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Laboratory Water Types

Norms define different laboratory water grades for both technical and economical reasons. The purpose of these norms is to ensure that the right water quality is used for a specific application, while limiting laboratory operating costs – Type I water is more expensive to produce than Type II or Type III water.

Type III Water

Type III water is the lowest laboratory water grade, recommended for glassware rinsing, heating baths and filling autoclaves, or to feed Type I lab water systems.

Type II Water

Type II water is the grade used in general laboratory applications such as buffers, pH solutions and microbiological culture media preparation; as feed to Type I water systems, clinical analyzers, cell culture incubators and weatherometers; and for preparation of reagents for chemical analysis or synthesis.

Type I Water

Type I water is the grade required for critical laboratory applications such as HPLC mobile phase preparation, blanks and sample dilution in GC, HPLC, AA, ICP-MS and other advanced analytical techniques; preparation of buffers and culture media for mammalian cell culture and IVF; production of reagents for molecular biology applications (DNA sequencing, PCR); and preparation of solutions for electrophoresis and blotting.

Using Type I water for Type II water applications is a common laboratory practice in order to decrease the risk of artifact generation during experimental procedures.

Laboratory Water Specifications

Different published norms define the quality required for specific laboratory water applications: ASTM® and ISO® 3696 for laboratory applications; CLSI guidelines for clinical laboratories. Some laboratories will also use norms defined in the European or the US Pharmacopoeia.

The table below outlines the different water specifications based on the different water types.

Contaminant	Parameter and unit	Type III	Type II	Type I
Ions	Resistivity (MW.cm)	>0.05	>1.0	>18.0
Organics Pyrogens	TOC (ppb) (Eu/ML)	<200 NA	<50 NA	<10 <0.03
Particulates (units/mL)	Particulates > 0.2 µm	NA	NA	<1
Colloids	Silica (ppb)	<1000	<100	<10
Bacteria	Bacteria (cfu/mL)	<1000	<100	<1

These values are only guidelines, as some specific laboratory applications may require a quality superior to the quality indicated by the norms. For instance, several molecular biology applications require Type I water that is both RNase-free and DNase-free; elemental trace analysis at sub ppt levels requires water of a higher purity than regular Type I water; and glassware washing may require pyrogen-free water for some experiments. Millipore has done extensive research into laboratory water applications. This information, compiled as internal research notes or references to scientific articles, is provided on demand by our Application Specialists. (Visit www.millipore.com/offices to find your nearest contact).

Water Systems Adapted to Specific Needs

Millipore’s range of water purification systems is designed to provide laboratories with systems covering the three different water types in an efficient and economical way with adapted monitoring and quality assurance.

The graph below shows a summary of the systems available and can help you select the system best suited to your application needs. However, each laboratory has its own constraints and our application specialists are available to answer your questions and support you in the design of the system that best matches your needs.

Millipore lab water systems can be combined to achieve specific laboratory objectives. For instance, a RiOs system combined with a reservoir and a Milli-Q system will fulfill the following requirements
in a laboratory:

Production of Type III water for non-critical applications such as feed to a glassware washer
Production of Type I ultrapure water for critical laboratory applications

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