High concentration

A concentrated solution for better results

The majority of British colloidal silver manufacturers offer solutions between 10 and 25 ppm. After months of research and laboratory tests, Institut Katharos succeeded in producing a solution dosed at 40 ppm, double the average concentration on the market.


Before we go any further, let’s explain the acronym ppm: it means parts per million. In reality the ppm number is a proportion unit just like a percentage, it could well be converted to “parts per hundred”.

In the context of colloidal silver, this means that in a 40 ppm colloidal silver solution, there are 40 milligrams of silver in 1 litre of purified water. Likewise there are 20 milligrams of silver in 1 litre of 20 ppm colloidal silver.






1. An pure colloidal silver


Many factors must be taken into account when producing high quality colloidal silver. One of the most essential criteria is its concentration. We have to remember that at the start of the 20th century concentrations of 100,000 ppm were being sold. The current production method allows the effectiveness of the colloidal silver to be improved significantly so that its concentration can be reduced. This production mode is via electrolysis, where silver ions are released into purified water via electric current.


Several studies*1-4 have revealed that the concentration of the colloidal silver solution has a direct impact on its efficacy.

Let us look at a study completed at the University of Kenya*1 proving that 20 ppm colloidal silver is more effective than 5 ppm colloidal silver (we can see for example that the 20 ppm colloidal silver kills about 200 times faster than the 5 ppm colloidal silver for isolate 1):


Let’s also look at a study published in the journal “Advances in Natural Sciences: Nanoscience and Technology” which concludes that the higher the concentration, the more effective the colloidal silver is*2.

Two bacteria were tested after 24 hours:

Here is a third study that tested the antifungal qualities of colloidal silver on green onions. Concentrations between 1 and 200 ppm were tested and the higher the concentration the less fungi developed*3:

In the final study concentrations between 5 and 50 ppm came up against E. coli bacteria*4. The authors wrote:

“The results indicated that the activity of respiratory chain dehydrogenases of E. coli could be inhibited by SNPs [silver nanoparticles], and the higher concentration of SNPs, the lower the activity of enzymes.

Based on this information we conducted numerous tests over many months in order to be able to produce a colloidal silver with a concentration of 40 ppm.


We are proud to be the only manufacturer, who produces such a highly concentrated colloidal silver via electrolysis. It is the most effective production method and independent laboratories have certified our colloidal silver.



2. A colloidal silver that offers good value for money


In addition to offering a high concentration, our solution is one of the most inexpensive colloidal silvers, per milligram of silver, on the market.


We must think in terms of the quantity of active ingredients, in this case the amount of silver in the solution. Many food supplements like omega­3 or vitamin D are dosed differently depending on the manufacturer. Some vitamin D pills contain for example 100 IU (international units) whereas others contain 5,000 IU, which is 50 times more! If both products contain the same number of pills and the first package is two times cheaper than the second, it is in reality 25 times more costly in terms of vitamin D concentration. For that reason you have more interest in choosing the second package in terms of a price­performance ratio.

The same logic applies for colloidal silver.


3. A natural colloidal silver


Our cost-­efficient and highly concentrated colloidal silver does not cause argyria, in light of the amount of silver that would be required for this. As mentioned above, concentrations of colloidal silver at the start of the 20th century were around 100,000 ppm and could even reach 300,000 ppm for certain products like Argyrol*5.


Two scientific studies mention a limit in terms of how many grams of silver would need to be ingested or applied in order to develop the first signs of argyria. Another study by Dr. Altman proves the body’s ability to excrete silver easily.


Scientific report from the middle of the 20th century

In “Argyria; the pharmacology of silver” published in 1939, the authors Hill and Pillsbury mentioned that they registered 357 cases of argyria in the USA between 1700 and 1939*5. In nearly all of these cases the argyria was caused by the ingestion or spraying of silver nitrates, Argyrol (silver proteins for the nose between 100,000 and 300,000 ppm) or Collargol (silver protein ointment of 150,000 ppm).



According to the researchers argyria problems begin after the ingestion of 6 grams of silver nitrates (not colloidal silver). The equivalent would be 150 litres of colloidal silver with a concentration of 40 ppm or 300 bottles of 500 ml.


EPA Report

Another more recent study (1996) was conducted by the EPA (Environmental Protection Agency).

According to the EPA:

“No evidence of cancer in humans has been reported despite frequent therapeutic use of the compound over the years. [...] An uncertainty factor  [...] is applied to account for minimal effects in a subpopulation which has exhibited an increased propensity for the development of argyria. The critical effect observed is a cosmetic effect, with no associated adverse health effects."

The EPA suggests a maximum daily dose of 350 micrograms for a person weighing 70 kg*6 assuming 4% retention of the ingested silver. This is slightly less than 10 grams of colloidal silver over 70 years for a person weighing 70 kg, or the equivalent of five hundred 500ml ­bottles of colloidal silver.


Dr. Robert Altman published 1999 a study with the title “Colloidal silver - Where does it go when you drink it? How long does it stay there?”. Here is its interesting conclusion*7:

"Ingestion of properly prepared CS does not result in silver accumulating in the body. There is no evidence that silver deposits significantly in hair or fingernails and, in fact, the data support the conclusion that after taking more than 2 mg of CS per day for several months, silver seems to be purged from the body (mostly through urine) at about the same rate at which it is consumed."

As you can see it is extremely difficult to reach the theoretical thresholds of argyria with colloidal silver concentrated at 40 ppm.

To date no cases of argyria have been reported following the ingestion or use of colloidal silver that is manufactured by electrolysis and without additives.



1) Study published in 2007 in "Scientific Research and Essay": “Antibacterial efficacy of colloidal silver alone and in combination with other antibiotics on isolates from wound infections” - with a concentration of 20 ppm all bacteria died, whereas one single species survived with a concentration of 5 ppm:



2) Study “Powerful colloidal silver nanoparticles for the prevention of gastrointestinal bacterial infections” published in 2012 in the journal “IOP publishing” - the higher the concentration the more effective the solution:



3) Study “The Effect of Nano-Silver Liquid against the White Rot of the Green Onion Caused by Sclerotium cepivorum” published in 2012 in the journal “Advances in Natural Sciences: Nanoscience and Nanotechnology” - the higher the concentration the more effective the solution:



4) Study, published in 2009, comparing a solution of 10 ppm and of 50 ppm: “Antibacterial activity and mechanism of silver nanoparticles on Escherichia coli”



5) Report by William R. Hill and Donald M. Pillsbury on over 300 reported cases of argyria in "Argyria - The Pharmacology of Silver", 1939:



6) Revised EPA report on silver,1996: https://web.archive.org/web/20150206003217/http://www.epa.gov/iris/subst/0099.htm


7) Study by Dr. Altman on the capacity to eliminate silver: “Colloidal Silver: Where does it go when you drink it? How long does it stay there?":




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