Differentiation of protonated aromatic regioisomers related to lignin by reactions with trimethylborate in a Fourier transform ion cyclotron resonance mass spectrometer.

Several lignin model compounds were examined to test whether gas-phase ion-molecule reactions of trimethylborate (TMB) in a FTICR can be used to differentiate the ortho-, meta-, and para-isomers of protonated aromatic compounds, such as those formed during degradation of lignin. All three regioisomers could be differentiated for methoxyphenols and hydroxyphenols. However, only the differentiation of the ortho-isomer from the meta- and para-isomers was possible for hydroxyacetophenones and hydroxybenzoic acids.

Mass spectrometry for small molecule pharmaceutical product development: a review.

Developing a pharmaceutical product has become increasingly difficult and expensive. With an emphasis on developing project knowledge at an earlier stage in development, the use of information-rich technologies (particularly MS) has continued to expand throughout product development. Continued improvements in LC/MS technology have widened the scope of utilizing MS methods for performing both qualitative and quantitative applications within product development.

Identification and counting of carbonyl and hydroxyl functionalities in protonated bifunctional analytes by using solution derivatization prior to mass spectrometric analysis via ion-molecule reactions.

A mass spectrometric method has been developed for the identification of carbonyl and hydroxyl functional groups, as well as for counting the functional groups, in previously unknown protonated bifunctional oxygen-containing analytes. This method utilizes solution reduction before mass spectrometric analysis to convert the carbonyl groups to hydroxyl groups. Gas-phase ion-molecule reactions of the protonated reduced analytes with neutral trimethylborate (TMB) in a FT-ICR mass spectrometer give diagnostic product ions.

Identification of aliphatic and aromatic tertiary N-oxide functionalities in protonated analytes via ion/molecule and dissociation reactions in an FT-ICR mass spectrometer.

A mass spectrometric method is presented for the identification of compounds that contain the aliphatic or aromatic N-oxide functional group. This method utilizes gas-phase ion/molecule reactions of tri(dimethylamino)borane (TDMAB), which rapidly derivatizes protonated aliphatic and aromatic tertiary N-oxides, amides, and some amines via loss of dimethylamine in a Fourier transform ion cyclotron resonance mass spectrometer. The mechanism involves proton transfer from the protonated analyte to the borane, followed by addition of the analyte to the boron center and elimination of dimethylamine.

Identification of the aromatic tertiary N-oxide functionality in protonated analytes via ion/molecule reactions in mass spectrometers.

A mass spectrometric method is presented for the rapid identification of compounds that contain the aromatic N-oxide functional group. This method utilizes a gas-phase ion/molecule reaction with 2-methoxypropene that yields a stable adduct for protonated aromatic tertiary N-oxides (and with one protonated nitrone) in different mass spectrometers. A variety of protonated analytes with O- or N-containing functional groups were examined to probe the selectivity of the reaction.

Compound screening for the presence of the primary N-oxide functionality via ion-molecule reactions in a mass spectrometer.

A mass spectrometry method is presented for the identification of compounds that contain the primary N-oxide functional group. This method utilizes a gas-phase ion-molecule reaction with dimethyl disulfide that rapidly and selectively derivatizes the protonated primary N-oxide functional group in a mass spectrometer to yield an ionic reaction product (with 31 Da higher mass than that of the protonated molecule) that is diagnostic for the presence of a primary N-oxide functionality. A variety of protonated analytes containing different functional groups were tested in Fourier transform ion-cyclotron resonance and triple quadrupole mass spectrometers to probe the selectivity of the reaction.

Ion-molecule reactions for the characterization of polyols and polyol mixtures by ESI/FT-ICR mass spectrometry.

A mass spectrometric method is described for the identification and counting of hydroxyl groups in an analyte. Analytes introduced into a FT-ICR mass spectrometer and ionized by positive mode ESI were allowed to react with the neutral reagent diethylmethoxyborane. This results in derivatization of the hydroxyl groups of the analytes by replacement of a proton with a diethylborenium ion.

Ion-molecule reactions for mass spectrometric identification of functional groups in protonated oxygen-containing monofunctional compounds.

Protonated oxygen-containing monofunctional compounds react with selected methoxyborane reagents by proton transfer followed by nucleophilic substitution of methanol at the boron atom in a Fourier transform ion cyclotron resonance mass spectrometer. The derivatized oxygen functionality can be identified by H/D exchange, collision-activated dissociation, or both. This information on the identity of the functionalities in the analyte, in conjunction with molecular formula information obtained from exact mass measurements on either the protonated or derivatized analyte, facilitates structure elucidation of unknown organic compounds in a mass spectrometer.

The first total synthesis of lipid II: the final monomeric intermediate in bacterial cell wall biosynthesis.

Bacterial peptidoglycan is composed of a network of beta-[1,4]-linked glyan strands that are cross-linked through pendant peptide chains. The final product, the murein sacculus, is a single, covalently closed macromolecule that precisely defines the size and shape of the bacterial cell. The recent increase in bacterial resistance to cell wall active agents has led to a resurgence of activity directed toward improving our understanding of the resistance mechanisms at the molecular level.