Cadmium and lead cloud point preconcentration and determination in tobacco samples by thermospray flame furnace atomic absorption spectrometry

Abstract

A espectrometria de absorção atômica com forno tubular na chama (TS-FF-AAS) foi empregada para a determinação de Cd e Pb em diferentes tipos de amostras brasileiras de tabacos após a pré-concentração no ponto nuvem (CP) otimizada por planejamento Doehlert. Para a separação das fases no procedimento por ponto nuvem, Triton ® X-114 e 2-(bromo-2-piridilazo)-5-dietilaminofenol (Br-PADAP) foram utilizados como surfactante não iônico e agente complexante, respectivamente. Cádmio e chumbo foram determinados após digestão ácida e pré-concentração por ponto nuvem, sendo que as variáveis otimizadas por planejamento Doehlert foram: volume do agente complexante, volume de Triton ® X-114 e pH. Um ponto de máximo foi obtido nas superfícies de resposta para Cd e Pb. Para as determinações dos elementos por TS-FF-AAS, um volume de amostra de 50 µL foi introduzido no tubo de Ni posicionado sobre a chama, usando ar como carregador na vazão de 0,4 mL min -1 . Os limites de detecção e os desvios padrão relativos após a combinação de CP e TS-FF-AAS foram de 4,0 e 13 µg kg -1 e 3,1 e 0,7% para Cd e Pb, respectivamente. A exatidão do método proposto foi avaliada realizando-se testes de adição-recuperação e empregando-se material de referência certificado (folhas de chá e folhas de pessegueiro). As recuperações variaram de 93 a 103 e 93 a 107% para Cd e Pb, respectivamente. Todos os resultados obtidos para as amostras dos materiais de referência estão em concordância com os valores certificados a um nível de confiança de 95 ou 99% aplicando-se o teste t-Student.A thermospray flame furnace atomic absorption spectrometer (TS-FF-AAS) was employed to determine Cd and Pb in different Brazilian tobacco samples. Sample pretreatment consisted of acid decomposition and cloud point (CP) preconcentration optimized by Doehlert design. To promote phase separation in the cloud point procedure, polyoxyethylene(8) isooctylphenyl ether (Triton ® X-114) and 2-(bromo-2-pyridylazo)-5-diethyl-amino-phenol (Br-PADAP) were used as a nonionic surfactant and a complexing agent, respectively. The variables of the cloud point preconcentration procedure optimized by Doehlert design were: complexing agent volume, Triton X-114 volume, and pH. A response surface maximum point was obtained for Cd and Pb. For TS-FF-AAS, a sample volume of 50 µL was introduced into the hot Ni tube using air carrier at a flow rate of 0.4 mL min -1 . The limits of detection and relative standard deviations obtained for Cd and Pb when CP and TS-FF-AAS were associated were 4.0 and 13 µg kg -1 , and 3.1 and 0.7%, respectively. Accuracy was checked by addition-recovery experiments, as well as by using two certified reference materials (tea and peach leaves). Cadmium and lead recoveries ranged from 93 to 103 and 93 to 107%, respectively. All results obtained for reference materials were in agreement with certified values at 95 or 99% confidence levels by t-Student test.

Solid Phase Extraction to On-Line Preconcentrate Trace Cadmium Using Chemically Modified Nano-Carbon Black with 3-Mercaptopropyltrimethoxysilane

“…Therefore, the element has been included in the list of harmful and potentially harmful constituents in tobacco products and tobacco smoke according to US Food and Drug Administration (FDA). 53 The amount of Cd 2+ obtained in the present study was slightly higher and lower than those amounts determined by Andrade et al 54 and Lemos et al, 55 respectively, in cigarettes commercialized in Brazil. The amount of Cd 2+ also determined in certified reference (TORT-2, lobster hepatopancreas) by this method (26.47 ± 0.25 µg g −1 , n = 3) was statistically equal to the certified value (26.7 ± 0.6 µg g −1 ) with 95% confidence interval (Student's t-test), thus confirming the accuracy of the proposed method even for biological sample submitted to acid digestion.…”

Al(III), Cu(II), Co(II), Pb(II), Mn(II), and Fe(III) DETERMINATIONS IN VARIOUS SAMPLES by FAAS AFTER SOLID PHASE EXTRACTION

“…These results are almost comparable with some studies done in literature [18][19][20]. Comparison with the other SPE methods…”

Analytical chemistry in Brazil: healthy and growing

“…A more conventional CPE procedure was applied for the determination of Cd and Pb in tobacco samples using thermospray flame furnace atomic absorption spectrometry, TS-FF-AAS. 22 A nickel tube atomizer was used for improving the efficiency of atom cloud formation after sample introduction by thermospray employing a capillary ceramic tube. The efficiency of nickel and titanium tubes was compared for determination of Cu in biological samples and foods.…”