I have reverse osmosis water in our lab to use, but I don't know how much pure is it to tabulate? Thank you.
I suggest measuring conductivity and TOC. Then compare it against the ASTM Type I and Type II benchmarks.
Most laboratory water purification systems contain a resistivity or conductivity meter and cell to monitor the purity level of the water. Resistivity is the reciprocal of conductivity and either may be used to inexpensively monitor the ionic purity of water. Resistivity or conductivity of water is a measure of the ability of the water to resist or conduct an electric current.
The ability of water to resist or conduct an electric current is directly related to the amount of ionic material (salts) dissolved in the water. Dissolved ionic material is commonly referred to as total dissolved solids or TDS. Water with a relatively high TDS will have a low resistivity and a high conductivity. The opposite is true for water with low TDS.
Important question. To varify your reverse osmosis water is pure or not for future uses in research purpose, you should compare presence of anions, cations, conductivity, dissolved organic carbon (DOC) with Milli-Q ultrapure water (MILLIPORE, USA). Such comparisson will give you reliable information to future uses.
Important question. To varify your reverse osmosis water is pure or not for future uses in research purpose, you should compare presence of anions, cations, conductivity, dissolved organic carbon (DOC) with Milli-Q ultrapure water (MILLIPORE, USA). Such comparisson will give you reliable information to future uses.
Purity of research grade water is measured by Electrical conductivity, Total dissolved solids , pH and total suspended solids. In addition to this trace elements and TSS must be within desirable limit of research activity in which such water is required.
Thanks everyone for your valuable feedback, really appreciate your help.
I think as a first tool you have to measure TDS and conductivity and compare results with the allowable limits of these parameters of distilled or deionized water.
pH EC TDS parameter check additionally what type of instrument you use check their quality
Water in your lab is probably pure or ultrapure water.
If there is just Reverse osmosis (RO) system, it is pure water. You can test by measuring conductivity or TDS. Reverse osmosis removes 95 to 99.5% of conductivity or TDS, so the water quality outlet depends on inlet quality. If you choose TDS or conductivity, measure outlet water first then inlet water. Oulet water TDS or conductivity should be less then 5% of the one of inlet water. TDS value between 1 to 15 mg/L is good indication (for RO permeate), but if the inlet water have 400 ppm of TDS, you will get something between 2 and 20 ppm of TDS in your pure water.
If there are another treatment after your RO system, let's say a Deionisation resin (DI system), your water can be close to ultrapure water. In that case, you can still measure conductivity or TDS (you'll get something less than 1), but the most indicated water purity measurement for ultrapure water is resistivity.
Note that TDS and conductivity are kind of "rough" or generic parameters for water purity. Depending on the kind of work or reseach is done in your lab, you need more specific analysis. A chemistry lab will scrutinise for some specifcs metals, volatile compounds, etc. Microbiology lab will scrutinize for bacteria, endotoxins, etc.
Preliminary test is TDS or conductivity which should be in the range of 1 to 3 ppm for most of the basic experiments involving water quality assessment. Ideally speaking research grade water is ultra pure water. The resistivity of the ultra pure water is 18.2 mho, indicating no dissolved ions or even CO2 which forms carbonic acid in aqueous media. That is why ultra pure water is generally collected and used immediately depending on the nature of the experiment. For many experiments in water analysis double distilled water suffices. Ultra pure water is ideal for doing bacterial contamination studies or where we desire to detect the concentration of the contaminant at ppb or ppt level. Double distilled water is sufficient for most of the physico-chemical parameters analysis depending on the detection limits your instruments can measure.
Thank you
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