Skip To Content

Search for: index_lists_z.html

Although NMR offers some strategies for determining the presence of a fluorine atom(s), fragment loss of a CF3 group can be determined from a mass spectrum. The EI MS for 2,2,2-trifluoro-N,N-dimethylacetamide (Mmi = 141 Da) is shown below. The ion peak at m/z 72 indicates the loss of a CF3 group. Although the ion peak...

MS and NMR are complementary tools for structure elucidation. Knowing when to apply which tool can assist an elucidator in solving for an unknown structure quickly and with less frustration. Although the sample data below is for a simple organic structure, it is working through many simple examples that one refines the skills needed for...

Many organic chemists employ Mass spectrometry (MS) as a convenient verification tool for their product in a synthetic reaction. Derivatization such as adding a protective (or protecting) group can often be detected by MS. The EI mass spectrum for tert-butyl 3-aminopiperidine-1-carboxylate is shown below. The ‘terminal’ atoms belonging to the protective group, tert-Butyloxycarbonyl (BOC or...

A previous blog described how a sodiated ion peak can be used to locate or calculate the molecular ion for an unknown compound. In a similar fashion, the dimer ion peak can be used to identify the mass of the unknown even if the molecular ion is no visible. The ESI+ MS data below shows...

Whenever a GC column is used to identify and/or quantify a sample, the column stationary phase can bleed into the MS source along with the sample. High column bleed can hinder the analysis of a sample. The resulting spectral interference typically manifests itself as discrete peaks and/or an increase in the drift of the baseline, which...

Characteristic isotopic patterns in MS can assist the elucidator in revealing the presence or absence of atoms. For the Br, Cl, S and Si atoms, a good approach is to examine the peak intensity of the A+2 signal. The respective contributions by the isotopes 81Br, 37Cl, 34S and 30Si are approximately 49.3, 24.3, 4.2 and...

The explanation offered herein covers one possible scenario to a complicated situation. Please note that other explanations are possible. The LC/MS data shows an unknown at 1.8 minutes exhibiting an [M+H]+ at m/z 260 and an [M-H]- at m/z 256. The difference of 4 mass units lends itself into a scenario of conflicting data. One...

Many analytical data rely on common calculations. This solution shows the formula used in the calculations. NMR and MS data were collected on two unknown compounds. The TOF-MS data shows the [M+H]+ at m/z 300.0000 and 600.000 at an error of 0.001 Da. The 500 MHz 1H NMR spectrum shows two chemical shifts at 1500.00...

The structure of Verrucosin C (C29H41O7S−) was quickly and unambiguously elucidated using Structure Elucidator in fully automatic mode. This was possible due to the comprehensiveness of the initial data set provided, including 2D NMR spectroscopic data.