Research on the identification and assay of hydroquinone in the preparation of
whitening night cream in Purwokerto beauty clinic has been studied. Ultravioletvisible
spectrophotometry method was used with the addition of phloroglucin as
forming a color complex. The results were linearity value (r) 0.99322, the limit of
detection 1.08 μg/mL; limit of quantitation 3.6 μg/mL; recovery 99.62% and
precission with a coefficient of variation value 0.88%. The method was applied to
assay of four samples taken with simple random sampling obtained hydroquinone
levels of 0.00344, 2.53, 2.84 and 3.36%.