Quantitative quadrupolar NMR (qQNMR) using nitrogen-14 for the determination of choline in complex matrixes

Accurate detection of perchlorate in epoxy resins via chlorine-35 quantitative quadrupolar NMR (qQNMR)

“…As previously observed [18][19][20] we found a linear correlation within the number of scans (Fig. 1a).…”

“…To the best of our knowledge, there is a lack of vali-dated methods based on nuclear magnetic resonance (NMR) able to quantify perchlorates. In the vast majority of applications of quantitative NMR (qNMR), the nucleus of choice is based on a nuclear spin of one half (I = 1/2) such as 1 H, 13 C, 19 F and 31 P, 5,6 and only a few are centered on a quadrupolar nuclei (I > 1/2) for quantitative purposes (see further below). In both situations, qNMR is based on the direct proportionality between the absolute integral of each signal and the number of magnetically equivalent nuclei giving rise to that resonance.…”

“…17 Our group has already validated three qQNMR methods for the first time. The first method based on 11 B (I = 3/2) was developed for the quantification of boric acid in commercial biocides, 18 and the second and third employed 14 N (I = 1) for the quantification of choline in complex matrixes such as coffee, quinoa or nutritional formulations 19 and L-carnitine in food supplements. 20 Chlorine-35 is the major isotope of the chlorine atom (natural abundance of 75.8%), being as active in terms of NMR as its isotope chlorine-37.…”

An Optimized Two-Dimensional Quantitative Nuclear Magnetic Resonance Strategy for the Rapid Quantitation of Diester-Type C19-Diterpenoid Alkaloids from Aconitum carmichaelii

“…Quantitative nuclear magnetic resonance (qNMR) is a general term for quantifying 1 H, 13 C, 14 N, 19 F, or 31 P nuclear magnetic resonance signals of target compounds or components using 1D NMR (e.g., 1 H, 13 C, 14 N, and 19 F NMR) spectra − or 2D NMR (e.g., 1 H- 1 H COSY, 1 H- 13 C HSQC, and 1 H- 14 N HSQC) spectra. − Since qNMR was first reported in 1963, it has shown incomparable application potential in natural products, metabolites, and pharmaceutical analysis . Quantitative 1 H NMR has been recognized as a general quantitative method, which has been widely used in purity determination, , content determination, metabolic analysis, , authenticity identification, , quality control, , and other applications due to its advantages of nondestructive analysis, short measuring time, and simple methodology, and because it does not require a specific reference standard .…”

Quantitative NMR Interpretation without Reference

“…Also, most of the proposed quantitative methods are based on proton NMR experiments, but other nuclei have been used since the beginning: 31 P [ 24 , 25 ], 2 H [ 26 ], and 13 C [ 19 , 27 , 28 ]. In recent years, 23 Na [ 29 ], 19 F [ 30 , 31 ], 35 Cl [ 32 , 33 ], 11 B [ 34 ], 7 Li [ 35 ], and quadrupolar nuclei like 27 Al [ 36 , 37 ] and 14 N [ 38 , 39 ] were added to the list. While some of the proposed methods are 2D experiments or CPMAS, mostly 1D liquid state experiments have been described.…”