Measurement of glycated hemoglobin is widely used for the diagnosis and monitoring of diabetes mellitus. Matrix assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometry (MS) analysis of patient samples is used to demonstrate a method for quantitation of total glycation on the β-subunit of hemoglobin. The approach is accurate and calibrated with commercially available reference materials. Measurements were linear (R2 > 0.99) across the clinically relevant range of 4% to 20% glycation with coefficients of variation of ≤ 2.5%. Additional and independent measurements of glycation of the α-subunit of hemoglobin are used to validate β-subunit glycation measurements and distinguish hemoglobin variants. Results obtained by MALDI-TOF MS were compared with those obtained in a clinical laboratory using validated HPLC methodology. MALDI-TOF MS sample preparation was minimal and analysis times were rapid making the method an attractive alternative to methodologies currently in practice.
As a low molecular weight protein with the ability of binding metal ions and high inducibility, metallothionein (MT) is often regarded as an important biomarker for assessment of heavy metal pollution in water environment. In the light of that the traditional process of enrichment and identification is time-consuming and complicated, we prepared a core-shell nanoparticle, gold-coated iron oxide nanoparticles (Fe3O4@Au NPs) herein. It possessed the advantages of fast response to magnetic fields and optical properties attributing to Fe3O4 and Au nanoparticles, respectively. The Fe3O4@Au nanoparticles could be used to enrich MT simply through Au–S interaction, and the purified proteins were determined by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS). The results showed that the Fe3O4@Au nanoparticles could directly enrich MT from complex solutions and the detection limit could be as low as 10 fg mL?1. 相似文献
Seven triterpenes were selected for study of their photoaging behavior by graphite‐assisted laser‐desorption/ionization mass spectrometry as the primary analytical tool. The triterpenes serve as simplified reference systems for complex triterpenoid resins, which are used as varnishes on paintings. Some of the triterpenes are main components of such natural resins; others were chosen for their particular functional groups or carbon skeleton to evaluate specific influences on the aging process. Progressive aging resulted in incorporation of oxygen and simultaneous loss of hydrogen, recognizable in the mass spectra by the appearance of signals with mass increments of 14 and 16 Da. Degradation of aging products also led to compounds with lower masses than the initial triterpenes. The general aging behavior of the triterpenes studied was found to be rather similar, although differences in reactivity, and, therefore, in the extent of oxidation were found, depending on the functional groups. Compounds with aliphatic ketone groups were much more reactive under the test conditions than others. A mixture of five triterpenes showed the highest reactivity. Yellowing, an important aspect of aging with regard to varnishes on paintings, was found to be related to a general breakdown of the initial triterpenes and was not caused by a single compound. 相似文献
Matrix assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) is a technique that has seen a sharp rise in both use and development. Despite this rapid adoption, there have been few thorough investigations into the actual physical mechanisms that underlie the acquisition of IMS images. We therefore set out to characterize the effect of IMS laser ablation patterns on the surface of a sample. We also concluded that the governing factors that control spatial resolution have not been correctly defined and therefore propose a new definition of resolution.
Tissue imaging using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a well-established technique that, in recent years, has seen wider adoption and novel application. Applications such imaging mass spectrometry (IMS) and biotyping are beginning to gain greater exposure and use; however, with limitations in optimization methods, producing the best result often relies on the ability to customize the physical characteristics of the instrumentation, a task that is challenging for most mass spectrometry laboratories. With this in mind, we have described the effect of making simple adjustments to the laser optics at the final collimating lens area, to adjust the laser beam size and shape in order to allow greater customization of the instrument for improving techniques such as IMS. We have therefore been able to demonstrate that improvements can be made without requiring the help of an electrical engineer or external funding in a way that only costs a small amount of time.
A new method of liquid sample introduction for a time-of-flight mass spectrometer (TOF-MS) has been developed by applying the method of matrix-assisted laser desorption ionization to aerosols. Analyte biomolecules are dissolved in a methanol solvent along with a UVabsorbing matrix and formed into an aerosol with a pneumatic nebulizer. The aerosol particles are dried in a heated skimmer tube before ionization by pulsed 355-nm UV laser radiation. Mass analysis is achieved in a linear TOF-MS. Results for the ionization of bovine insulin (5733.5 Mw) are reported. 相似文献
Microporous sol-gels prepared from a tetramethyl orthosilicate precursor with 5-hydroxytryptophan, 5-HTPP, as a dopant were investigated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI). Spectra of 5-HTPP and its oxidation products were obtained when (a) the matrix, -hydroxycinnamic acid, was included in the sol, (b) thin wafers of silica were used, and (c) the surface of the gel was abraded after mounting the sol-gel on the MALDI sample puck so that laser reflection was minimized. The methodology permitted elucidation of the 5-HTPP oxidation pathway. In microporous silica a low molecular product, the dione, was obtained whereas in a mesoporous matrix, dimeric products were formed. 相似文献
