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Analysis of PFOA and PFOS in Water Using Reversed-Phase HPLC with Suppressed Conductivity Detection
June 1st 2007Suppressed conductivity detection is a well-developed method for detecting charged species. Reversed-phase high-performance liquid chromatography (RP-HPLC) is a well developed method of separating substances on the basis of hydrophobicity. There are some situations where it is advantageous to use these two methods together. Perfluoro-acids (PFOAs) are one class of compounds that are ionic, hydrophobic and have low UV absorbance and are, therefore, suited to this combination.
Thermal Desorption-GC–MS Analysis of Polycyclic Aromatic Hydrocarbons on Fine Particulates in Air
June 1st 2007Polycyclic aromatic hydrocarbons (PAHs) are commonly found throughout the environment in soil, water and adsorbed to fine particulate matter in air. Of the 16 common PAHs, 7 have been classified as animal carcinogens by the International Agency for Research on Cancer (IARC). Resulting from this classification, PAHs are monitored and regulated in the environment.
The Application of GC–MS to the Analysis of Pesticides on Foodstuffs
March 2nd 2007Pesticide contamination of foodstuffs has become a worldwide concern, prompting various levels of regulation and monitoring. Traditionally, pesticides are quantified with gas chromatography (GC) combined with selective detectors (ECD, FID, etc.). Selective GC detectors are great tools to quantify one or two classes at a time. However, screening for a number of different classes of pesticides requires multiple runs utilizing various GC configurations to achieve sufficient chromatographic resolution for unambiguous quantification. Gas chromatography–mass spectrometry (GC–MS) provides positive confirmation of various pesticides in a single analytical run because its superior selectivity allows interference-free quantification even with peak coelution. GC–MS has become a preferred technique for pesticide analysis because of its single-run capability.
Accelerated Buffer System for Amino Acid Analysis
March 2nd 2007The continual increase in sample numbers in busy labs means that it is often difficult for quality control or contract analysis labs to maintain short turnaround times, particularly when instruments are already running at full capacity. To address the need for faster analysis while retaining the quality of separation offered by dedicated amino acid analysers, an improved formulation of sodium citrate based buffers has been developed by Biochrom.
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.
Gas Chromatography–Time-of-Flight Mass Spectrometry in Food Analysis
January 1st 2007Gas chromatography (GC) coupled to time-of-flight mass spectrometry (TOF-MS) offers unique solutions for various analytical applications including the analysis of food quality, authenticity and safety markers. This article provides a general overview of TOF-MS basic features, highlighting its advantages and limitations compared with GC using conventional mass analysers. Examples of recent results obtained for selected food contaminants and flavour components are described to illustrate the potential of this recently introduced technique.
Innovations in Food Analysis — Analysis of Peptides, Additives and Flavours
December 2nd 2006The analysis of peptides and additives using a new HPLC innovative column technology, Pathfinder, was shown. For the analysis of flavours in lemon juice GC–MS with a new MS library, FFNSC, with linear retention indices was used.
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 Polybrominated Diphenyl Ethers Using the Clarus 500 GC–MS
July 2nd 2006This application note will demonstrate a GC–MS analysis of common polybrominated diphenyl ether (PBDE) congeners. An optimized method will allow the Clarus GC–MS to provide ample separation and high yields of all PBDE congeners. The extended mass range of the Clarus 500 MS and high-mass calibration will produce mass spectra with very high levels of accuracy.
Trace Analysis of Brominated Flame Retardants with High Resolution GC–MS
July 2nd 2006Polybrominated diphenyl ethers (PBDEs) are among the most important and widely used flame retardants. Recent legislation banned certain PBDE congeners.? EU directive 2003/11/EC prohibits the use of Penta-BDE and Octa-BDE for the member states of the European community.? Therefore, analysis of PBDEs have received increased interest as a result of their known toxicity.
Qualitative and Quantitative Analysis of Brominated Flame Retardants (PBB and PBDE)
March 2nd 2006On 13 February 2003 the European Union published the new regulation on electric and electronic waste, (WEEE, Waste Electrical and Electronic Equipment) as well as the restriction of the use of certain hazardous substances in electric and electronic equipment (RoHS). Thus both regulations became effective, and in January 2005 they were transferred into national law. According to RoHS, lead, mercury, cadmium, chromium (VI), polybrominated biphenyls (PBB) and polybrominated diphenylethers (PBDE) are forbidden from July 2006. Shimadzu, one of the leading manufacturers of analytical instrumentation offers the complete hardware and software for the secure identification of hazardous substances as well the know-how and competence.
Tandem GC–MS Analysis of Pesticides in Food Oils by Large Volume Injection with a Back-flush Option
September 2nd 2005As the global sourcing of foodstuffs becomes more common, the number of pesticide analyses performed continues to increase to test these sources for compliance with various regulations. The sheer number of analyses dictates that utilized methods must be reliable, robust and inexpensive.
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.