Analysis of quinolizidine alkaloids in Sophora flavescens Ait. by capillary electrophoresis with tris(2,2 '-bipyridyl) ruthenium (II)-based electrochemiluminescence detection

A capillary electrophoresis method coupled with electrochemiluminescence detection for the analysis of quinolizidine alkaloids was established, especially, oxymatrine (OMT) which could not be measured by previous electrochemiluminescence methods was detected sensitively herein. Complete separation of sophoridine (SR), matrine (MT) and OMT was achieved within 13 min using a background electrolyte of 50mM phosphate buffer at pH 8.4 and a separation voltage of 15 kV. The calibration curves showed a linear range from 2.8 x 10(-8) to 4.4 x 10(-7) M for SR, 2.7 x 10(-8) to 4.4 x 10(-7) M for MT.

Analysis on Iridoid Glycosides in Crude and Processed Extracts from Cornus Officinals by Liquid Chromatography-electrospray Ionization Mass Spectrometry

The iridoid glycosides in crude and processed extracts from cornus officinals have been analyzed by high performance liquid chromatography-electrospray ionization mass spectrometry. Samples were analyzed by a reversed-phase C18 column using a binary eluent under gradient conditions. Seven iridoid glycosides could be separated and detected. The [M-H](-) ions of iridoid glycosides in the negative ion mode were observed, which reflect their molecule mass information. An in-source collision induced dissociation (in-source CID) experiment was carried out in order to identify the structures and to measure the contents of iridoid glycosides. The epimers were discovered in the experiment for the first time, namely 7 alpha-O-ethyl-morroniside and 7 beta-O-ethylmorroniside.

Structural analysis of selected characteristic flavones by electrospray tandem mass spectrometry

Seven structure analogical flavonoid aglycones have been analyzed using electrospray ionization tandem mass spectrometry (ESI-MSn) in the negative-ion mode. The spectra obtained ESI-MSn allowed us to propose plausible schemes for their fragmentation mechanism. By analyzing the product ions spectra of deprotonated molecule ions [M-H](-), some neutral diagnostic losses and specific retro Diels-Alder fragments were obtained. By using all of these characteristic fragment ions we can specially differentiate the flavone isomer.

Short-capillary electrophoresis with electrochemiluminescence detection using porous etched joint for fast analysis of lidocaine and ofloxacin

Fast analysis of ofloxacin and lidocaine, as bactericide and analgesic or anesthetics, is of clinic importance for understanding the patient's medical process. This paper presented a high throughput, simple analysis method of lidocaine and ofloxacin by capillary electrophoresis coupled with electrochemiluminescence (ECL) using porous etched joint. To shorten the analysis time and to improve the analytical performance, a capillary with 10 cm in length was used as the separation channel. The cyclic voltammograms of Ru(bpy)(3)(2+) with different capillary length at same field strength showed that the porous etched joint eliminated the effect of electrophoretic current on the ECL detection. Following micro total analysis systems (muTAS), some advantages of which this approach has, the fabrication of channel in chip was not needed. Compared with capillary electrophoresis with 40-cm-long capillary, the high sample throughput and low zone broadening may be the main advantage of the present system. Under optimal condition, the detection limits of lidocaine and ofloxacin based on peak height were 3.0 x 10(-8) and 5.0 x 10(-7) mot L-1 and a 60 h(-1) of sampling frequency was obtained.

Structural analysis of saponins from medicinal herbs using electrospray ionization tandem mass spectrometry

The underivatized saponins from Tribulus terrestris and Panax ginseng have been investigated by electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn). In ESI-MS spectra, a predominant [M + Na](+) ion in positive mode and [M - H](-) ion in negative mode were observed for molecular mass information. Multi-stage tandem mass spectrometry of the molecular ions was used for detailed structural analysis. Fragment ions from glycoside cleavage can provide information on the mass of aglycone and the primary sequence and branching of oligosaccharide chains in terms of classes of monosaccharides. Fragment ions from cross-ring cleavages of sugar residues can give some information about the linkages between sugar residues. It was found that different alkali metal-cationized adducts with saponins have different degrees of fragmentation, which may originate from the different affinity of a saponin with each alkali metal in the gas phase. ESI-MSn has been proven to be an effective tool for rapid determination of native saponins in extract mixtures, thus avoiding tedious derivatization and separation steps.

Analysis of strychnos alkaloids using electrospray ionization Fourier transform ion cyclotron resonance multi-stage tandem mass spectrometry

The fragmentations of four strychnos alkaloids have been investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) in the positive ion mode. Experiments using multi-stage tandem mass spectrometry (ESI-FT-ICR-MSn) allowed us to obtain precise elemental compositions of product ions at high mass resolution. The experimental data demonstrated that the nitrogen bridge and the coordinated oxygen atom on the nitrogen bridge in the alkaloid compounds were the active sites in the MS2 fragmentations. The loss of CH3 or the OCH3 group in those alkaloids, which have an OCH3 substituent, was the dominant fragmentation mode in the MS3 fragmentations. Logical fragmentation schemes for strychnos alkaloids have been proposed and these should be useful for the identification of these compounds.

Determination of Nb and Ta in Nb/Ta minerals by inductively coupled plasmas optical emission spectrometry using slurry sample introduction

The determination of Nb and Ta in Nb-Ta minerals was accomplished by slurry nebulization inductively coupled plasma optical emission spectrometry (ICP-OES), using a clog-free V-groove ceramic nebulizer. Samples were first wet-ground to appropriate particle sizes with narrow size distribution and 90% of the particles in the slurry were smaller than 2.32 mu m in diameter. Subsamples were then dispersed in pH 9 aqueous solutions, and agitated in an ultrasonic bath for 15 min prior to analysis. Due to the lack of slurry standards matching well with the samples, calibration was simply carried out using aqueous solution standards. Results were compared with those obtained from a conventional fusion decomposition procedure and acid digestion procedures and a good agreement between the measured and referred values was obtained. The technique provided a good alternative for the rapid determination of Nb and/or Ta in their corresponding minerals.

Determination of ultra-trace concentrations of elements in high purity tellurium by inductively coupled plasma mass spectrometry after Fe(OH)(3) coprecipitation

In this work, a method was established for the determination of impurities in high purity tellurium by inductively coupled plasma mass spectrometry (ICP-MS) after Fe(OH)(3) coprecipitation. After comparison of coprecipitation ability and separation efficiency between Fe(OH), and Al(OH)(3), Fe(OH)(3) was chosen as the precipitate. A separation factor of 160 for 200 mg tellurium was obtained under conditions of pH 9 and 2 mg of Fe3(+). The 13 elements, such as Bi, Sn, Pb, In, Tl, Cd, Cu, Co, Ni, Zn, Ti, Be and Zr, could be almost completely coprecipitated under these conditions. In addition, Te memory effect imposed on the ICP-MS instrument was assessed, as well as Te matrix effect that caused the low recovery of Ga, As, Sb and V in real sample was discussed. Finally, the method was evaluated through recovery test and was applied to practical sample analysis, with detection limits of most of the elements being below 0.15 mug g(-1) and R.S.D. below or at approximately 10%, which indicated that this method could fully satisfy the requirements for analysis of 99.999% similar to 99.9999% high purity Te.

Major, minor and trace-elemental contents analysis in northeast soybeans by ICP-AES

Major, minor and trace elemental contents in northeast China soybeans were determined by using inductively, coupled plasma atomic emission spectrometry (ICP-AES). Three different sample digestion methods including two wet digestions, HNO3-HClO4 and HNO3-H2SO4 and a dry ash method were compared. Owing to the high oil content in soybeans, long time is needed and access acid should be added, with mixed acid digestion methods, which may result in higher sample blank. Therefore, the dry ask method would be more proper for the pre-treatment of soybean samples. Potassium and phosphorus are major elements in soybeans, so the effect of potassium and phosphorus on the other elements was investigated. Results showed that the potassium and phosphorus did not affect the determination. of other trace elements. There are not significant differences in trace elemental contents for the eleven northeast China soybeans.

Matrix effects in inductively coupled plasma mass spectrometry by use of organic solvents

Matrix effects arising from ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine in inductively coupled plasma mass spectrometry have been studied. Addition of ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine into solution has an enhancement effect on the signal intensity of analyte with ionization potential between 9 and 11 eV. The ethylenediamine and triethanolamine have higher enhancement effect on the signal intensity of Hg than that of ethanol, propanol, glycerol and acetic acid. Addition of ethylenediamine and triethanolamine into solution has a suppression effect on the signal intensity of Ph and Sr. The mechanism of the enhancement or suppression was investigated. The signal enhancement of Hg in the presence of ethylenediamine and triethanolamine is not caused by improved degree of ionization of Hg and nebulization efficiency. The suppression effects of Ph and Sr in the presence of ethylenediamine and triethanolamine are due to decrease of atomization efficiency of these elements. A method for the determination of Hg in the biological standard samples Ly ICP-MS was developed.

Determination of ultra-trace rare-earth elements in human plasma by inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS),a highly sensitive inorgnic analytic technique,fits to determine ultra-nace rare-earth elements in human plasma. Under the optimized conditions detection limits for 15 rare-earth elements are in the range of 0.7 (for Eu)-5.4 (for Gd) ng.L-1. Indium as an internal standard element is used to compensate for matrix suppression effect and sensitivity drift. Three kinds of preparation methods, diluted with 1% HNO3, digested with HNO3-H2O2 and with HNO3-HClO4, are checked and compared,and the former is the simplest way to be measured. The samples diluted with 1% HNO3, stored in 4 degrees C, are very steady for 16 days. With the method, 11 healthy plasma samples in Changchun area of China are analysed.

Characteristics in frequency domain by inductively coupled plasma atomic emission spectrometry with charge injection detection

The charactesistics of two-dimension spectra obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) with charge injection detection (CID) in frequency domain were studied in the present paper. The measurement spectra were Fourier transformed and the frequency distribution of the spectra was obtained. Results showed that the spectra in frequency domain could he divided into two parts:high frequency and low frequency signals. The later stood for measurement spectra and the former for background and noises. However, the high frequecny signals could not be smoothed simply to reduce noises because the background was deteriorated even though the spectral signal did not change significantly.

Determination of the impurities elements in high-purity cadmium by inductively coupled plasma mass spectrometry

A method for the determination of impurity elements in high purity cadmium by inductively coupled plasma mass spectrometry was developed. The spectral interference arising from Cd was discussed and the magnitude of interference by the polyatomic ion of Cd was compared. The effect of the high concentration Cd on the analyte signal was studied. The results showed that Cd possessed both significant suppression effects on the light mass elements signal and enhancement effects on the heavy mass elements signal,and the effects can be corrected by the use of internal standard elements. In this paper, Y and Bi was employed for the light mass elements and the heavy mass elements,respectively. As, Be, Co, Cu, Ga, Ge, Mn, Mo, Pb, Ni, Sr, Au, Tl, Th, V and U in high purity cadmium were determined. Detection limits are 0.005-0.052 mu g L-1,and the recoveries of standard addition are 82%-108%.

THEORETICAL-ANALYSIS OF NERNSTIAN PLOTS IN THE THIN-LAYER SPECTROPOTENTIOSTATIC TECHNIQUE

The Nernstian plots in a spectropotentiostatic experiment for complex electrode processes were studied theoretically. The plots are linear for an electron transfer process coupled with a preceding or succeeding chemical reaction, and the electron stoichio

RESOLUTION OF CLOSELY SPACED LINES WITH KALMAN FILTERING IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

Effects of some factors on the performance of our Kalman filter in discrimination of closely spaced overlapping signals were investigated. The resolution power of the filter for overlapping lines can be strengthened by reduction of the step size in scans. The minimum peak separation of two lines which the Kalman filter can effectively handle generally equals two to three times the step size in scans. Significant difference between the profiles of the analysis and interfering lines and multiple lines from matrix in the spectral window of the analysis line are very helpful for the Kalman filter to discern closely spaced analysis and interfering signals correctly, which allow the filter well to resolve the line pair with very small peak distance or even the entirely coincident lines.