Aysel Berkkan

Determination of lead in dialysis concentrates using flow injection hydride generation atomic absorption spectrometry.

Flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) was used for determination of lead in dialysis concentrates. The parameters such as acidity, concentration of oxidising and reducing agents and argon gas flow rate were investigated to reach the best peak height sensitivity. No significant background signal was observed at high salt concentrations. The detection limit, concentration giving a signal equal to three times standard deviation of the blank signal, was 0.7ngml(-1) for a 500mul injection volume. Precision of the measurements at the 20ngml(-1) level was 3.7% R.S.D. The dialysis concentrates analysed by FI-HGAAS were found to have 10-70ngml(-1) of lead. The same samples were analysed by ETAAS after removing the matrix using solid phase extraction with Chelex 100. The results were in agreement with those obtained by FI-HGAAS.

Effects of Juniperus oxycedrus ssp. oxycedrus on tissue lipid peroxidation, trace elements (Cu, Zn, Fe) and blood glucose levels in experimental diabetes.

ETHNOPHARMACOLOGICAL RELEVANCE Juniperus oxycedrus L. (Cupressaceae) fruits and leaves are used internally and pounded fruits are eaten for diabetes in Turkey. AIM OF THE STUDY To evaluate the interrelationships between the levels of chosen trace elements (copper, iron, and zinc) and hepatic, renal lipid peroxidation (TBARS) in streptozotocin-induced diabetic rats treated with Juniperus oxycedrus ssp. oxycedrus (J.o.s.o.) leaf and fruit extracts for 10 days. MATERIALS AND METHODS J.o.s.o. fruit and leaf extracts were administered in STZ-induced diabetic rats, at doses of 500 and 1000 mg/kg. The blood glucose levels were measured in the 1st, 4th, 7th and 10th day of experiment. Fe, Cu, and Zn contents and lipid peroxidation levels of liver and kidney tissues were determined by atomic absorption spectrophotometry and ultraviolet spectrophotometry, respectively. RESULTS Treatment of diabetic rats with the J.o.s.o. fruit and leaf extracts decreased the blood glucose levels and both the levels of lipid peroxidation in liver and kidney tissues. J.o.s.o. extracts have augmented Zn concentrations in liver of STZ-induced diabetic rats. CONCLUSIONS Results indicated that J.o.s.o. fruit and leaf extracts might be beneficial for diabetes and its complications.

Synchronous fluorescence spectroscopy for determination of tahini adulteration

In this study, a quick and simple method was developed for detection of tahini adulteration with sunflower oil. The synchronous fluorescence spectroscopy (SFS) data of oil samples were collected by scanning the excitation and emission monochromators simultaneously with 20, 40, 60 and 80nm wavelength intervals within the range of 250-600nm. Three different multivariate calibration methods, namely partial least squares (PLS) analysis, principal component regression (PCR), and multiple linear regression (MLR) were used for data analysis. Wavelength selection feature of the chemometric software was also used in order to determine the optimum range of each dataset collected at 20, 40, 60 and 80nm wavelength intervals. All regression methods with and without wavelength selection mode were applied to these each dataset individually. Application of wavelength selection mode adversely affected the root mean square error of cross validation (RMSECV) and root mean square error of prediction (RMSEP) values and other quality parameters of all calibration and validation models which were built by using each dataset collected at 20, 40, 60 and 80nm wavelength intervals. Taking all parameters into consideration, the best results were obtained through the application of PLS analysis without wavelength selection mode on the SFS data collected at all wavelength intervals. The lowest detection limits of adulteration, 0.09% and 0.15% were obtained through the use of 40 and 80nm as wavelength intervals, respectively. RMSECV and RMSEP values were calculated as 0.74 and 1.26 for 40nm, and 0.65 and 0.81 for 80nm wavelength intervals.

A rapid tool for determination of titanium dioxide content in white chickpea samples

Titanium dioxide (TiO2) is a widely used additive in foods. However, in the scientific community there is an ongoing debate on health concerns about TiO2. The main goal of this study is to determine TiO2 content by using laser induced breakdown spectroscopy (LIBS). To this end, different amounts of TiO2 was added to white chickpeas and analyzed by using LIBS. Calibration curve was obtained by following Ti emissions at 390.11nm for univariate calibration, and partial least square (PLS) calibration curve was obtained by evaluating the whole spectra. The results showed that Ti calibration curve at 390.11nm provides successful determination of Ti level with 0.985 of R2 and 33.9ppm of limit of detection (LOD) value, while PLS has 0.989 of R2 and 60.9ppm of LOD. Furthermore, commercial white chickpea samples were used to validate the method, and validation R2 for simple calibration and PLS were calculated as 0.989 and 0.951, respectively.

Detection and quantification of a toxic salt substitute (LiCl) by using laser induced breakdown spectroscopy (LIBS)

The use of Li salts in foods has been prohibited due to their negative effects on central nervous system; however, they might still be used especially in meat products as Na substitutes. Lithium can be toxic and even lethal at higher concentrations and it is not approved in foods. The present study focuses on Li analysis in meatballs by using laser induced breakdown spectroscopy (LIBS). Meatball samples were analyzed using LIBS and flame atomic absorption spectroscopy. Calibration curves were obtained by utilizing Li emission lines at 610nm and 670nm for univariate calibration. The results showed that Li calibration curve at 670nm provided successful determination of Li with 0.965 of R2 and 4.64ppm of limit of detection (LOD) value. While Li Calibration curve obtained using emission line at 610nm generated R2 of 0.991 and LOD of 22.6ppm, calibration curve obtained at 670nm below 1300ppm generated R2 of 0.965 and LOD of 4.64ppm.

DÖRT FARKLI FLUORİD SALINIMI YAPAN RESTORATİF MATERYALDEN FLUORİD EMİLİMİNİN SIĞIR MİNESİNDE DEĞERLENDİRİLMESİ: İN VİTRO ÇALIŞMA

Aim: The aim of this study was to compare the fluoride uptake from four different of fluoride releasing restorative materials by bovine enamel and to determine the effect of time on this uptake. Material and Method: A glass ionomer cement (Fuji II), resin-modified glass ionomer cement(Fuji II LC), giomer (Beautifil) and compomer (Dyract AP) were elected. A total of 120 bovine enamel slabs were prepared from the buccal surfaces of the bovine teeth. The slabs were divided into 5 subgroups (n=6) representing 5 time intervals (1, 7, 14, 21 and 35 days). Fluoride-ion selective electrode method was used to determine the enamel fluoride uptake was determined. Results: Glass ionomers and giomer had significantly higher fluoride uptake than compomer (p<0.05). Glass ionomers and giomer had similar fluoride uptake in all test intervals. Conclusion: Considering the enhanced physical properties and long-term fluoride release similar to glass ionomers, giomers are found to be promising. Keywords: Giomer, glass ionomer, fluoride uptake, fluoride-ion selective electrode