Cleaning the pH meter probe prior to measuring the pH of media

EN 1040:2005

Quantitative suspension test for the evaluation of basic bactericidal activity of chemical disinfectants and antiseptics.

EN 1040 is a phase 1 suspension test for the evaluation of basic bactericidal activity in chemical disinfectants. The result of a basic suspension test cannot be used to substantiate product claims and it is not valid for product registration. The test is applicable to active substances (antibacterial biocides) and to formulations under development that are planned to be used in food, industrial, domestic and institutional, medical and veterinary areas.


Test Conditions


The standard refers to the parameters to be observed when testing products for basic bactericidal activity. This includes the test microorganism, test temperature and contact time. 

One of the major differences between phase 1 basic suspension tests and phase 2 step 2 suspension tests is that phase 1 basic suspension tests do not include interfering substances in the test procedure.

Refer to the table below for the minimum test conditions for EN 1040.


Test Method


In a phase 1 suspension test, 8 parts of the test product is added to 1-part test microorganism and 1-part water. The mixture is allowed to interact for the duration of the contact time. One part of the mixture is added to 8 parts of neutralizer and 1-part water for 5 minutes to halt bactericidal activity. The final mixture is then acquired and incubated for 2 days to allow surviving bacteria (if any) to proliferate. The bacterial colony is counted and compared against the original culture size.

Diagram 1: EN 1040 test method


Log Reduction


Log reduction refers to the extent to which a product is capable of reducing the number of microbes. For example, 4-log reduction means the number of microorganisms on a surface has been reduced by 10 000 times. A product that is 99.9% effective against a certain microbe is said to have achieved 3-log reduction against that microbe.

For a product to pass EN 1040, it must be able to achieve 5-log reduction against the respective test microorganisms listed in Table 1. In other words, the product must be able to kill 99.999% bacteria while meeting all the other requirements of the European standard.

Difference between test product that pass & fail EN 1040 for S. aureus

Email us at to see how we can help you