| Navel orange is a kind of food which is well known by people. Orange has a beautiful look and a delicious taste. It's one of the best fruits as a present to your friends It contains many beneficial components which are good for human health, such as amino acids, sugar, trace elements, rare earth elements, vitamin C and so on. These components can not only be helpful to the body, but also have a role of beauty products. Navel orange is a treasure, of which peel is also common in Chinese herbal medicines, with the promotion of digestion. This "magic" orange naturally aroused the concern of researchers. Thus the researches of compositions of navel orange are growing. Gannan of Jiangxi province is abound in navel orange and Gannan navel orange has become a typical sample for study. On the bases of refering to domestic and foreign literatures, this paper used anion-exchange chromatography with integrated pulsed amperometric detection, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry and other technical means, respectively, made researches about amino acids, trace elements, rare earth elements and other components in navel orange to control their qualities. These researches are in favor of rational use of navel orange for consumers, and helpful to farmers to develop the resources rationally. By using fingerprint technology, We build three-dimensional fluorescent fingerprint of navel oranges to distinguish differential patterns. The main contents of this paper are as follows:1. We established an anion-exchange chromatography with integrated pulsed amperometric detection method to detect 17 amino acids in navel orange (arginine, lysine, asparagine, alanine, threonine, glycine, valine, serine, proline, isoleucine, leucine, methionine, phenylalanine, glutamic acid, aspartic acid, cystine, tyrosine). Amino acids by AminoPac PA10 column was used in this experiment, some factors which may have an impact on the separation and determination of amino acids, such as gradient elution conditions, flow rate and extraction conditions were investigated. gave The best chromatographic conditions of this experiment were: water,250 mmol·L-1 sodium hydroxide solution and lmol·L-1 sodium acetate gradient as eluents; flow rate:0.15 mL·min-1; injection volume:25μL; column temperature: 35℃. The amino acids have good linearity in the measured concentration range with amino acids in the corresponding good linearity with correlation coefficients greater than 0.995, a detection limit of 0.01-0.19 mg·L-1. Added 2 mg·L-1 and 8 mg·L-1 standard solution as two levels of concentration of spike recovery experiments, recoveries were 72.5%～130.5% and the relative standard deviation were of 0.5%～10.1%. These showed that the method has good accuracy and precision, which can basically meet the real samples with satisfactory results.2. A method with inductively coupled plasma atomic emission spectrometry (ICP-AES) combined with microwave digestion was established to detect 21 kinds of trace elements like As, B, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Ni, P, Pb, Zn, Bi, Cd, Sr, Na, La, Y in Gannan navel orange. The distributions and differences studied of trace elements in the flesh, peel and the corresponding soil of Gannan navel orange from 10 counties were also analyzed. The results showed that the use of microwave could digest samples fully, and they could meet the ICP-AES detection. The average recoveries of the elements were 77.7%-115.7%, relative standard deviations were less than 9.20%. The method can basically meet the requirements of the actual samples; orange flesh and skin are rich in K, Ca, Mg, P. There are differences in the contents of trace elements from different area. The elements higher in the cultivation of the soil were mostly abundant in the orange flesh and peel. The results of this chapter further explored the correlation between the quality of navel orange and the trace elements.3. A method with inductively coupled plasma mass spectrometry (ICP-MS) combined with microwave digestion was established to detect 15 kinds of rare earth elements like Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu in Gannan navel orange. The distributions of rare elements in the flesh, peel and the corresponding soil of Gannan navel orange were studied. The method detection limit was 1.5～13.4 ng·L-1, Three concentration levels of standard solution were respectively used to the spike recovery experiments, the average recoveries were 80.5%～113.6%, relative standard deviations were 0.03%～10.97%. And that this method could satisfy the actual sample analysis requirements. This paper summarized the experimental data of rare earth elements in the orange flesh, peel and soil, and obtained the differences and similarities among the oranges. It's useful to further monitored the quality of navel orange and identify the origin and authenticity of oranges. It also gave a guide to consumers to eat oranges reasonably.4. Three-dimensional fluorescence spectroscopy was used to obtain the fingerprints of Gannan navel orange. Principal component analysis was also used to classify the orange samples. The results showed that there were significant differences among the three-dimensional fluorescence fingerprints. The principal component analysis can be correctly applied to classify samples. Thus the method of identifying navel oranges from different areas were established. |
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