Rapid, Simple and Matrix‐Versatile Determination of Paclobutrazol in Complex Samples Using Salting‐Out Assisted Liquid–Liquid Extraction Preconcentration and High‐Performance Liquid Chromatography With Ultraviolet Detection

ABSTRACT Paclobutrazol (PBZ) is a widely used triazole plant growth regulator whose residues in fruits, traditional Chinese medicinal materials, and biological matrices raise increasing concerns for food safety and pharmacopoeial quality control. Routine monitoring is dominated by liquid chromatography–tandem mass spectrometry (LC‐MS/MS), whereas high‐performance LC with ultraviolet detection (HPLC‐UV) is rarely used because PBZ absorbs in the deep ultraviolet region near 220 nm, where co‐extracted matrix components often cause severe interference. Here, a simple salting‐out assisted liquid–liquid extraction procedure based on acetonitrile and sodium sulfate was developed to provide simultaneous clean‐up and preconcentration prior to HPLC‐UV. Under the optimized conditions, PBZ showed good linearity over 0.5–5.0 µg/mL, with a limit of detection of 0.10 µg/mL. The method was successfully applied to representative complex matrices, including Ophiopogon japonicus , passion fruit, citrus, urine, and plasma, giving recoveries of 83.6%–107% with relative standard deviations ≤4.0%. These results demonstrate that an optimized salting–out–assisted liquid–liquid extraction step can substantially improve the feasibility of deep‐ultraviolet detection of PBZ using widely available instrumentation, providing a rapid and cost‐effective option for routine screening and quality control.