Characterization and Uncertainty Assessment of a Certified Reference Material of Chloramphenicol in Methanol (GBW(E)082557)

Figure 1

The H-NMR spectra of (a) internal standard (ethyl paraben and methanol-D₄) and (b) sample solution (chloramphenicol, ethyl paraben, and methanol-D₄).

(a) Ethyl paraben

(b) Ethyl paraben + chloramphenicol