Desenvolvimento de métodos de preparo de amostras para posterior determinação de As, Cd e Pb em carne e produtos cárneos

Abstract

Sample preparation methods, such as microwave-assisted wet digestion, dry ashing, wet digestion in open system and tetramethylammonium hydroxide (TMAH) solubilization were evaluated for subsequent As, Cd and Pb determination in meat (poultry, bovine, equine and pork), liver (pork), kidney (beef and pork) and its products (sausage, ham and spicy sausage). The determination was executed using atomic absorption spectrometry with graphite furnace (GF AAS), optical emission spectrometry with inductively coupled plasma (ICP OES) and mass spectrometry with inductively coupled plasma (ICP-MS) techniques. Regarding the methods recommended by the AOAC, the wet decomposition in a closed system was adequate for the subsequent determination of As, Cd and Pb but in dry ashing method As losses occurred. The proposed methods (wet open system and solubilization with TMAH) were optimized by evaluating parameters such as sample mass, reagents volume, time, temperature and others. The selected conditions for open decomposition system using digestion block were 2 g of sample mass, 10 mL of HNO3 + 1 mL of H2O2 at 150 ºC for 2 hours. The alkaline solubilization procedure was executed employing factorial design. The selected conditions were 500 mg of sample mass, 500 μL of TMAH and water bath solubilization at 90 ºC/120 min with 150 rpm agitation. The As, Cd and Pb recovery by spiking was satisfactory for open system decomposition (95 to 105%) and TMAH solubilization (95 to 104%). The results obtained for the certified reference materials (bovine muscle and liver) were in agreement (> 95%) with certified valves. The sample preparation methods proposed were considered appropriate for subsequent As, Cd and Pb determination in meat and similar products, offering low cost and high samples throughput. Moreover, they can be applied for both fresh and freeze-dried samples and the determination can be made by ICP OES and GF AAS. Among the samples analyzed, all showed levels of As, Cd and Pb below the maximum recommended in the legislation.