Ion analysis

The mass spectral fragmentations of 9,10-dimethoxy-2,3,4,6,7,ll/)-hexa-hydro-l//-pyrimido[6,l-n]isoquinolin-2-ones 140 and -2,4-diones 141, under electron ionization (at 70 eV) were examined by metastable ion analysis, a collosion-induced dissociation technique and exact mass measurement (97RCM1879). Methyl substituent on N(3) in 140 (R = Me) had a larger effect on both the fragmentation and on the peak intensities, than a methyl substituent on C(6) (R = Me). The ionized molecules of 140 (R = H) were rather stable, whereas 4-phenyl substitution on C(4) of 140 (R = Ph) promoted the fragmentations of the molecular ions. The hexahydro-1//-pyrimido[6,l-n]isoquinoline-2,4-diones 141 were more stable, than the hexahydro-l//-pyrimido[6,l-n]isoquinolin-2-ones 140, and the molecular ions formed base peaks. 

From Orion Guide to Ion Analysis, Orion Research, Cambridge, MA, 1983. With permission. 

The four-sector mass spectrometer is the ultimate in MS-MS instrumentation and consists of two high-resolution mass spectrometers in series. The strength of these instruments is in terms of their high-mass and high-resolution capabilities for both precursor-ion selection and product-ion analysis. Their cost, however, precludes their primary use for LC-MS and therefore they will not be considered any further here [12]. 

Wetai Ion Analysis. We have reported a sensitive trace-metal analysis based upon HPLC separation of p-aminophenyl EDTA chelates and fluorescence detection by postcolumn reaction with fluorescamine (23). An application of the pyridone chemistry already discussed leads to a fluorescent-labeled EDTA (VIII). 

We have developed reverse-phase ion-pairing HPLC separations of substituted EDTA metal chelates of several transition metals (including Cd, Zn, Fb, and Hg) and several lanthanides (La, Ce, Eu, Dy, Er, Yb, Lu). Detection levels of these chelates are currently being assessed. A sensitive metal ion analysis employing an inherently fluorescent EDTA seems feasible. 

Tian, Q. et al., Screening for anthocyanins using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry with precursor-ion analysis, product-ion analysis, common-neutral-loss analysis, and selected reaction monitoring, J. Chromatogr. A, 1091, 72, 2005. 

Digestion of PGA by the PelL enzyme yielded a mixture of unsaturated ohgogalacturonides, giving evidence that PelL is an endo-deaving lyase (17). An exo-enz3mie, such as the EC 16 PelX, would generate a single product (15). The PelL protein differs from the major E. chrysanthemi pectate lyases in its ability to cleave both PGA and methylated pectin (17). The PelL activity has a basic optimum pH and an absolute requirement for Ca + ions. Analysis of culture supernatants demonstrated that PelL is an extracellular enzyme, such as the other secondary pectate lyases (17). 

Figure 10 Capillary ion analysis of 30 anions 1 = thiosulfate, 2 = bromide, 3 = chloride, 4 = sulfate, 5 = nitrite, 6 = nitrate, 7 = molybdate, 8 = azide, 9 = tungstate, 10 = monofluorophosphate, 11 = chlorate, 12 = citrate, 13 = fluoride, 14 = formate, 15 = phosphate, 16 = phosphite, 17 = chlorite, 18 = galactarate, 19 = carbonate, 20 = acetate, 21 = ethanesulphonate, 22 = propionate, 23 = propanesulphonate, 24 = butyrate, 25 = butanesulphonate, 26 = valerate, 27 = benzoate, 28 = D-glutamate, 29 = pentane-sulphonate and 30 = D-gluconate. Experimental conditions fused silica capillary, 60 cm (Ld 52 cm) x 50 p i.d., voltage 30 kV, indirect UV detection at 254 nm, 5 mM chromate, 0.5 mM NICE-Pak OFM Anion-BT, adjusted to pH 8.0, with 100 mM NaOH. (From Jones, W. R. and Jandik, R, /. Chromatogr., 546, 445,1991. With permission.)...

Capillary electrophoresis is still in a state of evolution and a technique of choice for certain applications (chiral analysis small ion analysis in food and beverage industries bioanalysis). The number of reviews [365,858,884,889-896], books and manuals [365,897-903] published on (HP)CE/CEC/CZE in the last decade is overwhelming, in particular in relation to the importance of the technique (see also Bibliography). CE-LIFS has been reviewed [904]. 

Appropriate use of RF and DC voltages means that some ions can be selectively retained and product ions generated. Some of these ions can then be selected and their product ions generated. In this manner, a fragmentation chain can be established. The ion trap is a typical tandem-in-time mass spectrometer, in which precursor and product ions are created and analysed in the same physical space ionisation and ion analysis, on the other hand, take place at different times ( MS/MS in time )- The operation can be repeated several times, making it possible to perform MS11. Ion trap mass spectrometry thus consists of ... 

Ion trap MS is particularly suited for chemical structure elucidation, as it allows for simultaneous ion storage, ion activation and fragmentation, and product ion analysis. The fragmentation pathway of selected ions and the fragmentation products provide information on the molecular structure. Compared with triple-quadrupole and especially with sector instruments, the ion trap instrument provides more efficient conversion of precursor ion into product ions. However, the CID process via resonance excitation, although quite efficient in terms of conversion yield, generally results in only one (major) product ion in the product-ion mass spectrum. MS/MS with a quadrupole ion trap offers a number of advantages ... 

Several authors have developed highly sensitive CL detection coupled to CE for ion analysis. Huang et al. [96] used luminol as a component of the separation electrolyte that prevented loss of the light signal. Detection limits of 20 zmol, 2 amol, 80 amol, 740 amol, and 100 fmol for Co(II), Cu(II), Ni(II), Fe(III), and... 

Other studies in this specific area are also based on the catalytic effect of a variety of metal ions such as copper (II), cobalt (II), nickel (II), iron (III), and manganese (II) on the luminol-hydrogen peroxide reaction providing a rapid and efficient detection mode for these five ions, when an online CL detector is used before separation by CE [88], This contribution combines capillary ion analysis (CIA) and CL detection by means of a postcapillary reactor similar to the one originally developed by Rose and Jorgenson [80] and finally modified by Wu... 

CE possesses great potential for profiling small ionic species. The utilization of CE for ion analysis has proven to be competitive with HPLC in the areas of... 

The technique offers many similar advantages to ion chromatography, namely multiple ion analysis, little or no sample pretreatment, speed, sensitivity and automation. 

Laramee, J.A. Mazurkiewicz, P. Berkout, V. Deinzer, M.L. Electron Monochromator-Mass Spectrometer for Negative Ion Analysis of Electronegative Compounds. Mass Spectrom. Rev. 1996,15, 15-42. 

Example The reduced sample consumption of nanoESI allows for the sequencing of the peptides (Chap. 9.4.7) obtained by tryptic digestion of only 800 fmol of the protein bovine semm albumin (BSA, Fig. 11.6). [66] The experiment depicted below requires each of the BSA-derived peptide ions in the full scan spectrum to be subjected to fragment ion analysis by means of CID-MS/MS on a triple quadrupole instmment (Chaps. 2.12 and 4.4.5). 

CE has been touted as a replacement for HPLC in the pharmaceutical industry. This was a shame, since the techniques are so different. For many measurements, it is an orthogonal technique to HPLC. Whereas HPLC separates based on interaction with the stationary phase, CE separates based on the ratio of charge to mass. There are numerous examples of where CE exceeds the resolving power of HPLC (e.g., ion analysis, chiral analysis, DNA quantification, separation, large molecule analysis, etc.). 

Many applications for ion analysis use a UV detector with indirect detection, though other electrochemical, laser-induced fluorescence (LIE), or mass spectrometry detectors have been described. The main advantage of UV detection is its availability on commercial instruments and that both UV-absorbing and non-UV-absorbing analytes may be detected. Nowadays, electrochemical detectors are also available specific background electrolytes (BGEs) must be used and the detector has to be adapted to existing CE instruments. 

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