Sol-gel based biogenic silica composite as green nanosorbent for chemometric optimization of micro-solid-phase extraction of beta blockers

An environmentally friendly micro-solid phase extraction (μ-SPE) method utilizing a plant based nanocomposite as a sorbent for determination of trace level beta blockers (ß-blockers) in hospital wastewater prior to Liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis. μ-SPE extraction conditions were evaluated using a multivariate chemometric approach. Rice husk silica-carbon nanocomposite (5–20 Wt.% Fe) in glycerol were synthesized via hydrolytic sol-gel method. The nanosorbent were fully characterized and then evaluated for μ-SPE of trace level ß-blockers in hospital wastewater. To establish the best extraction conditions at minimal experimental cost, multivariate techniques based on fractional factorial (FFD) and central composite designs (CCD) with desirability function (DF) were used to optimize the extraction conditions. Experimental results showed good agreement with predicted values and logical DF was realized at relatively low extraction time. Under optimized conditions, good linearity ranges (0.02–5.0 μg L⁻¹) with correlation of determinations higher than 0.9954 were obtained. The limits of detection and quantitation for the five ß-blockers (atenolol, alprenolol, pindolol, acebutolol and propranolol) ranged from 4.0–6.4 and 13.0–19.0 ng L⁻¹, respectively. Inter-day and intra-day precision (percent relative standard deviations, n = 5) were lower than 8.3% while relative recoveries for hospital wastewater samples (80.6–105.1%) were in satisfactory ranges. This experimental approach therefore, demonstrated simplicity, reduction in the experimental runs, effectively increased sensitivity of LC–MS/MS and was hence suitable for complex matrix sample analysis.