Verification of the atomic absorption spectroscopy with graphite furnace analytical method for the quantification of cadmium in cocoa almonds (Theobroma cacao)

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Lourdes Salome Araujo
Wilson Tapia
Adrián Villamarín Ortiz


The flame atomic absorption (AA) spectroscopy method for determination of cadmium (Cd) in cocoa almond (Theobroma cacao) used by Agrocalidad is toxic to humans and the environment; that is why we use the atomic absorption spectroscopy method with graphite furnace (GFAAS) because it is more reliable and safer. Thus, we verified four performance parameters of GFAAS method, to quantify Cd in cocoa almond, by using certified reference material (MRC) and samples from four farms (A,B,C,D) located in the most important cocoa area of Ecuador, Flavio Alfaro city, province of Manabi; an interlaboratory test was performed and finally we developed a protocol (PEE/B/14). On the MRC (Code 07806B and 07167) was verified: linearity, precision, veracity and uncertainty in accordance with international standards Eurachem (2016) and IRAM (2010); linearity was between 0 and 8 ppb with R2 = 0.9988; standard deviation was 0.0005 and 0.0022 respectively; slant was 0.007 and the recovery percentage was 109.75; standard uncertainty was 0.00013 and 0.00082. The content of Cd in samples from farm A was 0.54 ppm, B and D farms 0.26 ppm and 0.15 ppm in farm C. In the interlaboratory test, the same concentration of Cd was established for simple C3 and, in accordance with the stipulated by the European Union, cocoa from the four farms could be exported without restrictions.
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