title: Broadband quantitative NQR for authentication of vitamins and dietary supplements.
abstract: We describe hardware, pulse sequences, and algorithms for nuclear quadrupole resonance (NQR) spectroscopy of medicines and dietary supplements. Medicine and food safety is a pressing problem that has drawn more and more attention. NQR is an ideal technique for authenticating these substances because it is a non-invasive method for chemical identification. We have recently developed a broadband NQR front-end that can excite and detect14N NQR signals over a wide frequency range; its operating frequency can be rapidly set by software, while sensitivity is comparable to conventional narrowband front-ends over the entire range. This front-end improves the accuracy of authentication by enabling multiple-frequency experiments. We have also developed calibration and signal processing techniques to convert measured NQR signal amplitudes into nuclear spin densities, thus enabling its use as a quantitative technique. Experimental results from several samples are used to illustrate the proposed methods.
authors.affiliation: Case Western Reserve University, Cleveland, OH 44106, USA. Electronic address: cxc717@case.edu.
authors.forename: Cheng
authors.initials: C
authors.lastname: Chen
authors.affiliation: University of Florida, Gainesville, FL 32611, USA. Electronic address: fzhang67@ufl.edu.
authors.forename: Fengchao
authors.initials: F
authors.lastname: Zhang
authors.affiliation: University of Florida, Gainesville, FL 32611, USA. Electronic address: swarup@ece.ufl.edu.
authors.forename: Swarup
authors.initials: S
authors.lastname: Bhunia
authors.affiliation: Case Western Reserve University, Cleveland, OH 44106, USA. Electronic address: sxm833@case.edu.
authors.forename: Soumyajit
authors.initials: S
authors.lastname: Mandal
mesh_terms: D000465:Algorithms; D002138:Calibration; D002214:Capsules / Q000032:analysis; D019587:Dietary Supplements / Q000032:analysis*; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D014815:Vitamins / Q000032:analysis*
chemical_list: D002214:Capsules; D009587:Nitrogen Isotopes; D014815:Vitamins
keywords: Authentication; Broadband front-end; NQR; Quantitative measurement