Application Notes: General

UHPLC columns can significantly improve chromatographic separations, but they also present unique challenges. Once the UHPLC system components are optimized, perhaps your greatest concern is protecting the column from the damaging effects of microparticulates and sample contaminants.

Synthetic fused silica capillary tubing is used in the manufacture of most gas chromatography (GC) columns. In this note, we discuss recent advances in the dimensional control of the most popular tubing sizes.

Silymarin, derived from the milk thistle plant, has been used as a natural remedy for the treatment of a number of liver diseases as well as in the protection of the liver from potential toxins. More recently, silymarin has been connected to antitumor promoting activity (1). It is therefore of interest to have available analytical methods for the analysis of silymarin components in various matrices.

Vitamin K is a group of structurally similar, fat-soluble vitamins that are needed for the post-translational modification of certain proteins, mostly required for blood coagulation but also involved in metabolic pathways in bone and other tissue.

According to law enforcement and health officials, "bath salts" are powerful synthetic stimulants, designed to be comparable in effect to cocaine or methamphetamine, carrying similar risks. Unlike cocaine or methamphetamine, these stimulants are currently legal in many parts of the United States and available at a low cost in many convenience stores and head shops.

Coenzyme Q10, found naturally in the body, is involved in the production of body energy. Thus, heart, lung, and liver have the highest concentration of Q10.

On June 14, 2011, the FDA issued stricter regulations on how sunscreen manufacturers can label over-the-counter sunscreen products. In the summer of 2012, manufacturers with an annual sale of $25,000 or more will have to characterize the active ingredients found in their sunscreens (1).

A simple and efficient supported liquid extraction (SLE) procedure for the extraction of THC and metabolites from human plasma at low levels has been developed.

Recognition of DNAs and RNAs wide range of biological actions has driven modern biopharmaceutical research into the therapeutic value of oligonucleotides.

Many modern stationary phases suffer from poor chromatographic performance for basic compounds at low pH, especially when using low-ionic strength mobile phases such as formic acid.

Nicotine is a famously addictive alkaloid found in tobacco. Controlled doses of nicotine compounds are sometimes used to help tobacco users quit smoking.

Since the gas flow required for the separation step in gas chromatography is frequently lower that that required to optimize the detection, nitrogen is used as a make-up gas to increase the gas flow for detection.

The separation of closely related compounds is of interest to many disciplines including natural products, flavors and fragrances, and pharmaceuticals.

GC–MS analysis of urine for drugs of abuse is commonplace, but can be complicated by high matrix effects and frequent co-elution.

In the recently published 2nd edition of Modern Size Exclusion Liquid Chromatography: Practice of Gel Permeation and Gel Filtration Chromatography (1) it is stated that the debate about which column to place first when running a series of SEC columns is still open.

Cationic surfactants are used as disinfectants, corrosion inhibitors, phase-transfer catalysts, wetting agents, dispersants, and even mobile phase modifiers in liquid chromatography.

Cocaine is a central nervous system stimulant derived from Erythroxylon coca.

Illicit cocaine, amphetamine, methamphetamine, and ecstasy (MDMA) are often encountered in the form of salts and identification of the specific counter ion present may provide valuable information about the source of production and the manufacturing pathway.

This note examines the benefits of using flash or HPLC for compound purification. Results show that flash is a viable alternative to HPLC.

This article reports a new sample injection mechanism for an autosampler that directly transfers a sample to column without passing it through any flow-changing device, and hence minimizes a delay volume and reduces a carryover signal to the extreme level.

Urine is often used to analyze drugs of abuse because it is easy to collect and is available in copious amounts.

Method development in reversed-phase liquid chromatography (RPLC) can be challenging for structurally similar compounds.

Methods: Vials and closures were exposed to acetonitrile for 2 h and subsequently analysed by LC-UV, LC–MS, and GC–MS to characterize the interferences.

P-hydroxybenzoic acid esters, also called parabens, are widely used as antimicrobial preservatives in cosmetic products.

For many years, the use of guard columns has been advocated by column manufacturers and other experts to protect and extend column lifetime and performance of analytical columns from potential damage caused by the presence of chemical contaminants and microparticulates in the sample and mobile phase.

Phenol formaldehyde resins are formed by a step-growth polymerization. GPC/SEC with RI and UV detection is often used to characterize resins and to quantify the amount of different oligomeric species.

The analysis of tea tree oil requires a severe quality control due to its potential to induce and elicit skin allergies. Tea tree oil is an essential oil and consists of a large number of constituents. Heart-cut Multidimensional GC–MS is very well suited to analysis of samples of such high complexity.

The release of certain chemicals from building products is of increasing concern due to their potentially detrimental effect on human health and the environment; therefore, new regulations requiring the production of low emission materials are currently being implemented. Novel sampling technology has been developed to help building product manufacturers obtain informative emissions data to develop compliant products and maintain product quality on a routine basis.