A chemical remediation study was evaluated to reducing chlorpyrifos risk from irrigation water. Some chemicals used as catalyst were prepared in Nano-particle phase and were tested in vitro to check their ability to cracking out tested pesticide. An analytical study was used to evaluate catalysts efficiency and the environmental fats for chlorpyrifos using liquid chromatography tandem mass spectrometry. In previews studies the use of gas chromatography coupled with single mass were used to checks compounds with and without a chemical fragmentation test, Also infra-red and NMR determination were used to support compound fat structures. In this investigation a tandem mass was used for the determination of chlorpyrifos breakdown products by using mass scan before multiple reactions monitoring mechanism as a finger prints for the chemical reaction products and also to have relationship between the main compound and its founded products.
Twenty five pesticides were tested by silver vanadate nanoparticles in visible light at room temperature for 24 hours, only 3 pesticides (chlorpyrifos, dimethoat, malation) were affected till be displayed from solution test, Its clearly they relationships to each other as a organophosphate classification which led us to physicochemical theory about the reaction of silver vanadate nanoparticle to breakdown persisted pesticides in environment specially in irrigation water.
Table 1 showed dramatically dissipation in 15 min for chlorpyrifos and dimethoat when malation was more resist for more 30 min.
An analytical study was done to investigate chlorpyrifos breakdown fragments using tandem mass spectrometry (Q trap) and hybrid orbitap technique for mass scanning and exact mass determination, Chlorpyrifos and its breakdown derivatives were scanned and determined as a way to investigates bonds breaking pathway.
Figure 1 showed the mass scan of chlorpyrifos by first mass filter including the isotopic distribution of compound due to the present of 3 chlorine atoms, After scanning 350 Dalton was used as mass separation for parent chlorpyrifos in Q1 before special fragmentation in collision cell for two fragments (274 and 198), then Q3 was used as linear ion trap for filtering each fragment before second fragmentation and scanning to found up third mass part from analyte (MS/MS/MS).
Figures 2 and 3 showed two different fragments comes from tow fragments from chlorpyrifos (350,274,144 and 350,198,107) as a triple mass finger print for tested analyte. The present of 144 Dalton fragment from 198 parent ion was due to the loss of H2o + Cl when the other fragments 107 was due CO2 + Cl + HCN losses . From the other hand, multiple reactions monitoring mechanism was used to determines all founded compounds in the solution after one day from chlorpyrifos silver vanadate nanoparticles reaction. Figure 4 showed the full scan results found in solution before optimizing best energy and mass unit voltage to found up fragments for these compounds derivatives.
Figures 5 and 6 showed the products of two chosen breakdown fragment, the first one was 174 which broken to 5 detected fragment under instrumental fragmentation and the other was 198 gives 2 fragments one of them was found as third products to main chlorpyrifos, this result led us to similar found in between chemical and instrumental degradation. The present of 198, 199.8 and 202 masses was due to 35Cl3, 35Cl2 37Cl, and 35Cl 37Cl2 isotopomers of TCP (3,5,6-trichloro-2- pyridinol) respectively.
Mass determination with high resolution was studied using hybrid orbitrap mass spectrometry. A high accuracy scan ranged between 85 to 355 Dalton was done for tested solution after Nano reaction as shown in Fig. 7; instrumental method was adjusted for both scanning and special fragmentation for any founded masses between target ranges. Four masses were found in confirming with previews test (Qtrap-6500+): 283.27, 274.27, 197.92 and 169.06.
As showed in Figs. (8–12) the fragments ions with high abundance produced by founded masses after Nano reaction were found 113, 106.945, 108.9423, 209.1536 and 96.0704 respectively which were supported by the triple quadrupole mass instrument and led us to have good idea about the breakdown path way of chlorpyrifos pesticide after remediation reaction with Nano silver vanadate.
This data was in agreement with that found before, the products produced by silver nitrate nanoparticles reaction in 48 hours led to protonated TCP 198 Dalton which produced 144 and 107 Dalton fragments when using 3200 QTrap MS/MS instrument (Bootharaju et al. 2012). Also an accurate mass of 197.9235 was found when scanning chlorpyrifos after Fe oxidation using Triple TOF 5600 mass spectrometry instrument (Liu et al. 2019). From the other hand, the present of 107 as a fragment product from both parents 298 and 274 can explain a possible structure of 274 which was supported in the shown spectrum of TOF triple mass for chlorpyrifos fragmentation (Liu et al. 2019). The use of silver/copper nanoparticles as a catalysts for chlorpyrifos degradation led to TCP and DETP (Diethyl thiophosphate) (Rosbero et al. 2017).
Possible structures for chorpyrifos breakdowns were showed in Figs. (8–12) of orbitrap MS2 scanning and fragmentation can explained the possible pathway of chlorpyrifos when using Nano-silver vanadate in aqueous solution as in vitro examination for this pesticide remediation.
Possible structures for chlorpyrifos breakdowns were showed in Fig. 13 and supported by all previews data that the fragmentations 282 and 198 could be found due to the loss of 2 chlorine atoms in a substitution reaction in chlorpyrifos to get 282 mass and by breaking the single bond between oxygen and phosphorus to get 198 mass, this theory can be supported by the isotopic distribution showed in this scan Fig. 13 and also can explained the possible pathway of chloropyrifos when using silver vanadate nanoparticles in aqueous solution as in vitro examination for this pesticide remediation.