Chapter 9, Problem 80E

One method of analyzing amino acids is the van Slyke method. The characteristic amino groups $\left(-{\text{NH}}_2\right)$ in protein material are allowed to react with nitrous acid. ${\text{HNO}}_2$, to form ${\text{N}}_2$ gas. From the volume of the gas, the amount of amino acid can be determined. A 0.0604-g sample of a biological sample containing glycine, ${\text{CH}}_2\left({\text{NH}}_2\right)\text{COOH}$, was analyzed by the van Slyke method and yielded 3.70 mL of ${\text{N}}_2$ collected over water at a pressure of 735 torr and 29 °C. What was the percentage of glycine in the sample?

${\text{CH}}_2\left({\text{NH}}_2\right){\text{CO}}_2\text{H}+{\text{HNO}}_2\to {\text{CH}}_2\left(\text{OH}\right){\text{CO}}_2\text{H}+{\text{H}}_2\text{O}+{\text{N}}_2$