Jiang Xin-yu

Microwave-assisted extraction of polysaccharides from solanum nigrum

The microwave-assisted method was used to extract polysaccharides from solanum nigrum. The optimum experimental parameters, mechanism of the extraction and the effect of microwave-assisted extraction process on the structures of polysaccharides were investigated. The extract was analyzed by the modified phenol-sulfuric acid method at 490 nm. The optimum experimental parameters were obtained by orthogonal experiments as follows: extraction time 15 min, microwave radiation power 455 W and the process ratio of materials mass to solvent volume 1:20. The results show that compared with the conventional reflux extraction, the microwave-assisted extraction has a higher yield in shorter time, with no effect on the finally obtained polysaccharides as seen from the FT-IR spectra. The scanning electron microscopy images reveal that the mechanism of the extraction is related to the structural changes of the plant cells in different extracting conditions.

Study on Adsorption and Separation of Naringin with Macroporous Resin

X-5 resin, with higher adsorption and easier desorption of naringin, was selected from five kinds of macroporous resins through static adsorption and desorption experiments. Effects of concentration, pH value, and flow rate of naringin extract on the adsorption of naringin by X-5 resin were studied. Meanwhile, the effect of these factors on the desorption of naringin from X-5 resin was also investigated. The experimental results show that the adsorption isotherm of naringin by X-5 resin can be described by the Langmuir isotherm equation. The static maximum adsorption capacity of naringin is 32.6 mg/g with naringin concentration at 2.7 g/L, while the dynamic adsorption capacity of naringin is 23.8 mg/g with naringin extract flow rate at two times that of resin volume per hour. The optimal eluant is 60% (v/v) ethanol-water with pH value of 10. The desorption ratio will rise to more than 85% when the flow rate of this optimal eluant is one to two times that of resin volume per hour.

Extraction Separation of Germanium with Hydroxamic Acid HGS98

The extraction separation of germanium from indium raffinate in hydrometallurgical zinc process was discussed. The conditions and mechanism of the extraction with hydroxamic acid HGS98 have been investigated in detail. The results show that using 2% (mass fraction) hydroxamic acid HGS98 and 5% D2EHPA as synergist, germanium is extracted (1-stage) over 99% in 5 min at phase ratio (Vo: Va) of 1:5 from indium raffinate with original acidity. Then, using 2 mol·L−1 NH4F as strip liquor, the stripping recovery is over 98% in 15 min at phase ratio of 1:1. This process has the following advantages: easy to operate, high recovery and selectivity, and lower investment cost. It provides a new way to recover rare metal — germanium from metallurgical spent residues.

Lutein and lutein esters in marigold flowers by high performance chromatography

Lutein and lutein esters in marigold flowers was quantitatively determined by high performance chromatography (HPLC) with ODS-C18 column. A mixture of CH3CN - CH3OH -CH3COOCH2CH3 with volume ratio of 55 : 1 : 44 was used as mobile phase at a flow rate of 1.0 mL/min and detection was carried out at 460 nm. The column temperature was about 20°C. The contents of lutein and lutein esters were determined by analytical curve of lutein since lutein and lutein esters have the same spectral characteristics. Determination results of hexane extracts and saponified samples of lutein show that the saponification transforms the esters into free lutein. The increase of the content of dipalmitate and palmitate stearate reveals that the reaction includes transesterifications.