Determination of carbendazim residues in Moroccan tomato samples using local enzyme-linked immunosorbent assay and comparison with liquid chromatography

The fungicide carbendazim (CBZ) is not approved for agricultural uses in some countries but is still used by many farmers due to its effectiveness. For this reason, in previous work of the same authors, they developed a competitive enzyme immunoassay (ELISA) using rabbit polyclonal antibodies to detect CBZ. This study aimed to validate this in-house ELISA after extraction with methanol for CBZ analysis in tomato samples, and the results were compared with the conventional high-performance liquid chromatography (HPLC) method after QuEChERS extraction. The results showed that both ELISA and HPLC methods have good repeatability, reproducibility and high precision with a good variation verified by principal components analysis (PCA). ANOVA tested the detection limit (LOD), and quantification limit (LOQ), and the values for ELISA (LOD = 0.026± 0.001 µg/L and LOQ = 0.083 ± 0.003 µg/L) were significantly lower than those obtained by HPLC (LOD = 0.61 ± 0.02 µg/L and LOQ = 1.85 ± 0.07 µg/L). ELISA and HPLC were used for analyzing CBZ in 100 Moroccan tomato samples. These two methods detected the presence of CBZ above the Maximum Residue Limit (MRL) level in 9 samples. However, the presence of the  CBZ was detected in the 79 samples by ELISA and quantified in 66 samples. In contrast, the presence of CBZ was detected in 57 and quantified in 35 samples by HPLC. These results showed that the ELISA system coupled with a simple methanol extraction is much more sensitive than HPLC after QuEChERS extraction

N′-(1-Allyl-2-oxoindolin-3-yl­idene)benzohydrazide

In the title compound, C18H15N3O2, the dihedral angle between the ring systems is 15.1 (1)°. The amino H atom is hydrogen bonded to the exocyclic O atom of the five-membered ring, forming an S(6) motif

1-Benzyl-3-methyl­quinoxalin-2(1H)-one

The asymmetric unit of the title compound, C16H14N2O, contains three independent mol­ecules. The dihedral angles between the quinoxaline and phenyl planes in the three mol­ecules are 82.58 (8), 85.66 (9) and 85.36 (9)°. The crystal packing is stabilized by C—H⋯O and C—H⋯N hydrogen bonds

N′-(3-Methyl­quinoxalin-2-yl)-N′-phenyl­benzohydrazide

In the crystal structure of the title compound, C22H18N4O, the quinoxaline system makes dihedral angles of 86.59 (7) and 63.37 (9)° with the benzohydrazide and phenyl rings, respectively. The benzohydrazide ring makes a dihedral angle of 72.46 (10)° with the phenyl ring. The crystal structure is stabilized by inter­molecular N—H⋯O hydrogen bonds, C—H⋯O contacts and C—H⋯π inter­actions

3-[2-(1H-Benzimidazol-2-ylsulfan­yl)eth­yl]-1,3-oxazolidin-2-one

In the title compound, C12H13N3O2S, the oxazolidin ring displays an envelope conformation. The dihedral angle between the benzimidazole ring and the 1,3-oxazolidin-2-one mean plane is 69.85 (13)°. In the crystal, mol­ecules are linked by inter­molecular N—H⋯N hydrogen bonds, forming a chain parallel to the b axis

2-Phenyl­thieno[2,3-b]quinoxaline

The title compound, C16H10N2S, is almost planar (r.m.s. deviation for all non-H atoms = 0.080 Å). The dihedral angle between the three fused-ring system and the phenyl ring is 9.26 (3)°. The S atom and the opposite C atom of the thio­phene ring are mutually disordered with an occupancy ratio of 0.7706 (19):0.2294 (19)

Pharmacological Profile of Quinoxalinone

Quinoxalinone and its derivatives are used in organic synthesis for building natural and designed synthetic compounds and they have been frequently utilized as suitable skeletons for the design of biologically active compound. This review covers updated information on the most active quinoxalinone derivatives that have been reported to show considerable pharmacological actions such as antimicrobial, anti-inflammatory, antidiabetic, antiviral, antitumor, and antitubercular activity. It can act as an important tool for chemists to develop newer quinoxalinone derivatives that may prove to be better agents in terms of efficacy and safety

3-[2-(2-Amino-1H-benzo[d]imidazol-1-yl)ethyl]-1,3-oxazolidin-2-one

In the title compound, C12H14N4O2, the benzimidazole ring is almost planar (r.m.s. deviation = 0.03 Å), with the fused ring system slightly folded at the shared atoms, with a dihedral angle of 3.4 (1)°. The oxazolidinone ring displays a twisted conformation on the –CH2–CH2– bond and its mean plane makes a dihedral angle of 57.4 (1)° with the benzimidazole ring mean plane. In the crystal, molecules are linked by N—H...O and N—H...N hydrogen bonds, forming chains propagating along the a-axis direction. The chains are linked by C—H...O and C—H...N hydrogen bonds, forming a three-dimensional structure, which is reinforced by C—H...π interactions