Screening Of Organophosphorus Pesticides Research Articles

A colorimetric paper sensor based on the domino reaction of acetylcholinesterase and degradable γ-MnOOH nanozyme for sensitive detection of organophosphorus pesticides

Despite the tremendous achievements of existing sensing techniques, sensitive and portable sensing of organophosphorus pesticides (OPs) in a non-polluting manner remains a challenging issue. This work proposed a facile colorimetric paper sensor using γ-MnOOH nanowires (NWs) as a degradable nanozyme and 3,3′,5,5′-tetramethylbenzidine (TMB) as a chromogenic indicator for rapid and sensitive screening of OPs and acetylcholinesterase (AChE) activity. The sensing mechanism was based on the easy disintegration of the oxidase-like γ-MnOOH NWs into invalid Mn2+ ions by the selective reaction with thiocholine (TCh) produced by AChE and acetylthiocholine iodide (ATCh), triggering a remarkable activity loss of MnOOH nanozymes towards TMB oxidation. The concentration of OPs, as an AChE inhibitor, was measured by the changes in absorbance at 652 nm or blue color of oxTMB products. Such detection platform in solution state achieved relatively low limits of detection (LODs) for AChE activity (0.007 mU mL−1), and for two typical OPs, i.e., omethoate (0.35 ng mL−1) and dichlorvos (0.14 ng mL−1), respectively. Further, the portable assembly of such AChE-nanozyme tandem reaction on test paper performed well, reaching LODs of 0.1 mU mL−1 for AChE, 10 ng mL−1 for omethoate, and 3 ng mL−1 for dichlorvos, respectively. Meanwhile, this sensing system showed great selectivity and anti-interfering capacity in both solution and solid states, and worked well in real serum and vegetable samples. The abovementioned results, along with evidence of its good ecological sustainability, demonstrated the superiority of this well-performing platform for application in the food, environmental, and medical fields.

Highly-sensitive organophosphorous pesticide biosensors based on nanostructured films of acetylcholinesterase and CdTe quantum dots

The optical transducer of CdTe semiconductor quantum dots (QDs) has been integrated with acetylcholinesterase enzyme (AChE) by the layer-by-layer (LbL) assembly technique, resulting in a highly sensitive biosensor for detection of organophosphorus pesticides (OPs) in vegetables and fruits based on enzyme inhibition mechanism. The detection limits of the proposed biosensors are as low as 1.05×10−11 M for paraoxon and 4.47×10−12 M for parathion, which are significantly better than those of the conventional GC/MS methods or amperometric biosensors (0.5nM). These biosensors are used for quick determination of low concentrations of OPs in real vegetable and fruit samples and exhibit satisfactory reproducibility and accuracy. Moreover, the stock stability of the biosensors are very good due to the stabilizing environment for the enzyme in the nanostructures made by LbL technique. Many advantages provided by these biosensors, like fluorescent change recognized by naked eyes and mass production with low cost, will facilitate future development of rapid and high-throughput screening of OPs.

Screening of organophosphorus pesticides in environmental matrices by various gas chromatographic techniques

Gas chromatography with nitrogen-phosphorus detection (GC-NPD) using three different capillary columns, DB-1701, RSL-300 and DB-5, was employed for the identification of 25 organophosphorus pesticides and various transformation products. Spectral information on and typical fragment ions of the different compounds were obtained by gas chromatography-mass spectrometry with electron impact and negative-ion chemical ionization. Clean-up methods involving Florisil, Empore C 18 extraction discs, C 18 cartridges and gel permeation chromatography using Bio-Beads S-X3 were evaluated for the isolation of selected organophosphorus pesticides from water and biota samples. Recoveries for water samples varied from 77 to 120% with a relative standard deviation of 2–8% whereas recoveries of 30–130% were obtained with biota samples. Applications are reported for the determination of pyridafenthion in water samples from the Ebro delta (Tarragona, Spain).