Thermospray Flame Furnace Atomic Absorption Spectrometry Research Articles

Direct determination of Cu and Zn in fruit juices and bovine milk by thermospray flame furnace atomic absorption spectrometry

In the present work, thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was employed for Cu and Zn determination in bovine milk and fruit juice samples without any pretreatment. TS-FF-AAS system was optimized and a sample volume of 300 μl was injected into the carrier stream (0.014 mol l −1 HNO 3 at a flow rate of 0.4 ml min −1), and it was introduced into a hot Ni tube. The detection limits obtained for Cu and Zn in aqueous solution were 2.2 and 0.91 μg l −1, respectively, and 3.2 μg l −1 for Cu in a medium containing water-soluble tertiary amines. The relative standard deviations varied from 2.7 to 4.2% ( n=12). Sample preparation was carried out by simple dilution in water or in water-soluble tertiary amines medium. Accuracy was checked by performing addition-recovery experiments as well as by using reference materials (whole milk powder, non-fat milk powder, and infant formula). Recoveries varied from 97.7 to 105.3% for Cu and Zn. All results obtained for reference materials were in agreement with certified values at a 95% confidence level.

Improvements in thermospray flame furnace atomic absorption spectrometry

In thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) a nickel atomization tube is placed in the acetylene/air flame on a holder built onto a standard AAS burner head. The liquid to be analyzed is transported by a low or high-pressure pump through a very hot, simple, inexpensive ceramic capillary tip acting as a flame-heated thermospray into the flame furnace. This results in complete sample introduction and increases the residence time of the sample in the absorption volume. This leads for 17 elements to a 3–110-fold improvement in the power of detection compared to conventional flame AAS. The absolute detection limits (3s values, N=25) lie between 0.2 μg l −1 (Zn) and 310 μg l −1 (Se) according to the element. The R.S.D. ( N=15) is 1.4–5.5% according to the element and applied concentration. TS-FF-AAS can easily be incorporated on any standard flame AAS instrument and can be automated with a standard autosampler.

Simultaneous sample digestion and determination of Cd, Cu and Pb in biological samples using thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) with slurry sample introduction

In a Ni tube placed in an oxidizing air/acetylene AAS flame simultaneous digestion/oxidation of biological samples and powerful trace determinations were performed. A ceramic capillary was used for sample introduction. This capillary acted as a flame-heated thermospray nozzle (TS-FF-AAS). Slurry samples, prepared in 0.3 mol L−1 HNO3, were transported by a new 0.6 MPa (84 psi) flow injection system through the hot capillary into the flame tube furnace. A nitric acid vapour environment exists inside the tube at temperatures above 1000 °C oxidising the samples. The element traces could then be measured by AAS. For these investigations, 300 µL slurry samples (0.1 to 1.0% w/v) from various biological materials, such as pig kidney (CRM 186), bovine liver (SRM 1577), spinach (SRM 1570), orchard leaves (SRM 1571) citrus leaves (SRM 1572), tomato leaves (SRM 1573) and tomato puree were used. Reference values were additionally obtained by electrothermal atomic absorption spectrometry (ETAAS). The standard deviation (n = 10) was between 3 and 5% using the same slurry and about 10% when the whole process was repeated on subsequent days. The detection limits for Cd, Cu and Pb were found to be 0.5, 4.3 and 3.5 µg g−1, respectively. A t-test showed no differences between the found and certified values at a 95% confidence level. In all experiments the calibration could be performed with aqueous standard solutions.