Mass direct injection atmospheric

Toh, T.H., Prior, B.A. and van der Merwe, M.J., Quantitation of plasma membrane ergosterol of Saccharomyces cerevisiae by direct-injection atmospheric pressure chemical ionization/ tandem mass spectrometry. Anal Biochem., 288, 44—51 (2001). 

Kolalowski, B. M., Grossert, J. S., and Ramaley, L., Studies on the positive-ion mass spectra from atmospheric pressure chemical ionization of gases and solvents used in liquid chromatography and direct liquid injection, J. Am. Soc. Mass Spectrom., 15, 311-324, 2004. 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

Specifically for triazines in water, multi-residue methods incorporating SPE and LC/MS/MS will soon be available that are capable of measuring numerous parent compounds and all their relevant degradates (including the hydroxytriazines) in one analysis. Continued increases in liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) sensitivity will lead to methods requiring no aqueous sample preparation at all, and portions of water samples will be injected directly into the LC column. The use of SPE and GC or LC coupled with MS and MS/MS systems will also be applied routinely to the analysis of more complex sample matrices such as soil and crop and animal tissues. However, the analyte(s) must first be removed from the sample matrix, and additional research is needed to develop more efficient extraction procedures. Increased selectivity during extraction also simplifies the sample purification requirements prior to injection. Certainly, miniaturization of all aspects of the analysis (sample extraction, purification, and instrumentation) will continue, and some of this may involve SEE, subcritical and microwave extraction, sonication, others or even combinations of these techniques for the initial isolation of the analyte(s) from the bulk of the sample matrix. 

Atmospheric pressure ionization (API) was the first technique to directly interface solution phase with a mass analyzer. [26] In API, a solution of the analyte is injected into a stream of hot nitrogen to rapidly evaporate the solvent. The vapor passes through a Ni source where electrons emitted from the radioactive Ni isotope initiate a complex series of ionizing processes. Beginning with the ioniza-... 

A restriction to the operation of GC-MS can be caused by solvent peaks. If the solvent injected onto a packed column flows via a separator into the ion source of the mass spectrometer, it results in an unacceptable increase in pressure which causes the built-in pressure protection devices to shut the mass spectrometer down. It also much reduces the lifetime of source components such as filaments and heaters. Therefore a valve is fitted at the end of the column, which allows effluent to be vented to a pump or to tile atmosphere until the solvent has passed. The flow rates associated with the use of capillary coliunns are such that the pressure generated by the solvent is not as great as with a packed column. The total effluent may therefore be passed directly into... 

For further analytical investigations 0.2 mg polymer samples were removed from electrodes and pyrolysed in a Jeol pyrolyser unit, Model 727. Pyrolyses were carried out in a helium atmosphere at a temperature of 400° C for 30 sec. The volatile pyrolysis products were fed directly to the injection part of a Jeol gas chromatograph, Model JGC 1100, equipped with a flame ionization detector the apparatus incorporated a 2.5 m X 2 mm stainless steel separation column filled with OV 101 10 % supported on Varaport 80/100 mesh. The volatile pyrolysis products, isolated by gas chromatography, were analysed using a LKB mass spectrometer,Model 2091, equipped with a PDP11 computer. Mass spec-trometric analyses were carried out with an electron beam energy of 70 eV. 

The reacting solution was first examined by atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The solutions were injected with a dual syringe pump into an effective micromixer, which was coupled directly to the ion source of the mass spectrometer. For comparison, two compounds were examined separately by APCI-MS, and the respective quasimolecular ions were observed. The radical cations 14 and 15 were characterized unambiguously by APCI-MS/MS (Figure 4.3). 

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