Lai S, Nielsen B, Andrews N, Thompson CK.
J Hosp Infect. 2021 Jul 21:S0195-6701(21)00270-X. doi: 10.1016/j.jhin.2021.07.007. Epub ahead of print. PMID: 34302884.
Highlights
- Microbiology testing laboratories commonly use sample bottles containing sodium thiosulphate as the neutralising agent for oxidising biocides and these are readily available as commercially prepared and sterilized products.
- Bottles are typically supplied with a concentration of 18 mg/L sodium thiosulphate (after filling with the sample) which will neutralise up to 5 mg/L free chlorine; this is recommended for sampling of drinking water and neutralising typical levels of oxidising biocides.
- Sampling bottles with a higher dose of 180 mg/L will neutralise up to 50 mg/L free chlorine.
- The higher dose of 180 mg/L would be required to neutralise neutralise up to 0.08 mg/L of silver and 0.6 mg/L of copper ions.
- EDTA has been found to be ineffective as a neutraliser for silver and therefore should not be used in sample bottles for bacterial tests including those for pneumophila and P. aeruginosa.