In order to effectively evaluate the pollution status of available lead (Pb) in farmland environment, a method for the determination of available Pb in greenhouse soil by atomic absorption spectrometry with primary secondary amine (PSA) as solid phase dispersion adsorption material was established. In combination with neutral salt (such as 0.01 mol/L CaCl2) extraction technology, neutral lead-containing aqueous solution was obtained. Based on the rapid adsorption of Pb in neutral environment and the rapid desorption of Pb under acidic conditions, the pretreatment method of sample enrichment and purification based on PSA was established by optimizing the parameters. The samples after enrichment and purification were determined by atomic absorption spectrometry. Results showed that the linearity of the method was good in the range of 0.010 ∼ 0.050 mg/kg (R2 = 0.9990). The limit of detection was 0.0051 mg/kg and the limit of quantity was 0.017 mg/kg. The recoveries were 97.6% to 99.2% and the relative standard deviation was 0.79% ∼ 1.56% at the concentrations of 0.010, 0.030 and 0.050 mg/kg.
As a “rare bird on the plateau”, the Tibetan chicken is rich in nutrition and has high medicinal value. In order to quickly and effectively identify the source of food safety problems and to label fraud regarding this animal, it is necessary to identify the geographical traceability of the Tibetan chicken. In this study, Tibetan chicken samples from four different cities in Tibet, China were analyzed. The amino acid profiles of Tibetan chicken samples were characterized and further subjected to chemometric analyses, including orthogonal least squares discriminant analysis, hierarchical cluster analysis, and linear discriminant analysis. The original discrimination rate was 94.4%, and the cross-validation rate was 93.3%. Moreover, the correlation between amino acid concentrations and altitudes in Tibetan chicken was studied. With the increase in altitude, all amino acid contents showed a normal distribution. For the first time, amino acid profiling has been comprehensively applied to trace the origin of plateau animal food with satisfactory accuracy.
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