Determination of lead in bone by electrothermal atomic absorption spectrometry with Zeeman effect background correction

Abstract

Um método para a determinação de traços de Pb em ossos por espectrometria de absorção atômica é descrito. Boas precisão e exatidão foram obtidas utilizando-se calibração externa com padrões aquosos e NH 4 H 2 PO 4 como modificador. O limite de detecção alcançado foi de 0,07 ng mL -1 na solução de leitura, correspondendo a 0,022 g g -1 na amostra original. Conseqüentemente, o limite de quantificação encontrado foi de 0,23 ng mL -1 . Uma precisão de 3,5% foi obtida na leitura de 400 ng de Pb na presença da matriz. A exatidão do procedimento foi confirmada pela boa concordância entre os valores certificado e encontrado na análise de um material certificado de referência (NIST SRM 1846, bone meal).A simple method for measuring trace levels of Pb in bone by electrothermal atomic absorption spectrometry is described. It is shown that Pb can be accurately measured with good precision and accuracy using external calibration with aqueous Pb analytical solutions containing NH 4 H 2 PO 4 as modifier. The detection limit was found to be 0.07 ng mL -1 , corresponding to 0.022 g g -1 in the original sample. Consequently, the limit of quantification was found to be 0.23 ng mL -1 . The precision of the procedure, expressed by the relative standard deviation, was 3.5% for 400 ng Pb in sample measurements. The accuracy of the procedure was confirmed by the good concordance between found and certified values in the analysis of a bone meal certified reference material, NIST SRM 1846.

Separation and preconcentration procedures for the determination of lead using spectrometric techniques: A review

“…The Pd-Mg modifier is the one most commonly used, since it produces the best results. This modifier allows for the application of pyrolysis temperatures ranging from 1200 to 1400 • C, which enables the separation of most interfering elements [13][14][15][16][17]. The stabilizing effect of this modifier also raises the atomization temperature to 2000 • C, which allows a characteristic mass of about 16 pg [13].…”

Direct determination of lead in bones using slurry sampling and high-resolution continuum source electrothermal atomic absorption spectrometry

“…Several analytical methods such as X-ray fluorescence (XRF) 13,14,17 , proton-induced X-ray emission (PIXE) 1 , inductively coupled plasma optical emission spectrometry (ICP-OES) 18,19 , two-jet plasma atomic emission spectrometry 20 , inductively coupled plasma mass spectrometry (ICP-MS) alone 2,11,12,21 or combined with laser ablation (LA-ICP-MS) 9,22 , hydride generation (HG-ICP-MS) 23 , atomic fluorescence spectrometry (AFS) 24 or electrothermal atomic absorption spectrometry (ETAAS) 1, 3,6,12,15,16,21,[25][26][27][28][29][30][31][32] previously assessed the validity and limitations for the purpose of quantification of Pb in both human and animal samples. Among these methods, ETAAS 1, 5,10,25,27,[31][32][33][34][35][36] still represents the most commonly used one in routine analytical practice because of its high sensitivity, favourable detection limits and relatively low cost of the instrumentation. However, due to the complex matrix, laborious sample preparation, relatively low analytical concentration and high volatility of some lead species, the analysis of bone or teeth samples is difficult 1, 33,34,37 .…”

“…To alleviate these problems attributed to PO molecular absorption, instrumentation with several different background correction systems have been employed 3, 5, 6, 10, 15, 16, 21, 25-27, 30-33, 36, 38, 39 . Among conventional line source atomic absorption spectrometers (LS AAS), Zeeman systems using both transverse 21,31,33,36 and longitudinal 3, 25, 32, arrangement were found 3,5,16,21,25,30,33,34,36,39 to be the most reliable for this purpose. However, it has been shown that under the influence of the magnetic field the rotational lines of molecular spectrum of the gaseous phosphorus monoxide (PO) have split thus making the analysis of samples with high phosphorus content when using Zeeman effect background corrections prone to errors 39,40 .…”

“…In many cases, modifiers such as Pd(nitrate) 27 , Pd/Mg(nitrates) 25,34 , W-Rh permanent modifier 25 had to be applied to further attenuate the interferences produced by phosphate matrix as well as to increase the thermal stability of Pb to yield reliable results for digested 25,27 or solid 25 calcified tissues. Application of phosphate modifiers has also been widely recommended for thermal stabilization of Pb during the analysis of bone digestates 1, 3,31 , as calcium hydroxyapatite, i.e. the main component of bone matrix and an endogenous source of phosphate, was shown 1, 3, 33 to be less efficient for this purpose.…”

Mineral and essential element measurements in dolphin bones using two analytical approaches

“…Bone samples were pulverised, homogenised and dried overnight at 80°C and then left to cool in desiccators. Aliquots of about 1000 mg from each sample were weighed and then digested in a microwave oven (Millestone Ethos D) with a mixture of nitric and perchloric acids at 80°C [41]. After cooling, the solution obtained was transferred to a 50-mL plastic tube and made up to 30 mL with Milli-Q water (18.2 MΩ cm −1 ; ±20°C) and the modifier solution (NH 4 H 2 PO 4 ) according to Pereira et al[41] The Merck certified standard solutions were analysed together with the samples in order to evaluate the analytical quality control.…”