Transverse heated filter atomizer: atomic absorption determination of Pb and Cd in urine

Abstract

A transverse heated filter atomizer (THFA) was applied to the direct determination of Cd and Pb in urine, and its analytical performances were investigated using a PerkinElmer SIMAA 6000 atomic absorption spectrometer. Seronorm certified human urine reference materials and six realistic samples collected locally were used for the method validation. The urines were diluted ten-or five-fold with 0.2% HNO 3 . Cd and Pb nitrate solutions were employed as standards. Recoveries of the elements from the urine samples were investigated with the analyte addition method. Compared to the transverse heated graphite atomizer (THGA) with a platform, the THFA provided a significant reduction of spectral background and chemical interferences from the urine matrix, without the use of chemical matrix modifiers, a 1.5-2 times increase of the determination sensitivity and, therefore, a reduction of limits of detection up to 0.018 and 0.2 mg L 21 for Cd and Pb, respectively. The use of a THFA collector made from carbon fiber and a tungsten wire improved recoveries of lead and cadmium in urine (¢92%). A sampling temperature 150 uC enabled us to skip the drying period, thus a significantly reduced temperature program was obtained. The accuracies of the measurements of Cd and Pb in the Seronorm urine materials were in good agreement with the recommended values: 4.1 ¡ 0.1 mg L 21 of Cd (recommended 5) and 92 ¡ 1 mg L 21 of Pb (recommended 85). The lifetime of the THFA for Pb determination was longer than 700 firings, with the sensitivity loss not more than 25% after 500 firings.

Feasibility of filter atomization in high-resolution continuum source atomic absorption spectrometry

“…Taking into account this assumption, the investigation of analytical performances of the GFA in this work was undertaken using 40 mg of carbon fiber as collector. An examination of other than carbon fiber materials for collectors [20][21][22][23][24] was beyond the scope of this research. …”

“…Optical arrangement of the line source based AA instruments employed earlier with filter atomization [15][16][17][18][19][20][21][22][23][24] place rigorous restrictions on both parameters. Light losses due to reduced aperture of the light beam and intense radiation from the filter at high temperatures caused increase of noise from the photo detectors and, respectively, limited opportunities for the determination of less volatile elements.…”

“…Filter atomization in conventional AAS based on line sources was used as alternative to the traditional platform tube technique for the direct determination of high and medium volatile elements in samples associated with strong spectral and chemical interferences [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. It provided reduction of interferences without involvement of chemical modifiers and the possibility for using larger sampling volumes of organic or inorganic liquids, while keeping the temperature program short.…”

“…It provided reduction of interferences without involvement of chemical modifiers and the possibility for using larger sampling volumes of organic or inorganic liquids, while keeping the temperature program short. Analytical characteristics of the transversely heated filter atomizer (THFA) have been verified in the analysis of organic extracts [18], fuels [19] and biological samples [20][21][22][23][24]. The atomizers were produced modifying commercial transversely heated graphite atomizers (Perkin Elmer) by furnishing the tube with filter and collector, instead of a platform.…”

Determination of As, Cd, Cu, Hg and Pb in biological samples by modern electrothermal atomic absorption spectrometry

“…One possibility is the use of GFAs based on the introduction of on line sources that may be particularly suitable for high and medium volatility elements such as As and Hg, thereby avoiding use of chemical modifiers while coping with large sample sources. Following this approach, a transversely heated GFA has been used with good results for determination of Cd and Pb in biological samples [156,181], opening a new means for further advances. Additional improvements in the atomizer (particularly those related to GF or GFA composition), in software and in detectors, can prevent vapor condensation on the atomizer surface, improving long-term repeatability of analytical signals, and further reducing background interferences and the time between sequential measurements by more efficient cooling of the atomizer.…”