Quasar™ C18 LC columns, based on ultra high purity silica and manufactured to tight specification, 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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|Inner Diameter||3 mm|
|Particle Size||3.0 µm|
|Product Brand Name||Quasar|
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.
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.
The most commonly used LC reversed-phase alkyl bonded stationary phase is octadecyl carbon chain (C18)-bonded silica, which is denoted as USP classification L1. C18 columns have a broad applicability from pharmaceuticals to food and environmental analyses. However, not all C18 columns are alike. Simply swapping a C18 column from one manufacturer to another can result in differences in retention time, resolution and even selectivity. Differences can arise due to variations in hydrophobicity, silanol activity, packing quality, particle size distribution, and silica purity, to name a few.
This technical note provides details of a comparative study between twenty-four silica-based C18 phases, from a number of manufacturers covering the following areas: