vuIver$$ualur$\text{'}(\frac{?}{\text{b}\text{a}\text{r}}(g$ sample $))$

Relative standard deviation of interlaboratory results as a function of sample concentration $($expressed as g analyte$/$g sample$).$ The shaded region has been referred to as the "Horwitz trumpet" because of the way it flares open. $[$Data from W$.$ Horwitz, "Evaluation of Analytical Methods Used for Regulation of Foods and Drugs," Anal. Chem. $1982,54,67A,$ with dashed plateau below ${10}^{-7}g$ analyte$/$g sample from $M.$ Thompson, $"$An Emergent Optimum Precision in Chemical

Measurement at Low Concentrations," Anal. Methods $2013,5,4518.]$

$1wt\%RSD$~~

$4$

$\%$

$1$ part per million $RSD$~~

$\%$

$10$ parts per trillion $RSD$~~

$\%$

The relative standard deviation within a laboratory is typically $0\mathrm{.}5-0\mathrm{.}7$ of the between$-$laboratory variation. If your class analyzes an unknown containing $10wt\%N{H}_3,$ what is the minimum expected relative standard deviation for the class?

$RSD$~~ubrace$(ubrace{)}_{\text{I}\text{n}\text{c}\text{o}\text{r}\text{r}\text{e}\text{c}\text{t}}$