Summary A method for determining histamine in wine by precolumn derivatization with PITC (phenylisothiocyanate) with reversed-phase HPLC and UV detection is reported. Histamine can be determined together with the 24 amino acids within 40 min, or separately in a shorter time (less than 4 min) if a prior solid phase extraction clean-up is used. 相似文献
The anthocyanin composition of rose wine made from cv. Öküzgözü, a variety of grape native to Turkey, and the effect of maceration time (3, 6, 12, 18, or 24 h) on the anthocyanin content of the wine have been investigated. High-performance liquid chromatography with diode-array detection (HPLC-DAD) and mass spectrometry (MS) were used for anthocyanin analysis. Thirteen different anthocyanins, including five glucosides, five acetyl glucosides, and three coumaroyl glucosides were identified and quantified. It was found that an important characteristic of Öküzgözü rose wine was the presence of a large amount of malvidin-3-glucoside and its acylated esters. The total anthocyanin content of the wine increased with increasing maceration time. On the basis of sensory analysis, the most preferred wine was that produced with 3-h maceration, because of its better color and general flavor attributes. 相似文献
The simultaneous determination of mono-organic acids and carbohydrates by ion chromatography with both conductometric and pulsed amperometric detection is described. The carbohydrates, such as mannitol, arabinose, glucose, fructose, lactose, sucrose, raffinose, and maltose, as well as monoorganic acids including acetate, glycolate, formate, pyruvate, and fluoride are separated as anions by ion-exchange chromatography with 0.080 mol/L sodium hydroxide eluent at 1 mL/min within 12 min. Carbohydrates are determined by pulsed amperometric detection and mono-organic acids are determined by suppressed conductivity detection. The species in beverages are determined. 相似文献
A method for the quantification of total d-gluconate by flow-injection analysis was developed using an immobilized-enzyme reactor and fluorescence detection. d-Gluconate was quantified using co-immobilized gluconate kinase (GK) and 6-phosphogluconate dehydrogenase (PGDH) reactor. d-Gluconate was phosphorylated to 6-phospho-d-gluconate by GK in the presence of ATP, and then the 6-phospho-d-gluconate produced was oxidized by PGDH with NADP+. The NADPH produced by the GK-PGDH reactor was monitored fluorometrically at 455 nm (excitation at 340 nm). A linear relationship between the responses and concentrations of d-gluconate was obtained in the ranges of 1.0 × 10−6–1.6 × 10−4 M. The relative standard deviation for 10 successive injections was 0.57% at the 0.1 mM level. This analytical method was applied to the quantification of d-gluconate in honeys, vinegars and noble rot wines, and the results showed good agreement with those obtained using the conventional F-kit method. 相似文献
An acid urease column was applied to a fluorometric flow-injection analysis (FIA) system as a recognition element for determination of urea in rice wines.
The acid urease has specific properties of showing its catalytic activity in low pH range and tolerance to ethanol in comparison to those of a urease from jack-beans. The enzymes were covalently immobilized onto porous glass beads with controlled pore size and then, packed into a small polymer column. The flow-type of the biosensing system was assembled with a sample injection valve, the immobilized enzyme column, and a flow-through quartz cell attached to a fluorescent spectrophotometer. Citrate buffer (50 mM, pH 5.0) as the carrier solution was continuously pumped through the system. Sample solutions were introduced into the system via a rotary injection valve. A standard urea solution was measured through monitoring variations in fluorescent intensity attributable to fluorescent isoindole derivatives formed by coupling with ammonia molecules released in the enzymatic hydrolysis of urea and orthophthalaldehyde reagents. The fluorescent intensity was measured under the conditions of λex = 415 nm and λem = 485 nm. A wide, linear relationship was obtained between the concentration of urea (1.0–100 μM) and the variation in fluorescent intensity. The monitoring did not suffer from ethanol and various amino acids contained in rice wines. Real samples pretreated with ion exchange resins for removal of endogenous ammonia were introduced into the FIA system and urea in the samples was determined. These results were compared with those obtained with use of an F-kit method. The proposed FIA system should present sensitive, selective and convenient analysis of urea in alcoholic beverages. 相似文献
A reversed-phase liquid chromatographic method, optimised for the separation of trans-, and cis-resveratrol, catechin, epicatechin, quercetin and rutin, is reported. Separation was achieved using a C18 column and a gradient
elution with acetonitrile and 5% formic acid aqueous solution. The analyses required an equilibration period of 10 min and
a run time of 25 min for completion. Identification was based on retention characteristics and by relative UV spectra, obtained
by photodiode array detector and were compared with commercial standards. Analyses were performed without any sample pre-treatment.
Detection was carried out by UV–Vis detector at three different wavelengths. The detection limit ranged from 0.16 μgm L−1 (cis-resveratrol) to 1.5 μgm L−1 (+)-catechin. Investigation was extended to quantitative determination of phenol compounds in Italian red wine and to investigate
the stability of the six antioxidants. 相似文献