Abstract <p>In this comparative study, green and simple methods were developed for extracting and preconcentrating Brilliant Blue dye from environmental water samples using dispersive solid-phase microextraction (<b>DSPµE</b>) coupled with ultraviolet−visible spectrophotometry. Two adsorbents, zein nanoparticles (<b>ZNP</b>s) and benzalkonium-coated zein-functionalized magnetite nanoparticles (<b>Fe</b>_<b>3</b><b>O</b>_<b>4</b><b>@Zein@BZC</b>), were evaluated and compared. Various experimental parameters, including sample pH, buffer concentration, adsorbent dosage, extraction time, ionic strength, and the type and volume of the eluent, were thoroughly investigated and optimized for both adsorbents to determine the most effective extraction conditions. Under the selected conditions, linearity was achieved in the ranges of 0.025–1.00 µg/mL for DSPµE-ZNPs and 0.05–2.0 µg/mL for DSPµE-Fe₃O₄@Zein@BZC, with correlation coefficients (<i>r</i>²) greater than 0.99. The limits of detection were found to be 7 and 9 ng/mL, respectively. The proposed methods were effectively applied to real water samples, including canal, tap, and river water, achieving recovery percentages between 97.0 and 102.0% for both adsorbents, with relative standard deviations below 3% (<i>n</i> = 5). Greenness and whiteness evaluations were conducted for both adsorbents to assess their environmental profiles comprehensively. Three greenness tools (complex metric for green analytical procedure index, MoGAPI; analytical greenness metric for sample preparation, AGREEprep; and sample preparation metric of sustainability, SPMS) were used to perform greenness and whiteness evaluations, as well as thorough calculations of sample, extraction, and preparation procedures, and the degree of whiteness was ascertained using the red-green-blue scale.</p>