Test & measurement
OPTIMISING CHROMATOGRAPH PERFORMANCE
Gas and liquid chromatography are indispensable techniques used in the pharmaceutical and clinical fields. They are essential for the separation, identification, and quantification of complex mixtures. These methods offer high sensitivity and precision, making them ideal for analysing a wide range of substances, from small organic compounds to large biomolecules. Creating new pieces of equipment to carry out these tasks requires numerous flow control components and it is important to focus on those that deliver the best results. Troy Stehr, industry account manager – Lab and Medtech at Bürkert, looks at the challenges of creating chromatographs that deliver the accuracy and repeatability demanded by medical and pharmaceutical applications.
CHALLENGES TO ACCURACY The development of new chromatographic systems, however, presents several challenges. A primary obstacle is the precise control of gas and liquid flow, which is fundamental to achieving accurate and reproducible results. Inconsistent flow rates can lead to poor separation, compromised detection limits, and unreliable quantification, ultimately affecting the integrity of the analytical results. Ensuring a stable and precise flow rate is essential to ensuring precision and repeatability. Variations in flow can cause peak broadening or tailing, affecting resolution and sensitivity. Using advanced flow control technologies such as electronic pressure control (EPC) in gas chromatographs and precision dosing in liquid chromatographs can maintain consistent flow rates. In addition, real-time monitoring and feedback systems can adjust parameters
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n the pharmaceutical industry, chromatography is crucial for drug development, quality control, and ensuring the purity of active pharmaceutical ingredients (APIs). Clinically, it aids in the diagnosis and monitoring of diseases through the analysis of biomarkers, therapeutic drugs, and metabolites.
dynamically to ensure flow stability. Temperature stability is equally important; fluctuations can affect the viscosity of the mobile phase and the interaction between analytes and the stationary phase, leading to inconsistent retention times. By implementing precise temperature control systems, such as oven temperature programming or thermostat- controlled column compartments, these issues can be mitigated.
DURABILITY AND MAINTENANCE Increasing demand for high-throughput analysis and point-of-care testing is driving the need for compact, automated chromatographic systems. Microfluidic technology as well as automated sample preparation and injection systems can reduce sample and reagent consumption, improve throughput, and enable portable applications. Clearly, for equipment that is used regularly, a robust build quality and simple maintenance procedures are important. Frequent interventions for maintenance caused by system wear and tear can lead to downtime and increased operational costs. Developing durable materials and components, along with automated maintenance protocols, can enhance system longevity and reduce downtime.
The choice of valve can also have a significant effect on maintenance costs and process
availability. In a laboratory with an eight-hour working day, valves clocked at 1 Hz, operating for six hours will perform 21,600 switching operations per day. Using a conventional solution, the valve reaches 10 million operations and can be used for 463 days. However, selecting a Bürkert solution that can achieve 100 million operations means the equipment can operate for 4,630 days. This equates to a potential saving of 90 million circuits, a service life of more than 4,100 days and seven hours less maintenance, resulting in a more productive solution.
INDIVIDUAL CHALLENGES
There are also challenges within the individual fields of liquid chromatography. Analytical work can be affected by vague switching behaviour of the liquid control valves, which leads to imprecise mixing in the mobile phase, leading to an inaccurate gradient. The valves and their control blocks play a vital role in delivering accuracy and cleanliness to the process. The quality of valve blocks is determined by the design and manufacturing expertise that
August 2024 Instrumentation Monthly
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