Analysis of poly (arylene phosphonate) cyclic oligomer by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MAIDI-TOF-MS) was used for analysis of poly(arylene phosphonate) cyclic oligomers. A comparison was made by using 1,8,9-dithranol, 2,5-dihydroxybenzoic acid and retinoic acid as the matrix. The result showed that the retinoic acid produced the strongest ion signals under the conditions used. Different salts of metals were used as the cationization agents to examine the effect on the cyclic oligomers. It was found that the salts could produce metal-cyclic oligomer cation spectra and lithium was the stronger one than those of silver so, the suitable matrix and cationization agent for the new cyclic oligmer were obtained. They were very effective for the analysis of poly(arylene phosphonate) cyclic oligomer.

Use of nitrocellulose films for affinity-directed mass spectrometry for the analysis of antibody/antigen interactions

Combination of affinity extraction procedures with mass spectrometric analyses is termed affinity-directed mass spectrometry, a technique that has gained broad interest in immunology and is extended here with several improvements from methods used in previous studies. A monoclonal antibody was immobilized on a nitrocellulose (NC) membrane, allowing the corresponding antigen to be selectively captured from a complex solution for analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). This method was also used to rapidly determine the approximate binding region responsible for the antibody/antigen interaction. The tryptic fragments of antigen protein in buffer were applied to the antibody immobilized on NC film and allowed to interact. The NC film was then washed to remove salts and other unbound components, and subjected to analysis by MALDI-TOFMS. Using interferon-alpha (2a) and anti-interferon-alpha (2a) monoclonal antibody IgG as a model system, we successfully extracted the antigen protein and determined the approximate binding region for the antigen/antibody interaction (i.e., the tryptic fragment responsible). Copyright (C) 2001 John Wiley & Sons, Ltd.

Gaseous dipeptide complexes with metal ions by electrospray ionization and tandem mass spectrometry

Electrospray ionization (ESI) and tandem mass spectrometry have been used to investigate the gas-phase interactions of five metal ions and seven dipeptides. For silver ion, two complexes ([M+Ag](+) and [2M+Ag](+)) were obtained as well as the one complex ([2M+Met-H](+)) for transition-metal ions. Upon collision activation, there is an obvious difference in MS/MS data between metal ion complex and the protonated molecule. The fragment pathway of each complex is related to the structures of dipeptide and the nature of metal ion which suggest that there are several interaction between the metal ions and dipeptides in gas phase.

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.

Application of inductively coupled plasma mass spectrometry in biological samples analysis

Recent important applications of inductively coupled plasma mass spectrometry in biological samples analysis are reviewed. The sample preparation, sample introduction techniques, interference correction and typical applications are introduced in detail with 154 references.

Metal ion adducts in the structural analysis of ginsenosides by electrospray ionization with multi-stage mass spectrometry

The effect of metal (Li+, Na+, K+, Ag+) cationization on collision-induced dissociation of ginsenosides was investigated by electrospray ionization mass spectrometry combined with multi-stage mass spectrometry (ESI-MSn). The fragments of sodiated and lithiated molecules give valuable structural information regarding the nature of the aglycone and the sequence and linkage information of sugar moieties. However, the number and relative abundances of fragment ions from lithiated ginsenosides are significantly greater than for the sodiated species, The K+ adducts undergo glycosidic cleavages and very limited cross-ring reactions. The silver ion adducts fragment mainly through glycosidic cleavages. Copyright (C) 2001 John Wiley & Sons, Ltd.

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%.

Investigation of a series of synthetic cationic porphyrins using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used to study a series of synthetic cationic porphyrins as the perchlorate and bromide salts. This work presents the analytical results for the porphyrins obtained using 2,5-dihydroxybenzoic acid (DHB) and 1,8,9-anthratriol as matrices. The selective use of matrix affects ion formation from these porphyrins. By using DHB as the matrix, we not only observed [M - nCIO(4)](+) (n = 1-4) ions, but also obtained [2M - nCIO(4)](+) (n = 2-7) ions from the synthetic cationic porphyrins. The space volume of the side chains (R groups) and the nature of the anions (Br- or CIO4-) affected the relative importance of monomeric and dimeric ions of the porphyrin. The possible mechanisms of desorption and ionization of these cationic porphyrins were also considered in this study. MALDI-TOFMS proved to be a very useful method for obtaining structural information on these synthetic cationic porphyrins. Copyright (C) 1999 John Whey & Sons, Ltd.

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.

Trace analysis of Zn-doped compound semiconductor material by resonant ionization mass spectrometry

An experimental setup and the procedure for the laser resonant ionization mass spectrometry (RIMS) have been described. Both an optical spectrum and a mass spectum have been shown. The detection limit that can be reached by using this procedure has been estimated.

Determination of mercury in biological samples using organic compounds as matrix modifiers by inductively coupled plasma mass spectrometry

A method was developed for the determination of total mercury in biological samples. The effects of aqueous ammonia, ethylenediamine and triethanolamine on Hg signal intensity by inductively coupled plasma mass spectrometry has been evaluated and the possible mechanisms discussed. It has been proved that the signal intensity of Hg significantly increases with adding, in the presence of small amounts of aqueous ammonia, ethylenediamine or triethanolamine. The normalized intensity (the signal intensity ratio with amine and without amine) of Hg increases as the concentration of aqueous ammonia, ethylenediamine or triethanolamine increases, but the degree of enhancement of aqueous ammonia was smaller than that of ethylenediamine and triethanolamine. The normalized intensity of Hg with aqueous ammonia, ethylenediamine and triethanolamine decreases as the nebulizer flow rate increases, but decreasing degree of aqueous ammonia was smaller than that of ethylenediamine and triethanolamine. The higher the RF powers the higher the normalized intensity of Hg at the same nebulizer flow rate. The addition of aqueous ammonia, ethylenediamine and triethanolamine into analytical solutions significantly improved the transport efficiency of Hg. The detection limit of Hg is improved about ten times by the addition of ethylenediamine or triethanolamine under the optimum experimental parameters. The method has been used to determine mercury in biological standard reference materials (SRM). The analytical results are very close to the certified values and the determined values for similar samples.

Characterization of cyclic arylether ketone (sulfone) containing hexafluoroisopropylidene unit by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

The cyclic aryletherketone( sulfone) oligomers containing hexafluoroisopropylidene unit were characterized by matrix-assisted laser desorption ionization time-of-night mass spectrometry(MALDI-TOF-MS) using Na+ and Ag+ as cationization agents. The affinities of cyclic oligomers to the cation were studied. The analysis result showed that 1,8,9-dithranol, in the presence of silver trifluoroacetate, was very effective for the characterization of cyclic arylether ketone ( sulfone) containing hexafluoroisopropylidene unit.

Determination of purity and molecular weight of calmodulin by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The purity and molecular weight of calmodulin have been determined by means of matrix-assisted laser desorption/ionization time of flight mass spectrometry, and the results have been discussed. The experimental results demonstrate that this method is high sensitive and rapid as compared with other traditional methods.

Determination of rare earth elements in biological samples by inductively coupled plasma mass spectrometry

A method for the determiantion of rare earth elements in biological sampels by inductively coupled plasma mass spectrometry was developed. Oxide ion yield of the rare earth elements (RFE) decreased with the increasing of RF power and the sampling depth, or with the decreasing of carrier gas flow rate. The spectral interference arising from (PrO)-Pr-141-O-16 on Gd-157 must be corrected. if the concentration of Ba was high enough, it was necessary to correct the spectral interference arising from (BO)-B-135-O-16 on Eu-151, and it was not necessary to correct spectral interference arising from (NdO)-Nd-143-O-16 on Tb-159 etc. in the biological samples under the selected operation parameters. In the biological sample, the major matrix elements, such as K, Na and Ca, result in the suppression of REEs signals and the suppression degree of the Ca is grezter than that of the K and Na. The mussel sample was digested by thd dry ashing, wet digestion with HNO3 + H2O2 and HNO3 + HClO4, respectively. The analytical results of REEs were consistent with each other. Detection limits for REEs are 0.001 similar to 0.013 mu g/L. Recoveries of standard addition are 91.7% similar to 125%. REEs in biological samples were determined directly without separation and preconcentration procedure.