Water: pure and simple

Real-time test results require a constant supply of high purity water – the Royal Liverpool and Broadgreen University Hospital NHS trust let us in on the secrets of their water system

The Royal Liverpool and Broadgreen University Hospital NHS Trust in northern England treats nearly one million patients a year from Liverpool and the neighbouring Merseyside and Cheshire regions. The hospital provides general hospital services and emergency care to this population, and is also one of the country’s leading teaching trusts, with links to the University of Liverpool and John Moores University.

The hospital’s Automated Laboratory – one of the largest automated labs in the UK – has a sample throughput of 4,000 samples per day, with 40% of this load for in-patients and 60% for out-patients. For some tests, this hospital serves as the regional centre for general practioners for certain chemistries, and samples for fertility or hormonal assays are received daily from specialists throughout the UK and Ireland.

Sue Levine, manager of the hospital’s Automated Laboratory, explains the lab uses a number of analysers to perform its tests. The lab is set up with two similar lines of analysers, each made up of several general chemistry and immunoassay analysers linked together. The two lines (which include two D-modules, three P-modules and three E-modules), are configured to complement one another and allow the hospital to obtain optimum use from its analyser equipment. When there are numerous immunoassays to run, for example, the lab will use the line that includes the two E170 immunoassay analysers so that tests are processed as quickly as possible.

“In the past, practitioners and patients knew there was a certain waiting period between the time the sample was sent to the lab and the moment test results were available,” Levine said. “Today, this has changed, and there has been an evolution in the ways things work. We previously offered only a limited number of tests on call, but now we’re able to offer the entire repertoire of tests in real time – any of the tests 24/7, with no variation in quality. Doctors now have all of the test results that they need for their patients right away, including endocrinology. Emergency samples are prioritised, of course, as they require faster turnaround time.”

Water is a crucial element in all clinical laboratories: it is an essential reagent in clinical chemistry and immunoassay testing, necessary for delivering consistent, high quality results, maximising productivity and improving patient outcomes. Of all the fluidic reagents needed onboard an analyser, water is the most important.

Levine points out that a consistent supply of high purity water is crucial for the Automated Laboratory: “Water is a fundamental part of our service to practitioners who rely on our real-time results.”

Three important criteria govern the selection of a high purity water system for a biomedical lab.

The first criterion is water quality. It must meet the standards specified by the manufacturers of a lab’s diagnostics instruments. It must also be suitable for the lab’s other applications. In biomedical laboratories, high purity water is employed extensively in a wide variety of applications ranging from general chemistry to enzyme immunoassays, including toxicology, trace elements analysis and molecular testing assays. For each assay, different types of contaminants – ions, organics, bacteria, bacteria by-products, particles, and silica – may interfere with the analysis and alter the test results. Biomedical labs are also concerned with analytical factors linked to water quality that need to be controlled and optimised to reduce the number of test failures. Drifting calibrations, high blanks, and patient values trending towards the high/low end of the assay all can stem from poor water quality, which then contributes to erroneous patient results.

The second criterion to consider when selecting a water system is compliance with the Clinical and Laboratory Standards Institute (CLSI) guideline. This guideline was written to help ensure the use of suitable water purity in all laboratories in order to provide consistent clinical chemistry and immunoassay results. To follow the recommendations of this guideline, the final product from the water purification process must ensure accurate and reproducible results.

The third criterion is to ensure that the correct water purification system is selected for use with a laboratory’s clinical analyser, and that pure water is supplied on demand in the quantities required at all times.

The Automated Laboratory uses Elix high purity water systems from Millipore to provide the pure water it needs. “The pure water is used to feed our analyser lines, dilute and reconstitute reagents, reconstitute quality control and calibration materials and run blanks. We also use it to clean cuvettes, pipettes and syringes,” Levine explained. “We can check all the readings displayed on the water purification systems and understand at a glance what is needed. As the systems are installed in a separate room from the analysers, we opted for water sensors along with the systems. If ever there was a leakage, these sensors, together with an alert from the reservoir level detector, would inform us immediately before a water shortage could occur.”

“Our water system maintenance is also straightforward, as the systems let us know when a pack needs changing—and that’s very simple to do. We have a service plan with electronic records, so our consumables are ordered ahead of time and stored for use when we need them, which makes maintenance very minimal. Our water purifications systems provide the perfect answer to the needs of a high throughput lab,” she concluded.

The crucial nature of water in biomedical laboratories leads it to impact assays in many different ways. Therefore, care should always be given to the quality of water selected and its intended applications. Suitable and properly maintained water purification solutions can help provide optimal water quality for biomedical testing and also limit instrument downtime.