How to Choose an Appropriate Detergent

detergent bubblesby Carmen Raymond

Since pure water cannot remove sticky, organic soiling, protease, amylase, lipase or carbohydrase, most cleaning is performed using detergents and soaps. Soap cleans by emulsifying liquids. That means it enables oil and water to blend. Then, the contaminants are extracted during rinsing.

During World War I and World War II, animal and vegetable fats used to produce soap were in short supply, prompting the creation of detergents. The word “detergent” is derived from the Latin word "detergere," which means "to wash away."

Surfactants, which are easily made from petrochemicals, are the main components of detergents. Surfactants make water 'wetter' by making it less likely to adhere to itself and more likely to interact with oil and grease. Surfactants are just one component of modern detergents. Some detergents also contain:

  • Enzymes to degrade protein-based stains
  • Bleaches to de-color stains and add strength to cleaning agents
  • Blue dyes to counteract yellowing

Detergents, like soaps, are comprised of hydrophobic (water-hating) and hydrophilic (water-loving) molecular chains. Water naturally repels hydrophobic hydrocarbons, which are drawn to oil and grease. In a good detergent, the hydrophilic end of the molecular chain attracts water while the hydrophopbic (oil-binding) end of the molecular chain attracts oil and grease.

Mechanical energy or friction magnifies the cleaning ability of the detergent, helping the detergents or soaps binding to the soil. By swishing the soapy water around, the soap or detergent is able to drag the grime away from dirty surfaces and into the greater pool of rinse water. The detergent and soil are washed away during the rinsing process.

Warm or hot water also helps the soap or detergent remove the soil. It pulls the grime away into the rinse water by melting fats and oils. Detergents are similar to soap, but they are less likely to form films (soap scum) and are unaffected by mineral content in the water (hard water).

When it comes to selecting the best detergent for your cleaning needs, the pH of the detergent is critical.

  • Acidic cleaners are widely used to brighten or etch metals, and they are good at removing mineral particles and oxidation. Acidic cleaners are generally effective at extracting acid labile substances such as starches, carbonates and insoluble hydroxides.
  • Alkaline cleaners are very effective, since most soils are acidic. Organic traces are removed with alkaline cleaners. Oils, fats, greases, proteins and a variety of other soils are among them. An alkaline cleaner, or a mixture of an alkaline cleaner and an acidic cleaner, can be used in most cleaning applications.

Life science companies understand that having the reagents and samples to communicate predictably and efficiently is critical to their lab product's success: in other words, getting the chemistry correct.

WPI offers alkaline cleaners for the pharmaceutical, biotech, medical device, healthcare, precision engineering, and other sectors.