Quasar™ C18 LC columns, based on ultra high purity silica and manufacturered to tight spefications, provides high efficiency separations and excellent peak shape for a wide range of compounds. Our methodology to yield high surface coverage enhances the pH stability and extends the working range. If data integrity and high producitvity are top priorities for your lab, then this column can support your needs for any application.
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Levothyroxine sodium is the sodium salt of levothyroxine, a synthetic form of thyroxine (a major endogenous hormone). It is primarily used in the treatment of hypothyroidism (commonly known as an underactive thyroid), where the thyroid gland produces insufficient quantities of hormones T3 and T4. Thyroid hormones are vital within the body as they increase the metabolic rate of several cells and maintain brain function and body temperature. Lack of these vital hormones can lead to varied symptoms including depression, loss of memory and weight gain. Levothyroxine sodium is one of the most common drugs in the world, and in 2017 was the second most prescribed drug in the USA. This application brief describes the use of a Quasar cyano column for the analysis of levothyroxine sodium in accordance with the official Levothyroxine Sodium USP monograph.
Azithromycin, discovered in 1980, is a semi-synthetic macrolide antibiotic derived from erythromycin. The drug is primarily used to treat various bacterial infections including respiratory infections, acute bacterial sinusitis, skin infections, Lyme disease, and some sexually transmitted infections. The mode of action of azithromycin is by inhibiting bacterial protein synthesis through binding to the 50S subunit of the bacterial ribosome, thereby inhibiting translation of mRNA. The USP monograph for the analysis of azithromycin states the use of a high pH mobile phase (pH 11), which requires a specific and expensive column. The method also uses amperometric electrochemical detection, which is often unavailable in many laboratories. HPLC with a UV or PDA detector provides a good alternative as it is available in most laboratories. This application brief describes the use of a Quasar™ C18 column in the analysis of azithromycin.
The aerobic mold which yielded cephalosporin C was found in the sea near a sewage outfall nearby Cagliari harbour, Sardinia, by the Italian pharmacologist Giuseppe Brotzu in July 1945. Since their discovery and subsequent commercialization in 1964, the cephalosporins today are broad-spectrum ß-lactam antibiotics used for the treatment of a number of bacterial conditions including septicaemia, pneumonia and meningitis. The pharmacology of cephalosporins is similar to that of the penicillin class of compounds. This application brief describes use of a Quasar biphenyl column in the analysis of several cephalosporins, a mixture of first and second generation ß-lactam antibiotics.
Indoxyl sulfate is one of the most extensively studied solutes that accumulates in the plasma when the kidneys fail. Originally called "indican", it was first isolated by Obermayer and Popper in 1911. High concentrations of indoxyl sulfate in blood plasma are known to be associated with the development and progression of a number of pathological conditions including chronic kidney disease and vascular disease. The scientific literature documents the use of older generation C18 columns, using type A silicas. This application brief will illustrate the application of a new generation C18 column, based on type B silica, for the analysis of indoxyl sulfate, Figure 1, as part of a research study to measure the total levels in a simulated blood serum environment.
Retinol, one of the main forms of vitamin A, is regularly used in the treatment and protection of skin. By inducing the biosynthesis of collagen and promoting skin cell production, retinol helps to reduce the signs of early UV-induced skin aging. Retinol is also an anti-oxidant, allowing it to neutralize free radicals that may damage healthy skin cells. HPLC with UV detection is commonly used to assess and quantify retinol in a variety of samples.3 This application brief describes the use of a Quasar C18 column for the rapid analysis of retinol.