Determination of End-Points in Hydrolytic Potentiometric Titrations in the Ca2+ - F- System

Mathematical modelling of a multi-component titration system of hydrolytic titrations of metal ions is described. A comparison of the calculated and experimental titration curves and end volumes in the Ca2+ -F_ system at different pH values of titrated solutions is presented. The determination of the end-point of titrations by several approximation and mathematical methods is described

Diversity for olive oil composition in a collection of varieties from the region of Valencia (Spain)

Olive (Olea europaea) has a long history of cultivation in the Mediterranean region of Valencia (Spain) and many local varieties exist in the area. According to their economic importance, varieties are classified as National, Principal, Secondary, Local, Disseminate, and Minor. We have evaluated during four seasons the olive paste moisture content, fat content, and olive yield, and the olive oil acidity, peroxide index, K232 and K270 parameters, total phenolics, K225 parameter, and fatty acids content in 45 varieties from the Collection of Olive Varieties from the Region of Valencia. Considerable diversity existed among varieties for all traits studied, and the variety effect was much greater than the season effect. Wide ranges of variation have been found for most traits, with differences among varieties being of more than 10-fold for total phenolics. The coefficient of genetic variation and heritability values have been generally high, in particular for fatty acids content. A few varieties were found to present values outside the ranges established in the regulations for several olive oil composition traits, although in some cases, like a variety with above the limit content of oleic acid, they are of interest for breeding. Several correlations were found to be significant between the K232 index and fatty acids profile, in particular with oleic acid. The values obtained for variety averages as well as the principal components analysis show that economically relevant varieties present a lower diversity for composition than varieties with low economic importance. In this respect, selection among traditional materials can be of interest to recover neglected varieties with specific composition profiles, as well as to identify sources of variation for breeding programmes. Discriminant analysis allowed a correct classification of 99.4% of samples, showing that composition profiles, in particular fatty acids content, is a powerful tool for chemometry and fingerprinting of olive oil. Overall, the results show that the wide diversity found in the collection studied, in particular in the less economically important varieties, is of interest for the selection and breeding of olive varieties with improved quality.Authors are grateful to Sergio Paz (Instituto Valenciano de Investigaciones Agrarias, Moncada, Spain) for his technical help, and also to the Laboratorio Agroalimentario de la Conselleria de Agricultura, Pesca, Alimentacion y Agua of the Generalitat Valenciana for the providing the facilities and funds for this research.Ruiz Dominguez, ML.; Raigón Jiménez, MD.; Prohens Tomás, J. (2013). Diversity for olive oil composition in a collection of varieties from the region of Valencia (Spain). Food Research International. 54(2):1941-1949. doi:10.1016/j.foodres.2013.06.023S1941194954

Discrimination of n-3 Rich Oils by Gas Chromatography

Exploring the capabilities of instrumental techniques for discriminating n-3 rich oils derived from animals is a very important though much neglected area that was emphasized more than 100 years ago. In this study the potential of gas chromatography (GC) for discriminating full fatty acid methyl ester (FAME) profiles from fish (cod liver and salmon) and marine mammal (seal and whale) oils is evaluated by means of principal component analysis (PCA). The FAME profiles from plant oils such as rapeseed, linseed and soy oils and seven different brands of n-3 supplements are also used in the discrimination process. The results from the PCA plots can reliably distinguish between plant, n-3 supplements, fish and marine mammal oils. By removing the contribution of the n-3 supplements and plant oils it is possible to discriminate between types of fish and marine animal oils. GC offers a rapid, simple and convenient means of discriminating oils from different species, brands and grades

Chemometric characterisation of the quality of ground waters from different wells in Slovenia

The quality of ground water as a source of drinking water in Slovenia is regularly monitored. One of the monitoring programmes is performed on 5 wells for drinking water supply, 3 industrial wells and 2 ground water monitoring wells. Two hundred and fourteen samples of ground waters were analysed in the time 2003-2004. Samples were gathered from ten different sampling sites and physical chemical measurements were performed. The following 13 physical chemical parameters were regularly controlled: temperature, pH, conductivity, nitrate, AOX (adsorbable organic halogens), metals such as chromium, pesticides (desethyl atrazine, atrazine and 2,6-dichlorobenzamide), highly-volatile halogenated hydrocarbons (trichlorometane, 1,1,2,2-tetrachloroethene and 1,1,2-trichloroethene). For handling the results different chemometrics methods were employed, such as basic statistical methods for the determination of mean and median values, standard deviations, minimal and maximal values of measured parameters and their mutual correlation coefficients, cluster analysis (CA), the principal component analysis (PCA), the clustering method based on Kohonen neural network, and linear discriminant analysis (LDA). The study gives the opportunity to follow the quality of ground waters at different sampling sites within the defined time period. Monitoring of general pollution of ground waters and following measuring can be used to search the pollution source, to plan prevention measures and to protect from pollution, as well.V Sloveniji spremljamo kakovost podzemne vode na številnih mestih, saj je podzemna voda pomemben vir pitne vode. Kot vir podatkov za kemometrično obdelavo smo izbrali monitoring v katerem je vključeno 5 vodnjakov, ki so namenjeni za oskrbo s pitno vodo, 3 industrijski vodnjaki in 2 kontrolni vrtini. Opravili smo analizo 214 vzorcev podzemnih vod v letih 2003 in 2004. Vzorce smo odvzeli na omenjenih desetih merilnih mestih in opravili fizikalne in kemijske analize. Fizikalno kemijske preiskave vključujejo merjenje naslednjih 13 parametrov, ki so podlaga za oceno kemijskega stanja podzemnih vod: pH vrednost, temperatura vode, električna prevodnost, vsebnost nitrata, vsebnost adsorbljivih organskih halogenov (AOX), vsebnost Cr(VI) in skupnega kroma, vsebnost pesticidov kot so desetil atrazin, atrazin in 2,6-diklorobenzamid, ter vsebnost halogeniranih ogljikovodikov kot so triklorometan, 1,1,2,2-tetrakloroeten in 1,1,2-trikloroeten. Za obdelavo rezultatov meritev smo uporabili različne kemometrične metode, osnovne statistične metode za določitev povprečne vrednosti in mediane, standardnih odmikov, minimalnih in maksimalnih vrednosti merjenih parametrov in njihovih medsebojnih korelacijskih koeficientov, analizo grup (CA), metodo glavnih osi (PCA), metodo grupiranja, ki temelji na Kohonenovih nevronskih mrežah in metodo linearne diskriminantne analize (LDA). Z metodo glavnih osi in s Kohonenovimi nevronskimi mrežami smo poizkusili poiskati podobnosti med posameznimi merilnimi mesti. Študija daje možnost, da sledimo kakovost podzemne vode na posameznih merilnih mestih in v določenem časovnem obdobju. Časovno sleditev splošnega onesnaženja podzemnih vod ter rezultatov posameznih merjenih parametrov, ki presegajo dovoljene meje, lahko uporabimo za iskanje vzrokov onesnaženja in za načrtovanje preventivnih ukrepov za zaščito pred onesnaženjem

Presence of nonylphenols in plastic films and their migration into food simulants

Nonylphenols (NP) possess estrogenic activities and may cause increased risk of cancerous and reproductive abnormalities in several living organisms. Despite their harmful nature, NPs are used as additives in food packaging material, especially plastic, which is the main food contact material in today\u27s packaging landscape. According to the fact that food packaging is one of the major potential food contaminant sources regarding NPs, there is a need for more information on identifying and quantifying of these chemicals when migrating into food. Seventeen plastic films for food packaging were analyzed for the presence of NPsnine of them were plastic films for deep freeze food packaging. We determined and quantified NPs by Gas Chromatography-Mass Spectrometry (GC-MS) using the internal standard method. All plastic films for deep freeze food packaging contained NPs within a concentration range from 11.9 to 43.7 mg/kg. We also studied the migration of NPs from three of the plastic films for deep freeze food packaging into food simulants. The migration of NPs from these plastic films into 95% ethanol and 10% ethanol was higher than the amount migrating into distilled water or 3% acetic acid.Nonilfenole (NP) uvrščamo med motilce delovanja endokrinega hormonskega sistema. Zaradi posnemanja delovanja naravnih hormonov lahko povzročijo povečano tveganje nastanka raka in reproduktivne nepravilnosti v živih organizmih. Kljub neugodnim lastnostim, se kot dodatki uporabljajo v embalažah za živila, predvsem v plastičnih folijah. Embalaža za živila je lahko eden izmed glavnih izvorov NP v živilih. Zato so podatki o vsebnosti NP v embalaži in predvsem podatki o prehajanju NP v hrano zelo pomembni. Prisotnost NP smo preverili v sedemnajstih plastičnih folijah, ki se uporabljajo za embalažo živil. Devet izmed vzorcev je bilo plastičnih folij, ki se uporabljajo za hranjenje globoko zamrznjene hrane. Vsebnost NP smo določili s plinsko kromatografijo v povezavi z masno spektrometrijo (GC-MS) z metodo internega standarda. V vseh preiskovanih folijah, ki se uporabljajo za embalažo zamrznjene hrane smo zaznali NP v koncentracijskem območju od 11,9 mg/kg do 43,7 mg/kg folije. Z migracijskimi poskusi smo preverili prehod NP iz treh plastičnih folij v modelne raztopine. V modelni vodni raztopini z 95 % in 10 % etanola je migrirala večja količina NP kakor v samo destilirano vodo ali v modelno vodno raztopino z 3 % ocetne kisline

Presence of dioxins in textile dyes and their fate during the dyeing process

Considerable levels of highly toxic polychlorinated dibenzo-p-dioxins (PCCDs) and polychlorinated dibenzofurans (PCDFs) were determined in two among the sixanalysed disperse textile dyes. The dioxin homologue profile of these dyes was similar to that found in some environmental and industrial samples, connected with the textile industry. Dyes contaminated with dioxins were further used in industrial polyester dyeing processes at laboratory scale. We observed the changes in dioxin contents, dioxin transformations and their distribution during the textile dyeing process. After the dyeing and textile finishing processes the content of dioxins was up to fifteen times higher. More than 85% of the total dioxin content was found in dyed polyester. Other 15% was discharged with waste dye bath. Our results confirmed that the presence of dioxins in some textile dyes may be a significant source regardinghuman exposure and environmental contamination.Dioksine predstavljata skupini toksičnih obstojnih spojin polikloriranih dibenzo-p-dioksinov in polikloriranih dibenzofuranov. V okviru naših raziskav smo preverili prisotnost dioksinov v tekstilnih barvilih. Analizirali smo šest vzorcev tekstilnih barvil. V dveh vzorcih tekstilnih disperznih barvil smo določili znatne vsebnosti dioksinov. Porazdelitev dioksinov v teh vzorcih barvil je podobna porazdelitvi dioksinov določeni v nekaterih vzorcih povezanih s tekstilno industrijo. Barvila, ki vsebujejo dioksine smo uporabili v poizkusih barvanja in spremljali spremembe v porazdelitvi in koncentraciji dioksinov skozi postopek barvanja. Masna bilanca dioksinov v postopku barvanja pokaže povečanje vsebnosti dioksinov, medtem ko ostaja njihova porazdelitev nespremenjena. Pri barvanju pri visokih temperaturah in v alkalnem mediju nastajajo dioksini iz prekurzorskih (predhodnih) spojin. Več kot 85% celotne vsebnosti dioksinov smo določili v vzorcih obarvanega poliestra. Preostalih 15% smo določili v odpadni barvalni kopeli. Rezultati raziskav dokazujejo, da prisotnost dioksinov v nekaterih tekstilnih barvilih predstavlja znaten doprinos k vsebnosti teh spojin v širšem okolju

Određivanje završne točke u hidrolitnim potenciometrijskim titracijama u sustavu Ca2+ - F-

Mathematical modelling of a multi-component titration system of hydrolytic titrations of metal ions is described. A comparison of the calculated and experimental titration curves and end volumes in the Ca2+ -F- system at different pH values of titrated solutions is presented. The determination of the end-point of titrations by several approximation and mathematical methods is described.Opisan je matematički model višekomponentnoga sustava hidroliznih potenciometrijskih titracija. Prikazana je usporedba izračunanih eksperimentalnih titracijskih krivulja te završnih volumena u sustavu Ca2 + — F- pri različitim početnim vrijednostima pH titriranih otopina. Opisano je računanje završne točke titracije različitim aproksimativnim računskim metodama

Evaluation of analytical methods for the determination of free formaldehyde on textile substrate

Release of formaldehyde from durable press-treated fabrics is a problem for human health and safety because formaldehyde is suspected to be carcinogenic. The accuracy of the standard test method for the free formaldehyde determination, Japan Law 112, depends on the formaldehyde content of the sample. The detection of low formaldehyde contents is particularly important in fields, like children clothing, so the application of high-performance liquid chromatography was evaluated. The results obtained by the standard testmethod, Japan Law 112, where UV/Vis spectrometer was used, were compared with the results obtained by HPLC method in which separation was performed on an RP C18 column with water-methanol as a mobile phase. It was shown that the detection limit and limit of quantification were improved using the HPLC method