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|Inner Diameter||4.6 mm|
|Particle Size||2.6 µm|
|Product Brand Name||Quasar|
Fluconazole is an azole anti-fungal medication used primarily in the treatment of a wide range of fungal infections. Examples include thrush, urinary tract infections and the prevention of fungal infections in immunocompromised patients undergoing chemotherapy. The mechanism of action can be described as fungistatic, the growth and replication of fungi is inhibited by fluconazole rather than directly attacked. This process is achieved by inhibiting enzymes which are important in the production of fungal membranes, allowing the immune system ample opportunity to target and degrade the pathogen. Fluconazole has generic status and is thus globally produced and prescribed. It is on the World Health Organization’s (WHO) list of essential medicines, which serves as a model of the safest and most effective medications needed by a health system. This application brief describes the use of a Quasar C18, on both porous silica and SPP silica phases, for the analysis of fluconazole in accordance with the official USP monograph.
Pharmaceuticals are continuously entering our waterways via human excretion of incompletely absorbed medication and improper disposal of unused drugs via drains and toilets. A report found that the six most consistent highest reported concentrations in finished drinking water for active pharmaceutical ingredients (APIs) were from ibuprofen, triclosan, carbamazepine, phenazone, clofibric acid, and acetaminophen.
Ibuprofen (Figure 1) is a widely used analgesic and antipyretic for adults and children and since it’s one of the most reported pharmaceutical in finished drinking waste, it is important to determine the amount removed by different water treatment processes. HPLC is an essential technique to determine the quantity of ibuprofen in water and help optimise a process for its removal. This application brief describes the use of a Quasar superficially porous particles (SPP) C18 column for the analysis of ibuprofen in water.
The knowledge about tocochromanol-related compounds, especially tocotrienols, tocodienols,tocomonoenols, and others, is still limited due to several challenges faced in analytical chemistry. These challenges include separation resolution, co-elution, price and absence of standards, and low analyte concentration in plant material. Application of different column stationary phase chemistries can assist in the challenges faced in compound separation.
Superficially porous particle (SPP) columns can also be used to improve separation of these compounds. SPP particles are made of a solid, non-porous core surrounded by a shell of a porous silica material, resulting in a shorter diffusion path in comparison with fully porous based columns. With a shorter diffusion path within the SPP particle itself, coupled with a uniform packed bed and ultra-inert silica surface, reductions in run times can be observed. Such phases benefit from increased efficiency, with separation resembling that of a UHPLC column. They can be used on standard HPLC instrumentation, without concerns regarding high backpressures, which often compromise column longevity.
In this application brief, five different Quasar™ SPP column phases were screened for the separation of four tocopherol and four tocotrienol homologs, with focus on resolving β and γ isomers.
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:
Salbutamol (also known as albuterol) is a bronchodilating agent which is ubiquitously used in the treatment of asthma and chronic obstructive pulmonary disorder (COPD). It is a polar hydrophilic compound (see Figure 1) which can be problematic when analyzing using reverse phase HPLC. Polar compounds can elute very close to the solvent front. It is therefore ideal for an eluting compound to have a capacity factor (k) between 1 and 10. Polar compounds with poor retention can have k values close to zero. Analyses with this level of retention are not reproducible and so it is important to increase the affinity that polar compounds have for the stationary phase. The technical note investigates the impact on retention of salbutamol by changing the chemistry of the stationary phase. When analyzing salbutamol in accordance with the British Pharmacopeia, the monograph stipulates the use of 'end-capped octadecylsilyl silica gel for chromatography (5 µm)'. This definition does not specify the type of end capping giving scope to the evaluation of different stationary phase whilst still adhering to BP requirements. Salbutamol sulfate was analyzed according to the British Pharmacopeia monograph: Salbutamol Pressurised Inhalation, Suspension. This analysis was performed on four Quasar columns: C18, AQ, AQ Plus and SPP C18/PFP in order to obtain the maximum improvement in the retention of salbutamol.