Certification of elements in and use of standard reference material 3280 multivitamin/multielement tablets.

Standard Reference Material 3280 Multivitamin/ Multielement Tablets was issued by the National Institute of Standards and Technology in 2009, and has certified and reference mass fraction values for 13 vitamins, 26 elements, and two carotenoids. Elements were measured using two or more analytical methods at NIST with additional data contributed by collaborating laboratories. This reference material is expected to serve a dual purpose: to provide quality assurance in support of a database of dietary supplement products and to provide a means for analysts, dietary supplement manufacturers, and researchers to assess the appropriateness and validity of their analytical methods and the accuracy of their results.

Chemical comparison of Prunus africana bark and pygeum products marketed for prostate health.

The bark of Prunus africana may contain atranorin, atraric acid, beta-sitosterol and its esters, ferulic acid and its esters, and N-butylbenzene sulfonamide, compounds that have been shown to improve the conditions of benign prostatic hyperplasia, enlarged prostate. An analytical scheme, involving liquid-solid extractions, saponifications, and LC-APCI-MS (triple quadrupole) analysis, was developed, optimized, and validated to determine the compounds at µg/g levels. Limits of quantification were in the low ng/mL range except for beta-sitosterol. All of the compounds plus two internal standards eluted in under 10 min on a phenyl-hexyl column with gradient elution involving water-methanol and acetonitrile. The mass fraction of the compounds in Prunus africana bark (four samples) and commercial pygeum products (seven samples), derived from bark, were compared. Bark and pygeum were similar in their content of atranorin and atraric acid, found at low µg/g levels, and in the fact that ferulic acid was almost totally (> 90%) in the form of esters. In contrast, the total amount of ferulic acid was on average four times higher in bark (450 µg/g) than in pygeum while the opposite was true for total beta-sitosterol. Some pygeum samples had levels of total beta-sitosterol above 10,000 µg/g while the compound in bark was relatively invariant at about 680 µg/g. The fraction of free beta-sitosterol varied significantly between bark (33%) and pygeum (nearly all). In pygeum, the measured total beta-sitosterol concentration generally followed the labeled values for phytosterol content. No N-butylbenzene sulfonamide was found in any of the bark and pygeum samples.

Determination of trace level cadmium in SRM 3280 Multivitamin/Multielement Tablets via isotope dilution inductively coupled plasma mass spectrometry.

Cadmium was quantified at 80.15±0.86 ng/g (mean±95% expanded uncertainty) in NIST SRM 3280 Multivitamin/Multielement Tablets, using isotope dilution mass spectrometry. The method described utilized various precipitation and solid-phase extraction separation methodologies to isolate Cd from Sn and Mo, present respectively, at 11.1±0.9 mg/kg and 70.7±4.5 mg/kg in the tablet matrix. This allowed for measurement of (111)Cd/(113)Cd and (111)Cd/(114)Cd isotope ratios using both quadrupole collision cell technology inductively coupled plasma mass spectrometry (Q-CCT-ICP-MS) and sector field (SF)-ICP-MS equipped with a desolvating nebulizer system to mitigate the MoO(+) and MoOH(+) molecular ion interferences that typically affect the envelope of Cd isotopes.

Isolation of individual capsaicinoids from a mixture and their characterization by (13)C NMR spectrometry.

Individual compounds were isolated from a laboratory mixture of capsaicinoids by a multi-stage approach. First, the capsaicinoids were fractionated into capsaicins and non-capsaicins by argentation solid phase extraction (SPE) on a silver-charged propyl sulfonate resin. Second, compounds in each fraction were isolated by semi-preparative liquid chromatography on a C(30) phase in aqueous methanol. Third, the individual components of the original mixture were concentrated by reversed phased (C(18)) SPE. The structure of each purified compound was confirmed by (13)C NMR spectrometry and spectral comparison to known standards, purchased or synthesized locally. The chemical shifts of 15 capsaicinoid standards were measured on a 600MHz instrument, and their assignments to particular carbons were made by reference to Distortionless Enhancement by Polarization Transfer (DEPT) NMR experiments and NMR spectral prediction software.

Quantitative determination of capsaicinoids by liquid chromatography-electrospray mass spectrometry.

Eight naturally occurring capsaicinoids have been determined in Capsicum by use of high-purity standards, with norcapsaicin as an internal standard. The solid standards were rigorously checked for purity. The sensitivity of electrospray ionization (ESI), atmospheric-pressure chemical ionization (APCI), and coordination ion-spray (CIS; with silver) toward the capsaicinoids were measured and compared. The highest sensitivity was found for positive-ion ESI. Method validation of the liquid chromatography-ESI-mass spectrometry (LC-ESI-MS) determination is reported, including tests for repeatability (4%), detection limit (5 pg injected), linear range (20-6 ng injected), quantitation (excellent linearity; < 2% relative standard deviation), and recovery (99-103%). The major and minor capsaicinoids in a commercial plant extract and in chili pepper fruits were quantified.

Reversed-phase liquid chromatography and argentation chromatography of the minor capsaicinoids.

An investigation of the liquid chromatography of the minor capsaicinoids in a commercial capsaicinoid mixture is reported. Twelve stationary phases including C8, C18, C30, phenyl, and cation-exchange chemistries were examined in combination with isocratic aqueous methanol and aqueous acetonitrile mobile phases. A phenyl stationary phase and aqueous acetonitrile mobile phase baseline-resolved 7 of 11 capsaicinoids, and selected ion chromatograms (LC-ESI-MS) demonstrated this was the most effective reversed-phase separation. Argentation chromatography with an alkyl or phenyl column and aqueous silver nitrate-methanol mobile phase revealed the presence of the 6-ene-8-methyl and 6-ene-9-methyl homocapsaicin isomers and the absence of 7-ene-9-methyl homocapsaicin. A mixed phenyl-cation-exchange stationary phase (charged with silver ion) enabled unique and useful separations of the capsaicinoids.