分析测试技术与仪器

Reasearch Advances in Chiral Separation of Amino Acids by Capillary Electrophoresis

SUN Ya-ming, BI Qing, WANG Li-tao, ZHANG Xiao-li, ZHANG Xia, DONG Shu-qing, ZHAO Liang

2015, (3): 129-139.

Abstract(1525)

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Abstract:
Capillary electrophoresis (CE)attracted widespread attention, because of its simple operation, minimal consumption of chemicals and high separation efficiency. It is also the research focus in recent years due to its powerful chiral separation ability. Amino acids are the basic modules of proteins and most of which have chiral centers. Chiral amino acid is an important feature of biological systems. Comparatively large difference in biological activity exists among the amino acid enantiomers. Therefore, chiral separation of amino acids plays an important role in understanding the life activities of both human and animal. In article the development and applications of chiral separation of amino acids by three separation modes of CE, including capillary zone electrophoresis (CZE), micellar electrokinetic capillary chromatography (MEKC) and capillary electrochromatography (CEC) in the last five years are reviewed.

Simultaneous Determination of Sweeteners and Antioxidants in Food by Liquid Chromatography-Tandem Mass Spectrometry

LU Qiao-mei, ZHANG Lan

2015, (3): 140-145.

Abstract(1140)

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Abstract:
A method for the simultaneous analysis of four sweeteners (acesulfame-K, sodium saccharin, sodium cyclamate and aspartame) and two antioxidants (tert-butylhydroquinone and butylated hydroxyanisole) by liquid chromatography-quadrupole time-of-flight mass spectrometry has been established. An extend-C₁₈chromatographic column and ESI (-) were used, respectively. Six compounds were separated rapidly in 6 min with 1 mmol/L of ammonium acetate-acetonitrile as the mobile phase with gradient elution. Results showed that the limit of detection ranged from 0.250 0 to 5.000 ng/mL, and the relative standard deviation of day-to-day was less than 10.71% (n=3). This assay was suitable to liquid sample detection, with average recoveries in the range of 83.24%~118.3%. The proposed method with good accuracy and high sensitivity can be applied to the rapid analysis of sweeteners and antioxidants in food.

Microwave Assisted Extraction of Total Flavornoids from Potentilla Discolor Bunge by Response Surface Methodology

CAI Shu-min, CHEN Yi-ting, ZHANG Mei-zhu, YANG Yi-jie

2015, (3): 146-152.

Abstract(1267)

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Abstract:
The response surface methodology (RSM) was applied to optimize the extraction conditions of total flavornoids in potentilla discolor by the microwave-assisted extraction (MAE). Based on the results of single factor experiments, the effects of three independent variables (the concentration of ethanol, extraction time, extraction temperature, solid to liquid ratio) and interaction on the total flavornoids yield were investigated. The results showed that the optimum conditions for the extraction of flavonoids were: ethanol concentration, 55 %, extraction temperature, 82 ℃, extraction time, 10 min, and ratio of solvent to material, 32 mL/g, under these conditions, the flavonoids yield was 6.96 mg/g, which was consistent with the predicted value in the main.

Determination of Methanol Content in B-100 Biodiesel by Headspace Gas Chromatography

LIN Hai, LI Chun-xiong, LIN Jing, LI Zhan-jiang, LIU Yi-feng

2015, (3): 153-157.

Abstract(1110)

PDF(24)

Abstract:
A test method for the determination of methanol content in B-100 biodiesel by headspace gas chromatography has been established. The B-100 biodiesel sample was dissolved in N,N-dimethylacetamide and equalized at 90 ℃ for 45 min in the head-space sampler,then separated and determined on a gas-chromatograph through a HP-INNOWax capillary column. An external standard quantitative formula was established with the correlation coefficient more than 0.999. The limit of quantitation is 0. 005%. The relative standard deviations(n = 6) were between 4.96% and 6.83%. The recoveries was between 92% and 110%. This method is simple,rapid, accurate, and can be applied to the determination of methanol content in B-100 biodiesel.

Determination of Sodium Formaldehyde Sulfoxylate in Food by Capillary Zone Electrophoresis

LIU Wen-ye, WU Nan, LI Jiang, ZHAO Shan, DING Xiao-jing, YANG Yi

2015, (3): 158-163.

Abstract(1365)

PDF(20)

Abstract:
Sodium formaldehyde sulfoxylate is an illegal food additive and is strictly prohibited in China. However, it is sometimes adulterated in food such as silk noodles, fine dried noodles, crystal sugar and bean curd stick in order to bleach, and improve the texture and antisepsis. To ensure the food safety, a new method for the accurate assay of sodium formaldehyde sulfoxylate in food by capillary zone electrophoresis (CZE) has been developed. An uncoated Φ 75μm fused-silica capillary of 70 cm total length (effective length: 60 cm) under a separation voltage of -12 kV was used. The separation buffer consisted of 50 mmol/L of Na₃PO₄, 10 mmol/L of NaOH, 0.5 mmol/L of cetyltrimethyl ammonium bromide (CTAB) and 1 g/L of polyethylene glycol (PEG) 35 000. The injection pressure and time were 3.45 ×10^-3 MPa and 13 s, respectively. The factors such as the separation buffer concentration and pH, concentration of PEG 35 000 and sample buffer, which affecting the separation and quantitation of sodium formaldehyde sulfoxylate were investigated in detail. The samples were ground into powder, extracted by 5 mmol/L of acetic acid and then centrifuged. The supernatant was directly injected after filtered through 0.45 μm cellulose acetate membrane. The corrected peak areas (Ac) versus concentrations (ρ, mg/L) of sodium formaldehyde sulfoxylate showed a good linear relationship within the range from 15~400 mg/kg with a correlation coefficient (r) of 0.999 1. The limit of detection (LOD) was 4 mg/kg (S/N=3) and the limit of quantitation (LOQ) was 12 mg/kg (S/N=10), respectively. The average recoveries at three spiked levels were in the ranges of 90.0%~95.6% with RSDs all less than 8%. Four food samples (a total of 12) collected from local supermarket and farmer's market were analyzed by the current method. No positive sample was found.

Comparative Study of Chiral Separation of Sixteen Chiral Compounds on Cellulose-Based Chiral Stationary Phases

LEI Li-juan, WANG Wei-qiang, YANG Chen-xuan

2015, (3): 164-170.

Abstract(1145)

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Abstract:
Three cellulose-based chiral columns[cellulose tris(4-methylphenylcarbamate) (ATEO-OG), tris(3, 5-dimethylphenylcarbamate) (ATEO-OD), and tris(4-methyl benzoate) (ATEO-OJ)] were prepared in our laboratory. The comparasion and chiral separation of sixteen chiral compounds on the obtained cellulose-based chiral columns have been described. The effect of chromatographic conditions on chiral separation was investigated. The results showed that 16 chiral compounds were separated chirally with different degree on the three chiral stationary phases, and the chiral recognition ability of ATEO-OD was higher than the other two, baseline or partial enantioseparation of 16 compounds was obtained. ATEO-OG and ATEO-OJ has the same chiral recognition ability.

Correction of Spectral Interference of Zn to W in Geological Samples by ICP-AES

HU Jia-ming

2015, (3): 171-175.

Abstract(1124)

PDF(32)

Abstract:
A method for the determination of W in geological samples by inductively coupled plasma-atomic emission spectrometry(ICP-AES) has been developed. The sample was decomposed by HNO₃-HF-HClO₄. The spectral interference of Zn 207.908 to W 207.911 was discussed,and the interference can be corrected using the interference correction method (IEC).The results showed that the spectral interference of Zn to W can be thus effectively eliminated,the results after the spectral correction were evidently better than the results without the spectral interference correction by the IEC.

Effect Factor and Data Calculation of Carbon and Nitrogen Content of Soil and Sediment Determined by Element Analyzer

CUI Ying

2015, (3): 176-179.

Abstract(1231)

PDF(50)

Abstract:
The results determined by an element analyzer are affected by the pretreatment (drying, acidification), weight of sample and calculation standard. The present results suggested that acidification would decrease the nitrogen content 2.6%~40%, the determination of carbon is significantly affected by the sample weight, the results will be more accurate if calculated by the standard which is more similar with the samples.

Determination of Manganese in MB1 Magnesium Alloy by Aluminum Base Spark Source Atomic Emission Spectrometry

WANG Cong, YING Min, YAO Le

2015, (3): 180-183.

Abstract(1244)

PDF(23)

Abstract:
A mathod for the determination of manganese in MB1 magnesium alloy using an aluminum base spark source atomic emission spectrometer has been established. The linear correlation coefficient of manganese calibration curve was 0.967 6, RSD was 1.66%. The determination results of 8 unknown samples were consistent with those obtained on an atomic absorbtion spectrometer.

Opening Use and Management of Gel Permeation Chromatograph

LIU Peng, ZHOU Qiu-xuan

2015, (3): 184-186.

Abstract(1299)

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Abstract:
The gel permeation chromatograph(GPC) is a essential tool for the scientific research in polymer chemistry. With the rapid development of polymer chemistry, how to improve the efficiency of the use of the instrument is a thorny problem. Therefore, the research of the opening use and management becomes very important. In this paper, the experience of opening using the GPC is summarized.

Troubleshooting and Regular Maintenance to ASC Chuck of ZSX PrimusII X-Ray Fluoresence Spectrometer

LIU Jiang-bin, WANG Yu-gong, DANG Liang, YIN Tiao-gang, ZHU Jian-guo

2015, (3): 187-189.

Abstract(1609)

PDF(78)

Abstract:
In the paper,a general introduction of sudden faults, the corresponding troubleshooting to ASC chuck of RIGAKU ZSX Primus II X-ray fluorescence spectrometer in the use process, and the requirements for regular maintenance of this instrument are described.

2015 No. 3

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