Nusret Ertaş

Assessment of cytogenetic damage in lymphocytes and in exfoliated nasal cells of dental laboratory technicians exposed to chromium, cobalt, and nickel

Dental laboratory technicians may be exposed to metal alloys that are used in the production of crowns, bridges and removable partial dentures. These alloys consist of 35-65% cobalt, 20-30% chromium, 0-30% nickel, and small amounts of molybdenum, silica, beryllium, boron and carbon. The aim of this study was to assess whether dental technicians are occupationally exposed to chromium, cobalt and nickel, by analyzing urinary excretion levels of these metals and to investigate the genotoxic effects of occupational exposure associated with dental prostheses production operations by analyzing cytokinesis-blocked micronucleus (CB-MN) frequencies in peripheral lymphocytes and micronucleus (MN) frequencies in exfoliated nasal cells from 27 dental laboratory technicians and 15 control subjects. The differences in the urinary excretion of metals between technicians and controls were statistically significant. The mean (+/-S.D.) CB-MN frequencies ( per thousand ) in peripheral lymphocytes were 4.00 (+/-2.98) among the dental technicians and 1.40 (+/-1.30) among the controls, a statistically significant difference (P<0.005). The mean (+/-S.D.) MN frequencies ( per thousand ) in nasal cells were 3.50 (+/-1.80) among the dental technicians and 1.19 (+/-0.53) among the controls, which was also a statistically significant difference (P<0.005). There was a significant correlation between duration of exposure and MN frequencies in lymphocytes (r=0.642, P<0.01), but not in nasal cells of technicians. Our data reveal that in vivo exposure to chromium, nickel and cobalt metals is evident and that this occupational exposure may contribute to the observed genotoxic damage in two types of cells, e.g. lymphocytes and exfoliated nasal cells. However, it cannot be determined which compound(s) are responsible for the genotoxic damage observed in this study.

Dispersive liquid-liquid microextraction combined with field-amplified sample stacking in capillary electrophoresis for the determination of non-steroidal anti-inflammatory drugs in milk and dairy products.

Dispersive liquid-liquid microextraction (DLLME) was coupled with field-amplified sample stacking in capillary electrophoresis (FASS) for the determination of five non-steroidal anti-inflammatory drugs (NSAIDs) in bovine milk and dairy products. After extraction, the enriched analytes were back-extracted into a basic aqueous solution for injection into CE. Under optimum conditions, enrichment factors were in the range 46-229. Limits of detection of the analytes ranged from 3.0 to 13.1 μg kg(-1) for all matrices analysed. Calibration graphs showed good linearity with coefficients of determination (R(2))≥ 0.9915 and relative standard deviations (RSD%) of the analyses in the range of 0.6-6.2% (n=5). Recoveries of all NSAIDs from bottled milk, raw milk, yogurt and white cheese samples were in the ranges of 86.6-109.3%, 84.3-100.5%, 77.4-107.3%, and 90.9-101.6%, respectively. DLLME-FASS-CE was demonstrated to be a rapid and convenient method for the determination of NSAIDs in milk and dairy products.

Electrochemically controlled solid-phase microextraction (EC-SPME) based on overoxidized sulfonated polypyrrole

A method for the extraction and selective determination of cations is proposed using electro-synthesized overoxidized sulfonated polypyrrole film. The polymer film is used for the selective extraction of trace levels of nickel and cadmium ions by solid-phase microextraction (SPME). The cation uptake and release properties of the overoxidized sulfonated polypyrrole film electrode were examined under both open circuit and controlled potential conditions for prospective applications in electrochemically controlled solid-phase microextraction. Increased extraction efficiency and selectivity toward cations were achieved in high saline content of water. Simple preparation of film coatings on a platinum wire was possible using a constant potential method. Applied positive and negative potentials facilitated the extraction and desorption of cations, respectively. Nickel and cadmium ions were desorbed into sample aliquot and determined by electrothermal atomic absorption spectrometry (ETAAS). The cation uptake and release mechanism is affected both by the cation exchange at the negative sulfonate and carboxylate moiety on the film and the altered solution pH occurring at the counter electrode caused by the applied potential. The method was validated using a standard reference material and tested for the determination of cadmium ion in commercial table salt samples.

Quantitative determination of piroxicam in a new formulation (piroxicam–β-cyclodextrin) by derivative UV spectrophotometric method and HPLC

A derivative ultraviolet (UV) spectrophotometric method for the determination of piroxicam in piroxicam--beta-cyclodextrin tablets was developed. Phosphate buffer (pH 7.8, 0.1 M) and ethanol were used as a solvent system throughout the study. In this study, determination of piroxicam was conducted by using first order derivative amplitudes at 261.4 nm (n=4). Standards for the calibration graph ranging from 2.40 to 20.0 microg/ml were prepared from working standard. The proposed method is accurate with 99.70%+/-0.50 recovery value and precise with coefficient of variation (CV) of 1.29. The results were compared with those obtained using a high-performance liquid chromatography (HPLC) procedure. A reversed-phase C(18) column with aqueous phosphate buffer:methanol, 60:40, v/v, mobile phase was used. UV detector was set at 254 nm. Calibration solutions used in HPLC were ranging from 5 to 20 microg/ml. Results obtained in HPLC were comparable to those obtained by derivative UV spectrophotometric method.

A novel silica trap for lead determination by hydride generation atomic absorption spectrometry

Abstract A novel silica trap for lead determination at concentration levels of ng/l was developed using hydride-generation atomic absorption spectrometry. The device consists of a 7.0-cm silica tubing which is externally heated to a desired temperature. The lead hydride vapor is generated by a conventional hydride-generation flow system. The trap is placed between the gas–liquid separator and silica T-tube; the device traps analyte species at 500 °C and releases them when heated further to 750 °C. The overall efficiency is 49%. The presence of hydrogen gas is required for revolatilization; O 2 gas must also be present. The analytical plot is linear up to 2.0 ng/ml for a collection period of 60 s. The response is also linear with respect to increasing collection periods up to 4 min. For 60-s trapping, the detection limit is 19 ng/l.

Determination of bismuth using on-line preconcentration by trapping on resistively heated W coil and hydride generation atomic absorption spectrometry

A novel analytical system was developed to trap and preconcentrate bismuth from the vapour phase stream. Bismuthine formed by sodium tetrahydroborate reduction was trapped on a tungsten coil previously heated to 270 °C. The analyte species were re-volatilised by increasing the coil temperature to 1200 °C and then transported to an externally heated silica T-tube by using a mixture of argon and hydrogen as the carrier gas. The base width of the transient signal was less than 0.5 s. The reproducibility of the analytical signal was influenced by the rate of heating of the tungsten coil at the releasing stage. The precision of the analytical system was found to be 5.8% RSD (n = 13) for 0.010 ng ml−1 Bi when peak height was used. Due to sharp signals, peak area readings gave higher RSD values but they could be used for quantitation. The relationship between the analytical signal and the sample volume was found to be linear between 0.5 ml and 60 ml when using 0.100 ng ml−1 Bi. When the sample volume was increased to 25 ml, the blank values became significant. The calibration plot for an 18 ml sampling volume was linear between 0.030 and 0.500 ng ml−1 Bi. A limit of detection of 0.0027 ng ml−1 (3s) was obtained with 18 ml of sample volume. The concentration limit of detection achieved was comparable with or better than those obtained by techniques such as ICP-MS and HG-ETAAS. When the distance between the trap and atomiser was increased to 200 cm, a 72% and 24% decrease was observed in the peak height and peak area, respectively. In order to validate the accuracy of the method, two geological standard reference materials and one certified water standard reference material were analysed and the results were found to be in good agreement with the certified values at the 95% confidence level.

Determination of parabens in human milk and other food samples by capillary electrophoresis after dispersive liquid–liquid microextraction with back-extraction

Dispersive liquid-liquid microextraction (DLLME) with back-extraction was used prior to capillary electrophoresis (CE) for the extraction of four parabens. Optimum extraction conditions were: 200 μL chloroform (extraction solvent), 1.0 mL acetonitrile (disperser solvent) and 1 min extraction time. Back-extraction of parabens from chloroform into a 50mM sodium hydroxide solution within 10s facilitated their direct injection into CE. The analytes were separated at 12°C and 25 kV with a background electrolyte of 25 mM borate buffer containing 5.0% (v/v) acetonitrile. Enrichment factors were in the range of 4.3-10.7 and limits of detection ranged from 0.1 to 0.2 μg mL(-1). Calibration graphs showed good linearity with coefficients of determination (R(2)) higher than 0.9957 and relative standard deviations (%RSDs) lower than 3.5%. DLLME-CE was demonstrated to be a simple and rapid method for the determination of parabens in human milk and food with relative recoveries in the range of 86.7-103.3%.

X-ray Photoelectron Spectroscopic Characterization of Au Collected with Atom Trapping on Silica for Atomic Absorption Spectrometry

The nature of analyte species collected on a cooled silica tube for atom-trapping atomic absorption spectrometric determination was investigated with the use of X-ray photoelctron spectroscopy (XPS). An XPS spectrum of gold deposited on atom-trapping silica tubes reveals a Au 4f7/2 peak with a binding energy of 84.8 (±0.2) eV, which falls in the middle of the binding energies corresponding to zerovalent Au(0) at 84.0 eV and that of monovalent Au(I) at 85.2 eV. The corresponding energy for Au vapor deposited on silica is also 84.8 eV. Deposition of AuCl4- solution on silica results in two different Au 4f7/2 peaks with binding energies of 84.8 and 87.3 eV corresponding, respectively, to Au(0) and Au(III). Deposition of the same AuCl4- solution on platinum metal again gives two peaks, this time at 84.4 and 87.0 eV energies corresponding again to Au(0) and Au(III). Combining all these data, we conclude that gold is trapped on atom-trapping silica surface as zerovalent Au(0) with a 0.8-eV matrix shift with respect to the metal surface. A similar 0.6-eV shift is also observed between the binding energy of 4f7/2Hg22+ measured in Hg2(NO3)2·2H2O powder and that deposited on silica.

Determination of inorganic and total mercury by flow injection vapor generation atomic absorption spectrometry using a W-coil atomizer

A tungsten coil (150 W, 15 V) was used as the atomizer for the proposed Flow Injection Vapor Generation Atomic Absorption Spectrometry (FI-VGAAS) system to determine inorganic mercury and total mercury concentrations. In the proposed method inorganic mercury was measured when the W-coil is at room temperature and total mercury was measured when the W-coil temperature was set to 500 °C. The organic mercury concentration was calculated by subtracting the inorganic mercury concentration from the total mercury concentration. The calibration graphs were linear up to 100 ng ml−1. Limit of detection (LOD) values for inorganic mercury and methyl mercury were 0.60 ng ml−1 and 0.89 ng ml−1 respectively. The precision of the method in terms of RSD was between 2–3%, and the sampling frequency was 100 h−1. In order to validate the proposed method, known concentrations of methyl mercury and inorganic mercury were spiked into deionized water and tap water samples. Certified reference materials (CRM) IAEA-085 and NRC DOLT-3 were analyzed after microwave assisted extraction with 6.0 mol l−1HCl solutions. Both inorganic mercury and methyl mercury concentrations were in agreement with the certified values.

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.