Water is perhaps the most utilized reagent in a laboratory and is often critical for an experiment. As instruments have become more sensitive and applications increasingly complex, the demand for high-purity water has also increased. A few years ago, parts per million (ppm) was a very small level of contamination, but now people are looking for parts-per-billion (ppb) or parts-per-trillion (ppt) levels of contamination, says Renaud Bardon, director for North American Sales Lab Water at Millipore Inc.
There are several types of contaminants in water, such as particulates, organics, inorganics, microorganisms and pyrogens. In the past, people were mainly concerned with ionic contaminants and measured ionic conductivity or resistivity as a way to determine water purity. Today people are more concerned with organic contaminants, particulates and microorganisms, such as bacteria and gases that are dissolved in water, says Bardon.
There are eight commonly used methods to purify water: distillation, deionization, reverse osmosis, activated carbon filtration, microporous filtration, ultrafiltration, ultraviolet oxidation and electrodialysis. The National Committee for Clinical Laboratory Standards (NCCLS) has specified three types of water: I, II and III, as well as special-purpose water, depending on their use. While Type I refers to water with minimal interference and maximum precision to be used for most analytical applications, type III water refers to that used for general washing. The special-purpose water refers to water that has been treated to remove specific contaminants.
When selecting the right system for purifying laboratory water, several factors need to be considered. However, according to Bob Applequist, product manager at Labconco, the most important one is to fit the product to the application. You have to differentiate between the need for pure and ultrapure water. In most cases, the pure water generated from tap water can be used for most applications, while ultrapure water generated from a point of- use system can be used for applications that have more specific and stringent purification needs. The first-step purification or the system that is used to convert tap water into pure water has to be very good and efficient, says Bardon. If you have that first step right, then converting that pure water into ultrapure water is going to be very easy and consistent.
When considering a water purification system, both the quality and the quantity of water have to be taken into account. You have to take into account instantaneous as well as daily water volume requirements, says Bardon. For labs that have variable demands on quality and quantity, flexibility and modularity become very important. The key then is to invest in a flexible system that will meet your needs today and can grow with the lab and change with the applications, says Matthew Hammond, global sales and marketing director for ELGA LabWater.
After choosing the right system, performing regular, preventative maintenance is equally important. The newer versions have built-in alarms and calibrators that warn customers if certain components are coming to the end of their life cycles. Sample the water routinely to make sure that it doesnt contain the impurities that will interfere with your analysis, says Hammond. The level of monitoring can be done daily, weekly or monthly, depending on the stringency of the application and the laboratory environment. Whatever system you buy, make sure its dynamic, so that the water can recirculate regularly, says Hammond. Water needs to be kept moving, as still water ends up building biofilms quicker. So look for a system that is easy to sanitize. If properly maintained and used, most water purification systems can last up to two decades.
Finally, ensure that the pure water obtained is being used in the right way. I know of customers who will invest a large amount of money buying an ultrapure water purification system and then dispense that water into a plastic container before they use it, says Hammond. Its an unfortunate truth, but for most people, water is just a utility. Its the most pure reagent that is available at a relatively low cost, and so it often doesn't get the respect it deserves."
Lab Manager Magazine has introduced our first ever, Independent Guide to Purchasing a Lab Water Purification System and a survey for current owners of lab water systems or future purchasers.
|Guide to Purchasing a Water Purification System (PDF)||SURVEY: Lab Water Purification (Future Buyers & Current Owners)|
Tanuja Koppal, PhD, is a freelance science writer and consultant based in Randolph, N.J.
Proprietary type I systems produce 2-3 liters/minute of 18+ Megohm-cm reagent grade water directly from tap water. Analytical, biological, and ultra-low TOC models are available with or without built-in reverse osmosis pretreatment. They accept 100-240 VAC at 50/60 Hz input power and operate internally on 12 VDC. Systems with built-in RO can operate on tap water containing up to 1,000 PPM of TDS. Systems are CSA-certified, have the CE mark and include a 2-year warranty.
The PURELAB flex water purification system integrates in-hand monitoring and pure water dispensing in one product. The dispensers easy-to-read digital display shows both volume and water purity (either resistivity or conductivity and Total Organic Carbon). The dispense handset has precise fingertip control (like a pipetter) and can be easily programmed with pre-set volumes that can be repeated with the press of a button. The system is easily upgradeable to facilitate changes to laboratory layout and applications.
The WaterPro RO stations large capacity filters and membrane produce reverse osmosis purified water that may be dispensed at a typical rate of 1 liter per minute (at inlet water at 25 C) or manually from a valve or optional gun. The timed dispense feature allows unattended operation. The system may also be used to produce laboratory grade feedwater for final purification by a polishing station and allow dispensing of both RO-purified and Type I water.
The Milli-Q Integral lab water purification system features unique Points-of-Delivery (POD) dispenser systems that give users direct control over water quality throughout the entire purification process. Separate POD dispensers deliver either ultrapure water (from the Q-POD unit) or pure water (from the E-POD unit) at adjustable flow rates ranging from drop-bydrop to 2 L/min. POD dispensers can be adapted with contaminant-specific final polishers to remove pyrogens, nucleases, bacteria, particulates and organics.
Siemens Water Technologies
The Axius E-Plus RO/CEDI water purification systems with reverse osmosis and continuous electro-deionization deliver more consistent water quality. They combine the proven technologies of reverse osmosis (RO) and continuous electro-deionization (CEDI) to produce high quality ASTM type II water. With low initial upfront costs, simple maintenance and minimal consumable change-outs, the systems provide an economical and environmental choice for consistent high purity water up to 1300 liters per day, direct from tap.
The Gemini-Mini Basin is a wall mounted, high flow, point-of-use polisher that can dispense ultra-pure water at a rate of 3.7-lpm; a flow rate over 3 times faster than traditional polishing systems. With PLC control, the Gemini-MB can be intuitively programmed to automatically fill and stop at precise volumes. Flexible dispensing features include: the ability to program four independent batch volumes; remote dispense gun with full recirculation; and submicron filter and direct feed of equipment downstream. Filtration technology includes: multi-pass UV sterilization of the flow path and dispensing port; TOC UV destruction unit to reduce the total organic carbon content of the product water; submicron filtration to remove bacteria and viruses; and ultra filtration for R-nase, D-nase-free water.
Thermo Fisher Scientific
The Barnstead NANOpure® water purification system offers a combination of reliable, ultrapure water with easy operation and maintenance and low operating cost. Application-specific models utilize cartridge packs tailored for specific feed water types and uses. They provide the ideal water for the most sensitive requirements, including: IC, ICP/MS, HPLC, GC/MS, HPLC and TOC determinations. These advanced systems produce water that consistently achieves 18.2 megohm- cm resistivity and TOC values of < 1 ppb.
If you are in the market for a new Laboratory Water Purification Systems , Lab Manager and LabX can have qualified companies contact you directly.
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