Deep Eutectic Solvent-Based Microextraction of Lead(II) Traces from Water and Aqueous Extracts before FAAS Measurements

Abstract

Microextraction procedures for the separation of Pb(II) from water and food samples extracts were developed. A deep eutectic solvent composed of α-benzoin oxime and iron(III) chloride dissolved in phenol was applied as a phase separator support. In addition, this deep eutectic mixture worked as an efficient extractor of Pb(II). The developed microextraction process showed a high ability to tolerate the common coexisting ions in the real samples. The optimum conditions for quantitative recoveries of Pb(II) from aqueous extracts were at pH 2.0, conducted by adding 150 µL from the deep eutectic solvent. The quantitative recoveries were obtained with various initial sample volumes up to 30 mL. Limits of detection and limits of quantification of 0.008 and 0.025 µg L−1 were achieved with a relative standard deviation (RSD%) of 2.9, which indicates the accuracy and sensitivity of the developed procedure. Recoveries from the reference materials, including TMDA 64.2, TMDA 53.3, and NCSDC-73349, were 100%, 97%, and 102%, respectively. Real samples, such as tap, lake, and river water, as well as food samples, including salted peanuts, chickpeas, roasted yellow corn, pistachios, and almonds, were successfully applied for Pb(II) analysis by atomic absorption spectroscopy (AAS) after applying the developed deep eutectic solvent-based microextraction procedures.

Deep Eutectic Solvents Application in Food Analysis

“…Currently, studies on the synthesis and application of HDESs for the extraction of a great variety of analytes from food matrices have expanded rapidly, which has led to an increase in the number of articles published in recent years. As can be seen in Table 2, several HDESs have been used for the extraction of both organic (phthalic acid esters [18,96,99], dyes [97,104,110,117], PAHs [17,85], sterols [98], pesticides [100,105,112,122,124,126,127], herbicides [102], insecticides [125], preservatives [101], pigments [86], antibiotics [87,103,108,114], fluorescent whitening agents [106], vitamins [107], mycotoxins [16], bisphenols [115], perfluoroalkyl substances [120] and terpenes [121]) and inorganic compounds (Co, Cd, Ni, As, V and Pb [109,111,113,116,118,119,123]) from aqueous phases (water [96,113,118,124], soft drinks…”

“…When it comes to solid samples such as dried fruits, cereals, onion, parsley or even dairy products (milk, yogurt, cheese, etc. ), they are usually digested with H 2 O 2 :HNO 3 (1:3, v/v) [109], although in some cases only HNO 3 is used [119,123], before the application of microextraction techniques. However, if a previous step such as QuEChERS (quick, easy, cheap, effective, rugged and safe) [112], is carried out before the extraction technique in dried fruits for example, it would only be necessary to grind and homogenize them.…”

“…Nowadays, the above-mentioned low solubility of HDESs in aqueous samples has allowed their large application as extraction solvents in microextraction methods, complying with the principles of GAC. Among the different variants of the LPME, DLLME constitutes once more one of the preferred options for the application of HDES for the analysis of samples of diverse nature, including water [96], soft drinks [85,110], infusions [124], honey [105], dried fruits [119], flour [107], fruit juices [124] and egg yolk [125]. In this sense, it is important to highlight that in certain cases, no additional solvents have been necessary to obtain a good dispersion of the HDES into the sample [18,86,[96][97][98]110].…”

Determination of Lead Employing Simple Flow Injection AAS with Monolithic Alginate-Polyurethane Composite Packed In-Valve Column

“…For chronic exposure, it can harm and affect humas health, for example, it can cause nephritis of the kidney, brain damage, and central nervous system disorders [ 1 ]. Atomic absorption spectrometry (AAS) is among one of the various methods for the determination of lead due to its availability in laboratories and high selectivity in the detection of Pb 2+ [ 2 , 3 , 4 ]. Other techniques employed as standard methods include, electrothermal atomic absorption, inductively coupled plasma, inductively coupled plasma/mass spectrometry, anodic stripping voltammetry, and colorimetric employing dithizone [ 5 ].…”

Editorial for the “Green Chemistry” Section in the Journal Molecules: Focus on Solvents

“…I think it is helpful for potential authors to recognise that in many of the journals that cover general green chemistry, contributions to organic synthesis and materials science usually outweigh the analytical sciences. This means that Molecules has a somewhat privileged role-highlighting solvent applications relating to extraction and analysis [3][4][5][6][7][8][9], yet performed in a way which is environmentally acceptable.…”