Determination of trans fatty acids in foodstuffs by gaschromatography-mass spectrometry

U okviru doktorske disertacije optimizovani su uslovi određivanja metilestara masnih kiselina, uključujući i trans izomere, primenom kapilarne gasne hromatografije–masene spektrometrije, na kapilarnoj koloni SP-2560 (dužina x unutrašnji prečnik: 100 m x 0,25 mm, debljina sloja stacionarne likvidne faze 0,20 μm, biscijanopropil polisiloksan). Korišćenjem standarnih rastvora metilestara masnih kiselina optimizovani su temperaturni program, odnos razdeljivanja i uslovi akvizicije podataka SCAN tehnikom. Razvijena je metoda za pripremu uzoraka u cilju određivanja sastava masnih kiselina u prehrambenim proizvodima gasnom hromatografijom–masenom spektrometrijom zasnovana na istovremenoj mikrotalasnoj ekstrakciji i esterifikaciji (SMEE). Validacija metode je izvedena poređenjem sa rezultatima dobijenim gasnom hromatografijom–masenom spektrometrijom nakon ekstracije po Soxhlet-u i derivatizacije masnih kiselina u metilestre masnih kiselina. Rezultati dobijeni primenom razvijene i referentne metode bili su statistički isti, kako u pogledu sastava masnih kiselina, tako i efikasnosti ekstrakcije. Rezultati su pokazali da su prednosti SMEE u odnosu na konvencionalnu metodu: kratko vreme pripreme uzoraka i samim tim manja potrošnja energije, kao i upotreba malih količina skupih organskih rastvarača. Dobro slaganje rezultata dobijenih primenom referentne i metode zasnovane na istovremenoj mikrotalasnoj ekstrakciji i esterifikaciji pokazuje da bi se SMEE mogla primeniti kao rutinska metoda za pripremu uzoraka prehrambenih proizvoda u cilju određivanja trans masnih kiselina (TFA). Određen je sastav masnih kiselina, sa posebnim akcentom na trans masne kiseline, u 273 uzoraka prikupljenih sa našeg tržišta u periodu od juna 2006. do juna 2009. godine. Sadržaj trans masnih kiselina u analiziranim uzorcima prehrambenih proizvoda, sirovina i međuproizvoda koji se koriste u pekarskoj i konditorskoj industriji, kretao se u veoma širokom intervalu, od 0,0% do čak 48,7%. Prosečan sadržaj trans masnih kiselina iznosio je 0,2% u uljima, 6,5% u jestivim margarinima, 19,9% u margarinima za domaćinstvo, 9,8% u industrijskim margarinima, 24,3% u namenskim mastima, 10,8% u masnim punjenjima, 1,6% u mlečnim proizvodima, 10,9% u slanom trajnom pecivu, 10,2% u čajnom pecivu, 6,3% u tvrdom keksu, 11,0% u vafel proizvodima, 10,6% u čokoladnim proizvodima i 9,2% u karamelama. Od ukupno 124 analizirana uzorka, koja se ne koriste za direktnu upotrebu u ishrani (namenske masti, masna punjenja, industrijski i margarini za domaćinstvo) 86 uzoraka (69,3%) sadrži više od 5% trans masnih kiselina, 25 (20,2%) sadrži manje od 5% TFA, dok u 13 uzoraka (10,5%) nije detektovano prisustvo trans izomera. Od ukupno 140 analiziranih uzoraka, koji se koriste za direktnu upotrebu u ishrani 74 uzoraka (52,8%) sadrži više od 2% trans masnih kiselina, 20 (14,3%) sadrži manje od 2% TFA, dok u 46 uzoraka (32,9%) nije detektovano prisustvo trans izomera.In this thesis, operating conditions for fatty acids determination, including trans isomers, by capillary gas chromatography–mass spectrometry, on capillary column SP-2560 (100 m x 0.25 mm, with a 0.20 μm film thickness of biscyanopropyl polysiloxane liquid phase) were optimized. Temperature program, split ratio and condition of data acquisition by SCAN technique were optimized using standard solutions of fatty acid methyl esters. A sample preparation method based on simultaneous microwave assisted extraction–esterification (SMEE) was developed for the determination of the fatty acid composition of foodstuffs by gas chromatography–mass spectrometry. The proposed sample preparation method was validated by comparison with the reference Soxhlet extraction method followed by derivatisation by methyl ester formation and the same determination step. The fatty acid compositions, as well as extraction efficiencies obtained by the use of the proposed SMEE method and reference method were statistically similar. The results showed that compared to the conventional method, SMEE method offer the advantages of short sample preparation time, low consumption of expensive organic solvents and less energy consumption. This good agreement between results provided, both by the SMEE and reference method, demonstrates the usefulness of the former as the routine method for the treatment of food samples prior to trans fatty acid analysis. The fatty acid composition, and trans fatty acid content of 273 samples collected from June 2006 to June 2009 year were determined. Trans fatty acid content in the analysed samples of food products, raw materials and intermediate products used in bakery and confectionery industry was ranged in a very wide interval, from 0.0% to 48.7%. The average contents of trans fatty acids were 0.2% in oils, 6.5% in the edible margarines, 19.9% in cooking margarines, 9.8% in industrial margarines, 24.3% in shortenings, 10.8 % in fat fillings, 1.6% in dairy products, 10.9% in crackers, 10.2% in tea cookies, 6.3% in biscuits, 11.0% in wafer products, 10.6% in chocolate products and 9.2% in the caramels. From the total of 124 analysed samples, which are not used for direct human consumption (shortenings, fat fillings, industrial and cooking margarines) 86 samples (69.3%) contained more than 5% trans fatty acids, 25 (20.2 %) contained less than 5% TFA, while 13 samples (10.5%) had an undetectable levels of trans isomers. From a total of 140 analysed samples, which are used for direct human consumption 74 food samples (52.8%) contained more than 2% trans fatty acids, 20 (14.3%) contained less than 2% TFA, while 46 samples (32.9%) had an undetectable levels of trans isomers

FORMULATION OF SUNFLOWER AND FLAXSEED OIL BLENDS RICH IN OMEGA 3 FATTY ACIDS

The recommendations of the World Health Organization (WHO) are aimed at increasing the consumption of foods rich in omega 3 fatty acids. The recommended ratio of omega 6 and omega 3 fatty acids in diet is 4-10 : 1, which allows muscle building, hormone production, reduces risk of the cardiovascular diseases, reduces blood pressure, triglyceride concentrations, improves brain functions, mood, intelligence etc. However, just some foods (eg. flaxseed oil, fish oils etc.) are rich in these compounds. The aim of this study was to examine the possibility of enriching refined sunflower oil (RSO) with omega 3 fatty acids by adding cold pressed flaxseed oil (CPFO). Samples: refined sunflower oil, cold pressed flaxseed oil, their blends in the mass ratio 70:30, 50:50 and 30:70 were analised, and the obtained results were compared with the one comertial vegetable oil blend present on the market of R. Serbia. The content of saturated fatty acids in analysed samples ranged from 9.63 to 10.3 2%, monounsaturated from 17.15 to 30.44 % and polyunsaturated from 59.78 to 73.15 %. The ratio of omega 6 : omega 3 fatty acids found in the samples was between 853 : 1 and 0.33 : 1

Određivanje sadržaja metribuzina u formulacijama pesticida primenom elektroanalitičke metodologije

The work presents results of the determination of metribuzin content in commercial pesticide formulations by applying chronopotentiometry with thin film mercury electrode as an electrochemical sensor. In the analyzed pesticide formulations, a single well defined reduction peak of metribuzin is observed at the potential around -880 mV. The content of the herbicide in commercial formulations is determined using the calibration curve method, by applying the initial potential of -0.21 V, and the final potential of -1.10 V. Recovery values based on the declared and found content of the active ingredient are in the range from 100.67% to 101.68%, with the values of relative standard deviation lower than 1.00%, indicating high accuracy and precision of the presented method

Development and Validation of Chronopotentiometric Method for Imidacloprid Determination in Pesticide Formulations and River Water Samples

A new electrochemical method for determination of imidacloprid using chronopotentiometry on thin film mercury and glassy carbon electrode was presented. The most important experimental parameters of chronopotentiometry were examined and optimized with respect to imidacloprid analytical signal. Imidacloprid provided well-defined reduction peak in Britton-Robinson buffer on thin film mercury electrode at -1.0V (versus Ag/AgCl (KCl, 3.5 mol/L)) and on glassy carbon electrode at -1.2V (versus Ag/AgCl (KCl, 3.5mol/L)). The reduction time was linearly proportional to concentrations from 0.8 to 30.0 mg/L on thin film mercury electrode and from 7.0 to 70.0mg/L on glassy carbon electrode. The detection limits were 0.17mg/L and 0.93mg/L for thin film mercury and glassy carbon electrode, respectively. The estimation of method precision as a function of repeatability and reproducibility showed relative standard deviations values lower than 3.73%. Recovery values from 97.3 to 98.1% confirmed the accuracy of the proposed method, while the constancy of the transition time with deliberated small changes in the experimental parameters indicated a very good robustness. A minor influence of possible interfering compounds proved good selectivity of the method. Developed method was applied for imidacloprid determination in commercial pesticide formulations and river water samples

Poređenje različitih metoda za uklanjanje rastvorenog kiseonika - primena pri elektrohemijskom određivanju imidakloprida

This study compares different methods for the removal of oxygen from the solution prior to the chronopotentiometric determination of the insecticide imidacloprid on glassy carbon electrode. The research included the application of the chemical method involving addition of sulfite ion, and the physical method of purging the sample with nitrogen stream, as well as their combination. By comparing analytical signals of imidacloprid, chemical method showed almost the same efficiency as conventional physical method, while the best reproducibility was achieved by applying chemical method with addition of the saturated sodium sulfite solution. The method is very simple and can be applied for deoxygenation of the solution prior to the chronopotentiometric analysis. The application of the chemical deoxygenation significantly shortened duration of the chronopotentiometric analysis of imidacloprid from approximately 15 min to 1 min.U ovoj studiji poređene su različite metode za uklanjanje rastvorenog kiseonika iz rastvora pre hronopotenciometrijskog određivanja insekticida imidakloprida na elektrodi od staklastog ugljenika. Istraživanje je obuhvatalo primenu hemijske metode dodatkom sulfitnog jona i fizičke metode provođenje struje azota kroz uzorak u trajanju od 5, 10 i 15 min, kao i njihovu kombinaciju. Poređenjem analitičkih signala imidakloprida, hemijska metoda pokazala je skoro istu efikasnost kao i konvencionalna fizička metoda, dok je najbolja reproduktivnost ostvarena primenom hemijske metode uz dodatak 0,8 cm3 zasićenog rastvora natrijum sulfita. Metoda je veoma jednostavna i može se primeniti za uklanjanje kiseonika iz rastvora pre izvođenja hronopotenciometrijske analize. Primenom hemijske deoksigenacije značajno se skraćuje trajanje hronopotenciometrijske analize imidakloprida sa 15 min na 1 min

Characterisation of the fatty acid profile of blended sunflower and flaxseed oil from the aspect of nutritional quality factors

U ovom radu ispitana je mogućnost poboljšanja nutritivnog kvaliteta rafinisanog suncokretovog ulja (S) dodavanjem hladno presovanog lanenog ulja (L) sa aspekta masnokiselinskog sastava, kao i određenih nutritivnih indeksa. Sadržaj masnih kiselina određen je primenom gasne hromatografije - masene spektrometrije, analizom metil estara masnih kiselina. Sadržaji zasićenih masnih kiselina (ZMK), mononezasićenih masnih kiselina (MNMK), polinezasićenih masnih kiselina (PNMK), kao i sadržaj ω3 i ω6 masnih kiselina određen je računski. Dodavanjem lanenog ulja uočeno je značajno povećanje sadržaja ω3 masne kiseline u dobijenim mešanim uljima. Pri mešanju nisu uočene značajne promene u sadržaju ZMK, sadržaj MNMK se dodavanjem lanenog ulja smanjio sa 30,44 % m/m na 17,15 % m/m, dok se sadržaj PNMK povećao od 59,78 % m/m do 73,15 % m/m. Dobijeni odnosi PNMK/ZMK za mešana ulja bili su u rasponu 6,07-7,54, što je u skladu sa smanjenjem faktora rizika za povećanje nivoa holesterola u krvi. Aterogeni i trombogeni indeksi bili su mnogo niži od 1, dok su HH indeksi bili relativno visoki 14,70-18,03, što je takođe u skladu sa preporučenim vrednostima sa nutritivnog aspekta kvaliteta ulja. Kriterijum koji je najviše uticao na kvalitet mešanih ulja bio je ω6/ω3 odnos, a optimalne vrednosti ovog odnosa (1-5) postignute su dodavanjem od 30 do 60% hladno presovanog lanenog ulja. U odnosu na kontrolni uzorak O, dobijena mešana ulja pokazala su veliku prednost po pitanju sadržaja PNMK, ω3, ω6, dok je izuzetno visok sadržaj MNMK i nešto niži sadržaj ZMK određen u uzorku O.In this paper, the possibility of improving the nutritional quality of refined sunflower oil (S) by adding cold pressed flaxseed oil (L) from the aspect of fatty acid content, as well as certain nutritional indices, was investigated. The content of fatty acids was determined using gas chromatography - mass spectrometry, by analysing fatty acid methyl esters. The contents of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), as well as the content of ω3 and ω6 fatty acids were calculated. By adding flaxseed oil, a significant increase in the content of ω3 fatty acid was observed in the obtained mixtures. No significant changes in the content of SFA were observed during mixing, the content of MUFA was reduced by the addition of flaxseed oil from 30.44 % m/m to 17.15 % m/m, while the content of PUFA increased from 59.78 % m/m to 73.15 % m/m. The obtained PUFA/SFA ratios for mixtures ranged from 6.07 to 7.54, which is consistent with a reduction in risk factors for increased blood cholesterol levels. Atherogenic and thrombogenic indices were much lower than 1, while HH indices were relatively high 14.70-18.03, which are also in accordance with the recommended values from the nutritional aspect of oil quality. The criterion that most affected the quality of mixed oils was the ω6/ω3 ratio, and the optimal values of this ratio (1-5) were achieved by adding 30 to 60% of cold pressed flaxseed oil. Compared to the control sample O, the obtained mixtures showed a great advantage in terms of PUFA content, ω3, ω6, while the extremely high MUFA content and slightly lower SFA content determined in sample O

Polyphenols and flavonoids contents in seed cake from Serbia confectionary sunflower (Helianthus annuus L.)

Polyphenols and flavonoids represent a group of compounds with high antioxidant activity. They are called nutraceuticals due to the many favorable effects on human health including anti-cancer, anti-inflammation, anti-allergenic, anti-microbial and anti-atherogenic actions. Those bioactive compounds can be extracted from many plant sources, including wastes from various food industries, and further be utilized for the development of various functional foods. Sunflower seed cake represents a waste from production of cold pressed sunflower oils. It can be exploited for isolation of various bioactive compounds which it contains. In this work, contents of total polyphenols and flavonoids were determined in sunflower seed cakes (n=20) in order to assess potential of this by-product as a source of beneficial natural compounds

Effect of abiotic and biotic stress on alteration of phytochemicals in maize leaf and grain - aftereffect on food quality and safety

Upotreba kukuruza u ishrani ljudi i životinja ima široku primenu jer predstavlja izvor različitih tohemikalija koje povoljno utiču na metaboličke procese. Tokom vegetacije biljka kukuruza izložena je različitim uticajima abiotičkog i biotičkog stresa. Napad jedne od najznačajnijih štetočina kukuruza, larve Ostrinia nubilalis zavisi od uslova sredine i može dovesti do smenjenja prinosa i do 30%. Oštećenja nadzemnih delova biljke povećavaju rizik od pojave truleži klipa, jer predstavljaju mesta sekundarne infekcije izazvane različitim patogenim gljivama. Jedna od neophodnih agrotehničkih mera je primena pesticida u poljoprivredi u cilju suzbijanju kako štetočina tako i korova, obezbeđujući stabilan prinosa. S druge strane, primena pesticida, nepovoljni uslovi spoljašnje sredine i biotički stres mogu dovesti do oksidativnog stresa, oštećenja ćelija i pojave slobodnih radikala i reaktivnih vrsta kiseonika (engl. reactive oxygen species - ROS). Ćelije i tkiva biljaka imaju razvijene antioksidativne sisteme odbrane koji ihibiraju ili vezuju slobodne radikale. Najznačajniji neenzimski antioksidansi su avonoidi, fenolne kiseline, karotenoidi, tokoferoli, tinska kiselina, vitamin C, i glutation. Osim promena u prinosu i antioksidativnom statusu, kod biljke može doći i do promena u količini i drugih tohemikalija kao što su proteini, šećeri, amnokiseline i masne kiseline. Do sada su nedovljno ispitani uticaji pesticida i abiotički stres koji mogu da izazovu promene na različitim tkivima kukuruza, pri čemu je više pažnje posvećano promeni tohemikalija izazvanoj uticajem spoljašnje sredine kao što je vodni decit. U cilju pronalaženja karakterističnog odgovora genotipa, u odnosu na promene tohemijskog sadržaja, kao i eventualno izdvajanje genotipa tolerantnog na potencijalni stres primenjuju su metode spekrofotometrije i savremene metode tečne i gasne hromatograje za odredjivanje tohemikalija u biljci.The use of maize in human nutrition and livestock feed is widely used because it is a source of various phytochemicals that have a positive efect on metabolic processes. During the growing season, the maize plant is exposed to various influences of abiotic and biotic stress. Ostrinia nubilalis larvae, one of the predominant maize pests, can reduce plant growth and cause stalk and ear damage, leading to a yield decrease of up to 30%. Damage to the above-ground parts of the plant increases the risk of cob rot, presenting sites of secondary infection caused by pathogenic fungi. One of the necessary agrotechnical strategies is the application of pesticides in order to control both pest and weed impact, providing stability of yield. On the other hand, the application of pesticides, negative environmental impacts, and biotic stress can lead to oxidative stress, cell damage and the appearance of free radicals and reactive oxygen species (ROS). Cells and plant tissues have developed antioxidant defense systems that inhibit or bind free radicals. The most important non-enzymatic antioxidants are flavonoids, phenolic acids, carotenoids, tocopherols, phytic acid, vitamin C, and glutathione. In addition to changes in yield and antioxidant status, alteration of other phytochemicals such as proteins, sugars, amino acids and fatty acids can also occur in the plant. The effects of pesticides and abiotic stress that they can cause on different tissues of maize have been insufficiently investigated. More attention has been given to the changes in phytochemicals content caused by the influence of the environment such as water deficit. In order to find the response of the genotype, in relation to changes in the phytochemical content, as well as the eventual selection of a genotype tolerant to potential stress, spectrophotometry methods and modern methods of liquid and gas chromatography were applied to determine phytochemicals in the plant

Ispitivanje kvaliteta podzemnih, izvorskih i rečnih voda sa područja jugoistočne Srbije

The study deals with mineral characterisation of natural waters from South-East Serbia. The contents of aluminium, arsenic, calcium, cadmium, cobalt, chromium, cooper, iron, potassium, magnesium, manganese, sodium, nickel, lead and zinc were analysed in spring, ground and river waters by inductively coupled plasma-atomic emission spectrometry (ICPAES) technique. The study area was in the Southern Serbia, and included slopes of Rtanj, Ozren, Bukovik, Vrdenik and Čemernik mountains, and the valley of South Morava. Obtained contents were compared with Serbian regulations on the quality of water for human use, and directive of World Health Organization (WHO) for maximum allowed concentrations of chemical substances. High contents of macro-elements, namely calcium, magnesium and potassium, were detected in several spring and ground water samples which are believed to be due to direct influence of rock minerals. Some water samples contained iron, manganese and copper in concentration up to 168.3, 8.10 and 14.9 μg dm-3, respectively, but within the permissible limits. Other heavy metals were not detected in analysed samples. Based on the derived results, tested ground and spring water samples have significant potential to be used as sources for the production of bottled water, but further investigations are necessary. Additional investigations have to be focused on complete physical, chemical and microbiological assessments of water resources. Systematic hydrogeological assessment also should be performed in all seasons. In the meantime, precautionary measures should be immediately taken to protect and preserve these water resources.Ovaj rad predstavlja analizu kvaliteta prirodnih voda iz jugoistočne Srbije. Sadržaj arsena, aluminijuma, kalcijuma, kadmijuma, kobalta, hroma, bakra, gvožđa, kalijuma, magnezijuma, mangana, natrijuma, nikla, olova i cinka je određivan u izvorskim i podzemnim vodama, kao i u rečnoj vodi. Analiza navedenih elemenata je izvedena ICP-AES tehnikom. Analizirani su uzorci voda iz oblasti jugoistočne Srbije, uključujući područja planine Rtnja, Ozrena, Bukovika, Vrdenika i Čemernika, kao i područje doline reke Južne Morave. Određeni sadržaji analiziranih elemenata su poređeni sa važećim pravilnicima Republike Srbije i preporukama Svetske zdravstvene organizacije (SZO). Visoki sadržaj makro-elemenata, odnosno kalcijuma, magnezijuma i kalijuma uočeni su u izvorskim i nekoliko uzoraka podzemnih voda, što može biti posledica direktnog uticaja magmatskih stena. Pojedini uzorci voda su sadržali nešto više sadržaje gvožđa, mangana i bakra u koncentraciji do 168,3, 8,10 i 14,9 μg dm-3, redom, ali u granicama propisanim Pravilnikom i u skladu da preporukama SZO. Ostali teški metali nisu detektovani u ispitivanim uzorcima. Na osnovu dobijenih rezultata se može zaključiti da testirani uzorci podzemnih i izvorskih voda imaju značajan potencijal u smislu proizvodnje flaširane vode, uz neophodna dodatna istraživanja. Dodatna istraživanja bi trebalo usmeriti na kompletnu hemijsku analizu i ispitivanje fizičkih i mikrobioloških karakteristika uzoraka voda. Pored toga, neophodno je sprovesti sistematsko hidrogeološko ispitivanje izdašnosti podzemnih i izvorskih voda tokom svih godišnjih doba. U međuvremenu treba preduzeti mere predostrožnosti kako bi se ovi vodeni resursi zaštitili i očuvali

Determination of residues of sulfonylurea herbicides in soil by using microwave-assisted extraction and high performance liquid chromatographic method

A modified method for the analysis of nicosulfuron, rimsulfuron and prosulfuron was developed and validated by using microwave-assisted extraction (MAE) and ultra-performance liquid chromatography with diode array detection in the ultraviolet region (HPLC-UV-DAD). The most important experimental parameters of extraction procedure and HPLC-UV-DAD technique were optimised in respect to those sulfonylurea herbicides. High recoveries of the microwave-assisted extraction were obtained by using a dichloromethane-acetonitrile mixture (2:1 volume ratio) acidified with acetic acid (0.8 vol.%) with the addition of urea. The mean recoveries at three spiking levels ranged from 97.47 to 98.76% for nicosulfuron, 97.88 to 99.17% for rimsulfuron and from 97.91 to 99.83% for prosulfuron. The limits of detection of nicosulfuron, rimsulfuron and prosulfuron were 0.95, 0.91 and 0.89 mu g kg(-1), respectively. The accuracy of the developed method was confirmed by HPLC coupled with tandem mass spectrometry parallel analyses. The developed method was used to investigate the dissipation dynamics of sulfonylurea herbicides in the real field trials in Vojvodina Province, Serbia. The obtained half-lives were 0.05, 0.23 and 0.15 days for recommended dose application of nicosulfuron, rimsulfuron and prosulfuron, respectively. Low residues and short half-life in soil suggested that the risk to sensitive rotational crops after application of those sulfonylurea herbicides is low when they are used in the appropriate dosages