Optimization and Validation of Ultrasound-Assisted Extraction for Total Phosphorus Analysis in Cane Syrup

Cane syrup, a nutrient-rich by-product of sugarcane, is valued for its bioactive compounds and mineral content, including phosphorus, a vital macromineral essential for human bone health, enzyme activity, and plant metabolism. Conventional methods for total phosphorus analysis in such viscous matrices face challenges, such as matrix interference, high reagent consumption, and environmental impact. This study optimized and validated an ultrasound-assisted extraction (UAE) method combined with UV-VIS spectrophotometry for determining total phosphorus in cane syrup. UAE parameters were optimized using a simplex centroid mixture design to assess the effects of HNO₃, HCl, and ultrapure water as extraction solvents. UV-VIS spectra revealed that HCl-rich extraction solvents enhanced pigment production via the Maillard reaction, interfering with spectrophotometric detection. In contrast, ternary acid mixtures minimize these effects. The optimal conditions (1.67 mL HNO₃, 2.00 mL HCl, and 1.30 mL H₂O) achieved recovery rates of approximately 100%, without significant matrix interference. The validation of UAE combined with UV-VIS spectrophotometry demonstrated excellent selectivity and linearity (R² > 98.0%), low limits of detection and quantification (0.296 μg g⁻¹ and 0.898 μg g⁻¹, respectively), and good precision (RSD < 11%). The method’s accuracy was confirmed through a paired t-test comparison with microwave-assisted digestion (MAD), showing no significant differences (p > 0.05). UAE proved to be more environmentally friendly than MAD, with lower energy consumption (4.17 vs. 62.50 Wh/sample) and reduced reagent usage, as indicated by the AGREEprep metrics (scores: 0.41 vs. 0.30). The total phosphorus content in cane syrup samples varied significantly (11.48–129.54 mg kg⁻¹), influenced by geographical origin and production processes. The validated UAE method provides a fast, cost-effective, and sustainable alternative for phosphorus analysis in complex food matrices, aligning with the principles of green chemistry.