Rapid and sensitive determination of plasticizer diethylhexyl phthalate in drink by diffuse reflectance UV spectroscopy coupled with membrane filtration

A rapid, sensitive and selective method for the determination of illegal additive diethylhexyl phthalate (DEHP) in drink was proposed. The method was based on membrane filtration-enrichment and diffuse reflectance UV (DRUV) spectroscopy. The DEHP solution was passed through the membrane, and then quantified directly on the membrane surface by using an integrating sphere accessory of the UV spectrophotometer. Effects of pH value, sample volume and vacuum degree were investigated in order to optimize the sensitivity. The absorbance of the UV spectra was linearly related to the concentration of DEHP in the ranges of 0.03–0.7 mg/L and 1–5 mg/L, with the squared correlation coefficients (R2) being 0.9911 and 0.9928, respectively. Under the chosen optimal conditions, the limit of detection (LOD) was 0.0079 mg/L. The recoveries were between 99% and 105% when the real drinks were analyzed, and the relative standard deviation (RSD) ranged from 1.0% to 5.0%.