Spider diagram and Analytical GREEnness metric approach for assessing the greenness of quantitative 1 H-NMR determination of lamotrigine: Taguchi method based optimization Noura H. Abou-Taleb a, * , Nahed M. El-Enany b , Dina T. El-Sherbiny a, c , Hussein I. El-Subbagh a a Medicinal Chemistry Department, Faculty of Pharmacy, Mansoura University, 35516, Mansoura, Egypt b Analytical Chemistry Department, Faculty of Pharmacy, Mansoura University, 35516, Mansoura, Egypt c Pharmaceutical Chemistry Department, Faculty of Pharmacy, Delta University for Science and Technology, 35712, Gamasa, Egypt ARTICLE INFO Keywords: Lamotrigine Quantitative proton nuclear magnetic resonance Taguchi Spider diagram Eco-scale Analytical GREEnness metric approach ABSTRACT An optimized eco-friendly quantitative proton nuclear magnetic resonance ( 1 H NMR) method was developed for determination of lamotrigine. Taguchi method was utilized as a chemometric approach for the first time to optimize different NMR experimental parameters. The optimum acquisition conditions were found to be 128 number of scans, relaxation delay 1 s and pulse angle 90  using L 16 (4 5 ) orthogonal array. The diagnostic doublet signal at 7.7 in the 1 H NMR spectra was selected as quantitative peak for determination of lamotrigine. NMR spectra were obtained in dimethyl sulfoxide-d6 using phloroglucinol as internal standard. The content of lamo- trigine was measured within the range of 5–50 μg/mL. The limits of detection (LOD) and limits of quantitation (LOQ) were 0.62 and 1.87 μg/mL respectively. The proposed method was successfully applied for determination of lamotrigine in tablet dosage form without interference from the commonly encountered excipients. The greenness of the developed method was assessed using Greenness Index with spider diagram, National Environmental Methods Index (NEMI), Analytical Eco-Scale and Analytical GREEnness metric approach (AGREE), it was found to be excellent green analytical method. By comparing with other reported methods, this study was the greenest one according to NEMI labeling and Analytical Eco-Scale score and the second one according to AGREE which ensure that quantitative NMR is a recent green analytical technique. 1. Introduction Lamotrigine (LMG) is an antiepileptic used for treatment of partial and generalized toxic-clonic seizures [1]. Several methods have been reported for determination of LMG, most of them employing high-performance liquid chromatography (HPLC) [2–10] and liquid chromatography tandem mass spectrometry (LC-MS/MS) [11,12]. Also several densitometric methods have been reported for determination of LMG [13–17]. Nuclear magnetic resonance (NMR) spectroscopy is used traditionally as a structure elucidation tool however, the interest for its quantification ability is continuously growing over years. The quantitative NMR (qNMR) depends on the proportional relationship between signal in- tensity and the number of nuclei that are responsible for that particular resonance [18]. Therefore, the drug content can be calculated taken into consideration the ratio of signals belonging to the drug with respect to those of an internal standard. This procedure can be carried out using either peak intensity (height) or peak integration (area). It should be noted that, throughout this work, integration of selected signals was used for quantitative analyses. To obtain accurate analysis results, the quan- titative peaks of the drug and internal standard should not exhibit interference with any other signals. Spectral acquisition parameters should be also optimized. Improvements in NMR instrumentation and technology such as shielded high-field magnets, cryoprobes, solvent suppression techniques, and versatile pulse sequences have led many investigators to exploit NMR as a viable quantitative tool. Indeed, qNMR is now widely used in various domains such as toxicology [19], metab- olomics [20], pharmaceutics [21–25], or environmental [26,27]. In the pharmaceutical field, 1 H and 13 C NMR spectroscopies are often used for identification and quality evaluation of drugs. Despite the huge possi- bilities of qNMR regarding drugs quantification, the number of mono- graphies in European pharmacopeia (EP) or US pharmacopeia (USP) is still limited may be due to its high cost and limited availability. To date, qNMR measurements are at least as reliable and precise as those obtained by routine analytical techniques, such as capillary electrophoresis (CE), HPLC coupled with diode array detection (DAD) or (MS/MS), however it * Corresponding author. E-mail address: nourahemdan@yahoo.com (N.H. Abou-Taleb). Contents lists available at ScienceDirect Chemometrics and Intelligent Laboratory Systems journal homepage: www.elsevier.com/locate/chemometrics https://doi.org/10.1016/j.chemolab.2020.104198 Received 13 August 2020; Received in revised form 6 November 2020; Accepted 12 November 2020 0169-7439/© 2020 Elsevier B.V. All rights reserved. Chemometrics and Intelligent Laboratory Systems 209 (2021) 104198