

@article {1582,
	title = {Measuring and mitigating inhibition during quantitative real time PCR analysis of viral nucleic acid extracts from large-volume environmental water samples},
	journal = {Water Res},
	volume = {46},
	number = {13},
	year = {2012},
	note = {Gibson, K E Schwab, K J Spencer, S K Borchardt, M A eng Research Support, Non-U.S. Gov{\textquoteright}t Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S. England 2012/06/08 06:00 Water Res. 2012 Sep 1;46(13):4281-91. doi: 10.1016/j.watres.2012.04.030. Epub 2012 May 16.},
	pages = {4281-91},
	type = {Journal Article},
	abstract = {Naturally-occurring inhibitory compounds are a major concern during qPCR and RT-qPCR analysis of environmental samples, particularly large volume water samples. Here, a standardized method for measuring and mitigating sample inhibition in environmental water concentrates is described. Specifically, the method 1) employs a commercially available standard RNA control; 2) defines inhibition by the change in the quantification cycle (C(q)) of the standard RNA control when added to the sample concentrate; and 3) calculates a dilution factor using a mathematical formula applied to the change in C(q) to indicate the specific volume of nuclease-free water necessary to dilute the effect of inhibitors. The standardized inhibition method was applied to 3,193 large-volume water (surface, groundwater, drinking water, agricultural runoff, sewage) concentrates of which 1,074 (34\%) were inhibited. Inhibition level was not related to sample volume. Samples collected from the same locations over a one to two year period had widely variable inhibition levels. The proportion of samples that could have been reported as false negatives if inhibition had not been mitigated was between 0.3\% and 71\%, depending on water source. These findings emphasize the importance of measuring and mitigating inhibition when reporting qPCR results for viral pathogens in environmental waters to minimize the likelihood of reporting false negatives and under-quantifying virus concentration.},
	keywords = {Drinking Water/virology Environmental Monitoring/methods GB virus C/*genetics/isolation \& purification Groundwater/virology RNA, Viral/*genetics/isolation \& purification Real-Time Polymerase Chain Reaction/*methods Reproducibility of Results Reverse Transcriptase Polymerase Chain Reaction/*methods Sewage/virology *Water Microbiology},
	issn = {1879-2448 (Electronic) 0043-1354 (Linking)},
	doi = {10.1016/j.watres.2012.04.030},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/22673345},
	author = {Gibson, K. E. and Schwab, K. J. and Spencer, S. K. and Borchardt, M. A.}
}
