Relationship between sensory and instrumental analysis of 2,4,6-trichloroanisole in wine and cork stoppers

The effect of different corks stoppers on the sensory and instrumental determination of 2,4,6-trichloroanisole (TCA) was studied in wine and cork. A relationship between both measurements was also established.Four types of cork were used to seal white wine bottles for 8 months. The stoppers were from different raw material: a high quality commercial batch (C), slabs with yellow stain (YS) and slabs with a high musty and mouldy taint (T). Spiked samples (S) were prepared from C batch by injecting 1002 ng of TCA into the cork stoppers.TCA was determined by gas chromatography with electron capture detection after headspace solid phase microextraction in bottled wine (12 per group) and after extraction with pentane in the case of corks (six per group). Seven semi-trained assessors evaluated the different samples using a ranking test in 12 and six sessions for wine and cork stoppers, respectively.Wines and corks from S samples showed the highest TCA values in both sensory and instrumental measurements, the lowest values being for C samples. YS and T corks had intermediate values, although in general TCA concentration was higher in T. A slight tendency to increase the TCA content in stoppers with yellow stain compared to C samples was observed in wine. A high correlation coefficient (r=0.82) was found between sensory and instrumental analysis for wine, whereas this coefficient was much lower (r=0.56) for cork stoppers. Some hypotheses are given in order to explain these differences.     

Evaluation of Italian wine by the electronic tongue: recognition, quantitative analysis and correlation with human sensory perception

The electronic tongue based on a sensor array comprising 23 potentiometric cross-sensitive chemical sensors and pattern recognition and multivariate calibration data processing tools was applied to the analysis of Italian red wines. The measurements were made in 20 samples of Barbera d’Asti and in 36 samples of Gutturnio wine. The electronic tongue distinguished all wine samples of the same denomination and vintage, but from different vineyards. Simultaneously the following quantitative parameters of the wines were measured by the electronic tongue with precision within 12%: total and volatile acidity, pH, ethanol content, contents of tartaric acid, sulphur dioxide, total polyphenols, glycerol, etc. The electronic tongue is sensitive to multiple substances that determine taste and flavour of wine and, hence, the system was capable of predicting human sensory scores with average precision of 13% for Barbera d’Asti wines and 8% for Gutturnio wines.     

Evaluation of soil to tea plant elemental correlation using instrumental neutron activation analysis

Instrumental neutron activation analysis using relative and k ₀-based internal monostandard methods were employed for determination of concentrations of 12 elements in soil and tea plants collected from three different tea producing regions in India namely Assam, Darjeeling and Kangra. A total of 17 tea leaf samples along with corresponding soil samples were analyzed for elemental content. The obtained concentration data was used for the soil–plant elemental correlation studies. Positive correlation was observed between elemental concentrations of tea plants and the associated soil with Pearson correlation coefficient values in the range 0.6–0.9 for ten elements. Variations in transfer factor values were also observed according to the geo-chemical variation.     

Compositional dynamics of a commercial wine fermentation using two-dimensional FTIR correlation analysis

We have demonstrated that compositional changes occurring during a commercial red wine fermentation can be effectively monitored using FTIR spectroscopy and modelled with the aid of two-dimensional correlation techniques. This study represents a novel application of two-dimensional spectroscopy and showed that the reaction rates for the conversion of fructose and glucose to alcohol were different, with the latter being more rapid. The use of a simple three-component model serves to aid interpretation of the data and the results obtained confirm the value of two-dimensional FTIR correlation spectroscopy as a chemometric tool which has considerable potential for process monitoring.     

Chemical and instrumental analysis of ferrites

More than thirty years since the manufacture of the first commercial ferrites, research and development efforts continue to produce ferrites with enhanced performance and new applications. Analytical chemistry has maintained a substantial role in the ferrite industry in the characterization of both raw materials and products, and the analytical literature of ferrites has grown accordingly. The continuing importance of ferrites to the electronic device industry requires further development of analytical methods suitable for characterization of ferrites so that their chemical composition may be related to performance and to the manufacturing processes used. As modem analytical techniques have been developed, their application to the characterization of ferrites and the detection of heterogeneity in these materials is increasing.     

Dynamic calibration and automated instrumental analysis

The role of the analytical machine and the computer command in automated instrumental analysis are discussed and the eminent role of true and adapted reference material is stressed. The application of charts in process control (SPC) neglects the analytical potential which is contained in trends. As an improvement on-line calibration is suggested employing a set of high quality reference samples in a moving manner with subsequent regressions after each new analysis of one of the members of the set. The number of members of the set and the sequence of their analysis determine the corrective force of the system and weighted regression provides for large concentration ranges. The performance of the correction system was tested by simulation and results of application to OES and XRF in practice over long periods of time are communicated. The analysis of steel and oxide matter in form of iron ore sinter and blast-furnace slag resulted at any time in negligible bias between nominal and observed values of the set of reference samples. Residual standard deviations near or equal to the repeatabilities of the methods were observed.     

Determination of trace and minor elements in coal: A comparison between instrumental photon and thermal neutron activation analysis

Instrumental photon and neutron activation techniques have been compared through the determination of sixteen major, minor and trace constituents in two British Columbian coals and a standard coal. Between the two techniques, the results generally agreed to within one standard deviation with replicate precision being maintained, for both techniques, below twenty percent at worst and down to five percent or better for several elements. Almost all of the elements having environmental, industrial or economic significance in fossil fuels can be determined with good sensitivity by either of these two methods, both of which share the advantages of being non-destructive and multi-element in nature and sufficiently accurate as demonstrated in this paper.     

Beyond the characterization of wine aroma compounds: looking for analytical approaches in trying to understand aroma perception during wine consumption

The volatile compounds present in wines are responsible for the quality of the wine aroma. The analysis of these compounds requires different analytical techniques depending on the type of compounds and their concentration. The importance at sensorial level of each compound should be evaluated by using olfactometric techniques and reconstitution and omission studies. In addition, wine aroma is influenced by other factors such as wine matrix, which could affect the compounds’ volatility, decreasing or increasing their concentration in the headspace above the wine. Moreover, when a wine is consumed, several oral physiological variables could affect aroma perception. The focus of this review is to outline the most recent advances in wine aroma analysis and the most innovative techniques in trying to elucidate the main factors that influence wine aroma perception during consumption.     

Relative retention analysis in HPLC: The correlation between incremental relationships

It was shown that, in the absence of specific intramolecular interactions, residual silanol groups of reversed-phase sorbents should not affect the linearity of plots in the coordinates used in the method of relative retention analysis for pairs of substances. The validity of the method proposed previously for analysis of the selectivity of separation of substances was supported experimentally (based on the analysis of retention of substituted benzoates). The possibility of the extension of incremental relationships to the system consisting of three different substances was justified.     

Teabags: Computer programs for instrumental neutron activation analysis

Described is a series of INAA data reduction programs collectively known as TEABAGS (Trace Element Analysis By Automated Gamma-ray Spectrometry). The programs are written in FORTRAN and run on a Nuclear Data ND-6620 computer system, but should be adaptable to any medium-sized minicomputer. They are designed to monitor the status of all spectra obtained from samples and comparison standards irradiated together and to do all pending calculations without operator intervention. Major emphasis is placed on finding all peaks in the spectrum, properly identifying all nuclides present and all contributors to each peak, determining accurate estimates of the background continua under peaks, and producing realistic uncertainties on peak areas and final abundances.     

Optimization of instrumental activation analysis conditions

In instrumental neutron activation analysis (INAA) work, a good commonsense rule of thumb is that the optimum conditions for the measurement of any induced activity, in a multi-element sample matrix, are an irradiation time, a decay time, and a counting time each approximately equal to the half-life of the radionuclide (if feasible). In the present work, the INAA Advance Computer Program (APCP) was used to test this rule on ten reference materials. For the 280 radionuclide/material combinations traced through all 14 APCP condition sets, the rule predicted the best set for 67% of them, was off by one set for 31% of them, and was only off by two sets of 2% of them.     

How stereochemistry influences the taste of wine: Isolation,characterization and sensory evaluation of lyoniresinol stereoisomers

Wine expresses its beauty by sending a sensory message to the taster through molecules coming from grapes, yeast metabolism or oak wood. Among the compounds released during barrel aging, lyoniresinol has been recently reported as a relevant contributor to wine bitterness. As this lignan contains three stereogenic carbons, this work aimed at investigating the influence of stereochemistry on wine taste by combining analytical and sensorial techniques. First, an oak wood extract was screened by Liquid Chromatography–High Resolution Mass Spectrometry to target isomers separable in a symmetric environment and a diastereoisomer called epi-lyoniresinol was isolated for the first time. Then, an original racemic resolution based on natural xylose-derivatives was carried out to obtain lyoniresinol enantiomers. Chiroptical spectroscopic measurements associated with theoretical calculations allowed the unambiguous determination of their absolute configuration. The taste properties of all these stereoisomers revealed that only one lyoniresinol enantiomer is strongly bitter whereas the other one is tasteless and the diastereoisomer is slightly sweet. The presence of these three compounds was established in an oaked Bordeaux wine by chiral and non-chiral chromatography, suggesting the significant influence of stereochemistry on wine taste.     

Comparison of elemental composition of hair between osteoporotic and normal women by instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) was carried out on hair samples from a group of twenty patients undergoing a study of osteoporosis. Half of these were judged normal. Fourteen elements were measured but only calcium was found to have a correlation with the disease state. Calcium levels in hair were significantly lower (99% confidence level) in patients with osteoporosis. Conversely, calcium levels in the blood of osteoporotic patients were significantly higher (95% confidence level) than those in normals. Though the group studied was small it is felt that the levels of calcium in hair may be of value in diagnosing osteoporosis.     

Multielemental analysis of soils by instrumental neutron activation analysis

The results of an instrumental neutron activation analysis of some elemental concentrations in different soil samples near the industrial areas at Tirupati, India, are reported. Altogether 14 elements, Sm, La, Cr, Co, Zn, Cs, Ce, Th, Rb, Na, K, Sr, Fe and Eu were determined. The samples were irradiated with neutrons at the 100 kW Triga - Mainz research reactor and the induced activities were measured by gamma-ray spectrometry using an efficiency calibrated high resolution high purity germanium (HPGe) detector in connection with a multichannel analyzer. The results are discussed.     

Multielement analysis of lichen by instrumental neutron activation analysis

Lichen (species Trypethelium Eluteriae) is analysed for different elements. Nondestructive instrumental neutron activation analysis is employed for the multielemental analysis. Gamma-ray spectrometry is used for the identification and quantitative estimation of elements. Concentrations of 24 elements are reported. Gamma-ray spectrum of the lichen irradiated for 16 hours, delayed for 10 days, and counted for 10 hours on a 50 cm³ coaxial Ge(Li) detector is given.     

Elemental analysis of limestone by instrumental neutron activation analysis

Limestone samples from Assuit Governrate in Upper Egypt were subjected to elemental analysis by instrumental neutron activation analysis and X-ray fluorescence techniques. The samples were properly prepared together with their standards and simultaneously irradiated in a neutron flux of the order 7 × 1011 n/cm² s using TRIGA research reactor at Mainz. After activation the samples were subjected to γ-ray spectrometry using a high purity germanium detection system and computerized multichannel analyzer. Nineteen elements: Na, Ca, Mn, Fe, Sc, Cr, Co, Zn, Sn, La, Ce, Nd, Eu, Sm, Yb, Lu, Hf, Th and U were analyzed. X-ray fluorescence spectrometry have been also used. The presence of any elements in higher or lower levels in certain limestone samples is contingent on the occurrence of its bearing minerals, nature of parent sediments and depositional environments of these sediments. The major elements in the samples were also observed to be among the elements that had high enrichment factors in the study of suspended dust particulate within and around cement industries. This confirms cement as the major contributor to the airborne particulate matter in the environs.     

Human hair instrumental neutron activation analysis and medicine

Periodically increasing and decreasing enthusiasm has accompanied the studies of medical significance of human hair elemental composition for at least two decades. In this field, nuclear analytical methods play an extremely important role, especially the instrumental neutron activation analysis (INAA). This paper tries to add some new knowledge to this problem. Two approaches are used — comparison of individual hair composition with certain diagnoses in clinic groups and comparison of population data with medical statistics. Rather large samples and multielement mathematical procedures helped reveal strong correlations valuable for diagnostic and health screening.     

Industrial applications of instrumental neutron activation analysis

Neutron activation analysis is shown as a useful diagnostic technique in semiconductor industry. A better acceptance of the method for applications in industry has been achieved through a specialized analytical service. Its main application is the characterization of high purity silicon in all stages of production. Irradiation of large sample volumes allowes a very sensitive detection of impurities in silicon with detection limits down to 10^–16 g/g. Other applications discussed are the analysis of silicon carbide, quartz, pure water and titanium. Special techniques described are autoradiography, depth profiling and surface analysis. In semiconductor process technology NAA was used to monitor contamination of silicon wafers.     

Analytical applications of delayed and instrumental neutron activation analysis

Delayed neutron activation analysis (DNAA) is a rapid and sensitive analytical method for the determination of fissile elements in a variety of samples. The present work describes two different analytical applications of delayed neutron activation for the analysis of biological and environmental samples, respectively. In the first application, DNAA was utilized to determine the natural uranium content in NIST standard reference materials (SRM) 1547 peach leaves and 1573a tomato leaves. Measured uranium mass fractions are comparable to the non-certified values listed on the certificates for these materials. In the second application, delayed neutron activation is coupled with instrumental neutron activation analysis (INAA) for the measurement of rare earth elements (REE) (cerium, lanthanum, neodymium, and ytterbium) in NIST SRM 2586, Trace Elements in Soil Containing Lead from Paint. DNAA was utilized to determine the uranium mass fraction in SRM 2586 for the subsequent application of a correction factor to account for cerium, lanthanum, and neodymium produced as part of the INAA irradiation. Measured and corrected mass fractions for the REEs described here are all within the uncertainty limits provided on the NIST certificate for SRM 2586. These results and the demonstrated sensitivity of the DNAA system establish and validate the use of this method for the determination of REEs and for potential nuclear forensics applications.