Application Notes: General

A novel centrifugal fraction collector CFCâ„¢ enables SFC users to simultaneously collect and concentrate fractions. The technique is particularly useful for chiral separations where large volumes of enantiomers are being purified by stacked injection methods.

In size exclusion chromatography, obtaining calibration curves over a wide range of molecular weights is a difficulty investigators often encounter when analyzing polymers with a broad molar mass distribution. To overcome this problem two procedures are typically used. One option is to use multiple columns of different pore sizes linked together in series. A second is to use a column packed with a mixed bed resin of different pore sizes at an optimized mix ratio. However, problems can occur with both of these methods, which include distortion of the chromatogram or deviations between the actual calibration curve and the calibration curve approximated from data obtained from the molecular weight standards.

Our work focuses on the synthesis of branched (functionalized) polydienes via a facile two-step synthesis. Despite the numerous strategies developed for the preparation of branched polymers in recent years, there is still a limited number of simple synthetic strategies based on common vinyl monomers.

The SHISEIDO CAPCELL PAK C18 MGIII is an HPLC column packed with a silicone polymer-coated phase, providing excellent peak profiles for basic compounds under acidic conditions, and generating ultimately minimized column bleeding in LC–MS.

In general, polymer-based columns have a broad pH range (pH 2 to 13), and some have high temperature tolerance (up to 150°C or higher). Considerably large selectivity changes can be obtained by varying analysis temperature and mobile phase pH. Having control on these two parameters over wide ranges can be especially useful in method development.

Viscotek has been a strong advocate of good chromatography as a prerequisite for GPC (Gel Permeation Chromatography) data accuracy. Our recent work in application development has been driven by extremely difficult samples from industrial, biopharmaceutical, and academic sources. These samples present challenges ranging from sample solubility, column adsorption, as well as detection issues. This report will attempt to highlight a new approach that could be very helpful in certain advanced GPC applications.

Traditionally the analysis of water-soluble vitamins by reversed-phase HPLC has been complicated by the lack of retention for these compounds on conventional silica C18 columns. Here we demonstrate efficient, multi-mode, baseline resolution of six water-soluble vitamins in 6 min using a ZirChrom®-SAX column.

Amylose is an occasionally-branched biopolymer and, together with amylopectin, the hyper-branched component, a constituent of starch. Determination of branching in amylopectin on the basis of amyloses may be performed with the help of synthetic amyloses. Synthetic amyloses from enzymatic (phosphorolytic) reaction were checked for their linearity.

The analysis of polar compounds in support of clinical and preclinical pharmacokinetic studies requires an analytical methodology capable of achieving ultra-low detection and quantification limits. The high sensitivity afforded by coupling HPLC with tandem mass spectrometry (MS–MS) has made it the technique of choice in this environment, but it is subject to the following limitations when reversed-phase liquid chromatography (RPLC) is used

An effective UHPLC–MS method for high throughput separation, identification and quantification of pseudoephedrine was developed on a Hypersil GOLD PFP 1.9 µm, 2.1 Ã- 100 mm column.

A new APCI/APLI source enables a high resolution TOF-MS to be coupled on LC and GC, thus increasing flexibility and performance of TOF-MS in combination with GC.

Under the registration, evaluation and authorization of chemicals (REACH) Regulations (EG) no. 1907/2006 the producer, manufacturer or importer of chemical substances/formulations have to register their products (more than 1 ton/year) at the chemical agency.

PEGylation, the process by which polyethylene glycol (PEG) chains are attached to protein and peptide drugs is a common practice in the development of biopharmaceuticals to prolong serum half-life and improve pharmacokinetics of a drug. There is increasing demand for chromatographic methods to separate the modified isoforms from the native protein. This application note describes the use of size exclusion and ion exchange chromatography for the characterization of PEGylated lysozyme.

Short analyses time and high resolution are in great demand from R&D and QC departments within the pharmaceutical industry. Sub-two micron ODS reversed phase columns have recently been introduced to meet these requirements, but these columns require an ultra-high pressure HPLC system to achieve optimum performance. TSK-GEL ODS-140HTP, 2.3mm columns from Tosoh Bioscience have been developed to offer a combination of short analyses time and high resolution separations that can be run at modest pressures, making these columns compatible with conventional HPLC instrumentation. The polylayer bonding chemistry of these columns results in highly efficient and physically stable columns when operated at high linear velocities. In addition, TSK-GEL ODS-140HTP, 2.3mm columns can be efficiently operated at pressures not exceeding 9000psi in UPLC® and other ultra-high pressure HPLC systems, as well as in traditional HPLC systems.

Synthetic fused silica capillary tubing has proven to be a vital component in many separation science techniques. Recently, it has expanded to serve an array of scientific markets. In most cases, an understanding of the internal surface chemistry is of fundamental importance.

There are many misconceptions about what it means to perform fast gas chromatography (GC) and what the term fast GC implies. Fast GC is often associated with the use of hydrogen as a carrier gas and, although this is certainly a good approach, it is not always necessary to shorten the analysis time. A second misconception is that changing column dimension results in time-consuming method development. Using high-efficiency GC columns can greatly reduce the analysis time and when coupled with the method translation software, the time spent on method development can be greatly minimized.

Viscotek has been a strong advocate of good chromatography as a prerequisite for GPC (Gel Permeation Chromatography) data accuracy. Our recent work in application development has been driven by extremely difficult samples from industrial, biopharmaceutical, and academic sources. These samples present challenges ranging from sample solubility, column adsorption as well as detection issues. This report will attempt to highlight a new approach that could be very helpful in certain advanced GPC applications.

An effective UHPLC-MS method for high throughput separation, identification and quantitation of pseudoephedrine was developed on a Hypersil GOLD™ PFP 1.9 µm, 2.1 x 100 mm column.

The use of mobile phase pH to control analyte ionization states (pH-LCâ„¢) in reversed phase HPLC separations is a highly effective way to change selectivity. The ionized species of an analyte is shown to have higher polarity (less hydrophobicity) than the neutral species, which results in a loss of expected retention for that analyte. This can be attributed to less interaction with the hydrophobic stationary phase and greater affinity with the aqueous portion of the mobile phase. Ionized species also participate in ionic interactions with exposed and activated silanols, which impact peak shape and reproducibility.

Size exclusion chromatography is a powerful tool for the characterization of molecules differing in size and molar mass. It is widely used and well known for the determination of molar mass distributions and molar mass averages. For membranes GPC-SEC is a useful characterization method as it can measure the membrane characteristic pore size distribution, average pore size and molecular cut-off significantly faster than other methods.

In the last few decades, the novel functions of polysaccharides have provided a major impetus for increasing scientific attention. Among the most promising aspects are their immunomodulatory and antitumor effects, thickening agents and stabilizer effects.

Glucosamine (GlcN) is a major structural component in the biosynthesis of glycosaminoglycans, compounds involved in normal joint function. Use of GlcN as a dietary supplement in the management of osteoarthritis has attracted considerable attention; it is one of the five nonvitamin, nonmineral supplements most frequently used by US adults (1). The US FDA currently regulates dietary supplements to ensure that they are produced under cGMP (2).

Urea is commonly used in protein purification, including large-scale purification of recombinant proteins for commercial purposes, and in recombinant protein manufacturing to denature and solubilize proteins (1). In aqueous solutions, urea degrades to cyanate and ammonium, with the maximum degradation rate occurring at neutral pHs commonly used in biological buffers (2). Cyanate is problematic in urea solutions because it carbamylates proteins, which causes unwanted modifications that can alter the protein's stability, function, and efficiency. Therefore, an accurate, sensitive method for determining cyanate in urea-containing buffers is required.

Amylose is an occasionally-branched biopolymer and, together with amylopectin, the hyper-branched component, a constituent of starch. Determination of branching in amylopectin on the basis of amyloses may be performed with the help of synthetic amyloses. Synthetic amyloses from enzymatic (phosphorolytic) reaction were checked for their linearity.

Use imaging mass spectrometry to determine the biodistribution of erlotinib (Tarceva®) in pancreatic tumors from treated and untreated mice.

Supercritical Fluid Chromatography (SFC) is quickly becoming a popular choice by chromatographers for analytical and preparative separations.

Phthalates are added to plastics to increase flexibility. Recently, concerns have been raised over the effect of phthalate exposure from plastic materials on human health.