Select Seals That Meet the Chemical Challenges of HPLC Pumps

High performance liquid chromatography (HPLC) is a chemical analysis technique with wide applications, from food and medical safety to manufacturing. HPLC can detect vitamin D levels in blood serum or performance enhancing drugs in urine. The technique has even been used to synthesize blood and determine DNA evidence in forensic investigations. In biotechnical and pharmaceutical manufacturing, HPLC enhances the production process by increasing separation 
efficiency, improving resolution and shortening analysis time. Instrumentation and system automation have evolved to keep pace with the quality of materials that support HPLC and its applications.

How HPLC Works

HPLC passes a liquid sample through a column of a particular absorbent solid material that reacts at divergent rates from an analyzing solvent. The rate of reaction and how the solution separates identify the original components. This technique can determine all the materials in a solution based on known reactions to base chemicals and solid state materials. HPLC instruments include a sampler, pumps and a detector. The sampler brings the mixture samples into the mobile phase stream, which carries it into the column. The pumps deliver the desired flow and composition of the mobile phase through the column. Some mechanical pumps mix multiple solvents in ratios changing over time, creating a composition gradient in the mobile phase. The detector—ultraviolet-visible spectroscopy, photodiode arrays (PDAs) or mass spectrometry are commonly used—generates a signal proportional to the amount of sample component emerging from the column and allows for quantitative analysis of the sample components. Instrument control software usually ties into the HPLC instrument and provides data analysis. Additionally, a high scan-speed detector capable of collecting enough data points across an analysis’s narrower peaks has often improved the production process.

HPLC Pumping Challenges

All piston pumps have multiple replacement parts, such as check values, piston seals and pump piston rods. When working with HPLC instruments, biotechnical and pharmaceutical manufacturers pay close attention to the parts and materials entering their supply chain in terms of their pumping needs. Seals in HPLC pumps must deliver exceptional leak tightness, high resistance to wear and tear, low coefficient of friction and no extrusion into gaps. An HPLC pump seal should withstand aggressive and abrasive processing and offer excellent temperature capabilities—operating in a range from -253 C to 300 C (-423 F to 572 F). Recommended seals can work at high speeds up to 15 meters per second (49 feet per second). Check valves (inlet and outlet) prevent flow from a high-pressure area into the low-pressure area inside the HPLC pump head. As a result, the pump’s piston can deliver a mobile phase flow through the column at high pressure. A properly functioning check valve opens and closes quickly and provides a secure seal across a wide pressure range. Check valves in HPLC pumps fail more often than other HPLC parts, such as pistons or piston seals, because they are exposed to repeated mechanical stress at high pressure. Failed check valves are also difficult to identify. Unlike external pump leaks, internal pump leaks do not lead to a substantial drop in pressure, and HPLC software programs will not detect them.

Service Kits Increase Longevity

Long-lasting instruments—with lifespans from five to 20 years—have led to instrument maintenance repair organizations (MROs) having a more common role in HLPC instrument upkeep. MROs now make service kits for HPLC part replacements because of instrument longevity. For example, pump manu
facturers and MROs can remove metallic spring energizers from an HPLC system because the energizer can affect production results in some cases. Some MROs have developed specialized kits based on consults with operations personnel to determine what parts, supplies and packaging requirements will ensure a customer’s instruments and machines continue to run smoothly. These organizations partner with material suppliers to efficiently manage inbound and outbound logistics through supply chain services.

The Future of HPLC

HPLC is the largest product segment in the analytical instruments industry. The techno-
logy serves several industries for research and development purposes, quality control and process engineering applications. Improvements in system automation, robotics and instrument design are propelling growth in the HPLC market. China and India are driving the market for analytical instruments in Asia, with Latin America offering good growth prospects. The rise in drug discovery and generic pharmaceutical production, as well as rapid industrialization, has fueled the HPLC market in these regions. Industry research forecasts the HPLC pumps market crossing the $100 million mark in 2014. The global market for HPLC systems and supporting accessories is projected to reach $3.7 billion by 2015.