Type | Conductivity at 25°C (max.) | Resistance at 25°C (min.) | pH at 25°C | TOC (max.) | Sodium (max.) | Chloride (max.) | Silica (max.) |
---|---|---|---|---|---|---|---|
1 | 0.056 µS/cm | 18.0 MΩ•cm | - | 50 µg/l | 1 µg/l | 1 µg/l | 3 µg/l |
2 | 1.000 µS/cm | 1.0 MΩ•cm | - | 50 µg/l | 5 µg/l | 5 µg/l | 3 µg/l |
3 | 0.250 µS/cm | 4.0 MΩ•cm | - | 200 µg/l | 10 µg/l | 10 µg/l | 500 µg/l |
4 | 5.000 µS/cm | 0.2 MΩ•cm | 5.0 - 8.0 | - | 50 µg/l | 50 µg/l | - |
Grade | pH at 25°C | Conductivity at 25°C (max.) | Oxidizable matter, oxygen content (max.) | Absorption at 254 nm and a length of 1 cm (max.) | Residue after evaporation by heating to 110°C (max.) | SIlicon content (max.) |
---|---|---|---|---|---|---|
1 | - | 0.1 µS/cm | - | 0.001 absorption units | - | 0.01 mg/l |
2 | - | 1.0 µS/cm | 0.08 mg/l | 0.01 absorption units | 1 mg/kg | 0.02 mg/l |
3 | 5.0 - 7.0 | 5.0 µS/cm | 0.40 mg/l | - | 2 mg/kg | - |
Glassware washing
This is a routine practice where glassware and instruments can be washed either by hand or using specifically designed equipment.
Type 3 water is sufficient for most applications, however for more sensitive techniques Type 2 should be used. For the critical applications such as cell culture, ICP-MS or clinical methods, glassware should be washed with Type 1 water.
Heating Baths
Often, it is thought that tap water will be sufficient for heating baths as the purpose is to keep constant and regulated temperatures. While this is true scaling poses a large problem and will affect the maintenance and product life. If the water is too pure on the other hand, rusting can occur.
Type 3 water is, therefore, sufficient for heating baths.
Autoclave Filling
Autoclaves are used in medical applications for the sterilization of equipment. This is done by subjecting the items to high-pressure steam to get the temperatures of the water greater than 100 °C.
Steam Generators
Steam generators are used in a range of applications, including clean room humidification, autoclaves and sterilisers. Most steam generators would benefit from pre-treatment of the water to avoid build-up.
Type 3 water can be used for steam generators, however, if the steam is being used in disinfection services in healthcare environments, it is advised to check the strict specifications which are applied by some authorities.
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Flame Atomic Absorption Spectroscopy (FAAS)
FAAS is used for determining metals and metalloids in solution at ppb or ppm levels.
To ensure precision and accuracy of measurements, Type 2 water with a resistivity greater than 5 MΩ.cm is suitable.
Graphite Furnace Atomic Absorption Spectroscopy (GF-AAS)
GF-AAS uses a small carbon tube rather than a flame to atomize the sample. It is a very sensitive method which is suitable for the measurement of ultra-trace levels of elements, typically below 1 ppb.
This means that Type 1 water would be required for GF-AAS.
ICP-AES or ICP-OES
Inductively Coupled Plasma Atomic (or Optical) Emission Spectroscopy (ICP-AES or ICP-OES) is an analytical technique used for the detection of trace metals and multi-element analysis.
Type I water is recommended for this technique.
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Cell culture is a commonly used laboratory technique, where cells are grown under controlled conditions typically outside of their natural environment. Ultrapure water (Type 1) should be used for the preparation of media and buffers to ensure that cells are free from bacterial, yeast and viral contaminants. Contamination of cell culture by metal ions, endotoxins, bacteria or fungi can impact the culture directly or indirectly (e.g. changes in pH).
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Water purification systems are used to feed many different functions within clinical analyzers. The most important aspect of water for automated pathology analysers is reliability, and therefore must be compliant with a the appropriate water quality standards such as CLRW.
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Gas chromatography is one of the most sensitive and commonly used analytical techniques for the separation and determination of various compounds. The use of water within the process of gas chromatography is rather limited, however Type 1 water will be required for sample preparation. In addition, water will be used for blank preparation and sample standards if the sample being analyzed is of an aqueous nature.
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Ion Chromatography
Ion chromatography allows the separation of ions and polar molecules based on their interaction with a column of ion-exchange media.
High-Performance Liquid Chromatography (HPLC)
High-pressure liquid chromatography, now known as high-performance liquid chromatography (HPLC), is a chromatographic technique used to identify, quantify, separate and purify individual compounds present in a mixture.
Ultra High-Performance Liquid Chromatography (UHPLC)
Ultra-high performance liquid chromatography (UHPLC) is a variant of HPLC which uses smaller particles to enhance chromatographic performance and requires higher pressures. In a similar way to HPLC, the water contaminants can negatively impact on results, however, due to the higher sensitivities of the UHPLC, this can be more extreme.
As LC is capable of extremely low detection limits, the recommended water requirement is Type 1 water.
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Quantitative analysis
Quantitative analysis is used to determine what ion is present in a solution.
SPE - Solid Phase Extraction
SPE consists in a sample preparation process used to separate compounds dissolved or suspended in a liquid mixture.
Total Organic Carbon (TOC) analysis
TOC is the amount of carbon found in an organic compound and it's used as an indicator of water quality
The recommended water requirement is usually Type 1 water.
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Inductively coupled plasma mass spectrometry (ICP-MS)
Advances in modern analytical instrumentation have continue to improve the sensitivity of trace metal analysis, to the point that elements are now measured at ppt and sub-ppt levels.
As a result of the very high sensitivity requirements, Type 1/1+ are recommended.
Gas Chromatography - Mass Spectrometry (GC-MS)
Combining gas chromatography with mass spectrometry, Gas Chromatography - Mass Spectrometry (GC-MS) is used to identify different substances and has a very wide range of applications.
The requirement for water purity is extremely stringent as very low TOC levels are required. Based on this, Type I water is suitable for this technique.
Liquid Chromatography - Mass Spectrometry (LC-MS)
Liquid Chromatography - Mass Spectrometry (LC-MS) combines the physical separation of liquid chromatography with the analysis capabilities of mass spectrometry.
Type I water is generally recommended for this application.
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Microbiological analysis is the use of biological, biochemical, molecular or chemical methods for the detection and dentification or enumeration of microorganisms.
Make sure that you are using the right water type for your application. For most applications Type 1 water is required.
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PCR
Polymerase Chain Reaction (PCR) is a molecular biology technique which is used to amplify a piece of DNA, and generates thousands to millions of copies of a specific DNA sequence.
DNA / RNA sequencing
It's the process that includes any method or technology used to determine the precise order of nucleotides in a strand of DNA.
DNA microarrays
It is a collection of microscopic DNA spot on a solid surface.
Nucleic Acid Electrophoresis
It is an analytical technique used to separate DNA or RNA fragments.
The recommended water requirement is Type 1+ water.
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