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difference between distilled water and deionized water - (Oct/16/2005 )

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DI water does not remove any uncharged materials or solids expect by limited passive "filtration". Distilled water does.


MilliQ water is NOT sterile.

Appl Environ Microbiol. 1993 May;59(5):1410-5. Links
Distribution of bacteria within operating laboratory water purification systems.McFeters GA, Broadaway SC, Pyle BH, Egozy Y.
Department of Microbiology, Montana State University, Bozeman 59717.

Experiments were conducted to measure communities of bacteria within operating ultrapure water treatment systems intended for laboratory use. Samples from various locations within Milli-Q Plus and Milli-Q UV Plus systems were analyzed for populations of planktonic bacteria at weekly intervals over 3 months of operation. Relatively high initial densities of planktonic bacteria (10(2) to 10(3) bacteria per ml) were seen within both units when they were challenged with source water of poor quality, although the product water continued to be acceptable with regard to bacterial numbers, resistivity, and endotoxin concentration. Under more normal operating conditions, significant differences were seen in planktonic populations throughout the systems with excellent product water quality. A great deal of variability was observed in biofilm populations analyzed from various system surfaces after 3 months of operation. The concentrations of planktonic bacteria and biofilm densities were much lower in the unit containing a UV lamp. These findings suggest that a range of microenvironmental conditions exist within purified water systems, leading to variable populations of bacteria. However, product water of excellent quality was obtained despite the bacterial communities.


QUOTE (mdfenko @ Apr 11 2007, 12:17 AM)
QUOTE (Zouden @ Apr 10 2007, 02:40 AM)
No. MilliQ water is sterile when it comes out of the machine, and it's probably more pure than the steam used in the autoclave.

it may be sterile when it gets past the ultrafilter but then it has to travel through tubing (usually tygon) which may (and often does) have organisms growing on it.

so, you probably should sterilize. if you don't want to use an autoclave then you can filter sterilize.

I think filter sterilize might be right, however, definately not autoclave, when you autoclave it ,steam gets into the MiliQ water, bringing in some ion i think.


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On a slightly pedantic note, does anyone have a clear definition of the differences between the two above terms? In the case in point the plant I am wormking on uses Milli Q RO water, which some people refer to as deionised and others as demineralised. The Millipore columns are fed from a double distilled storage tank, and the output leaves virually no dry residue on 0.02 micron filters.

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Double-distilled water is in commonest use in our lab, we use it for normal procedures.
MilliQ is more used in Proteomics.


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