Application Notes: LC-MS
>Application Notes: LC-MS
Analysis of Secondary Metabolites from Myxobacteria using ESI-TOF–MS and PCA
March 2nd 2007The exploration of myxobacterial metabolite profiles by LC–MS screening for the presence of new natural products is described. Extracts from fermentations of Myxococcus strains are analysed by UPLC-coupled ESI-TOF mass spectrometry and the obtained data are processed using principal component analysis (PCA). The generation of molecular formulae from accurate mass measurements facilitates rapid compound identification.
Determination of Soft Drink Ingredients
December 2nd 2006Soft drink formulas often include preservatives, artificial sweeteners, flavours or caffeine in their list of ingredients. Using the Acclaim OA column, as many as eight common additives may be determined in a single run. Many of these additives are hydrophilic organic acids for which this column was designed. Notably, benzoate and sorbate, which do not resolve on C18 columns at low pH, are fully separated.
De Novo Formula Generation with "Sub-ppm" Confidence using Compass OpenAccess and the micrOTOF
December 2nd 2006Accurate mass measurements are a key element of chemical characterization. However, the accepted mass accuracy tolerance of 3–5 ppm can still leave significant ambiguity in the proposed chemical formula. Consequently a further input from other analytical techniques such as NMR or MS/MS, along with some judgment based on the synthetic history is often required to arrive at a confident formula assignment.
LC–MS Analysis of Glyphosate and AMPA using Hypercarb Columns
December 2nd 2006Glyphosate [N-(phosphonomethyl) glycine] is a broad spectrum, non-selective herbicide, which acts by inhibiting the shikimic acid pathway in plants. Recent studies have raised global health and environmental concerns about glyphosate's use.1 Glyphosate readily breaks down into aminomethyl phosphonic acid (AMPA) in the environment; requiring accurate measurement. Both highly polar compounds present an analytical challenge to the chromatographer (Figure 1). Typical silica based reversed-phase C18 columns experience difficulty with the retention of such polar compounds, and may generate non-resolved co-eluting peaks, often with polar analytes eluting in the void volume. Traditional analytical methods require complex eluents and time consuming derivatization steps to achieve retention on a reversed-phase support.
Optimizing Column Lifetime of TSK-GEL Size Exclusion Columns
December 2nd 2006Column lifetime is a more and more important issue when developing an analytical method for HPLC. Besides sample treatment, column cleaning and storage, operational parameters of the analytical method will have an influence on column lifetime. This question may not always be addressed early enough in the methods development process.
Analysis of Zeaxanthin by Single Quadrupole LC–MS
March 2nd 2005(3R, 3’R)-zeaxanthin is one of several dietary carotenoids found in human ocular tissue. Research has shown that concentrations of zeaxanthin, as well as other carotenoids, are significantly lower than normal in the macula of persons diagnosed with neovascular age-related macular degeneration (AMD)...
Determination of Protease Inhibitors Used in the Treatment of HIV
March 2nd 2005Protease inhibitors are a class of anti-HIV drugs used in combination therapy to block replication of the HIV virus in a person's blood. It is important to monitor the levels of these drugs in the patient since resistance can develop at low levels and at high levels the drug can exhibit toxic effects.
