▁or ▁ 8   M ▁u rea . ▁Unfortunately ▁the ▁ext inction ▁coefficient ▁for ▁dil ute ▁solutions ▁was ▁under est im ated ▁in ▁the ▁original ▁ 1 9 5 9 ▁publication , ▁as ▁ 1 3 , 6 0 0   M − 1   cm − 1 , ▁and ▁as ▁noted ▁in ▁a ▁recent ▁article , ▁this ▁mistake ▁has ▁pers isted ▁in ▁the ▁literature . ▁Com mer cial ▁D T NB ▁may ▁not ▁be ▁completely ▁pure , ▁so ▁may ▁require ▁rec ry st all ization ▁to ▁obtain ▁completely ▁accurate ▁and ▁reprodu cible ▁results . ▁ ▁Ell man ' s ▁re agent ▁can ▁be ▁used ▁for ▁meas uring ▁low - m ole cular ▁mass ▁th i ols ▁such ▁as ▁gl ut ath ione ▁in ▁both ▁pure ▁solutions ▁and ▁bi ological ▁samples , ▁such ▁as ▁blood . ▁It ▁can ▁also ▁measure ▁the ▁number ▁of ▁th i ol ▁groups ▁on ▁prote ins . ▁ ▁References ▁ ▁External ▁links ▁Quant itation ▁of ▁sul f h yd ry ls ▁D T NB , ▁Ell man ’ s ▁re agent ▁( uses ▁incorrect ▁abs orb ance ▁coefficient ) ▁ ▁Category : Organ ic ▁dis ulf ides ▁Category : Ben zo ic ▁ac ids ▁Category : N it ro ben zen es ▁Category : B io chem istry ▁Category : Re ag ents ▁for ▁bio chem istry ▁Category : Re ag ents <0x0A> </s> ▁The ▁J unk ers ▁L 1 ▁was ▁the ▁first ▁engine ▁from ▁that ▁company ▁to ▁fly . ▁ ▁It ▁was ▁an ▁air - co o led