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Sorting out what compounds are present in a mixture is a difficult task. The process is further complicated when the compounds co-elute on a chromatographic run. An LC/MS (ESI+) was collected for an unknown sample comprising of small organic molecules. The total ion chromatogram (TIC shown in black) shows a signal at 2.86 minutes. The...

On the surface, both good data and poor data offer information about an unknown compound. The challenge is to differentiate between what is good data and what is poor data. The purpose of this puzzle is to examine some poor data. From an LC-MS+ TOF dataset, an unknown compound elutes at 2.86 minutes and spans...

Many analytical data rely on common calculations. This puzzle covers one such common calculation. 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 and 3000.00...

A key element in data interpretation is to identify any warning flags. Warning flags can help a chemist differentiate good data from bad data. For an unknown compound, the TOF-ESI+ mass spectrum below shows the expanded region around four isotope clusters at m/z 300.336 ([M+H]+), 322.307 ([M+Na]+), 599.672 ([2M+H]+) and 621.611 ([2M+Na]+). Are the intensities...

The warning flag for this puzzle is evident in the intensities of the signals. For an unknown compound, the TOF-ESI+ mass spectrum below shows the expanded region around four isotope clusters at m/z 300.336 ([M+H]+), 322.307 ([M+Na]+), 599.672 ([2M+H]+) and 621.611 ([2M+Na]+). The intensities of the 13C isotopes (i.e. the [M+1] signal) vary between 40...

The example of Cyathstrine A (molecular formula of C25H34O7) shows that the structure of a complex polycyclic natural product containing seven oxygen atoms was unambiguously determined using Structure Elucidator in a fully automatic mode almost instantly.

Predicting pKa isn’t just computational, it’s about understanding chemical behavior. Learn about the science behind pKa, how different pKa predictors work, and how ACD/Labs’ tools help chemists and regulators anticipate molecular behavior before synthesis or testing begins.

In this compound the riboflavin skeleton was supplemented by the formation of two additional fused heterocycles through a novel C−C bond and an oxygen bridge on the riboflavin backbone. The structure of mantidisflavin A (molecular formula C17H19N4O6) was elucidated using 1D and 2D NMR spectra in combination with HR-ESI-MS and IR.

Scientists at Merck published an article about using ChromGenius to predict retention times of new compounds. Abstract We introduce a new workflow that relies heavily on chemical quantitative structure-retention relationship (QSRR) models to accelerate method development for micro/mini-scale high-throughput purification (HTP). This provides faster access to new active pharmaceutical ingredients (APIs) through high-throughput experimentation (HTE)....