Extracted ion profile

Figure 3. Total ion current chromatogram and extracted ion profiles for ions of m/z 95.0, m/z 139.8, and m/z 144.9.

FIGURE 15.39 Extracted ion profile taken from the TIC shown in Figure 15.34 at m/z 314 representing the compound chlorpyriphos. The full mass scan spectrum of chropyriphos is shown in the bottom part of the figure. 

Gilbert, M. W. "The Use of Individual Extracted Ion Profiles versus Summed Extracted Ion Profiles in Fire Debris Analysis." Journal of Forensic Sciences 43 (1998), 871-876. 

Figure 3 Extracted ion profiles from the atmospheric pressure ionization mass spectrometry detector with identities established by El analysis of the same peaks.

In the ion-association extraction systems, hydrophobic and interfacially adsorbable ions are encountered very often. Complexes of Fe(II), Cu(II), and Zn(II) with 1,10-phenanthro-line (phen) and its hydrophobic derivatives exhibited remarkable interfacial adsorptivity, although the ligands themselves can hardly adsorb at the interface, except for protonated species [19-21]. Solvent extraction photometry of Fe(II) with phen is widely used for the determination of trace amounts of Fe(II). The extraction rate profiles of Fe(II) with phen and its dimethyl (DMP) and diphenyl (DPP) derivatives into chloroform are shown in Fig.9. In the presence of 0.1 M NaC104, the interfacial adsorption of phen complex is most remarkable. The adsorption of the extractable complex must be considered in the analysis of the extraction kinetic mechanism of these systems. The observed initial rate r° shows the relation... 

FIG. 9 Extraction rate profiles of the ion-association extraction of Fe(II) with phen and its dimethyl (DMP) and diphenyl (DPP) derivatives into chloroform in the presence of 0.1 M NaC104. Effect of stirring (4700 rpm) indicates the interfacial adsorption of the complexes. 

When working with non-radiolabeled drugs the major challenge is to find metabolites in the biological matrices. Because the enzymes responsible for metabolism are quite well characterized metabolic changes can partially be predicted. For example hydroxylation of the parent drug is in many cases the principal metabolic pathway. From a mass spectrometric point of view it results in an increase of 16 units in the mass spectrum. In the full-scan mode an extracted ion current profile can be used to screen for potential metabolites. In a second step a product ion spectrum is recorded for structural interpretation. Ideally, one would like to obtain relative molecular mass information and the corresponding product ion spectrum in the same LC-MS run. This information can be obtained by data dependant acquisition (DDA), as illustrated in Fig. 1.39. 

Advances in high resolution mass analyzers (TOF, FT-ICR, orbitrap) have greatly improved the detection and identification of metabolites based on accurate mass measurements. In single MS mode accurate mass determination is mainly used to differentiate between isobaric ions. Combined with LC-MS, it allows the detection of predicted metabolites by performing extracted ion current profiles... 

Fig. 3.1.7 Detection of HG by the GC-MS TIC method in the urine of patients with MCAD deficiency collected at different clinical statuses. A, left panel Organic acid profile of an acutely ill patient. The arrow indicates the portion of the chromatogram shown in the middle panel. Peak labeling 1 HG, 2 4-hydroxyphenylacetic acid. Right panel extracted ion chromatograms of the [M-15]+ ion of HG (m/z 230 red) and 4-hydroxyphenylacetic acid (m/z 281). Patient recovering from an acute episode. C Asymptomatic patient. The latter profile represents a situation where there is a high probability that HG may not be detected by a GC-MS TIC method...

True profile analysis requires scanning over the whole mass range for the acquisition of all data on excreted compounds. Quantitation has been more challenging on a quadrupole instrument because total ion current peaks are seldom a single component and extracted-ion chromatograms (EICs) when recovered from scanned data are of poor quality due to the lower sensitivity of scanning GC-MS. Thus, we developed profile analysis based on SIM of selected analytes but tried to ensure the components of every steroid class of interest were included. For ion traps the fundamental form of data collection (in non-MS/MS mode must be full -scans). Thus, the quantitative data produced are EICs obtained from scanned data. The EICs are of the same ions used for SIM in quadrupole instruments and the calibration external standards are the same. 

The analytes are determined by acquiring a full mass scan and obtaining the extracted ion current profiles (EICP) for the primary mass-to-charge ratio and at least two secondary masses of each analyte. Ions recommended for this purpose are listed in the EMSL methods. 

Figure 9. Illustration of the use of extracted ion-current profiles obtained with LC-MS, moving-belt interface, for the detection of carbamate and other pesticides. T op, extracted ion-current profile for 17 major ions second from top, extracted ion-current profile for m/z = 151 to m/z = 181 third from top, extracted ion-current profile for m/z = 86 to m/z = 305 bottom, UV absorption detection at 220 nm. (Reproduced with permission from reference 53. Copyright 1982 Preston Publications.)...

Figure 4, Extractable organic profile (ethyl ether/hexane, 5/95) of a random lot of flexible PUF reconstructed ion chromatograms (GC-MS). A, solvent extract B, Soxhlet blank. Component identification (scan number, component) 232, phenol 391, hexanoic acid, 2-ethyl 490, 2,4- or 2,6-toluene diisocyanate (TDI) 507,2-propanamine, 2-methyl 592, phenol, 2,6-bis-(l,l-dimethylethyl)-4-methyl 696, chloroctane (isomer) 737, anthracene-dw (internal standard) 1047, isooctane, ethenyloxy. Continued on next page.

GC-MS runs were stored as files by the data system on discs FORTRAN routines were written to compare selected parameters in file sets and to reduce the data to summary tables for hard copy output. These routines facilitated the determination of peak areas of components in extracted ion current profiles (EICP) for both total and selected ion chromatograms, calculated the removal of components of interest (e.g., those containing halogen isotopes) by treatment processes (GAC, CI2) or derivatization, summarized the occurrence of new components of interest in treatment or derivatization, and calculated the percent of the total ion current represented by a given component. The programs allowed operator discrimination between major and minor components in a file set by preselection of an ion current threshhold for data reduction. For data summarized herein, components were >4000 ion counts, which corresponds to a level >5 of the internal standard (decachlorobiphenyl) response. 

Fig. 8 HPLC-fo -UV Analysis of NDMA in beer. Extracted ion current profile, in the SIM mode for NDMA-acid complex (mlz 75) and that of its dissociative photolysis products, [(CH3)2NH2]+ (mlz 46) and [(CH3)(CH2)NH]+ (mlz 44). (Reprinted with permission from Ref. 86a. Copyright 1996, American Chemical Society.)...

Kuehl, D., Gu, M., and Wang, Y. (2006). Comparing mass defect filtering and accurate mass profile extracted ion chromatogram (AMPXIC) for metabolism studies. In Proceedings of the 54th ASMS Conference on Mass Spectrometry and Allied Topics, Seattle, WA. 

Figure 1.4.3 An example of extracted ion current profiles for benzene, benzene-d6, and a mixture of benzene and benzene-d6. 

Isotope ratio is measured as the ratio of the area of the primary ion of the unlabeled compound to that of the labeled compound. When the area is zero, it is assigned a value of 1. The retention times of the analytes in most cases are the same as that of their labeled analogs. The isotope can be calculated from the extracted ion current profile (EICP) areas. An example of EICP for benzene, benzene-d6, and a mixture of benzene and benzene-d6 is presented inFigure 1.4.3. Calculation to determine the RR is given below ... 

Figure 6.11 The LC/MS extracted ion current profiles for 10 combinatorial drug candidate library components, using the bioaffinity screening procedure shown in Figure 6.6. (A) Before passing through a spin column. (.B) After one cycle. (C) After two cycles. The enhancement of tight-binding ligands is evident. (Reprinted with permission from Davis et al., 1999. Copyright 1999 American Chemical Society.)...

Figure 6.33 Representative HPLC chromatograms of human serum samples for the CP-80794 SIM LC/MS assay. Extracted ion current profiles for (A) Blank (B) Blank plus internal standard (C) 0.1 ng/mL CP-80,794 (.D) 0.5 ng/mL CP-80,794. (Reprinted with permission from Fouda et al., 1991. Copyright 1991 Elsevier.)...

Cyclic Hydrocarbons. Some of the cyclic hydrocarbons found in the CHX coal extracts are shown in Table V. They were tentatively identified by capillary GC/MS except for the naphthalenes, for which authentic standards were available. Selected ion profiles were used to detect sesquiterpenes (m/e 206, 191), sesquiterpanes (m/e 208), o alkanes (m/e 141), alkyl benzenes (m/e 191, 163), steranes (m/e 217),... 

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