A simple method for determining the presence of cadmium (Cd) in thermoformed and biodegradable flexible films and flour and starch samples from cassava, using graphite furnace-atomic absorption spectrometry (GF-AAS), is proposed. The biopolymers used in contact with foods can contain Cd due to contamination from the origin of the material used to make them. The nitric: perchloric acid digestion with reflux was optimized, and the statistical quality parameters were standardized. The GF-AAS instrumental conditions and the graphite furnace heating program were adjusted through pyrolysis and atomization curves, and the optimal temperatures were 530 and 1750°C, respectively. In addition, under optimal conditions, the working range was from 0.1 µg/L to 1.0 µg/L, with limits of detection and quantification of 0.02 and 0.07 µg/L, respectively. The precision was evaluated using intermediate precision and repeatability of the method, which showed standard deviations of 1.6–4.8% and 2.1–4.8%, respectively. The percentage of recovery of Cd ranged from 96.2% to 97.3%. The results obtained support the suitability of the method for determining the presence of Cd in these samples. Cd concentrations in flexible films and starch were below the quantification limit. The other samples (thermoformed and flours) contained less than 1 mg/kg (maximum level set by the NTC 4096), indicating that these polymers meet this standard and therefore can be used for food containers and packaging for fresh fruits and vegetables.

Recently developed biopolymers can contain lead due to contamination from the origin of the material used to make them. A method for determining the presence of lead is proposed, using GF-AAS in thermoformed and biodegradable flexible films and flour and starch samples from Cassava. Acid digestion with reflux was optimized and the statistical quality parameters were standardized. The graphite furnace heating program was adjusted through pyrolysis and atomization curves. The working range was from 2.0 to 7.0 μg/L, with limits of detection and quantification of 0.618 and 1.853 μg/L, respectively. The precision was evaluated using intermediate precision and repeatability of the method, which showed standard deviations of less than 4.70% and 4.36%, respectively. The percentage of recovery ranged from 94.8% to 106.5%. The results obtained support the suitability of the method for determining the presence of lead. Lead concentrations were below 1 mg/Kg, indicating that these polymers can be used for food containers.

No abstract

In this study, trans-(±)-N,N′-bis(salicylidene)-1,2-cyclo-hexanediaminemanganese(III) chloride ([Mn(t-salcn)]Cl) was synthe-sized and used as a catalyst for the epoxidation of citral. The  percentage of converted citral in two methods, chemical and electro-chemical, was determined and compared; in the former method, the oxidizing agent NaClO was directly and completely added at the start of the reaction, while in the latter, ClO− was progressively generated in situ. The reaction was monitored by the quantification of citral using gas chromatography coupled to mass spectrometry. The results showed that in both cases, the major products correspond to epoxides from ci-tral isomers, although differences were observed in the value of per-centage of epoxides obtained, besides the generation of side reactions affecting the yield of the product of interest.