The Application Notebook-09-01-2012

The Application Notebook

Gas chromatography coupled with tandem mass spectrometry (GC–MS-MS) operated in MRM mode is a powerful technology for multi-residue analysis in complex food matrices. Good GC separation combined with MS-MS selectivity facilitates monitoring hundreds of MRM transitions within a short cycle time which allows for analysis of large number of compounds in complex food matrices. Nevertheless, MRM method development is time consuming and labor-intensive, which mainly comes from mapping retention time, MRM transition set-up and post-data processing.

Water samples from six urban and rural locations were extracted and analyzed by GC?GC–TOFMS. GC?GC–TOFMS provided an analysis approach for the detection of known EDCs as well as other non-targeted persistent pollutants.

Rapid and highly resolved chromatographic separations of proteins are becoming increasingly important to meet the growing demands for faster analyses, greater reliability and overall increased column performance. Additionally, highly selective and efficient separations for peptide and impurity profiling have grown among the biopharmaceutical industry, with an ever increasing need to obtain greater peak capacities.

The Application Notebook

New roles and applications in the areas of science and technology are continuously being found for synthetic polymers. Specifically, the use of synthetic polymers in medicine is growing, as these polymers offer unique and versatile platforms for applications such as implants, medical devices, surgical adhesives, drug delivery vesicles, and injectable polymer-drug conjugates (1,2). As the applications of synthetic polymers increases, there is a manifested need for methods to accurately and precisely characterize the materials.

The Application Notebook

Blockcopolymers such as SBS (styrene-butadiene-styrene) are an important product class and a typical example of complex polymers. In addition to the molar mass distribution, a chemical composition distribution may also be present in copolymers. While GPC–SEC is the established method for the determination of molar mass averages and distribution, gradient HPLC can be applied to separate based on chemical composition.

One fast, simple QuEChERS extraction for a broad range of pesticides.

The amount of benzene in gasoline is a concern because it is a known human carcinogen, and exposure to it has been linked to detrimental health effects. The challenge with the analysis lies in the complex composition of gasoline, which consists of hundreds of different compounds. Reformulated gasoline also contains additives to produce more complete combustion and subsequent lower emissions of harmful compounds.

The Application Notebook

When performing LC–MS-MS analysis, phospholipids are perhaps one of the most troublesome components of bioanalytical samples. The presence of phospholipids not only reduces the column lifetime and sensitivity but can also cause a phenomenon known as ion suppression.

The Application Notebook

Ultra sensitive LC–MS-MS quantification of steroids is particularly difficult due to the presence of countless other steroid interferences, many isobaric, in human plasma. In particular, for compounds such as ethinylestradiol (EE), where the required detection limit (LOD) is 1 pg/mL, this challenge is even greater. Not only must one use the highest sensitivity MS system, but both LC and sample preparation must also be carefully optimized for selectivity.

The Application Notebook
Pharmaceutical/Drug Discovery

September 01, 2012

Tolterodine, a quaternary ammonium compound, is used to treat urinary incontinence. To create the drug substance, tolterodine is paired with tartrate to form tolterodine tartrate. This drug substance can then be used to create drug products. One way to confirm the amount of a drug substance in a drug product is to assay for its counterion.

N-Methylcarbamates are widely used agricultural pesticides. For their determination, reversed-phase high-performance liquid chromatography (RP-HPLC) with fluorescence detection following postcolumn derivatization, per U.S. EPA Methods 531.2 and 8318, is typically used.

Gel permeation chromatography (GPC), also referred to as size exclusion chromatography (SEC), when applied to polyolefins analysis (Polyethylene, PE and Polypropylene, PP) has been considered a demanding task due to the high temperature required for operation and the use of hazardous chlorinated solvents for resin dissolution.

Residuals of pesticides widely used in agriculture are monitored in foods for human consumption through the use of statutory maximum residue levels (MRLs). Regulation EC 396/2005 adopted in the European Union sets MRLs for over 500 pesticides in over 300 food commodities, many at a default value of 0.01 mg/kg (the typical routine analytical method limit of determination).

During the manufacturing process of industrial gases, volatile oligomers of compressor fluids can enter the product stream. These impurities are typically within specification, but failure of a diaphragm or seal can spike the concentration in a fill batch and the industrial gas no longer meets product specifications. A screening method has been developed to extract, identify and quantitate chlorotrifluoroethylene-based impurities from the compressor fluid using a CUSTODION? solid phase microextraction (SPME) syringe and a TRIDION?-9 person-portable gas chromatograph–toroidal ion trap mass spectrometer (GC-TMS). The compounds were separated and detected rapidly in less than 5 min analysis time.

The Application Notebook

Organochlorine pesticides are man-made organic chemicals with a history of wide spread use in both the United States as well as globally. Tending to be very persistent in the environment, they have found their way into sediments and drinking water supplies posing serious health risks. Organochlorines have a wide range of both acute and chronic health effects, including cancer, neurological damage, and birth defects. Many organochlorines are also suspected endocrine disruptors.

Monoclonal antibody isoforms differ in modifications of individual amino acid side chains, or the N- or C-terminus. Typical modifications are deamidation, phosphorylation, acetylation, methylation, oxidation, or glycosylation. Fast separation of monoclonal antibody isoforms is important for profiling and mass spectrometric determination. Isoforms may differ in biological activity and stability, making a thorough characterization and quantification of the isoforms necessary to ensure consistent product quality.

The Application Notebook
Pharmaceutical/Drug Discovery

September 01, 2012

Poly(lactic-co-glycolic acid) (PLGA) is a copolymer based on glycolic acid and lactic acid. The two monomer units are linked together by ester linkages and form linear polyester chains. The obtained product is biodegradable and biocompatible, and it is approved by the Food and Drug Administration (FDA) for production of various therapeutic devices as well as for drug delivery applications.

The Application Notebook
Departments

September 01, 2012

LCGC is planning to publish the next issue of The Application Notebook special supplement in December. The publication will include vendor application notes that describe techniques and applications of all forms of chromatography and capillary electrophoresis that are of immediate interest to users in industry, academia, and government.

The Application Notebook

Avermectins are 16-membered ring macrolide drugs that are used as veterinary antihelmintics. The lowest allowable limit for these compounds in food products is set based on worldwide safety evaluations. Regulatory MRLs for avermectins can vary worldwide but are generally in the ppb concentration range. The sensitive analysis of avermectins in food products such as milk and meat can be challenging due to their complex sample matrices.

The Application Notebook

Often used for weed control, triazine herbicides have been found to have detrimental environmental and health effects. Much debate has focused on the level at which these compounds negatively impact health. To monitor and control human exposure to these herbicides, regulatory bodies have established allowable limits of triazines in drinking and wastewater.

The Application Notebook

This technical bulletin details the separation of 11 closely related nitroaromatic compounds, namely RDX, HMX, Nitrobenzene, 2-Nitrotoluene, Tetryl, 2,6-Dinitrotoluene, 4-Nitrotoluene, 1,3-Dinitrobenzene, 2,4-Dinitrotoluene, 2-amino 4,6-dinitrotoluene, 1,3,5-Trinitrobenzene. Our customers have reported that similar separations on silica-based phases produce run times as long as 30 min. Here we report a method on ZirChrom?-CARB at a column temperature of 125 ?C in under 4 min.

The Application Notebook

The health benefits of fish oil in one's diet has been widely established. Common edible fish sources include salmon, trout, tuna, swordfish, and others. The omega-3 fatty acids, EPA and DHA, in dietary supplements (capsules) are primarily derived from smaller oily fish, notably anchovy, horse mackerel, bunker, capelin, and sand eel.

The Application Notebook

Printing inks used on packing materials of consumer products contain colorants and pigments, binder systems, solvents, and additives. ASTM F 1884-04 (1), Standard Test Methods for Determining Residual Solvents in Packaging Materials determines residual solvents in packaging materials from printing processes utilizing solvent-based printing inks.

Throughout the drug development process, potential new drug candidates (or new chemical entities; NCEs) and their metabolites must be subjected to rigorous and extensive pharmacokinetic evaluations to determine their rates accumulation, metabolism, and excretion from the body. With regards specifically to the excretion, urinary excretion is typically the predominant route for the elimination of drugs and their metabolites, and urinary excretion profiling is an integral portion of the pharmacokinetic characterization of NCEs.

The Application Notebook

Acrylamide is a neurotoxic compound classified as a probable human carcinogen and genotoxicant (1). In 2002, researchers in Sweden uncovered the presence of acrylamide in certain fried and baked foods at relatively high levels (2).

This short review focuses on the physicochemical properties of core–shell particles and their resulting chromatographic efficiencies as they relate to the comparison of their mass transfer kinetics to those of columns packed with sub-2-?m fully porous particles.

The Application Notebook

Biofuels have emerged as an attractive alternative to fossil fuel. Biofuel refers to any fuel that is derived from biomass (typically, plant and animal waste). A common feedstock for bioethanol production is corn stover (leaves and stalks of maize plants left after harvesting). Corn stover processing involves acid treatment to release a mixture of water-soluble carbohydrates, followed by enzymatic reactions to convert the sugars to ethanol.

The Application Notebook
Pharmaceutical/Drug Discovery

September 01, 2012

Pharmaceutical compounds are often difficult to analyze on C18 columns alone because they may be charged or have very similar structures. Imtakt Corporation has introduced a family of multimode columns that are able to overcome these separation challenges: Scherzo SS-C18, Scherzo SM-C18, and Scherzo SW-C18, containing C18, anion, and cation ligands.

This application note shows that unspecific reaction of adenosine triphosphate can be completely prevented due to the iron- and steel-free design using the Agilent 1260 Infinity Bio-inert Quaternary LC System.

The Application Notebook
Medical/Biological

September 01, 2012

Pickering Laboratories specializes in the manufacturing of cation-exchange columns and eluants for amino acid analysis. Post-column derivatization with Ninhydrin offers unmatched selectivity and reproducibility of the analysis for most challenging matrixes.