Unmodified biopolymers as sustainable microextraction materials for the environmental monitoring of polycyclic aromatic hydrocarbons and personal care products

Abstract

Biopolymers present several interesting features for analytical microextraction such as biocompatibility, biodegradability, and ease for processing into different formats. However, most analytical sample preparation methods involve biopolymer-based composites, with the biopolymer acting as a support of the extractant agent. As a simpler alternative, this study proposes a strategy based on the use of unmodified biopolymers as sorbents in dispersive micro-solid-phase extraction (μ-dSPE). Two analytical applications were developed for this purpose: (1) the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental waters using HPLC and fluorescence detection, and (2) the monitoring of a group of personal care products (PCPs) via HPLC and diode array detection. Among the different biopolymers considered, chitosan, cellulose, agarose, and keratin were implemented in this microextraction technique as sorbent materials. Keratin, used for first time as unmodified sorbent, was selected for providing the highest extraction efficiency for both types of applications. Several parameters of the microextraction method were optimized, including the pH, ionic strength, extraction time, type of desorption solvent, amount of keratin, and number of desorption steps. Under optimum conditions, the microextraction step required only 5 mL of sample, a pH 5.5, 10% (w/v) NaCl, and 50 mg of keratin, with short vortex times for extraction and desorption (5 min). The obtained values for the eco-scale, AGREE, and AGREEprep methods were 86, 0.45, and 0.52, thus pointing out a certain degree of greenness for the analytical method. After optimization and proper validation, limits of detection between 2.7 and 150 ng⋅L-1 for PAHs, and between 0.59 and 3.8 µg⋅L-1 for PCPs were achieved. Besides, the method was successfully applied for the analysis of wastewater, achieving average relative recoveries of 99% for PAHs and of 93% for PCPs,% and relative standard deviation values lower than 20%.