This analytical method is a validated measurement procedure for the determination of o-phenylphenol [90-43-7] in workplace air in a concentration range of one tenth up to twice the currently valid occupational exposure limit in Germany of 5 mg/m³. For sampling a defined volume of air is drawn through a binder-free quartz fibre filter followed by a silica gel sorbent tube. The flow rate is set to 1 l/min and sampling duration is 2 hours (which correspond to a sampling volume of 120 l). o-Phenylphenol is extracted with 2-propanol and subsequently analysed using liquid chromatography with diode array detection. The quantitative determination is based on a calibration function. The limit of quantification is 0.0183 mg/m³ based on an air sample volume of 120 l. The mean recovery is 94% and the expanded uncertainty for the validation range of 0.5 to 10 mg/m³ is 27 to 30%.