Determination of Glyphosate and AMPA in Food Samples Using Membrane Extraction Technique for Analytes Preconcentration

Abstract

The method for determining glyphosate (NPG) and its metabolite AMPA (aminomethyl phosphonic acid) in solid food samples using UAE-SLM-HPLC–PDA technique was developed. Firstly, ultrasonic-assisted solvent extraction (UAE) and protein precipitation step were used for the analyte isolation. Then, the supernatant was evaporated to dryness and redissolved in distilled water (100 mL). The obtained solution was alkalized to pH 11 (with 1 M NaOH) and used directly as donor phase in SLM (supported liquid membrane) extraction. The SLM extraction was performed using 2 M NaCl (5 mL) as an acceptor phase. The flow rate of both phases (donor and acceptor) was set at 0.2 mL/min. The membrane extraction took 24 h but did not require any additional workload. Finally, the SLM extracts were analyzed using the HPLC technique with photo-diode array detector (PDA) and an application of pre-column derivatization with p-toluenesulfonyl chloride. Glyphosate residues were determined in food samples of walnuts, soybeans, barley and lentil samples. The LOD values obtained for the studied food were 0.002 μg g−1 and 0.021 μg g−1 for NPG and AMPA, respectively. Recoveries values ranged from 32% to 69% for NPG, 29% to 56% for AMPA and depended on the type of sample matrix. In the case of buckwheat and rice flour samples, the content of NPG and AMPA was below the detection level of a used analytical method.

Comparative Evaluation of Different Extraction Methods for Identification and Quantification of Glyphosate in Fortified Corn Flour

“…Glyphosate derivatization step can be made before or after column separation to form fluorescent-adducts to allow its detection and/or to reduce its polar characteristics and thus facilitate its chromatographic retention [32,33]. The extraction procedures used for the determination of glyphosate depend mainly on the type of matrix to be analyzed, and the most frequent approaches are solid-phase extraction, ultrasonication [20,27,34,35], agitation [27], and accelerated solvent extraction (ASE) [27,36]. However, there have been few efforts to systematically determine the best and most efficient extraction approach by comparing different protocols applied to different matrices.…”

pH and Design on n–Alkyl Alcohol Bulk Liquid Membranes for Improving Phenol Derivative Transport and Separation

“…However, stripping also takes place over a long period of time, being, in fact, a re-extraction [11]. By operating the two stages of extraction continuously (Figure 1b), the operating time was practically halved, while the amount of organic solvent required for the process was continuously reduced, passing from bulk liquid membranes (BLM) (Figure 1c) to supported liquid membranes (SLM) (Figure 1d), and then to emulsion liquid membranes (ELM) (Figure 1e) [12][13][14]. At the same time, the mass transfer surface area increased in the same direction [15].…”