Chemistry

Eight synthetic food colours were analysed by green liquid chromatography. Green liquid chromatography is an environmentally friendly technique which does not use organic solvents in the extraction procedure or in the chromatographic method. Analysis was carried out for the following colours: tartrazine (E102), indigotine (E132), Quinoline Yellow (E104), Ponceau 4R (E124), Sunset Yellow (E110), Brilliant Blue (E133), Allura Red (E129) and carmoisine (E122) in four different foods: cookies, coloured rice, saffron and fruit juice. The method was performed on an Eurospher-100 C8 (5 μm, 4.6 × 250 mm) column with ultraviolet (UV)-VIS detection and validated by determining the calibration lines, measurement of recovery, precision, and limits of quantification and detection (LODs and LOQs). LOD ranged from 0.04 mg kg -1 for E102 to 1.00 mg kg -1 for E122; LOQ ranged from 0.06 mg kg -1 for E102 to 1.12 mg kg -1 for E122. The levels of colours in foods were compared with Iranian National Standards, but only 7.5% of cookies, 30% of coloured rice, 8% of saffron and 12% of juice samples were in compliance with these standards. Tartrazine is prohibited in Iran, but it was found as the most prevalent food colour in the samples analysed. The results of these tests confirmed that HPLC avoiding the use of organic solvents is a suitable method and can be used for quantitative analyses or screening of food samples for synthetic food colours.

Clinical and epidemiologic studies showed that among dietary factors the type of fatty acids (FAs) in the diet plays an important role in determining risk of chronic disease. The aim of our study was to determine the levels of Trans FA (TFA) in edible oil samples consumed in Tehran, Iran analyzed by gas chromatograph (GC). The mean of total TFA was 0.45% ranging from (0.11% -1.61%) for liquid frying oils and 2.92% ranging from (0.46% -5.40%) for solid oils. The major TFA observed in these two groups was elaidic acid in solid oils. The highest content of total saturated fatty acid (SFA) was detected in solid oils with average of 32.07 and palmitic acid was the major SFA in these four groups. Linoleic and linolenic acid are the most important poly unsaturated fatty acid (PUFA). The variance in the percentage of TFA in the edible oils probably resulted from differences in the type of oils, quality, heating, processing technique and storage condition of the edible oils. The results indicated that, edible oils contain considerable proportions of trans fatty acids. Therefore, it is important to assess the content of TFA in edible oils in Iran.

The aim of this study was to investigate the fatty acids profile of five sesame cultivars including Branching Naz, Darab, Karaj, Dezful and Black sesame and the effect of time and temperature roasting procedure. The seeds oil content varied from 43±0.28 to 47±0.41% with the average content of 44.4±1.87%. Darab and Black sesame cultivar had the highest and lowest oil content respectively. Oleic and linoleic acids were the two-dominant fatty acids in the sesame seed oil about 80 to 85% of the total amount, whereas palmitic and stearic acids were present at 12 to 15%. Moreover, Dazful and Black sesame had the maximum and minimum content of oxidizability value respectively. The results of the present study showed that the fatty acid contents in studied cultivars were steady during different roasting conditions and fatty acid behavior of samples was good fitted with the high temperatures.

Complete removal of smear layer and debris during the process of root canal therapy is of paramount importance in order to achieve the objectives of endodontic treatment. The aim of this study was to compare the amount of extruded debris and smear layer using two widespread rotary nickel-titanium instruments. Fifty eight freshly extracted human mandibular first molar mesial canals were randomly assigned into two groups. The root canals were instrumented using Mtwo (VDW, Munich, Germany), and BioRaCe (FKG Dentaire, LaChauxde-Fonds, Switzerland) NiTi instruments. Debris and smear layer from the apical thirds part during instrumentation were evaluated by scanning electron microscope. Then, the scores of remaining debris and smear layer were calculated for each group and compared. Data were then statistically analyzed using Mann-Whitney U test. There were significant differences in the amount of smear layer among two groups (P < 0.05). The greatest amount of apical debris was extruded by the BioRaCe group and the least by the Mtwo group. The results of the present study showed that, although both instrumentation techniques apically extruded debris and smear layer through the apical foramen, the Mtwo instruments induced less extruded debris and smear layer than the BioRaCe rotary systems.

Milk is an important source of all basic nutrients required for mammals including human beings. The study was conducted to evaluate physiochemical quality of milk samples in selected dairy plant of Iran. Various physiochemical properties of milk were analyzed by Lactostar analyzer and compared to the related standards. Also another major concern of this study was to consider the presence of melamine in milk samples by high-performance liquid chromatography. The method was performed using a C8 column and detection at 240 nm. Total 38 different milk samples were analyzed. The results for milk sample analysis showed fat 2.17±0.05%, protein 2.89%±0.01%, lactose 4.37%±0.02%, total solid 10.66%±0.06%, and mineral of 0.22%±0.05% and in infant samples fat 23.38±4.25%, protein 24.18%±3.86%, lactose 37.33%±6.26%, total solid 91.32%±6.26%, and mineral of 16.17%±7.25%. To conclude the occurrence of melamine in infant milk samples and pasteurized milk samples collected from Tehran-Iran revealed ...

We have studied the molecular disorder in ( 13 C)Ala-and ( 13 C)Gly-labeled dragline silk from Nephila edulis through the distributions of isotropic chemical shifts in one-and two-dimensional 13 C-13 C NMR spectra obtained under MAS. The alanine residues were found to be present in two distinct major structural environments, in agreement with previous studies, where -sheets and 3 1 -helices were found. The distributions in chemical shift within each residue were found to be uncorrelated, even between spins in the same amino acid residue, and were of similar widths for both the crystalline and noncrystalline parts. Upon long-term mechanical stretching of the silk, the NMR spectra showed no significant changes in conformation nor changes in the degree of disorder but did show increasing structural damage to the silk threads.

We have studied the molecular disorder in ( 13 C)Ala-and ( 13 C)Gly-labeled dragline silk from Nephila edulis through the distributions of isotropic chemical shifts in one-and two-dimensional 13 C-13 C NMR spectra obtained under MAS. The alanine residues were found to be present in two distinct major structural environments, in agreement with previous studies, where -sheets and 3 1 -helices were found. The distributions in chemical shift within each residue were found to be uncorrelated, even between spins in the same amino acid residue, and were of similar widths for both the crystalline and noncrystalline parts. Upon long-term mechanical stretching of the silk, the NMR spectra showed no significant changes in conformation nor changes in the degree of disorder but did show increasing structural damage to the silk threads.

Microporous organo-montmorillonites (organo-Mt) bearing weak base OH sites were prepared through montmorillonite intercalation with polyol dendrimers at different proportions (0.5, 1.0 and 3.0 mass%). These materials turned out to be suitable for the reversible capture of carbon dioxide, inasmuch as high amount (0.5-2.5 mmol/g organo-Mt) of CO 2 can be retained, and easy regeneration can be achieved upon slight heating up to 100°C. The CO 2 retention capacity (CRC) was correlated to the number of OH groups of the dendritic moiety, the dendrimer content and the specific surface area. Excessive dendrimer size and content appear to affect the CRC value, due to a decrease in both the specific surface area and number of accessible OH groups. The retention of larger amounts of CO 2 than predicted by stoichiometry confirms that the OH groups interact with CO 2 only through physical interactions.