Rapid analysis of triterpenic acids by liquid chromatography using porous graphitic carbon and evaporative light scattering detection

An original system which uses Porous Graphitic Carbon as support and a mixture of organic solvents as mobile phase is proposed for the analysis of triterpenic acids by liquid chromatography. The separation of betulinic acid, ursolic acid, oleanolic acid, and 18alpha- and 18beta-glycyrrhetinic acids was carried out within a short time and monitored by evaporative light scattering detection as universal detection method. Molecular modelling studies show that the main contribution to the selectivity comes from the electrostatic interaction characterised by the dipole moment of the products.     

STUDY ON MAGNETIC FIELD-INDUCED 0RIENTATI0N OF A CHIRAL SIDE-CHAIN LIQUID CRYSTAL POLYACRYLATE USING INFRARED DICHROISM

Magnetic field-induced orientation of a chiral side chain liquid crystalline polyacrylate(P-11) was studied by using IR dichroism. For the investigated P-11, it has been shown thatthe magnetic alignment takes place over the entire temperature range between its meltingpoint and clearing point and the orientation level is strongly temperature-dependent, thedevelopment with time of the magnetic orieatation follows an exponeotial-type relation,and the smectic phase state influences the thermal relaxation process in the absence of themagnetic field.     

二甲胺修饰戊二醛交联壳聚糖树脂的制备及性能

研究了在均匀水相介质条件下，采用戊二醛稀溶液制备交联壳聚糖树脂的方法，并以三聚氯氰为活化剂，合成了二甲胺修饰戊二醛交联壳聚糖树脂．研究了该树脂的红外光谱及吸附性能．该树脂对铜(Ⅱ)和牛血清白蛋白(BSA)的吸附容量分别为42mg／g(干)和940mg／g(干)，其吸附行为均符合Freundlich等温吸附模型．该树脂制备工艺简单，机械强度较好，可作为金属离子或蛋白质分离纯化的吸附剂和色谱填料．     

Volatile phase profiling of mainstream smoke by glass capillary gas-chromatographic techniques

A heated injection system for a microprocessor-controlled GC has been developed for the (GC)² analysis of the volatile phase of whole smoke of a cigarette. Effects of injection port temperature and the presence of a Cambridge filter pad are demonstrated. Chromatograms are shown for smoke samples with and without a Cambridge Filter with the sample valve oven at 25°, 165° and 205°C. The use of a flame ionization and a nitrogen-phosphorous detector is illustrated.     

A photometric detector driven by beta radiation

It was recently found that typical Chromatographic carrier gases such as argon or nitrogen could be used in a modified flame photometric detector for general or selective determination of eluted molecules. The detector was powered not by a flame but by a radioactively stimulated, mild discharge. The luminescence arose from the second positive system of nitrogen (in argon), and various emissions from aroyl-containing molecules (in nitrogen).This study describes experiments that take away not only the flame but also the discharge: The energy that produces the luminescence is derived solely from the beta decay of⁶³Ni. Because of this low power input, the sensitivity of the present beta-driven photometric detector (-PD) is limited to about 25 ppm of nitrogen (in argon), and to about 5 pg/s for benzaldehyde and other well-responding aroyl compounds (in nitrogen). In accordance with mechanisms postulated earlier, other types of molecules do not produce significant responses in the absence of an electrical field.Material taken from doctoral thesis     

利用压电频移法测定水中的痕量亚硝酸盐

提出了利用压电频移法测定亚硝酸盐的方法。方法以碘离子与亚硝酸根之间的氧化还原反应为依据，通过测定由反应生成的碘所引起的压电晶体频率的变化，在被萃取水相中亚硝酸盐浓度为０．００９￣２．３ｍｇ／Ｌ范围内，频移值与浓度成正比：ΔＦ＝５．８＋２．５×１０＾３Ｃ（ｍｇ／Ｌ），ｒ＝０．９９０１。方法简便，用于天然水中亚硝酸盐的测定，结果令人满意。     

Hypercoulometric effect in an electron capture detector polarized with an additional voltage

Summary This paper reports measurements of the current characteristics and of the signal corresponding to a constant concentration of Freon F-11 for an electron-capture detector, supplied with a pulse voltage with a changeable pulse duration, amplitude and repetition time. It was found that an additional voltage applied to the detector cathode increased the detector signal by about 50% and that the maximal signal was observed at 5 V. The influence of the polarized voltage on the electron caputure efficiency coefficient (p) measured with two detectors in series was demonstrated and the reliability of the sample mass calculation by means of (p) is discussed.     

The IINS, IR and DFT studies of hydrogen bonds in 6-Furfuryl and 6-Benzylaminopurines

FTIR and IINS spectra of 6-Furfurylaminopurine (6-FAP) and 6-Benzylaminopurine (6-BAP) taken at different temperatures have been analysed and compared with the spectra calculated by the ab initio DFT/B3LYP method and the semiempirical PM3 method in the isolated molecule approximation, for the tautomers N3-H, N7-H and N9-H, and dimers with hydrogen bonds. For 6-FAP the best agreement between the calculated and experimental (at 20 K) spectra has been found for the N9-H tautomer, whose structure was established by X-ray diffraction. For 6-BAP the analogous agreement for the N9-H tautomer structure has been poor and much better for the N7-H tautomer. The vibrational spectra calculated for dimers of the molecules studied involved in hydrogen bonds, permitted also an interpretation of the bands whose positions and FWHM in the FTIR spectra changed with temperature.     

Voltammetric Detector for Liquid Chromatography: Determination of Triclosan in Rabbit Urine and Serum

A flow-electrolytic cell containing a strand of carbon fibers has been designed and characterized for use in a voltammetric detector for high-performance liquid chromatography. The detector was used for determination of triclosan (2,4,4-trichloro-2-hydroxydiphenyl ether) in rabbit serum and urine. Analysis of rabbit serum and urine 1 day and 1 to 5 days, respectively, after ingestion of oral triclosan revealed that the concentration of triclosan was higher than for control serum and urine. The concentration reached maximum levels after 6 h and 34 h or 44 h in serum and urine, respectively. When triclosan was determined in rabbit samples with the method proposed the results obtained were comparable with those obtained by high-performance liquid chromatography with ultraviolet detection.     

Highly sensitive determination of haloperidol in human serum by capillary gas chromatography using a surface ionization detector

A method has been developed for highly sensitive determination of haloperidol in human serum involving a simple extraction procedure followed by gas chromatographic separation. Target components were separated from the extracting solvents with a Van den Berg type solventless sample injector before introduction Into a DB-1 capillary separation column. A surface ionization detector (SID), which has highly selective sensitivity for Substituted amines, was employed for quantitation using bromperidol as an internal standard. Chloroform proved to be the best extracting solvent, yielding a quantitative detection limit of 5 ng/ml (S/N = 2). Comparison of the response to target compounds obtained by the SID, FTD (flame thermionic detector), and FID (flame ionization detector) showed the SID to be superior.