Mass Spectroscopy Articles

A fast and easy-to-use method for the identification and determination of active anionic ingredients in toothpaste is presented using ion chromatography in combination with electrospray mass spectrometry. The total analysis time is 22 min using a potassium hydroxide gradient to separate fluoride, carbonate, sulphate, glycerol, sorbitol, saccharin, monofluorophosphate, phosphate, pyrophosphate and tripolyphosphate in a single injection.

Introduction Caries are caused by bacteria-producing plaque on teeth. Fluoride is an active ingredient in toothpaste to reduce plaque. Today different chemical forms of fluoride are used in toothpaste. These forms include fluoride, monofluorophosphate and amine fluorides. In addition to carbonate, phosphates such as pyrophosphate and tripolyphosphate are used in toothpaste to reduce tartar. Saccharin is used as a sweetener, and sorbitol and glycerol as moisture control agents.

A system for automated off-line comprehensive packed column supercritical fluid chromatography (pSFCpSFC) was developed for the characterization of triglycerides (TGs) in vegetable oils. In the first dimension, TGs are separated according to their hydrophobicity using octadecyl silicagel as stationary phase. In the second dimension, separation occurs according to degree of unsaturation using a silver-loaded stationary phase. Fraction collection, concentration and re-injection are fully automated. The two orthogonal separation mechanisms give a better insight into the TG composition of vegetable oils. UV detection at 210 nm is normally applied for both columns. For unequivocal TG elucidation, a mass spectrometer (MS) operated in the atmospheric pressure chemical ionization mode may be coupled after the second UV detector. The potential of pSFCpSFC–MS is illustrated.

Introduction :

This month in “GC Connections,” John Hinshaw files a report of the 26th International Symposium on Capillary Chromatography and Electrophoresis, which was held in May.

Almost 350 scientists, researchers, students and industry representatives attended the 26th International Symposium on Capillary Chromatography and Electrophoresis — ISCCE 2003 — 18–22 May 2003 in Las Vegas, Nevada, USA. Returning to Las Vegas after two years, the symposium again was a clear success. The registration list included a wide sampling of European, American and Asian attendees, despite the last-minute cancellation of several foreign representatives from severe acute respiratory syndrome (SARS)–affected areas.

A positive chemical ionization GC–MS method for the analysis of acrylamide monomer in foods will be described and future areas for development offered. The method had a limit of detection of 5 ppb and was found to show good linearity to 1000 ppb. PCI SIM using ammonia as a reagent gas provided the best blend of sensitivity and selectivity.

Introduction :

The mass spectrometric response in complex biological samples is often directly related to the influence of co-eluting compounds on the ionization efficiency of analytes. This can lead to decreased sensitivity, selectivity and accuracy of liquid chromatography–mass spectrometry (LC–MS) analyses, especially when matrix composition varies from sample to sample. By applying certain sample clean-up and/or chromatographic separation strategies LC–MS method performance can be improved. In contrast to these approaches, this article will discuss other simple and effective strategies to improve LC–MS method performance.

Introduction :
High-throughput mass spectrometry–based protein identification requires a complete solution which includes a complete hardware setup starting from a 2D gel, and an integrated software package. The Bruker PROTEINEER™ line meets these requirements. The flow of information through the whole line enables data handling in a highly integrated level. The backbone of the PROTEINEER™ suite is the embedded Workflow Administration by Result-driven Processing (WARP™, Figure 1). The workflow for each sample is controlled across all PROTEINEER™ hardware components (robotics and mass spectrometers), and depends on the intermediate results from the mass spectrometric stages. For this task, all robots and mass spectrometers track sample IDs by electronic transponders and exchange the related processing parameters and results with the central control unit: ProteinScape™.

Through its primary retention mechanisms (dispersive and charge induced interactions), Hypercarb® shows greater retention and resolution for underivatized glyphosate and AMPA than silica based C18.

The analysis of highly polar analytes on traditional RP silica-based columns (without the use of ion-pair reagents etc) is difficult as the analyte–stationary phase interactions are minimal and so little to no retention is often achieved. This application note describes the use of a porous graphitic carbon column to achieve polar analyte and degradation product retention and separation using reversedphase conditions.
 
Glyphosate (N-phosphonomethyl glycine) is a broad spectrum, non-selective herbicide that acts by inhibiting the shikimic acid pathways in plants. Glyphosate readily breaks down into aminomethyl phosphonic acid (AMPA) in the environment; hence both compounds require accurate measurement to protect drinking water supplies.

>Introduction :

In the April edition of this magazine1 Ron Majors, in his annual report on new columns and accessories from the Pittsburgh conference, reported how at the 2002 conference the largest number of product introductions were for biomolecule separations and for liquid chromatography–mass spectrometry (LC–MS). He went on to state that speciality HPLC columns for chiral compounds, biomolecules, combinational chemistry, carbohydrate analysis and LC–MS represented the largest category of entries. Supporting these products was an increase in capillary and nano-LC columns for LC–MS. But more important the support accessories (e.g., mixers, valves and connecting tubes) were also shown for the new capillary columns.

A synthetic polymer is not a uniquely defined chemical compound. Not all molecules are identical. In ‘simple’ homopolymers the individual molecules vary (unavoidably) in size and (possibly) in end groups (functionality).*(See footnote at end of article.) Polymeric chains may be linear, branched to variable extents or even cyclic. In addition, some important polymers, such as polypropene, polystyrene and polyacrylates exhibit variations in chain (stereo-) regularity or ‘tacticity’. In some other instances, such as PVC, head-to-head vs. head-totoe, isomerism is a significant issue. Given all these possible variations between the individual molecules, we should stop calling homopolymers ‘simple.’ Molecules of copolymers enjoy several additional degrees of freedom.

Introduction :

The implementation of new tools within the discovery process, including combinatorial chemistry, proteomics and ADME/tox profiling, demand the creation of new strategies for pharmaceutical analysis. Sample generation has increased very rapidly and, as a consequence, traditional analytical approaches are unable to fulfil the requirements set by lead generation. Therefore, a great challenge has developed to create new, rapid, high-throughput analytical methods to speed-up the whole discovery process.

CE–MS

Capillary electrophoresis (CE) is a relatively new tool for chiral analysis. Chiralty is very important in biochemistry because different enantiomers can produce diverse pharmacological and toxicological actions. Fujiware and Honda described the use of CE in the pharmaceutical industry.1 Once a screening method has been developed, CE can be used as an additional technique for the detection of impurities.