Why Does Your Clean Laundry Stink? Chromatography Investigates!

Washing clothes is an onerous task with the washing basket forever full. Leave it a few days and the aroma can be quite disgusting — particularly if teenaged boys are involved. As we are encouraged to reduce the amount of water we use, the quantity of chemicals and to wash at 20?C to save energy — how can we be sure our clothes come out clean?

A team from the Department of Applied Sciences based at Northumbria University in Newcastle upon Tyne has looked at the problem of smelly laundry — both pre- and post-wash — and has developed a new chromatography method to measure specific markers linked to smelly washing.

Malodourous clothes — not just a body problem

Sweat from our bodies is odourless until the bacteria present on our skin get to work. The bacteria — Corynebacterium and some Staphylococcus species — break down our sweat, skin cells and other secretions and produce volatile compounds (VCs) including ammonia, hydrogen sulphide and fatty acids. It is these compounds that create our own personal smell.

But it is not just bodily processes that can cause our clothes to smell. Volatile compounds can be found in washing and drying machines — where poor hygiene practices can contribute to a build-up of bacteria in the machines. Whereas in the past we washed our clothes at 40?–60?C — nowadays we are encouraged to use much lower temperatures, and malodour is more noticeable at these lower temperatures.

T shirts, socks and SHS-MCC-GC-IMS

In the paper — Source, impact and removal of malodour from soiled clothing — published in the Journal of Chromatography A, the team developed a GC method to detect typical malodour VCs and evaluated a low temperature washing process.

The team used six males and two females who wore new socks on cleaned feet for a 10-hour period, before sealing the socks in bags. Nine male volunteers also wore a freshly laundered t shirt during a five-a-side football match to allow underarm odour analysis.

The clothing was assessed and graded for malodour before samples were taken from the socks (toe, ball and heel areas) and t shirts (underarm area) for instrument analysis. After sampling, the clothes were washed using a non-perfumed detergent at 20?C before they were again tested for malodour and samples taken for analysis.

The team used a method called static headspace -- multi-capillary column -- gas chromatography -- ion mobility spectrometry (SHS-MCC-GC-IMS) to analyse the samples. The method was chosen because of its selectivity towards the likely VCs. Other methods that can be considered when analysing smells are discussed in the article, Sample Preparation Options for Aroma Analysis.

Clean, smelly clothes?

The team identified six main compounds that contributed to malodourous clothes. As expected, both the socks and t shirts became less smelly after washing — but the research has shown that some VCs are present throughout the process. The team suggest these could be used as markers to measure the effectiveness of a washing process.

Now, where’s the Lynx?