Cleaner Clean Water The supply and measurement of purified lab water requires sophisticated systems to ensure high-quality application results. by Tim Studt
Laboratory water systems, such as the Sartorius arium 611, are designed to consistently provide ultrapure water for specific applications, along with numerous options for increased flexibility. | The most used material in the research lab is pure water; it’s a vital resource for just about every scientific application. While the basics and standards for providing pure lab water have not changed dramatically over the past few decades, refinements in the specific purification and measurement technologies and expanded applications continue to drive improvements in the quality, reliability and cost of pure water supplies.
“There are still a lot of issues with pure lab water,” says Karen Wisniewski, a product specialist at Thermo Fisher Scientific. Many of those issues revolve around taking water supplies for granted, she explains. “Pure lab water is often the most critically ignored part of an experiment. When researchers find contaminated water, they will likely blame themselves and often won’t even consider the water supply. Also, life science researchers know they need water purification systems, but they often don’t think about how to go about getting them.”
The contaminants looked for and found in pure lab water systems are fairly well established and include suspended particles, colloids, inorganic ions, dissolved organics and gases, microorganisms, pyrogens and viruses, and nucleases. Specific purification technologies are available to remove each of these contaminants.
Many of the developments involving pure lab water enhancements are related to life science applications. Excluding instrumentation, the top pure lab water applications where researchers expect to see the most technology growth over the next five years (according to an October 2009 Laboratory Equipment reader survey) include environmental testing (35% of respondents), nanotechnology (31%), biochemical reagent preparation (25%), cell and tissue culture preparation (24%), buffer preparation (16%), polymerase chain reaction (PCR, 16%), drug discovery (15%), and chemical processing (15%).
Water supplies
Millipore's LC-Pak is a point-of-use-polisher for ultrapure lab water used in LC-MS and UPLC instrument applications. |
The applications for pure lab water range from the life sciences and analytical instruments (which mostly require ultrapure ASTM Type I supply systems); to chemical and biochemical reagent prep and final glassware washing (Type II); to lab autoclaves and heating baths (Type III). Clinical water systems are also available that meet specific standards for clinical analyzers.
ASTM requirements for Type I pure water include a conductivity of 0.056 micromhos/cm, resistivity of 18.2 MΩ-cm, total silica of 3.000 µg/L, TOC of 50.000 µg/L, chlorides of 1.000 µg/L and sodium of 1.000 µg/L. ASTM Type II loosens those values to 1.000, 1.000, 3.000, 50.000, 5.000 and 5.000. And ASTM Type III values increase to 4.000, 0.250, 500.000, 200.000, 10.000 and 10.000. pH is no longer specified for Type I, II and III reagent water because these water grades don’t contain components to alter pH.
There are a number of lab water purification technologies available for meeting the specific requirements of each of these water types. The technologies include carbon adsorption, distillation, electrodeionization, filtration (and ultrafiltration), ion exchange, reverse osmosis and ultraviolet radiation. Users will often mix and match these water purification technologies to meet their specific water (and cost) requirements based on feed water quality, the type and level of expected contaminants, the volume of expected water usage on a daily basis, and the specific quality of water desired.
As noted, some areas of water purification technologies are evolving. Carbon adsorption and distillation are mostly mature with few changes expected by either users or equipment suppliers over the next several years. Both groups, however, expect to see changes in filtration (and specifically ultrafiltration) because of the development of improved filter and nano-filter media.
Continuing improvements in electrodeionization technologies are expected to be seen in this area over the next five years. “The increased integration of electrodeionization, such as Millipore’s ELIX technology, into ultrapure water systems will ensure consistent water quality and reduced operating costs,” says Renaud Bardon, director of sales and service lab water at Millipore. “Electrodeionization is also environmentally friendly because no chemicals are used to regenerate the ion exchange resins.”
Improvements are also expected in water purification systems due to new membrane technologies. “Nano materials research will introduce new thin film membranes that could change water purification technology dramatically,” says Bob Applequist, product manager at Labconco.
Some changes in ion exchange systems are expected in the continuing evolution of ion exchange resins. This process is often used as a pretreatment to reduce the hardness of feed water prior to reverse osmosis (RO) processing. Deionization (DI) systems effectively remove ions from water systems, but they don’t remove most organic contaminants or micro-organisms. Micro-organisms can actually attach themselves to the DI resins, thereby creating a culture media for bacterial growth and subsequent generation of pyrogens. DI systems are best used in combination with other purification technologies, such as RO, filtration, and carbon adsorption.
Water distribution
Support of analytical instrumentation and life science applications are the leading pure water systems in research laboratories. | While a variety of water types and technologies are available to researchers, the actual distribution of the water is an important consideration in the implementation of a pure lab water system.
“Ultrapure Type I water systems are always point-of-use systems,” says Thermo’s Wisniewski. Other than those restrictions, the primary consideration in this area is “how to use a water system without making my life harder,” she continues. “Central water systems generally require more work from the user and are thus not as highly considered.” She also notes that “final filters are much more prevalent now right at the end-use point,” mostly to ensure the quality of the water used in the actual experiment, and often to make the researcher feel more comfortable about the system capabilities. “Users will actually mix and match filters for their specific requirements.”
At the other end of the water system, researchers should always strongly consider the characteristics of the feed water, says Wisniewski. “They’re all different and will all require some different aspect of pretreatment.”
“Dispensing water at the point-of-use, such as with Millipore’s POD (point of dispenser) concept, considerably improves the ease of use and flexibility for the scientist,” says Millipore’s Bardon. “POD units designed for specific applications also enable advances in analytical detection. For example, Millipore introduced its POD Element that can remove trace elements and improve trace level analysis using ICP-MS, LC-MS and other hyphenated techniques.” POD-type units can also remove contaminants that affect life science experiments, such as RNAse and endotoxins. Millipore’s Biopak filter removes these contaminants at their point of use, which eliminates concerns about contamination occurring after water leaves the purification unit. Such devices also eliminate the need for cumbersome sanitizations.
Users and suppliers of pure lab water systems expect significant technology growth in ultrafiltration and electrodeionization systems over the next five years. | The development of new point-of-use lab water purification systems is expected to see dramatic changes over the next five years, says Greg Crescenzi, VP of marketing at Pall Life Sciences. He also expects to see the multi-staged purification of lab water supplies from a single consumable in the next five years. The developments achieved in pure lab water supplies and systems are likely to spill over into the production area as well. “We plan to adopt equivalent standards for production water, and we’ll see more dedicated equipment for lab water production and installations for distributing water in labs,” says Javier Escobar at Telstar Water Systems.
Water measurement
“Laboratory instruments will continue to become smaller, more productive and tailored to the needs of the industry, says Zoe Grosser, director of the environmental market at PerkinElmer. “Clean water is essential in the lab, and although those goals have been well achieved for several years on the organic side, decreased organic banks
are desirable. For example, laboratories may require measurement of additional analytes at increasingly lower levels while maintaining their productivity. Mass spectrometry will continue to play a more dominant role in the laboratory.”
Nearly half of all researchers continuously monitor the quality levels of their pure lab water supplies. | Resistivity is the most measured aspect of pure lab water supplies, according to the Laboratory Equipment reader survey. Nearly two-thirds of respondents picked this as a measurement criterion. Other criteria chosen include pH (41% of respondents), bacteria content (34%), total organic carbon (TOC, 31%), total dissolved solids (29%), particulates (24%), and absorbance (14%).
The instruments used by researchers to make these measurements include pH meters (48% of survey respondents), HPLC instruments (21%), particle characterizers (16%), flow meters (15%), temperature instruments (13%), microscopes (12%), and TOC analyzers (7%).
In conclusion, while the specifications and standards for pure lab water haven’t changed significantly over the past several decades, the systems monitoring and providing that water have evolved to ensure the most cost-effective and reliable water possible. ●
For more information, contact Labconco, www.labconco.com, 800-821-5525; Millipore, www.millipore.com, 800-548-7853; Pall Life Sciences, www.pall.com, 734-913-6357; PerkinElmer, www.perkinelmer.com, 203-402-7118; Telstar Water Systems, www.tpro.com, 34-91-3717970; and Thermo Scientific, www.thermo.com,
508-742-5254.
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