109 research outputs found
Determination of (E)-10-hydroxy-2-decenoic acid content in pure royal jelly: a comparison between a new CZE method and HPLC
No full textA new CZE method was developed and compared with HPLC for the determination of (E)-10-hydroxy-2-decenoic acid (10-HDA) in commercial pure royal jelly (RJ) samples of different geographical origin. The results obtained with the CZE method were highly correlated with those of HPLC (p < 0.01). Under optimized conditions, CZE employed minimal amounts of a 50 mM tetraborate buffer as BGE, without the addition of any organic solvent, EOF or pH modifier. The new CZE method showed a wide linear response range (0.006-0.800 mg 10-HDA/ml) good sensitivity (LOD and LOQ were 0.002 and 0.004 mg/ml, respectively) and excellent instrumental repeatability with respect to migration time and peak area (RSD% < 2.0 for intraday assay and < 4.0 for interday assay). The 10-HDA content in pure RJ ranged from 0.8 to 3.2 g/100g of RJ and a significant difference (p < 0.05) was found between the Italian and the extra-European RJs average values: 2.5 and 1.5 g/100g of RJ respectively, according to the CZE data. The possibility of application of CZE for routine analyses on RJ and RJ based products to verify their authenticity was here highlighted
Seasonal variation of Pb-210 activity concentration in outdoor air of Milan (Italy)
No full textWeekly measurements of 210Pb activity concentration on aerosol particles were performed at ground level in outdoor air in Milan (Italy) during the years 2000-2001. The experimental method was based on the delayed alpha spectrometry of in-grown 210Po activity detected on airborne particles collected on a filter support. On the same filter the 214Pb activity concentration was also measured during the sampling. 210Pb weekly concentration values showed a great variability and the average monthly values exhibited a seasonal pattern characterised by maxima in winter and minima in spring-summer. The same seasonal trend was also observed in 214Pb concentration values. 210Pb average yearly values were 0.70 and 0.82 mBq/m3 in 2000 and 2001, respectively, in good agreement with literature data registered at continental sites of similar latitude and longitude. The activity ratio 210Pb/214Pb was used to evaluate the residence time of fine aerosols in the urban air of Milan, which was 1-2 days
A study on nighttime-daytime PM10 concentration and elemental composition in relation to atmospheric dispersion in the urban area of Milan (Italy)
No full textIn this paper, results on a PM10 daytime–nighttime measurement campaign carried out in Milan to study the evolution of PM10 concentration and composition in relation to atmospheric dispersion conditions are shown. To account for the evolution of atmospheric dispersion conditions, Radon hourly concentration measurements were performed. The significant correlation between PM10 and 222Rn daytime concentrations evidences the dominant role of atmospheric dispersion in determining the temporal variation of PM10 levels. Whenever 222Rn concentrations accumulate during the night (indicating the formation of nocturnal atmospheric stability conditions), PM10 concentrations are higher than those registered during the daytime before, despite a decrease in emissions from active sources. On the contrary, when 222Rn concentrations do not accumulate during night hours, PM10 levels are lower than those measured during the daytime before.
As concerns the average elemental concentrations (in ng m−3), the nighttime–daytime variations are in the range −17% to +37%; during the night, soil-related elements (Al, Si, Ca, Ti) decrease while anthropogenic elements (Zn, Cu, Fe, Pb) increase.
A case study concerning a ‘green’ Sunday (when traffic was forbidden from 8 a.m. to 8 p.m.) is also discussed. The difference of PM10 concentration and elemental composition registered during the ‘green’ Sunday daytime and the following nighttime, together with the information on atmospheric dilution power obtained by Radon measurements, allowed the characterisation of the traffic source elemental profile and increased the comprehension of the low effectiveness of some PM10 reduction strategies
Factors influencing mass concentration and chemical composition of fine aerosols during a PM high pollution episode
No full textResults obtained during a winter field campaign for the fine fractions of particulate matter are presented. A high pollution episode together with an analysis of the main factors, which influence accumulation of pollutants is described. The measurement campaigns were carried out simultaneously at two sites in Northern Italy, Milan and Erba, during the winter of 2000. The daily variability in the mass concentration values and PM2.5/PM10 ratios appeared to be strongly dependent upon meteorological and atmospheric stability conditions and, in particular, wind regimes. During the intensive field campaign a high-pollution episode occurred that led to TSP and fine fraction concentrations well above the attention and alarm thresholds, reaching values of up to 200–250 μg m−3. The elemental concentrations were determined by ED-XRF analysis. The elemental composition of the particulate matter indicated that crustal matter oxides (soil dust) were the main component in particles with aerodynamic diameter dae>10 μm. They were an important part also in particles with 2.5<dae<10 μm, but strongly decreased in particles with dae<2.5 μm. In the finer fraction sulphates nitrogen and carbon compounds played a major role. The temporal patterns of mass and elemental concentrations, as well as the main components of PM were very similar at the two sites. The high-pollution episode was recorded at many locations in the Po plain, highlighting the role of meteorology and thermodynamic atmospheric conditions on pollution build-up on a large area
Determination and changes of free amino acids in royal jelly during storage
No full textFree amino acids (FAAs) in royal jelly (RJ) were determined and their identification was
confirmed with mass spectrometric detection (GC-MS). The presence of D-aminoacids was
evaluated using GC with a chiral column. The total FAA content was 7.3 mg/g RJ on average;
the major FAAs were proline, lysine, glutamate, b-alanine, phenylalanine, aspartate
and serine. The concentration of FAAs of the D-series was below the detection limit
of the method (0.1 mg/g RJ) in all the samples. The FAA fraction was monitored in RJ
frozen immediately after sample collection (control) and in aliquots of the same sample
stored at two different temperatures (room temperature and 4 °C) for different time
intervals (3, 6 and 10 months). The FAA content was constant throughout storage at
4 °C. However, at room temperature, proline and lysine increased after three months
to 6.8 and 3 mg/g, respectively and then decreased after 6 and 10 months to 3 and 1 mg/g
Determinazione dell'acido trans-10-idrossi-2-decenoico in campioni italiani e stranieri di gelatina reale:elettroforesi capillare e HPLC a confronto.
No full textUn nuovo metodo elettroforetico, basato sull’elettroforesi capillare zonale (CZE), è stato sviluppato e confrontato con l’HPLC nella determinazione del contenuto di acido trans-10-idrossi-2-decenoico (10-HDA), in campioni di gelatina reale (GR) pura. Il metodo impiegava, come elettrolita di supporto, modeste quantità (c.a. 50 ml per 100 corse) di un tampone di tertaborato di sodio 50 mM. Un ampio intervallo di risposta lineare (0,006-0,808 mg-HDA/ml), una buona sensibilità (limiti di rilevabilità e di quantificazione: 0,002 e 0,004 mg/ml, rispettivamente), una soddisfacente ripetibilità strumentale sia rispetto al tempo di ritenzione dell’analita che dell’area del picco (RSD% inferiore a 1,0 e 2,0% per il tempo di ritenzione nella stessa giornata e in tre giorni consecutivi, rispettivamente) e un tempo di analisi ridotto (13 minuti per ciascuna corsa, incluse le fasi di lavaggio) erano le principali caratteristiche del metodo CZE. I risultati ottenuti mediante CZE ed HPLC erano significativamente correlati (p<0,01). Una differenza significativa (p<0,05) è stata evidenziata tra il contenuto medio di 10-HDA nella GR italiana e in quello della GR di provenienza extra-europea (2,5 vs. 1,6 g 10-HDA/100 g GR, secondo i dati CZE
The role of atmospheric dispersion in the seasonal variation of PM1 and PM2.5 concentration and composition in the urban area of Milan (Italy)
No full textThe seasonal variation of PM1 and PM2.5 mass concentration and composition has been investigated in the great urban area of Milan. PM samplings were carried out 3 times a week during the year 2002. Mass and elemental concentrations were measured in all samples and in a limited number of filters also the elemental and organic carbon contribution (EC and OC) was determined.
In the urban area of Milan, PM2.5 comprises about 60% and 70% of the PM1 mass in summer and in winter, respectively. Among the measured PM components carbon compounds and sulphates are by far the major contributors and a significant contribution likely due to nitrates (not measured) should also be considered. PM1 and PM2.5 concentration and composition show a strong seasonal behaviour, which was studied in relation to atmospheric dispersion conditions.
Our approach is based on the use of Radon concentration as a natural tracer of differences in the average mixing layer height during the year. The application of a suitable "Radon index" allows the normalisation of PM mass and elemental data to account for the seasonal effect due to differences in atmospheric dispersion conditions
AN RBS, NRA AND SEM STUDY OF ANNEALING EFFECTS ON THE MICROSTRUCTURE OF PALLADIUM LAYERS
No full text
Composition, components and sources of fine aerosol fractions using multielemental EDXRF analysis
No full textThe extensive characterization of the elemental composition of some important components and of major sources of participate matter PM10 and PM2.5, sampled in parallel three times per week in Milan, for the whole year 2001 is described. More than 250 PM samples were analysed and major, minor and trace element concentrations were obtained by EDXRF. A strong seasonal modulation of particulate matter and element concentrations and an important contribution to PM from secondary compounds originating from gaseous precursors were observed. The main sources and their contribution were obtained by the application of absolute principal factor analysis to the large data set of elemental concentration. Copyrigh
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