To address accuracy and precision using methods from analytical chemistry and computational physics

Abstract

In this work the pesticides were determined by liquid chromatography-mass spectrometry (LC-MS). In present study the occurrence of imidacloprid in 343 samples of oranges, tangerines, date plum, and watermelons from Valencian Community (Spain) has been investigated. The nine additional pesticides were chosen as they have been recommended for orchard treatment together with imidacloprid. The Mulliken population analysis has been applied to present the charge distribution in imidacloprid. Partitioned energy terms and the virial ratios have been calculated for certain molecules entering in interaction. A new technique based on the comparison of the decomposed total energy terms at various configurations is demonstrated in this work. The interaction ability could be established correctly in the studied case. An attempt is also made in this work to address accuracy and precision. These quantities are well-known in experimental measurements. In case precise theoretical description is achieved for the contributing monomers and also for the interacting complex structure some properties of this latter system can be predicted to quite a good accuracy. Based on simple hypothetical considerations we estimate the impact of applying computations on reducing the amount of analytical work.

Computational electronic structure of the bee killer insecticide imidacloprid

“…Kozmutza and Pico ´(2009), using DFT theory, the B3LYP exchange-correlation potential and the 3-21G* basis set, found that according to MPA, only one nitrogen atom (N14) possesses a positive charge. 57 This contrasts with the statement of Tomizawa and Casida (2000), who found a slightly positive charge on N8 (0.0315) using the MNDO-PM3 semi-empirical molecular technique. 63 In the same work, Tomizawa and Casida (2000) found that the insecticide desnitroimidacloprid presents a slight negative charge on N8 (À0.0063), indicating that the nitro group is (2008).…”

“…Numerous procedures have been used for this purpose, such as Mu ¨liken Population Analysis (MPA), 54 Hirshfeld Population Analysis (HPA), 55 and Natural Population Analysis (NPA). 56 Although MPA is the most widely used approach, 57 Weinhold, Reed and Weinstock (1985) stated that MPA is insufficient in many cases; thus, the authors developed natural population analysis (NPA), based on natural atomic orbitals (NAOs), as a complete orthonormal set for optimally describing effective atom-like constituents within a molecular environment. 56,58 Other researchers relate that HPA is more accurate, as it can predict reactive sites within a molecule better than MPA, NPA and fitted electrostatic potentials.…”