App Notes

Gel Permeation Chromatography (GPC) is principally used to separate polymers and organic molecules based on their size. An important aspect in optimizing GPC separations is column selection, especially when multiple columns are used. Mobile phase selection and column temperature are also important factors that must be considered when developing a method, as they can influence the solubility and viscosity of diluent and analyte respectively. Column, mobile phase, and temperature selection will be discussed to optimize GPC methods using Phenogel GPC/SEC columns.

Kinetex 5 μm core-shell technology columns provide chromatographers a simple solution for dramatically improving the Performance of their methods developed on 5 μm fully porous columns. This newly introduced core-shell media delivers backpressures of a fully porous 5 μm particle at efficiencies equal to or better than a fully porous 3 μm particle. Without the need for extensive method development, replacing the fully porous 5 μm column with the Kinetex 5 μm core-shell column results in improved chromatographic resolution and sensitivity. In addition, the lower backpressure can provide many benefits such as longer column lifetime, higher throughput, and increased system compatibility.

Aeris WIDEPORE is a recently introduced core-shell HPLC | UHPLC column specifi cally designed to provide improved resolution of intact proteins larger than 10 kilodaltons (KDa) in molecular weight. The improved resolution of proteins is accomplished by the use of a new core-shell particle morphology which minimizes protein band-spreading that occurs during diffusion in and out of the coreshell particle. The result is narrower peaks and better resolution of closely eluting proteins. This improved resolution is especially useful for refolding, impurity, and post-translational modifi cation assays on intact biogeneric proteins where very slight differences between intact and modifi ed proteins elute closely on reversed phase columns. Several examples are shown demonstrating the utility of Aeris WIDEPORE core-shell columns for such applications.

An improved method for EPA Method 8270D has been exhibited on a Zebron ZB-SemiVolatiles GC column. The benefits of this method include • Fast run times while still maintaining resolution of key compounds like benzo[b]fluoranthene and benzo[k]fluoranthene • Great peak shape of typically poor performing compounds like phenols and amines

When compared to 1.7 μm fully porous materials, the ultra-high efficiency and low backpressures provided by Kinetex core-shell 2.6 μm columns, provides users opportunities to go beyond what is traditionally accepted for UHPLC runs. To match backpressures exerted by 1.7 μm fully porous columns, large increases in coreshell column length and/or system flow rate is required. When gradient conditions are maintained, increases in flow rate and length result in an increase in peak capacity on the order of 26 %. When MS conditions are optimized to compensate for new flow rates, sensitivity increases of up to 3.5 times are observed and furthermore, peak capacity figures increase by almost 70 %.

The scalability of the 1.7, 2.6, and 5μm Kinetex® core-shell particles is illustrated in this study. This flexibility makes Kinetex the only core-shell particles in the market that are optimized for different system platforms and are transferable from UHPLC systems to conventional HPLC systems to preparative applications.

Rezex ion exclusion HPLC columns are the solution for several published USP methodologies. The Rezex RPM (Pb+2) and RCM/ RCU (Ca+2) phases will give you the selectivity needed while the short Rezex RPM 100 x 7.8 mm columns will help to increase throughput.

Pesticides are classes of chemicals that are used to treat or con- trol outbreaks of pests, especially insects. Food production as well as safety and health organizations heavily rely on pesticides to increase food yields and / or control disease outbreak spread by insects. Some pesticides have proven hazardous to other animals or the environment and have either been restricted or banned. The need to monitor products, especially foods, for pesticides is es- sential as more pesticides are being discovered to have adverse effects.

Five different Lux® polysaccharide-based chiral stationary phases were explored in the reversed phase elution mode using mobile phases consisting of 0.1 % formic acid in acetonitrile or methanol to demonstrate the feasibility of LC/MS/MS analysis of a variety of acidic pharmaceutical racemates.

In modern mass production operations, many animal feeds, which are used in beef, pork, chicken and turkey production, contain antibiotics as prophylactics.1 The beta-lactam, macrolide, sulfonamide, tetracycline, and other antibiotics are an indispensable part of food animal production and help to maintain the optimal health of the animals. However, the residues of antibiotics remaining in animal-derived human foods may pose potential human health hazards toxicologically, microbiologically or immunopathologically.1, 2, 3, 4 Many countries have implemented a series of regulations governing the use, dosage, and withdrawal times for many of these antibiotic compound classes in animal production.