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181.
维生素B2片中维生素B2的测定及稳定性 总被引:1,自引:0,他引:1
以pH=7.0的水作为溶液,激发、发射波长分别为443、523nm,运用荧光光谱法测定了维生素B2的荧光强度,以荧光强度与浓度的关系作图,得到了回归曲线,本实验条件下,在5×10-8—6×10-7g/mL范围内呈良好的线性关系,回收率在98.53%—103.59%之间,该方法具有灵敏度高、重现性和稳定性好的特点,但维生素B2不稳定。 相似文献
182.
183.
建立了流动注射-氢化物发生-原子荧光光谱法测定奶制品中铅含量的分析方法,对仪器条件和反应条件进行了选择、优化。方法的检出限为0.30μg/L,相对标准偏差小于4.7%,回收率为90.0%—114.5%,符合食品中痕量元素的分析要求。 相似文献
184.
In recent years the use of monolithic polymers in separation science has greatly increased due to the advantages these materials present over particle-based stationary phases, such as their relative ease of preparation and good permeability. For these reasons, these materials present high potential as stationary phases for the separation and purification of large molecules such as proteins, peptides, nucleic acids and cells. An example of this is the wide range of commercial available polymer-based monolithic columns now present in the market. 相似文献
185.
《Analytical letters》2012,45(13):1099-1109
Abstract A comparison of liquid chromatography with electrochemical detection (LCEC) and gas chromatography mass spectrometry (GCMS) has been made for analysis of homovanillic acid (HVA) in rat brain tissue. The LCEC procedure gave slightly higher average values of HVA in the samples measured; however, the HVA content determined by both methods related significantly. Rat brain meostriatum was used as representative samples for comparison of the two analytical procedures. 相似文献
186.
《Analytical letters》2012,45(15-16):1573-1590
Abstract A direct flow injection flame atomic absorption spectrometry method of determining zinc salt solutions with concentrations of 100's g dm?3 is reported. It was shown that high concentrations of KCl, NaCl and NH4Cl do not significantly interfere with the determination of zinc in both the mg dm?3 and g dm?3 concentration ranges. Where g dm?3 concentrations were determined a secondary spectral line at 307.6 nm was found satisfactory. Galvanizing preflux solutions were analyzed both after dilution to the mg dm?3 range at 213.9 nm and directly injected at 307.6 nm. Precisions of better than 6.6% rsd were observed by the direct method compared with better than 4.8 by dilution techniques. Concentrations up to 110 g dm?3 in zinc were determined the total salt content being greater than 300 g dm?3. 相似文献
187.
《Analytical letters》2012,45(7):1791-1806
Abstract The direct quantitative determination of phosphine in gaseous mixtures or in air samples is associated with a number of difficulties. the paper describes an alternative technique based on the oxidation of phosphine to phosphate. Phosphate can be analysed either by inductively coupled plasma-atomic emission spectrometry (ICP-AES) or by a colometric method. Because the problem of a proper (quantitative) sampling of phosphine in the air of working environments and/or in gaseous mixtures is still unsolved, standard solutions of KH2PO4 have been used as analytes (“artifical samples”) in the ICP-AES method. The statistics concerning the sample variances, obtained from the 2 methods mentioned above, indicate no differences. 相似文献
188.
《Analytical letters》2012,45(5):461-464
Abstract Retention of some cations and anions on ion-exchange resin-loaded disks has been reported to be less than quantitative. A mixed-bed resin-loaded paper was made in which mixed cation-exchange and anion-exchange resins were incorporated into the paper to take advantage of the ‘crossed equilibria’ effect and improve ion retention. The use of mixed-bed paper disks in analysis for cesium by X-ray fluorescence spectrometry is described. 相似文献
189.
《Analytical letters》2012,45(9):1417-1428
Abstract The analysis of amino acids with post column derivatization using ninhydrin is usually carried out with automatic analyzers at wavelengths of 570 nm (for the quantitation of α-amino acids) and 440 nm (for the imino acids), or at only one wavelength, 520 nm, for the total acid content. The α-amino acids are reported to give an absorption maximum at 570 nm, after complex formation with ninhydrin; and α-imino acids have a γ at 440 nm, 520 nm is a compromise wavelength. This paper presents a study of the absorption of the complexes of amino acids with ninhydrin between 275 and 700 nm. Two new wavelengths are suggested for use, 290 and 404 nm. In the near UV (290 nm) all the tested acids show a common absorption maximum and good sensitivities. In the visible region at 404 nm, the sensitivities of the α-amino acids are very similar to those observed at 570 nm. At 520 nm the αamino acids have the lowest sensitivities. The α-imino acids (proline and oxyproline) show absorption maxima only at 290 nm; after that their sensitivities decrease with increasing wavelength. The paper offers some practical hints on changing the detector wavelength, and to adapt the HPLC's detector to work at one of these two, newly suggested, bands (290 or 404 nm). 相似文献
190.
《Analytical letters》2012,45(10):1261-1280
Abstract Results on an impaction-electrothermal atomization atomic absorption spectrometric system for the direct, and on a nearly real-time basis, determination of cadmium, copper, and manganese in the laboratory atmosphere are presented. Background levels for cadmium were 3 ng m?3, for copper were 100 ng m?3, and for manganese were 30 ng m?3 and were found to increase with activity in the vicinity of the system. Addition of a connecting faceplate to the impactor allowed a more convenient and accurate method of standardization to be achieved. 相似文献