Figure shows the time course of the formation of RuAAC derivatives in these crude carrot extracts. The data show that our test alkyne is derivatized by RuAAC regardless of the solvent tested or azide used. This indicates that complex samples such as carrot extract, potentially containing a diverse assortment of lipids, peptides, and metabolites, do not block or abolish RuAAC activity. Figure also shows that the rate of formation of the derivatives does not depend strongly on the azides used for derivatization, with rates between 0.5 hr -1 and 2 hr -1 . However, the absolute signal intensity is approximately five times larger when using primary alkyl azides 2b or 2c compared to aryl azide 2a, a difference we attribute to the enhanced ionization efficiency of these derivatives. Figure : RuAAC derivatization of internal alkynes is viable even in complex biological matrices. Internal alkyne 1, 5 mM, was spiked into to crude extract of lyophilized carrot. The Cp ⋆ RuCl(cod) catalyst and two azides were added to each extract. The formation of the corresponding 1,4,5-trisubstituted 1,2,3-triazoles (3a-3c) was tracked by LC-HR-MS as a function of time. Lines are best fits of the data to a pseudo-first order kinetic scheme. All tested extracts, regardless of solvent used, are suitable media for RuAAC, all tested azides react with 1 in these complex mixtures, and triazole formation generally follows first-order kinetics and is complete within 6 hr at room temperature. The triazole derivatives are stable at least on the timescale of this experiment. Ethyl azidoacetate (2b) and trimethylsilylmethyl azide (2c) both give rise to triazoles with more intense LC-MS signals that 4-azidotoluene (2a), despite reacting with similar first order rate constants.