OsPAL as a key salicylic acid synthetic component is a critical factor involved in mediation of isoproturon degradation in a paddy crop

Advance in Methodology and Strategies To Unveil Metabolic Mechanisms of Pesticide Residues in Food Crops

“…SPE is commonly used to clean up plant extracts for trace analysis of pesticides and metabolites (Table ). ,,,, SPE often offers satisfactory cleanup of interferents to detect multi-pesticide metabolites in a variety of plants. ,,,− First, the ultrasonic extraction of powdered plant tissues was conducted with mixed acetone–water (3:1, v/v). After acetone removal with a vacuum rotary evaporator, the residual aqueous extract was loaded onto a octadecylsilane (C18) SPE column.…”

“…UPLC is the most used tool in conjunction with MS for the separation of pesticide metabolites in plants. ,,,, It is critical that, if LC is used, new or unexpected metabolite fractions can be artifacts of the interaction of the LC solvent system (and especially if buffers are used), analogues that complicate the true identification of the species. In comparison to conventional HPLC, the diameter and particle size of UPLC chromatographic columns are reduced, the running time is shortened, and resolution is improved .…”

“…In comparison to conventional HPLC, the diameter and particle size of UPLC chromatographic columns are reduced, the running time is shortened, and resolution is improved . To date, the most important ion source for pesticide metabolism is atmospheric piezoelectric ionization (API), like atmospheric pressure chemical ionization (APCI), for neutral compounds (e.g., heavily halogenated analogues and highly aromatic compounds), electrospray ionization (ESI) as a soft ionization technique suitable for labile conjugates (e.g., glycosides and S conjugates), and atmospheric pressure photoionization (APPI) for unionizable or poorly ionizable compounds. , With regard to qualitative and quantitative analyses of pesticide metabolites, simple single mass spectrometers (MSs) cannot provide enough information, while the tandem MSs, like triple quadrupole MSs (TSQMS), ion trap, and Q-ToF, have become popular. ,,,,,, Q-ToF instruments, equipped with a mass filter and collision cell of TSQMS with a ToF region, can operate as true tandem MS, providing an accurate mass of the product ions. ,,,, The ion trap MSs provide greater sensitivity. , In addition, the ability of ion traps to achieve tandem MSs (MS n ) and the robust implementation of data-related operations are advantageous in structural analysis . Two dimensional (2D) linear trap quadrupole–electrostatic ion trap (LTQ–Orbitrap) that has great advantages in the study of pesticide metabolism in plants is a hybrid high-resolution mass spectrometer (HRMS) with higher sensitivity and resolution than Q-ToF. ,, …”

“…Many pesticide metabolites have a low content plus the high complexity of the plant matrix along with the hardship to prepare standard samples, which reminds one of the proverbial “needle in a haystack”. ,,,, The measurement of accurate mass by HRMS makes it possible to find metabolites through the haystack (i.e., the plant matrix) . Knowing molecular fragmentation and MS data interpretation can greatly help interpretation of the mass spectral information to elucidate the structures. ,,,, The transformations of pesticides in plants, the corresponding changes in accurate mass (mass shift 162.05282 for glucosylated metabolites), and the characteristic neutral losses in MS 2 have been summarized in Table . ,,,, …”

“…Thereafter, the unique spectrum of the target analytes can be obtained following “subtract any spectrum” from the control (Figure ). ,,,, The compounds corresponding to this unique spectrum are “possible metabolites of pesticide”. Currently, many HRMSs are equipped with powerful software processing systems (such as “mass profiler”), which is capable of analyzing all ion groups in the chromatograms of the two samples and compiling them into a database.…”