The simultaneous determination of 19 phenolic compounds was performed directly in wort and beer by a combination of reverse-phase high-performance liquid chromatography coupled with coulometric array detection. Chromatographic separation was achieved with an appropriate gradient of flow and a binary solvent based on phosphate buffer, methanol, and acetonitrile in a 45-min run. Eight serial coulometric detectors were used for on-line generation of voltammetric data to resolve coeluting compounds. The method was reliable and sensitive, the regression coefficient of standard calibration curves is 0.972 < or = r < or = 1.000, and the standard deviation value ranges from 0.010 to 0.129 mg/L for wort and from 0.002 to 0.332 mg/L for beer. The mean concentrations of phenolic acids were 22.1 and 33.8 mg/L, respectively, in worts and beers produced in Italy. These amounts represent 5 and 10% of the non-tannic, non-flavonoid phenols in wort and beer, respectively.

The photophysics and photochemistry of all-trans-R,ω-di(2-thienyl)polyenes (with chain length n ) 2, 3, 4) and R,ω-di(3-thienyl)polyenes (with n ) 3, 4) have been extensively studied by stationary and pulsed spectrometry. Fluorometric and laser flash techniques were used to measure the quantum yields and lifetimes of the lowest excited states of singlet and triplet multiplicity in nonpolar and polar solvents at different temperatures. The trans-cis photoisomerization was also investigated, at least for the shorter oligomers. The kinetic parameters of the radiative, nonradiative, and reactive relaxation pathways were evaluated and discussed by comparison with the parent compound having n ) 1 (trans-1,2-dithienylethene) and the better known R,ωdiphenylpolyenes.

Derivative Potentiometric-Stripping Analysis (dPSA) is described as an inexpensive and rapid method for the determination of Cu(II) in beer. Beer samples were analysed directly after degassing and addition of the analytical reagents (hydrochloric acid, mercury(II) chloride, and potassium metabisulfite). It was not necessary to digest the sample. During dPSA the metal ions are deposited on a glassy carbon-working electrode and then stripped by a suitable oxidant. Quantitative analysis was carried out by the method of standard additions. The recovery of the method was tested by adding 50 µg L -1 , 75 µg L -1 and 100 µg L -1 of Cu(II) (as Cu(II) chloride solution) to the beer. The mean recoveries of Cu(II) ranged from 95 ± 5% to 98 ± 2%. The reproducibility was evaluated by three repetitive analyses for each sample and the standard deviation ranged from 0.6 µg L -1 to 5.5 µg L -1 . The detection limit was 0.8 µg L -1 . The Cu(II) concentration determined in seven beer samples ranged from 28 µg L -1 to 48 µg L -1 and the results obtained were not significantly different from those obtained by atomic absorption spectrophotometry (AAS).

A simple method was developed to determine 10 organic acids simultaneously in tomato products using reversed‐phase high‐performance liquid chromatography column with the diode array detector set at 210 nm. After centrifugation and filtration, the samples were passed through an anion exchange resin and the organic acids were released using 0.1‐N HCl. The chromatographic separation was achieved with isocratic analysis in a 20‐min run. The method was reliable and sensitive, the coefficient of determination of the standard calibration curve is 0.9925 ≤ r2 ≤ 0.9999 and the limit of detection ranged from 0.08 to 6.00 mg/kg for trans‐aconitic acid and acetic acid, respectively. The limit of quantification ranged from 0.19 to 15.18 mg/kg for trans‐aconitic and acetic acid, respectively. To establish the efficiency of the anion resin, the procedure was applied to a standard solution of a mixture of organic acids. The organic acids recovery ranged from 87.0% ± 1.9 for citramalic acid to 109.9% ± 5.2 for fumaric acid.

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