Abstract: An atmospheric pressure ion-molecular reaction device has been developed.The design and performance of the device match the high sensitivity and specificity of the mass spectrometer(MS).The molecular types of ion-molecule reaction are expanded through the generation of ions and the introduction of neutral reactive molecules under atmospheric pressure.The ion molecule reaction time can be precisely controlled.At the same time, the organic reaction process can be realized online and can be combined with liquid chromatography, which is important for the comprehension of structure and activity judgment of some active reaction intermediates, thus, expands of the functions of the instrument and promotes its application scope, and a more comprehensive analysis for the active reaction intermediates can be provided for organic reaction researchers.
Abstract: In order to solve the in-situ measurement of high-temperature phase transition of micro-nano films (< 10 μm thick) on the substrate, in the present work a self-designed heating sample stage and the grazing incidence X-ray diffraction mode of a commercial X-ray diffractometer were skillfully combined, and thus a novel in-situ measurement method of high-temperature phase transition of micro-nano films was proposed.The characteristics of temperature distributions on the surface of the sample stage and the micro-nano films were investigated, and the temperature control effect of the in-house fabricated heating sample stage was hence verified.Finally, the X-ray diffraction (XRD) patterns of the micro-nano vanadium dioxide (VO2) films at different temperatures were obtained and the high temperature phase transition of micro-nano VO2 films was clarified.
Abstract: Quick measurement of heavy metal contents in water is important for monitoring the abrupt environmental pollution. A method for quick measurement of Pb and Cd contents in water using a portable instrument which is based on bio-enzyme (DNAzymes) sensor technique is reported. The instrument was calibrated based on the linear relations between the recommended and measured concentrations of standard solutions using a bio-enzyme sensor. The range of measurable concentrations were 2~100 μg/L for Pb and 0.1~1.0 mg/L for Cd. Heavy metals can be conveniently measured in the field within 3~5 min. Because the uses of DNAzymes can quickly obtain the contents of trace metals in polluted waters, it is promising in the instantaneous monitor of heavy metal pollution in the field.
Abstract: The decolorization process of reactive violet based on the microwave-assisted Fenton reaction has been studied. The experimental results showed that the combination of microwave and Fenton method can bring good synergistic effect. When the pH of the active violet solution was 4, the dosage of 30% hydrogen peroxide was 0.6 mL/L, and the concentration of ferrous sulfate was 0.3 g/L, the decolorization rate of the active violet can reach up to 98.13% after being exposed to 400 W microwave irradiation for 3 min and standing for 25 min.
Abstract: Using the standard material basalt as the experimental object, the elements were pretreated by acid dissolution and alkali melting methods, respectively, determined by inductively coupled plasma optical emission spectrometry, in both methods good results were obtained. The acid dissolution method is more effective in the digestion of the sample and the extraction of the elements, which made smaller deviation to the standard value. However, the alkali melting process is simpler with shorter time required, and did not affect the determination of Si elements. The latter method is more suitable for the pretreatment of common elements in normal geological samples. The former method is more suitable for the determination of common and trace elements in geological samples which are difficult to dissolve. Both of them need high requirements to the experiment details. In the future, it is necessary to improve the experimental methods and experimental details in order to obtain more convenient experimental methods and accurate results.
Abstract: An extraction method of total deoxyribo nucleic acid(DNA) from desert plants has been established. The steps of the method are as follows:add a small amount of PVPP powder to the leaves of desert plants and grind them for more than three times to get the ultra-fine powder of the sample, immediately add the pre-treatment buffer solution to the sample powder, mix them evenly and centrifuge them at low speed, then discard the supernatant and leave the precipitate, add an equal volume of preheated extraction cracking solution to the precipitate, mix them evenly on a warm bath at 60~70℃ for one hour, extract the supernatant using high-speed centrifugation. And then add the purified mixture to the solution and mix, extract and centrifuge, extract the supernatant of the mixture again, add the precooled isopropanol and precipitate DNA at -18℃ for more than half an hour, after that, centrifuge the isopropanol solution in high-speed, wash the precipitate twice with 70% ethanol, air dry and to dissolve the precipitate with ultra-pure water. The advantages of the technology are simple operation and less time-consuming, and the operation process is about 2~3 h. The yield of DNA was higher than 500 ng/μL. This method has the advantages of high purity, good integrity and wide applicability.
Abstract: To determine accurately the content of cyclic adenosine monophosphate (cAMP) by high performance liquid chromatography(HPLC) in jujube in northern China, Hibar ODS-C18 (250 mm×4.6 mm, 5 μm) was used as the chromatographic column, the mobile phase was methanol:2% acetic acid (volume ratio:5:95), the flow rate was 0.5 mL/min, and the detector was a Waters 996. The detection temperature was 25℃ and the detection wavelength was 254 nm. The standard curve was of good linearity in the range of 0.1~1.0 mg/mL. The recovery rate was 102.1% and the relative standard error was 0.63%. The conditions used in this method can completely separate cAMP and other components in jujube. We found that the contents of cAMP in jujube from different producing areas were different, and the content of cAMP in jujube from Xinjiang was the highest and reached 372 μg/g. This method can accurately determine the content of adenosine phosphate in jujube in northern China, with high sensitivity, thus provides an important technical basis for the extraction and high-value utilization of cAMP in jujube.
Abstract: Health care food, as a specific type of food, can regulate the function of human body, and is suitable for specific people. However, the phenomena of adding chemical drugs and illegal additives in health care food are endless. Therefore, it is urgent to set up an effective detection method with multiple indicators to provide technical guarantee for the quality and safety of health care food. Efficient sample pretreatment as well as sensitive analytical method are very important for the detection of illegal additives. The applications of pretreatment methods such as solvent extraction, solid phase extraction (SPE), and analytical methods including high performance liquid chromatography (HPLC), direct analysis in real time (DART-MS), surface-enhanced raman spectroscopy (SERS) and its tandem technique in the detection of trace illegal additives in recent three years are reviewed. A theoretical reference for the further research and establishment of efficient and simple pretreatment methods, new detection methods and technologies is provided.
Abstract: The effects of different sample preparation methods on the test results of conductive samples of lithium and non-conductive samples of milk powder were discussed. The experimental results showed that conductive copper film is better for the conductive sample lithium electrical material, and conductive or non-conductive film for non-conductive sample milk powder is better for the conductive or 3M film.
Abstract: X Ray fluorescence spectrometry(XRF) can be used to rapidly determine the total content of calcium in fluorite. However, the calcium carbonate included in total calcium will cause in inaccurate results of calcium fluoride. Moreover, copper, zinc and other non-ferrous metal elements can damage the platinum crucible, so acid treatment is required to remove calcium carbonate and other non-ferrous metals. The residues of different samples after acid treatment are different to the ones before and the ratio of the flux to sample is uncertain, thus the content of calcium fluoride cannot he accurately determined. The sample pretreatment conditions, melting conditions and equipment conditions are described. A method for the accurate determination of calcium fluoride in fluorite by fused XRF has been established, which has less interference, good accuracy and precision, simple operation and improved analysis efficiency.
Abstract: A determination method of calcium in iron-based powder metallurgy has been established using inductively coupled plasma atomic emission spectrometry(ICP-OES). The acidity ratio and the interference of various factors were optimized. The external standard method was used to quantify and draw the calibration curve to eliminate the influence of the matrix effect, and the interference correction test of the coexisting elements showed that the coexisting elements in the sample has no interference effect on the element to be measured. A pretreatment of the sample was required by the sequential dissolution in aqua regia, heating on an electric heating plate, and followed by the further addition of H2O2. Good linearity was then obtained in the range of 0.5~10 mg/L with a correlation coefficiency of 0.999 9, a relative standard deviation of the instrument precision of 0.14% (n=10), and the recovery rate of standard addition in the range of 98%~105%. The method is economical, simple, rapid and reproducible, and can meet the requirements of the analysis and detection.
Abstract: According to the GB 5009.24-2016 method(National food safty standard Determination of Aflatoxin group in food), a mathernatical model of uncertainty evaluation for the determination results of Aflatoxin M1 in milk by high performance liquid chromatography method has been established. The sources of uncertainty for the determination procedure were analyzed and the main uncertainty were quantified and synthesized. When the content of Aflatoxin M1 in milk was 0.842 μg/kg, its extended relative uncertainty was 0.0484 μg/kg(k=2). The major sources of uncertainty were standard purity and recovery rate.
Abstract: Phenomena of the decrease of sensitivity and the deterioration of stability of the instrument deteriorates in the measurement of the impurity elements in the gold-containing matrix solution Thermo IRIS Intrepid II coupled inductively plasma emission spectrometry(ICP-OES)were described. Through the analysis and diagnosis of the fault phenomena, the solution was given and the instrument resumed to the normal service state.
Abstract: High resolution gas chromatography-quadrupole time-of-flight mass spectrometry(GC-QTOF) can be acquired in single mode time-of-flight mass spectrometry(TOF), with the use of accurate mass number of collected ions to analyze unknown compound, and carry out structure identification, which are mainly based on the use of the National Institute of Standards and Technology(NIST) library of the low resolution and personal compound database and library (PCDL) of high resolution. GC-QTOF also can analyze unknown compounds by QTOF fragment ions, which are mainly based on the use of the molecular structure of software (MSC) and Chemspiders database (web) and so on. Besides to operate the instrument correctly with regular maintains, and make the instrument in good working condition, in order to get the accuracy and effectiveness of the test data. The use and maintenance of GC-QTOF from Agilent is introduced.