Abstract: According to GB/T 13174-2008,standard detergency and cycle of washing performance of reference liquid detergents appended with separate kinds and concentrations of fluorescent brightening agent were tested.Results showed that standard detergency and cycle of washing performance of the reference liquid detergents containing fluorescent brightening agent are significantly better than the reference liquid detergents if UV containing light source is used.Meanwhile,the more the dosage of fluorescent brightening agent,the higher the value of detergency and brilliance preserved.There are no obvious differences in standard detergency and cycle of washing performance between them if the light source does not include UV.It is clear that fluorescent brightening agent does not display detergency and anti soil re-precipitation performance,but it will improve the determination results of standard detergency and cycle of washing performance of liquid detergent obviously.The essential suggestions of more reasonable evaluation of detergency are that when washing is proceeded according to GB/T 13174-2008,the samples are tested by colorimeter under the illuminant without UV (in this case,the illuminant with wavelength lower than 400 nm has been filtered out),or the samples are tested under the illuminant with UV,but by using liquid detergents appended with fluorescent brightening agent as the reference.Meanwhile,there is no unified stipulation with respect to type and specification of the brightness meter to be used in GB/T 13174-2008.Different data of detergency and brightness preserved after cycle of washing will be obtained if the detergents appended with fluorescent brightening agent are tested with brightness meter of different types or specification.Therefore,the regulations in GB/T 13174-2008 should be revised for improvement as soon as possible.

Key words: liquid detergent, fluorescent brightening agent, detergency, cycle of washing performance, UV