Only small molecules like SDS permeate a porous membrane and are removed in a manner similar to cross flow filtration. Therefore, we developed an in-line matrix removal platform to enable the direct analysis of samples containing SDS and salts. Traditionally, methanol/chloroform precipitation and spin columns have been used but they lack reproducibility and are difficult to automate. Therefore, an efficient removal of SDS is absolutely required prior to mass analysis. However, the technique involves the use of sodium dodecyl sulfate (SDS), a surfactant that interferes with electrospray ionization. On the basis of these results, it is concluded that, during electrospray, specific non-covalent adducts have been formed and that there have been exchange reactions involving making and breaking of covalent bonds.Ī fractionation method called Gel Eluted Liquid Fraction Entrapment Electrophoresis (GELFrEE) has been used to dramatically increase the number of proteins identified in top-down proteomic workflows. Results are presented for interactions of vancomycin with diacetyl-l-lysyl-d-alanyl-d-alanine and interactions of vancomycin with deuterated vancomycin.
The products of electrospray from the dual-channel emitters have been analysed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. The common Taylor cone constitutes an extremely small “mixing volume” of the order of femtolitres. Loading of different solutions into the two different channels opens up the possibility to study short timescale interactions within a Taylor cone common to both channels. The emitters have been fabricated from “theta-shaped” borosilicate capillaries. Standards and real-world samples, such as drug tablets, ointment, and toy were analyzed to demonstrate the capability of desorption FAPCI/MS for rapid organic compound analysis.Ī novel nano-electrospray emitter has been developed containing two separated channels running throughout the length of the emitter. This approach provided a useful method to directly characterize samples with minimal pretreatment. For cream and solid sample analysis, the samples were positioned near the flame of the FAPCI source for thermal desorption and ionization. Liquid samples were introduced into the ion source through a heated nebulizer, and the analytes formed in the heated nebulizer reacted with charged species in the source. In this study, desorption FAPCI/MS was developed to rapidly characterize thermally stable organic compounds in liquid, cream, and solid states. It uses a flame to produce charged species that reacts with analytes for ionization, and generates intact molecular ions from organic compounds with minimal fragmentation. Protein ions were still detected from the solution containing 10(-2) M of SDS.įlame-induced atmospheric pressure chemical ionization (FAPCI) is a solvent and high voltage-free APCI technique. The DS-CTA ion pair has a low polarity and solubility in methanol and is excluded from the fused droplet. To remove the interferences from SDS, equal moles of positively charged cetyltrimethylammonium bromide (CTAB) was added into the SDS containing sample solution to form the dodecyl sulfate-cetyltrimethylammonium ion pair (DS-CTA). Because of its low solubility in methanol, TRIS molecules (concentration as high as 1 M) were efficiently excluded from the newly formed droplets and the protein ion signals were detected and observed in the mass spectra. The neutral sample aerosols then fused with the charged methanol droplets and electrospray ionization proceeded from the newly formed fused droplets to generate multiply charged protein ions. The aerosols were carried by nitrogen gas to the tip of a capillary where charged methanol droplets had been continuously generated by electrospraying an acidic methanol solution. The sample aerosols were generated at ambient temperature with a pneumatic nebulizer commonly used to produce sample aerosols in an atmospheric pressure chemical ionization (APCI) source. Multiply charged protein ions were detected from the solutions containing a high concentration of tris(hydroxymethyl) aminomethane buffer (TRIS) and sodium dodecyl sulfate (SDS) using fused-droplet electrospray ionization mass spectrometry (FD-ESI/MS).
0 kommentar(er)
