Daughter ions

Fixed-product ion scans (sector instruments). High-voltage scan or linked scan at constant B /E. Both techniques give a spectrum of all precursor (parent) ions that fragment to yield a preselected product (daughter) ion. 

Constant neutral loss (or fixed neutral fragment) scans. The linked scan at constant B[1 -(E/Eg)] /E gives a spectrum of all product (daughter) ions that have been formed by loss of a preselected neutral fragment from any precursor (parent) ions. 

Daughter ion. An electrically charged product of a reaction of a particular parent ion. In general, such ions have a direct relationship to a particular precursor ion and, indeed, may relate to a... 

Metastable ion. An ion that is sufficiently excited to dissociate into a particular daughter ion and neutral species during the flight from the ion source to the detector. The dissociation is most readily observed when it takes place in one of the field-free regions in a mass spectrometer. 

Stable ion. An ion that is not sufficiently excited to dissociate into a daughter ion and associated neutral fragments, or to react further in the time frame of the mass spectrometric analysis under stated experimental conditions. 

Parent ion/precursor ion An ion that undergoes fragmentation to produce a daughter ion and a neutral product. 

Product ion/daughter ion An ion related to a precursor or parent ion by a process such as fragmentation. For example, a parent ion fragments to produce a daughter ion. 

By CH4-chemical ionization two predominant ions from DDS were formed in the ion source m/z 163 (M + 1) and m/z 165 (M + 3), which were accelerated and separated in the first quadrupole. Decomposition by collision activation with argon then occurred in the second quadrupole and the resulting daughter ions were separated in the third quadrupole to give rise to collision-induced spectra (equations 41-43). When carrying out the analysis with a solid inlet MS-MS system (TSQ) it was observed that, when operating TSQ in the multiple ion detection mode and selecting the ions m/z 63, 83, 85,99 and 101, only in the third quadrupole was there no interference from other m/z 163 and 165 precursor ions . ... 

Optimized to provide maximum response for the (M + H)+ ion this process is usually automated. Then, the settings for the collision cell are optimized to produce maximum response of one or two characteristic daughter ions. Most modern instruments allow this to be done automatically. In general, sulfonylureas are very amenable to positive ion electrospray MS and MS/MS analysis, with excellent sensitivity compared with most other agrochemicals, and optimal responses can be easily obtained by proficient operators. 

If sulfonylurea herbicides can reasonably be expected to be present in an analytical sample (based on prior knowledge), one parent-to-daughter ion transition is usually considered sufficient to confirm its presence. In other cases where little is known about the sample history, two parent-to-daughter ion transitions are generally considered to be necessary for a definitive confirmation. Suggested ion transitions for most of the registered sulfonylurea herbicides are listed in Table 2. Furthermore, the ratio of the signals for the two transitions obtained for the sample should match that of an authentic standard within 30%, at most. ... 

Data collection Data are collected for negative daughter ion transitions of m/z 381 to 114 and m/z 381 to 99 for the A-desmethyl flucarbazone analyte and m/z 384 to 117 for the A-desmethyl flucarbazone-t/s internal standard... 

Data are collected for positive daughter ion transitions of mjz 130 to 115 for the NODT analyte and mjz 133 to 115 for the NODT-fi(3 internal standard... 

The question at this point was whether modifications could be made to the oxadiazole molecule to enhance metabolic stability and achieve comparable activity. This approach required knowledge of the site of metabolism and the nature of the metabolic products. This information was obtained from ion mass spectrometry. The identity of these products was determined by comparing the fragmentation pattern of metabolites A and B with the parent compound and the corresponding daughter ions (Fig. 25). 

Figure 2. (a) Reflection TOF mass spectrometer, (b) Depicts the electrostatic potentials. With a judicious selection of potential, the daughter ions arising from metastable decay arrive at the detector prior to the parent ions which have higher kinetic energy. MCP denotes a microchannel plate charged particle detector, (a) Taken with permission from ref. 22 (b) Taken with permission from ref. 19. 

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