Zhou Chun-shan

Separation and determination of non ionic surfactants of the nonylphenol polyglycol ether type by liquid chromatography

Abstract A normal-phase method for the separation and determination of non-ionic surfactants of the 4-nonylphenol polyglycol ether (NPEO) type by liquid chromatography is described, based on a LiChrosorb-Diol column and nonpolar linear gradient elution, with spectrophotometric detection at 275 nm. The method was applied to the determination of NPEO oligomers in the technical surfactants Arkopal N-20, N-40, N-60 and N-100 and in aqueous solutions from flotation processes. The relative standard deviations were 2.47–5.62%. The detection limits for nonylphenol polyglycol ether with 2, 4, 6, 8, 10, 13 and 15 ethoxy units were 51, 57, 64, 74, 85, 118 and 132 ng, respectively. The method can also be used for the determination of other alkylphenol polyglycol ethers. Reversed-phase LC with an octadecylsilica column was investigated and can be applied to the identification of the alkyl group present.

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.

Catalytic wave of cobalt and its analytical application in rapid determination of trace cobalt in complex zinc electrolyte solution

A polarographic catalytic wave of cobalt in the substrate solution (pH=8.5) of diacetyldioxime-potassium pyrophosphate-ammonium chloride was studied and a new method for rapid determination of trace cobalt in complex zinc electrolyte solution was developed. The results show that there is a very sensitive catalytic wave of cobalt at -1.23 V. At least three hundred thousand fold Zn2+ does not affect the determination of cobalt. The method is easy to operate and rapid, and when the signal-to-noise rate equals 2, the detection limit is 6 × 10−9 mol·L−1. A good linear relationship exists between the concentration of cobalt within 0.001–3.0 µg·mL−1 and the peak current. The method has successfully been used in the determination of trace cobalt in complex solution of the workshop for electrolyzing zinc.

Simultaneous determination of seven impurities in high-purity cobalt oxide by ICP-AES after matrix separation using 1-nitroso-2-naphthol as a precipitant

A method was developed for the simultaneous determination of seven trace impurities (Cd, Mn, Pb, Zn, Cu, Fe and Ni) in high-purity cobalt oxide by ICP-AES. The matrix effect was eliminated by precipitation with 1-nitroso-2-naphthol. The matrix effect of cobalt on the absorptions of trace impurities, the effects of reaction time, pH value, dosage of precipitant on the formation of cobalt-1-nitroso-2-naphthol complex, the effects of hydrochloric acid on the stability of this complex and masking of elements were studied. Recoveries of the impurities in spiked sample are from 90% to 110% with a precision of 1.1%–5.0% RSD. The detection limits of the seven elements are in the range of 0.01–0.24µg/g. The method can be applied to the analysis of high-purity cobalt metal, cobalt oxide and other cobalt compounds.

Microwave assisted-semi bionic extraction of lignan compounds from Fructus Forsythiae by orthogonal design

Microwave assisted-semi bionic extraction (MASBE) process for lignans from Fructus Forsythiae was studied. The influences of solvent pH value, microwave power, dosage of solvent and irradiation time were investigated. Optimum extracting parameters were determined by orthogonal experiments as follows: pH value of solvent at first extraction is 5.5–6.0, that at the second extraction is 7–8; microwave power is 700 W; mass ratio of Fructus Forsythiae to water is 1:12; irradiation time is 10 min, and extracting times is two. Under these optimal conditions, the yield of lignans reaches 0.364%. Compared with the conventional extraction methods, the MASBE process has the advantages of high extraction rate, high extraction selectivity.

Alkylated and silylated β-cyclodextrin for gas chromatographic chiral stationary phases

Three new chiral stationary phases, 2,6-di-O-heptyl-3-O-trimethylsilyl-β-cyclodextrin (DHTBCD), 2,6-di-O-pentyl-3-O-trimethylsilyl-β-cyclodextrin (DPTBCD) and 2,6-di-O-butyl-3-O-trimethylsilyl-β-cyclodextrin (DBTBCD), were synthesized. Chromatographic properties such as column efficiency, thermal stability and column life span, were studied. The separations of enantiomers, such as ketone, esters, alcohols and olefines, were investigated on the alkylated and silylated β-cyclodextrin stationary phases. The influence of diluent on chiral separation was studied. The experimental results indicate that the stationary phases show good chromatographic properties in separating enantiomers. It is observed that inclusion complexation and hydrogen bonding interaction hardly play a role in separating enantiomers.

Upgrade and separation of Co from solution with low-grade Co

Upgrade and separation of Co from solution with low-grade Co were studied. In the solution, the content of Co is about 1 g·L−1, while that of Ni, Zn, Mn, Mg, Si and Ca is 0.145, 1.108, 0.119, 6.672, 0.026 and 0.200 g·L−1, respectively. After absorbed with absorbent G − 1, the content of Co in the solution is less than 1 mg·L−1, the average loss rate of Co is 0.07%, while the average loss rate of Mg is 67.92%. It is demonstrated that the absorbent has selectivity to absorb Co. After the absorbent was eluted with HCl at room temperature, the solution with higher content of Co was obtained. Through being evaporated and concentrated, the contant of Co in the solution can be upgraded to 26.6 g·L−1. At the same time, most of Si, Mg is removed, the total recovery of Co can reach as high as 98.7%. The content of Pb, Ni, Cu, Zn, Mn in the discharge solution is 1.00, 0.26, 0.21, 0.09, 0.15 mg·L−1, respectively, and the discharge solution can reach the national discharge standard. CoCl2 solid can be obtained and can reach chemical purity.

Silylated and acetylated β-cyclodextrins for gas chromatographic stationary phases

Two new chiral stationary phases, 2,3-di-O-acetyl-6-O-trimethylsilyl-β-cyclodextrin (DATBCD) and 2, 6-di-O-trimethylsilyl-3-O-acetyl-β-cyclodextrin (DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β-cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β-cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer (k1) and separation factor(α)of α-phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.