Reference 

Color Change Conditions

54 ℃ ± 1 ℃

60% RH ± 10% RH

600 mg/L ± 30 mg/L

100%EO  40mins

FAILURES

PROCESSED AND 

SATISFACTORY

• The LISTER LCE50 Type 4 Chemical Indicator for EthyleneOxide is a paper strip 1.7 cm 

wide by 10 cm long printed with a chemical indicator ink that turns from red to blue when 

exposed to critical parameters of the ethylene oxidesterilization process

 (i.e., gas concentration, RH, time andtemperature), offering immediate visual results. 

• The chemical indicator strip is an easy-to-handle internal packmonitor for all warm and cool 

cycles of 100% EO and EO/HCFC (hydrochlorofluorocarbon) gas mixture sterilizer cycles.

 How the LISTER MULTIVARIABLE 

 CHEMICAL INDICATOR works?

The Ethylene Oxide chemical indicator strips can be placed in trays, containers, or pouches 

to be sterilized.

The indicator ink on the chemical indicator strips is designed for easy interpretation with a 

color change from red to blue (or lighter blue).

During a successful sterilization cycle, the indicator will show a passing result upon exposure 

to the critical sterilization variables outlined in ISO 11140-1 for Ethylene Oxide. 

The key variables include:

Ethylene Oxide Concentration: Ensuring there is an adequat concentration of ethylene oxide 

to kill microorganisms.

Relative Humidity (RH): Guaranteeing sufficient humidity to enhance the bactericidal effect 

of ethylene oxide.

Time: Ensuring the sterilization process lasts long enough for ethylene oxide to effectively 

kill all microorganisms.

Temperature: Ensuring the sterilization process is conducted at an appropriate temperature 

to maximize the 

bactericidal effect of ethylene oxide.

If any of these critical variables do not meet the requirements specified by the standard, the 

indicator will not show a passing result.This means that the sterilization cycle may not have 

achieved the expected sterilization effect and may need to be repeated.

The possibility of unit sterilization failure is high, and the release of this unit should be determined 

based on the results of Bl and risk assessment, and the sterilizer should be inspected.

The main failure causes are: 

» Inadequate cycle duration

» Improper cycle selection 

» Overloading/incorrect loading of the sterilizer

» Poor gas quality

» Sterilizer malfunction

» Blocking indicator with large metal mass