested
The pond was sampled at 6.00 am or We sampled the pond at 6.00 am
The pond was sampled at 6.00 am or We sampled the pond at 6.00 am
See also Active versus passive voice