title: Quantitative 1H NMR with external standards: use in preparation of calibration solutions for algal toxins and other natural products.
abstract: We examine the use of external standards for quantitative measurement by 1H NMR of solution concentrations of natural products and other low molecular weight, hydrogen-containing compounds and show that precision and accuracy ca. 1% is obtainable with a commercial 11.7 T spectrometer when standards and analytes are contained in separate but identical sealed precision glass NMR tubes. Numerous factors contributing to the intensity of the NMR signals are evaluated. Precise measurements of 360 degrees pulse lengths for each sample provide direct corrections for variations in probe Q-factor that enable samples in different solvents to be compared, provided single-coil excitation and detection is used throughout. Samples need not be prepared in deuterated solvents if the 1H spectra of the solvents are simple enough for peak suppression by presaturation. The approach is particularly suitable for hazardous materials kept in sealed tubes and for the preparation of certified calibration solution reference materials for use with LC-MS and other techniques where deuterated solvents should be avoided.
authors.affiliation: Institute for Marine Biosciences, National Research Council of Canada, 1411 Oxford Street, Halifax N.S., Canada B3H 3Z1.
authors.forename: Ian W
authors.initials: IW
authors.lastname: Burton
authors.forename: Michael A
authors.initials: MA
authors.lastname: Quilliam
authors.forename: John A
authors.initials: JA
authors.lastname: Walter
mesh_terms: D001688:Biological Products / Q000032:analysis*; D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods / Q000592:standards; D003903:Deuterium / Q000737:chemistry; D056890:Eukaryota / Q000737:chemistry*; D006575:Heterocyclic Compounds, 3-Ring / Q000032:analysis / Q000737:chemistry; D006844:Hydrocarbons, Cyclic / Q000032:analysis / Q000737:chemistry; D007097:Imines / Q000032:analysis / Q000737:chemistry; D007608:Kainic Acid / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards; D008387:Marine Toxins / Q000032:analysis* / Q000737:chemistry; D019319:Okadaic Acid / Q000032:analysis / Q000737:chemistry; D015203:Reproducibility of Results; D012530:Saxitoxin / Q000032:analysis / Q000737:chemistry; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D001688:Biological Products; D006575:Heterocyclic Compounds, 3-Ring; D006844:Hydrocarbons, Cyclic; D007097:Imines; D008387:Marine Toxins; D012996:Solutions; D012997:Solvents; D019319:Okadaic Acid; D012530:Saxitoxin; C407350:gymnodimine; D003903:Deuterium; C012301:domoic acid; D007608:Kainic Acid