ABSTRACT
Hydrophobic alginic acid derivatives were synthesized with various aliphatic hydrocarbon chains for fat removal in an analysis of multi-pesticide residues in a fatty food sample. First, alginic acid was chemically modified using eco-friendly ultrasound-assisted esterification with different alcohols, namely, hydrophobic alginic acid-methanol (HAA-C1), hydrophobic alginic acid-butanol (HAA-C4), and hydrophobic alginic acid-octadecanol (HAA-C18). The degree of esterification (DE) was determined by titration, and the results ranged from 57.3% to 63.7%. The physicochemical properties of the synthesized hydrophobic alginic acids (HAAs) were studied using FT-IR, XRD, TGA, and FE-SEM. Subsequently, the performance of the HAAs was checked and evaluated for the removal of fat from a fatty food sample by calculating the fat removal percentage and the determination of 214 pesticide residues in the fatty food sample. For the fat removal percentage application, the HAAs were able to efficiently remove between 77% and 83% of the fat; HAA-C18 had the highest percentage. Regarding the pesticide residue application, HAAs were also able to remove the fat content from the fatty food sample without a significant effect on the pesticide substances. The recoveries of the detected pesticide compounds were between 80% and 120% for all HAAs. However, there were various missing pesticide compounds for HAAs. The number of missing pesticide compounds was 19, 6, and 33 for HAA-C1, HAA-C4, and HAA-C18, respectively. HAA-C4 had medium hydrophobicity and it lost fewer pesticides than the other HAAs. This was because the multi-pesticide mixture had various classes of chemical structure; hence, it had different polarity powers. We concluded that HAAs are developable and applicable to be safely used as a green material in diverse fatty food sample analysis applications.
ABSTRACT
This study aimed to investigate the presence of pesticide residues in a variety of commonly consumed leafy vegetables, including Grape leaves, Lettuce, Arugula, Spinach, Purslane, Ocimum, Parsley, Jew's mallow, Celery, Coriander, and Mint. A total of 100 samples were collected from the Central Market of Jeddah, Kingdom of Saudi Arabia. Our methodology involved employing the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction method in combination with Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) to analyze a comprehensive database of 237 distinct pesticides. The range for limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.0001 to 0.0014 mg. Kg-1 and 0.0010 to 0.0064 mg. Kg-1 for tested pesticides, respectively. The recoveries were in the range of 70-172.9%, with a relative standard deviation (RSD) of less than 19.0% for all tested pesticides. The results revealed that 60% of the analyzed samples were free from pesticide residues, while 40% exhibited contamination with 17 different pesticide residues. Notably, the most prevalent pesticide detected was Triallate in the Ocimum samples, followed by Metalaxyl in Grape leaves, Mint, and Spinach, and Methomyl in Celery. Approximately 45% of the samples contained pesticide residues that fell below or were equal to the European Union Maximum Residue Levels (EU MRLs), while the remaining 55% exceeded these MRLs. Remarkably, high pesticide concentrations were observed in all Ocimum samples (Triallate, Pyridaben, Hexythiazox, Imidacloprid), 67% of Grape leaves (Metalaxyl, Azoxystrobin, Difenoconazole Isomer), and 40% of Celery (Azoxystrobin, Methomyl). In conclusion, this study sheds light on the contamination levels of commonly consumed domestically produced and purchased leafy vegetables in the Central Market of Jeddah. To ensure food safety and the well-being of consumers, we strongly recommend enhanced scientific assessments and continued monitoring of pesticide usage in agricultural practices.
