Effect of exhaustion hood flow rate in flow injection cold vapor and hydride generation atomic absorption spectrometry

The effect of exhaustion hood flow rate in the laboratory was investigated. It has been observed that this parameter significantly affects the analytical signal. This effect was more evident in cold vapor (CV) atomic absorption spectrometry (AAS) signal when unheated quartz T-tube atomizer (QTA) was used as atom cell. At maximum exhaustion hood flow rate, the peak height and peak area values for Cd decreased to 36% and 35%, respectively, of those obtained under no exhaustion. When CV cell with both ends covered with quartz plates was used, exhaustion hood flow rate did not affect the analytical signal significantly. The exhaustion hood flow rate effect was less pronounced in case of heated QTA as compared to unheated QTA. In addition to exhaustion hood flow rate, the air movements around the atom cell also influenced the analytical signal and precision of the measurement

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 degreesC. The analyte species were re-volatilised by increasing the coil temperature to 1200 degreesC 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

Flow injection-hydride generation-infrared spectrophotometric determination of Pb

novel analytical technique has been suggested for determination of Pb usingformation of PbH4(g) by chemical reduction and its subsequent spectrophotometric measurement in IR region, using the peak at 1821.4 cm(-1). The range of measurements is 1.0-30.0 mg l(-1) using a sample of 1.0 ml in flow injection mode. The 3 sigma limit of detection is 0.28 mg l(-1). The method has been applied to standard reference materials of Waste Water, EU-L-1, lead-base bearing metal 53e and Soil/Sediment #4 as well as soil samples collected from heavy traffic areas in Ankara

Correlation between total and EDTA/DTPA-extractable trace elements in soil and wheat

Wheat and wheat products are more important sources of energy and nutrients in diets of people in many cultures compared to other foods. The daily consumption of wheat is about 200 g/d/person in Western Europe and North America. On the other hand, 400-450 g of wheat and wheat products are consumed daily by average Turkish people. Wheat samples collected from the Iskenderun region in 1995 and 1996 and Ankara and Istanbul regions in 1995 were analyzed for their trace element content by instrumental neutron activation analysis (INAA). In addition, 13 soil samples were collected from the Iskenderun region in 1996. Total soil samples were analyzed by INAA and atomic absorption spectrometry (AAS), EDTA-extractable elements by INAA, and DTPA-extractable elements by AAS. Correlation analysis and enrichment factor calculations were applied to the trace element results. In wheat samples, a strong correlation was found between the elements such as Sc, La, Sm, Rb, and K whose main source is soil. The concentration of Se appeared to show larger variations among different regions. No significant correlation was observed for elements such as As and Se whose main sources in the atmosphere are anthropogenic activities