Today, as the general public continues to receive a steady stream of news about the contaminants that can be found in our water supplies, the obvious question for researchers is: “Are these substances also finding their way from the tap into the high purity water used in the laboratory, and if so, what are the consequences?”
Emerging contaminants are substances characterized by a real or perceived threat to human health or the environment, and for which no published health standard exists or is currently being developed. Although they are referred to as “emerging contaminants,” many of these compounds have existed for decades and their presence in water is not new at all. What is new, however, is the fact that these contaminants can now be measured at the very low concentrations at which they exist in our water supplies. The identification and measurement of emerging contaminants is closely related to the increasing sensitivity of analytical capabilities—such as mass spectrometry, a technology now able to detect virtually any new and potentially harmful contaminant at extremely low levels.
Impact on laboratories
Certain laboratories could be directly affected by the presence of emerging contaminants in the water they use for experiments. For example, analytical laboratories that assess and monitor the presence of such emerging contaminants must ensure their laboratory water is purified to the highest degree possible, so that even minute amounts of contaminant in the purified water do not interfere with trace level analyses. Similar water purity standards are also required by labs that develop sensitive methods for the detection of emerging contaminants and their metabolites in various matrices, as well as those that focus on toxicity testing.
Ensuring high purity lab water
Merck Millipore water purification systems remove a wide variety of contaminants by combining various purification technologies such as advanced reverse osmosis, electrode ionization (EDI), activated carbon, ion-exchange resins and ultra-violet photo oxidation. Point-of-use (POU) disposable cartridges (called Application Paks at Merck Millipore) have been designed to answer the needs of scientists requiring water free of specific contaminants.
At Merck Millipore, we routinely monitor reports of emerging contaminants and assess whether they are effectively removed via our existing water purification systems or perhaps will require additional purification steps. Two recent examples include perchlorates and endocrine disrupter chemicals (EDCs).
Perchlorate, used widely in explosives, solid rocket fuel, matches, and air bags, is one emerging contaminant that is currently receiving a great deal of attention. Chemically inert under most conditions, percholorate was not considered to be a hazardous substance until recently, and as a result, it was commonly disposed of through waste water systems. However, since the late 1990s and the development of a sensitive method for perchlorate detection in ground and surface water, an increasing number of environmental laboratories that monitor perchlorate in water and food now require perchlorate-free analytical grade water.
An ion chromatography method was developed at Merck Millipore to analyze perchlorate at the nano gram-per-liter level in high purity water. This method was then used to assess the removal efficiency of various combinations of water purification techniques. Since perchlorate was not present in the tap water used to feed our water purification systems, it was added to assess removal efficiencies. Our study showed that reverse osmosis alone removed 97 per cent of the added perchlorate, while ion-exchange resins and electrode ionization removed all remaining traces. A water purification system that combines these technologies ensures high purity water used in the laboratory that is free of perchlorate.
Endocrine disrupters (EDCs) are natural and synthetic substances that alter endocrine system functioning and consequently cause adverse effects in an organism or its progeny. Substances suspected of being EDCs include organohalogens (chloroform, dioxins), chemicals used in pesticides (DDT), and plastics (bisphenol A, phthalates). Research groups are actively designing sensitive analytical methods to identify and quantify EDCs for which high purity water is a requirement. In addition to EDCs entering the laboratory water from the tap, the materials used in the water purification system itself may contaminate water.
Merck Millipore designed a point-of-use disposable Application Pak that is optimized for EDC removal. This cartridge, which contains a specific type of activated carbon, is made of materials selected to prevent recontamination of the purified water. GC-MS analysis showed that water purified using a combination of technologies commonly used in our water purification systems with the addition of the specific Application Pak purifier contains no measurable amounts of EDCs such as phthalates and bisphenol A.
Water is central to a laboratory’s productivity and success. Scientists and water system manufacturers must work together to ensure that current water purification systems are able to remove contaminants that might impact experimental results, and when needed, design new strategies.
Authors are working with Merck Millipore