Determination of Lead in Whole Blood by Filter Furnace Laser-Excited Atomic Fluorescence Spectrometry

Abstract

Electrothermal atomization is considered one of the most efficient means to atomize samples prior to the detection of atoms by either fluorescence or absorption. However, this technique is far from perfect because of the interactions that can take place among the analyte, the carbon of the graphite atomizer and principally the components from the matrix containing the analyte of interest. Analytical matrices containing high amounts of organic matter very often present problems related to the decrease of analyte sensitivity. The two main causes are losses of analyte during the heating cycle because of formation of volatile molecular containing the analyte of interest and/or increases of background of molecular origin. The problem is usually addressed and, in many cases, minimized by the optimization of the temperature program together with stabilized temperature platform furnace (SPTF) technique 1,2 and by chemical modification. 3Although the choice of proper ashing temperatures and heating rates is very effective for elements with high thermal and chemical stability, this approach does not seem to be always effective for elements which form volatile molecular species like lead. 4 A platform, which delays the atomization of the analyte until a temperature equilibrium is reached between the walls and the center of the tube, in many cases is a very useful approach to minimize problems related with the formation of compounds after the vaporization of highly volatile and medium volatile elements. Chemical modifiers can chemically transform the analyte of interest making it less volatile, and so higher ashing and/or atomization temperatures can be applied. Chemical modifiers also can be employed to interact with interfering species in order to achieve a time-resolved release of products during the heating cycle achieving a separation of the analyte from the matrix components. A disadvantage of using chemical modifiers is that they are usually employed in concentrations of the order of thousands of times higher than the analyte concentration present in the sample. This procedure can introduce impurities into the sample and cause false analytical results, principally if detection of ultratrace amounts of a common element like lead is intended. In addition, finding an appropriate chemical modifier is not always guaranteed.The graphite filter furnace (FF) is a new concept of electrothermal atomization, recently introduced by Katskov 5 and it has been applied successfully in atomic absorption spectroscopy. 6 The possibility of the introduction of larger volumes of sample, the decreased preatomization time and temperatures, and the elimination of spectral background as well as chemical interferences without the use of chemical modifiers are improvements that the FF technique have to offer over the commonly used atomization techniques. The spool shaped graphite filter, made of porous graphite, is inserted inside a pyrolytic graphite tube where the sample is deposited in the gap between the wall of the tube and the filter, ou...

Atomic Spectrometry Update. Advances in atomic emission, absorption, and fluorescence spectrometry, and related techniques

“…By using a Katskov filter Pb in whole blood was determined directly by ETA-LEAFS employing aqueous standards for calibration. 569 Palladium in airborne particulates has been determined by ETA-LEAFS after dissolution of the sample in aqua regia followed by selective extraction. 570 The concentration of Pd in ambient air was found to be in the range 0.2-14.6 ng m 23 .…”

Comparative study of electrothermal atomic absorption spectrometric methods for the determination of silver in used lubricating oils

“…For the filter furnace technique, a spool shaped graphite filter made in the laboratory with porous spectroscopy grade graphite (Carbone of America, Palo Alto, CA, USA) was used. 34 A 10 ml volume of sample was introduced in the atomizer. When required, 5 ml of the chemical modifier solution was used.…”

“…The filter separates the cavity where the analyte is deposited from the analytical zone (center of the tube) where the analyte is probed by the characteristic radiation. [34][35][36] Preparation of the ruthenium permanent modifier. The ruthenium permanent modifier was prepared by repeating 25 times the procedure of pipetting 40 ml of a 500 mg l 21 ruthenium solution onto the platform and submitting it to the heating program described in Table 1.…”

In-vessel extraction using a microtube and its application to the fluorimetric determination of trace lead

“…6,7 Graphite furnace atomic absorption spectrometry is the most frequently used method for the determination of lead. Although electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry, 8 filter furnace laser-excited atomic fluorescence spectroscopy, 9 and on-line microcolumn preconcentration and separation coupled with flame atomic absorption spectrometry 10 have also been used for the determination of lead, the necessary instrumentation is complex.…”