Repeatability of the submitochondrial particle assay

A study assessing the intralaboratory precision of the in vitro submitochondrial particle (SMP) electron transfer (ETr) and reverse electron transfer (RET) assays was undertaken using the standard reference toxicants, pentachlorophenol (PCP), sodium dodecyl sulfate (SDS), and zinc sulfate 7-hydrate (ZnSO4 7H2O). One to three trials of each assay were manually conducted daily for at least 5 days with each toxicant using commercially available sources of particles and reagents. Composite coefficients of variation (CVs) for the ETr assay ranged from 20.6% for ZnSO4 to 29.3% for PCP (n > or = 15). Composite CVs for the RET assay ranged from 6.5% for SDS to 16.5% for PCP (n > or = 15). Comparison of intralaboratory results with in-house and published data demonstrates that the precision of both of these SMP assays is comparable to that of the more common in vivo, whole-organism bacterial, invertebrate, and fish toxicity tests.