LC ion traps

Figure 6.16 Stop-flow NMR spectra of the hydrolysis products of Remazol Black 5 acquired an LC-NMR-MS run 95% of the eluent was transfered to the NMR spectrometer and 5% t° the mass spectrometer. Equipment NMR spectrometer, Bruker DRX 600 probe head, 4 mm z-gradient LC probe between 256 and 1024 scans were acquired mass spectrometer, bruker Esquire-LC ion-trap machine, equipped with an ESI ionization source...

C. Blasco, G. Font, Y. Pic6, Analysis of pesticides in fruits by pressurized liquid extraction and LC-ion trap-triple stage MS, J. Chromatogr. A, 1098 (2005) 37. 

G.J. Dear, J. Ayrton, R. Plumb, I.J. Fraser, Rapid identification of drug metabolites using capillary LC-ion-trap MS, Rapid Commun. Mass Spectrom., 13 (1999) 456. 

U. Berger, M. Oehme, F. Kuhn, Quantitative determination and structure elucidation of type A- and B-trichothecenes by LC-ion trap MS", J. Agric. Food Chem., 47 (1999) 4240. 

G.C. Kite, E.A. Porter, F.C. Denison, R.J. Grayer, N.C. Veitch, I. Butler, M.S.J. Simmonds, Data-directed scan sequence for the general assignment of C-glycosylflavone 0-glycosides in plant extracts by LC ion trap MS, J. Chromatogr. A, 1104 (2006) 123. 

H.B. Xiao, M. Krucker, K. Putzbach, K. Albert, Capillary LC-microcoil H NMR and LC-ion trap-MS for on-line structure elucidation of isoflavones in Radix astragali, J. Chromatogr. A, 1067 (2005) 135. 

LC-ion trap MS was also used for the targeted analysis of the glucosinolates present in Brassica sprouts via extraction of the m/z 259 ion, and this is displayed in Figure 11. 

Plasma and serum are biological samples commonly collected from subjects in clinical studies for basic research. Tiller et al. (1997) spiked plasma extracts with T, hydrocortisone, a corticosteroid (not an anabolic steroid), and SR 27417, a platelet-activating factor, to prepare a calibration curve with nine concentrations for analysis by LC-ion trap MS. For T, the best ions for quantitation were deemed to be mIz 91, 109 and 253. The authors found the full-scan mode helpful in identifying the best ions for quantitation and matrix contaminants. 

Gedamke R, Zhao W, Gozo S, Mitroka J, Zhu M. A sensitive method for plasma metabolite identification using nano LC/ion trap MS in conjunction with a microplate scintillation counter. ASMS Archive Abstract 2003. 

Wuhloud, J.C.A., S.R. Gratz, B.M. Gamble, and K.A. Wobuk. 2004. Simultaneous analysis of hepatotoxic pyrrolizidine alkaloids and N-oxides in cornfrey root by LC-ion trap mass spectrometry. Analyst 129(2) 150-156. 

Benijts, T., Lambert, W., and De Leenheer, A. (2004) Analysis of multiple endocrine disrupters in environmental waters via wide-spectrum solid-phase extraction and dual-polarity ionisation LC-ion trap MS/MS. Analytical Chemistry 76, 704-711. 

Dilution "dilute and shoot" Ease, speed, cost, potential for automation Requires relatively clean matrix (i.e., urine) and analyte that requires no preconcentration Urine drug screen by LC— ion- trap MS [2]... 

One example of normal-phase liquid chromatography coupled to gas chromatography is the determination of alkylated, oxygenated and nitrated polycyclic aromatic compounds (PACs) in urban air particulate extracts (97). Since such extracts are very complex, LC-GC is the best possible separation technique. A quartz microfibre filter retains the particulate material and supercritical fluid extraction (SPE) with CO2 and a toluene modifier extracts the organic components from the dust particles. The final extract is then dissolved in -hexane and analysed by NPLC. The transfer at 100 p.1 min of different fractions to the GC system by an on-column interface enabled many PACs to be detected by an ion-trap detector. A flame ionization detector (PID) and a 350 p.1 loop interface was used to quantify the identified compounds. The experimental conditions employed are shown in Table 13.2. 

Batt AL, Aga DS (2005) Simultaneous analysis of multiple-classes of antibiotics by ion trap LC/MS/MS for assessing surface water and groundwater contamination. Anal Chem 77 2940-2947... 

A further extension of the DFG S19 method was achieved when polar analytes and those unsuitable for GC were determined by LC/MS or more preferably by liquid chromatography/tandem mass spectrometry (LC/MS/MS). Triple-quadrupole MS/MS and ion trap MS" have become more affordable and acceptable in the recent past. These techniques provide multiple analyte methods by employing modes such as time segments, scan events or multiple injections. By improving the selectivity and sensitivity of detection after HPLC separation, the DFG S19 extraction and cleanup scheme can be applied to polar or high molecular weight analytes, and cleanup steps such as Si02 fractionation or even GPC become unnecessary. 

A triple-quadrupole mass spectrometer with an electrospray interface is recommended for achieving the best sensitivity and selectivity in the quantitative determination of sulfonylurea herbicides. Ion trap mass spectrometers may also be used, but reduced sensitivity may be observed, in addition to more severe matrix suppression due to the increased need for sample concentration or to the space charge effect. Also, we have observed that two parent to daughter transitions cannot be obtained for some of the sulfonylurea compounds when ion traps are used in the MS/MS mode. Most electrospray LC/MS and LC/MS/MS analyses of sulfonylureas have been done in the positive ion mode with acidic HPLC mobile phases. The formation of (M - - H)+ ions in solution and in the gas phase under these conditions is favorable, and fragmentation or formation of undesirable adducts can easily be minimized. Owing to the acid-base nature of these molecules, negative ionization can also be used, with the formation of (M - H) ions at mobile phase pH values of approximately 5-7, but the sensitivity is often reduced as compared with the positive ion mode. 

As with GC/MS, LC/MS offers the possibility of unequivocal confirmation of analyte identity and accurate quantiation. Similarly, both quadrupole and ion-trap instruments are commercially available. However, the responses of different analytes are extremely dependent on the type of interface used to remove the mobile phase and to introduce the target analytes into the mass spectrometer. For pesticide residue analyses, the most popular interfaces are electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). Both negative and positive ionization can be used as applicable to produce characteristically abundant ions. 

LC/MS systems. Agilent 1100 Series HPLC system connected to a Thermoquest-Finnigan LCQ ion-trap mass spectrometer using an ESI interface at atmospheric pressure. 

Figure 7.32 shows the identification of an oxidation product of Irganox 1330 by means of APCI-MS. LC-APCI-MS/MS (high-resolution sector field-ion trap hybrid) has also been used for the analysis (elemental composition and structure) of Irganox PS 802 [636]. 

On-line NPLC-GC-FID and/or FUR analysis has been used in discriminating between paraffin waxes and paraffin oils present in, or migrating between, food packaging and food simulants FID was used for quantitation [967]. In a typical application, online coupled LC-GC-F1D has also been used for the analysis of food contamination by mineral oil from printed cardboard [968]. The technique has revealed that many foods are contaminated with mineral oil products. Grob et al. [969] have determined mineral oil in canned food by on-line LC-LC-GC-F1D. DEHP was determined in salad oil by means of conventional LC-GC [970]. HPLC-GC-MS/MS (ion trap) can serve highly useful purposes in areas of applications such as impurity... 

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