Detection and characterization of non-covalent complex between lappaconitine and beta-cyclodextrin by electrospray ionization tandem mass spectrometry

The non-covalent complexes between lappaconitine (LA) and beta-cyclodextrin (beta-CD) have been detected and characterized by electrospray ionization combined with ion trap tandem mass spectrometry (ESI-MSn). The experimental results showed that only 1:1 non-covalent complex can be formed in different starting molar ratios of LA to beta-CD. Furthermore, the diagnostic fragmentation of the beta-CD-LA complex, with a significant contribution of covalent fragmentation of LA leaving the N-acetyl anthranoyl (AN) moiety inserted to beta-CD, provided the convincing evidence for the formation of non-covalent complex between LA and beta-CD and the cite of LA molecule included to cavity of beta-CD assigned to AN residue.

Exploring the ester-exchange reactions of diester-diterpenoid alkaloids in the aconite decoction process by electrospray ionization tandem mass spectrometry

The chemical components in the decoctions of Chinese herbal medicines are not always the same as those in the crude herbs because of the insolubility or instability of some compounds. In this work electrospray ionization tandem mass spectrometry was used to explore the ester-exchange reactions for aconitine-type diester-diterpenoid alkaloids occurring during the process of decocting aconite root. The aconitines were screened in a diverse range of samples, including crude aconite, decoction of crude aconite, residues from decoction of crude aconite, prepared aconite, decoction of prepared aconite, decoction of prepared aconite with added palmitic acid, and decoction of a mixture of mesaconitine and hypaconitine standards with liquorice root. It was found that diester-diterpenoid aconitines were converted into lipo-alkaloids as well as monoester alkaloids by the decoction of aconite.

Characterization of aconitine-type alkaloids in the flowers of Aconitum kusnezoffii by electrospray ionization tandem mass spectrometry

The fragmentation mechanism of aconitine-type alkaloids in the flowers of Aconitum kusnezoffii (FAK) was investigated using electrospray ionization tandem mass spectrometry (ESI-MSn) firstly. The analysis of the collision-induced dissociation (CID) spectra of three purified aconitine standards and six previously reported aconitines indicated that the fragmentation of the protonated aconitines at low-energy CID follows a similar pathway. The elimination of a C-8-substituent such as an acetic acid or a fatty acid is the dominant fragmentation mode in MS2. Successive losses of CH3COOH, CH3OH, H2O, BzOH, and CO are the main fragmentation pathways of aconitine-type alkaloids in MS3 spectra. Based on these features, a rapid method for the direct detection and characterization of alkaloids from an ethanolic extract of FAK is described. All the known aconitum alkaloids are detected and a series of lipo-aconitines has been found for the first time in this plant.

Determination of gold, platinum and palladium in geological samples by inductively coupled plasma-mass spectrometry after separation and preconcentration with C-410 anion exchange resin

A method for the determination of Au, Pt and Pd in geological samples is described. Au, Pt and Pd can be separated and concentrated quantitatively by C-410 anion-exchange resin in the condition of 1.5 mol/L HCl with the adsorption rates of 91.2%, 100.0% and 95.7% respectively. No interference exists from coexisting elements except for Ge(IV), Cr(VI),Ti(IV) in inductively coupled plasma-mass spectrometry. The detection limits are 0.27 mug/L, 0.40 mug/L and 0.19 mug/L for Au, Pt and Pd respectively. The results of these elements in standard geological materials are in agreement with certified values with precision of 19.2% RSD for Au (n = 8), 28.1% RSD for Pt (n=8), and 15.6% RSD for Pd (n=8).

Determination of rare and rare earth elements in soils and sediments by ICP-MS using Ti(OH)(4)-Fe(OH)(3) co-precipitation preconcentration

A method was developed for the determination of trace and ultratrace amounts of REE. Cd. In. Tl. Th. Nb, Ta. Zr and Hf in soils and sediments. With NaOH-Na2O2 as the flux. Ti(OH)(4)-Fe(OH)(3) co-precipitation as the preconcentration technique and inductively coupled plasma mass spectrometry (ICP-MS) for measurement, the whole procedure was concise and suitable for batch analysis of multi-element solutions. An investigation was carried out of the Ti(OH)(4)-Fe(OH)(3) co-precipitation system, and the results obtained showed that the natural situation of Ti tightly coexisting with Nb. Ta, Zr and Hf in geological samples plays a very important role in the complete co-precipitation of the four elements. The accuracy of this procedure was established using six Chinese soil and sediment certified reference materials (GSS and GSD). and the relative errors between the found and certified values were mostly below 10%.

Analysis of flavonoid constituents from leaves of Acanthopanax senticosus Harms by electrospray tandem mass spectrometry

Three known flavonoids, quercetin, quercitrin (quercetin-3-0-rhamnoside) and rutin (quercetin-3-0-rutinoside), have been identified for the first time in the leaves of Acanthopanax senticosus Harms by using electrospray tandem mass spectrometry techniques (ESI-MSn). The flavonoid hyperin (quercetin-3-0-beta-galactoside), already known to be present, was also investigated. The diagnostic fragment ions of the aglycone quercetin were obtained in the ESI-MSn experiments, and a fragmentation mechanism proposed.

提高MALDI-MS测量溶菌酶分子量灵敏度的研究

近 1 0年来 ,基质辅助激光解吸质谱 (MALDI- MS)作为一种新兴的“软电离”质谱技术 [1,2 ] ,已很快地应用于生物大分子特别是蛋白质研究领域 [3 ] .MALDI- MS可在 1 0 - 12 mol甚至 1 0 - 15mol的水平上 ,准确地测定分子量高达几万到几十万的生物大分子 ;还可通过改变基质、溶液条件和样品的制备方法等实现大分子蛋白质非共价复合物的质谱检测 [4 ] .MALDI- MS能够得到如此广泛的应用 ,在很大程度上要归功于基质的辅助效应 .基质的作用主要可以概括如下 [5～ 7] :(1 )削弱样品分子间的相互作用 ;(2 )与样品分子结合并使之快速结晶 ;(3 )帮助样品分子从激光脉冲中吸收能量 ,使其产生瞬间相变 ,当能量达到本体解吸临界值时便可得到离子信号 .Garozzo等 [8]曾报道了以羟基苯乙酮为基质可提高测量多种谷蛋白粘胶质分子量的灵敏度 .其中以 2 ,4,6 -三羟基苯乙酮 (2 ,4,6 - THAP)与 TFA混合作基质和 2 ,6 -二羟基苯乙酮 (2 ,6 - DHAP)与 H2 O,ACN混合作基质灵敏度最高 .表明这类基质在通过气相离子 ...

Analysis of chemical constituents of essential oil in purple magnolia leaves by gas chromatography-mass spectrometry

The essential oil in purple magnolia leaves was extracted by steam distillation approaches. The oil obtained was dried with anhydrous magnesium sulfate. According to the analysis of gas chromatography/mass spectrometry, more than 40 peaks were separated and 32 compounds were identified. The identified constituents represent 95% of the peak area of the essential oil. The main compounds were germacrene-D, santolina triene, caryophyllene, 1,3,7-octatriene, 3,7-dimethyl, and camphene, etc.

Studies on negative electrospray ionization mass spectrometry on saponins

Two kinds of saponins have been investigated by negative electrospray ionization (NESI) mass spectrometry. Under ESI conditions, the [M - H](-) ions of saponins were observed which provide the molecular weights of saponins. The fragment pathways of [M - H](-) ions of these two saponins depend on their structures. For steroidic saponins, [M - H](-) ion only produces the fragment ions by the losses of sugar units. For oleanolic saponins, [M - H](-) ion yields the cross-ring ions as well as the fragment ions by the losses of sugar units. Moreover, the abundance of the former is higher than that of the latter. The characteristic fragments are used to provide the sequence and some linkage information of sugar moieties of saponins. Especially, their fragment difference strongly depends on the linkage between the aglycone and the sugar moieties.

Investigation of metalloporphyrins and their imidazole complexes using electrospray ionization mass spectrometry

Three compounds of metalloporphyrins were studied using electrospray ionization mass spectrometry. The bonding power between substitutional phenyl and porphyrin cycle and the coordinate conditions of metalloporphyrins with imidazole were discussed. The experimental result indicated that the bonding power between substitutional phenyl and porphyrin cycle in metalloporphyrins became weak from Mn, Fe to Co. The complexes abundances formed by metallophorphyrin with imidazole were stronger with the increase of the ligand concentration. At the same ligand concentration, the abundance of the complexes was intensified gradually and the stability of the ligands was become stronger from Mn, Fe to Co.

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%.

New method of mass spectrometry for distinguishing ephedrine and isoephedrine

Ephedrine and isoephedrine were first distingshed by electrospy ionization mass spectrometry and in-sourice collision-induced dissociation technique. Based on this observation, a unkown sample was identified for ephedrine.

Review on study of resonance electron capture mass spectrometry

Resonance electron capture mass spectrometry, in which an additional information coordinate, the energy of electron capture, is applied, has a high sensitivity and a high specificity. It is extensively used to study the structure elucidation, the mechanism of ion formation and the detection, identification and quantification of organic substances in mixture.

Studies on electrospray mass spectrometry of some narcotic drugs

Using electrospray ionization (ESI) and tandem mass spectrometry techniques, the protonic positions in protonated molecular ions of some narcotic drugs were studied, The data of ESI/MSn experiments of morphine and deuterium-loaded morphine were first discussed. The protonic position was considered to locate on oxygen atom of cyclic ether in morphine molecular, Compared with the same and different: ions among morphine, codeine, acetylcodeine and dihydrocodeine, the protonic positions in protonated molecular ions of these compounds were further determined. The fragmentation mechanism of morphine in ESI/MSn: experiments was also repored in the paper, and there were similar dehydrolysis mechanism in gas phase or in liquid phase for morphine.