No abstract

The 3-hydroxy-3-methylglutaryl neohesperidosides of hesperetin (brutieridin, 1) and naringenin (melitidin, 2) were isolated and detected from the fruits of bergamot (Citrus bergamia). The structures of these compounds were determined by spectroscopic and chemical methods.

The use of cavity ringdown spectroscopy (CRDS) for atomic absorption measurements in a 27-MHz low-power argon inductively coupled plasma (ICP) is described. These results are used to demonstrate the utility of CRDS for both plasma diagnostic and analytical measurements. In these experiments, an aqueous solution of lead was introduced into a modified torch designed to enhance the ICP conditions for atomic absorption measurements. Absorption intensity characteristics of the lead 283.3-nm absorption line as a function of observation height and lateral position in the plasma were recorded for three different ICP powers (700, 500, and 200 W). The radial distribution of the ground-state lead atom density was derived from Abel inversion of the lateral measurements. At the novel 200 W operating condition, spectral line shapes vs. height and lateral position were fitted to Voigt profiles. Line-of-sight values of the gas kinetic temperature and electron density at different plasma locations were estimated from Gaussian and Lorentzian broadening components, respectively. The results are discussed and compared with those from other methods. The unique flexibility of CRDS for atomic and ionic absorption measurements in an ICP and the potential application of the ICP-CRDS technique for analytical measurements are demonstrated. Analytical results are compared with theoretical estimates of the lead detection limit.

Food safety represents one of the main issues of national and international agencies appointed to health control. In April 2003, a French agency disclosed that powdered or smashed hot chili pepper imported from India and Pakistan was heavily contaminated with a carcinogenic azo dye known as Sudan I. This paper deals with a modern approach for assaying the content of this colorant in foodstuff down to a limit of a few tens of parts per billion. The isotope dilution method combined with APCI tandem mass spectrometry was used. The internal standard, 1-(d5-phenylazo)-2-naphthalenol, was obtained by simple chemistry, and its structure was determined by 1H NMR spectroscopy. The mass spectrometric method is more sensitive than the HPLC approach by a factor of 20.

5-Dimethylamino-1-sulfonyl naphthalene (DNS, commonly referred as dansyl) is a functionality, bearing well-established properties in directing the fragmentation, by mass spectrometry (MS), of the corresponding ionized sulfonylated derivatives. This property is shared also by its labeled analogs. The use of d(0)/d(6) DNS derivatives is now exploited in the application of the well-established isotope dilution mass spectrometric approach in the assay of complex mixtures. A new method for the quantitation of amino acids (AAs) in beverages is therefore presented, which relies on liquid chromatographic separation of their N-dansylated derivatives followed by comparative electrospray tandem MS/MS of the d(0)/d(6) isobaric mixtures. Labeled and unlabeled DNS derivatives of the selected AAs are readily available by microwave-assisted synthetic protocols. The novelty of the method is represented by the use of heavy and light DNS-isotopologue providing suitable reporter groups. Multiple-reaction monitoring has been applied in the assay of AAs in wine, pineapple juice and bergamot juice with good-to-excellent results as proved by both relative standard deviation, lower than 15%, and by the accuracy values in the range 90-110%.