My contribution to answering your question deals only with the amount of silver used in polyester fibers so as they have efficient antimicrobial properties. I hope that this information is helpful.

The silver content in polyester fibers vary enormously, and many of them have relatively lower silver content than what is stated below.

As far as I know, the fibers could be: silver - lined or nanoparticle-impregnated .

The fiber, lined with silver, may contain around 600 milligrams (mg) of silver per ounce of fiber. 1 ounce = 28.3495 g.

The nanoparticle-impregnated fiber, with the highest silver content, has about 75 mg per ounce of fiber.

Thanks Dr. Matar. We need to correctly know the silver content in the polyester fiber for this reason. Some times we observe good antibacterial effect (suitable for 90/10 blend)and sometimes not for same percentage of silver. We have already produced a very high percentage of silver polyester, and it gives permanent antibacterial effect.

Determination of silver content can be done via ICP-AES or AAS after acid digestion of the PET fibre. For this we use a microwave-induced digestion process in HNO3. In case silver ions fixed in zeolites are used for finishing of PET also HF should be added for performing the digestion.

Dr. Helga's suggestion is very good, but take care: If HF is to be used, then avoid the use of glassware since HF attacks glass . HF attack is enhanced by the presence of a strong acid, such as HNO3, and undesirable side products will form.

This is absolutely correct.

Thanks Dr. Helga and Dr. Nizar. I sent the sample to ITS and SGS international laboratory at Hong Kong. They used microwave-induced digestion process in HNO3, but the result is much lower than the actual amount we put into in it. I need to check, whether they used HF or not. Thank you for your suggestion. Could I take this opportunity to ask you which materials should be used if we can not use glass. Regards Manas

The glass substitutes we are using are made from PP and PFA, resp.

Regrads.

Helga

Thanks Dr. Thomas. Regards Manas

The silver compound may be aggregiated during the melt process.

With that reason, the silver content in the fiber could be different depending on sampling position.

I also recommend ICP with plentiful quantity of sample.

If you want to know the relationship between silver content and antimicrobial activity, TGA could be simple way.