Bruker Esquire

High-performance liquid chromatography (HPLC) techniques are widely used for separation of phenolic compounds. Both reverse- and normal-phase HPLC methods have been used to separate and quantify PAs but have enjoyed only limited success. In reverse-phase HPLC, PAs smaller than trimers are well separated, while higher oligomers and polymers are co-eluted as a broad unresolved peak [8,13,37]. For our reverse-phase analyses, HPLC separation was achieved using a reverse phase. Cl8, 5 (Jtm 4.6 X 250 mm column (J. T. Baker, http //www.mallbaker.com/). Samples were eluted with a water/acetonitrile gradient, 95 5 to 30 70 in 65 min, at a flow rate of 0.8 mL/min. The water was adjusted with acetic acid to a final concentration of 0.1%. All mass spectra were acquired using a Bruker Esquire LC-MS equipped with an electrospray ionization source in the positive mode. 

The mass spectrometry portion of the analysis was carried out by coupling a Bruker Esquire ion-trap mass spectrometer to the LC-NMR system with a 20 1 splitter. The major portion of the flow was directed to the NMR system while the minor fraction went to the mass spectrometer. The system was plumbed such that the sample reached the mass spectrometer and the UV detector at the same time. In this configuration, it is possible to use the mass spectrometer as an intelligent detector, thus allowing stop-flow experiments to be initiated on the basis of observed molecular ions or daughter ion fragments. Data were acquired with electro-spray ionization (ESI) in the positive-ion mode. 

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...

If, however, the applied frequency corresponds to a lower qz, the ions will be ejected at a lower V value. Thus, for the same maximum V value, the highest ejectable mass will be higher. This is another way to increase the mass range. For example, the Bruker Esquire instrument allows ions at fi = 2/11 to be ejected, corresponding to qz = 0.25, which allows the mass range to be extended up to 6000 Th. 

An Agilent 3D CE coupled to a Bruker Esquire 3(X)(F quadrupole ion trap (QIT)-MS with a sulfobutylether-cyclodextrin-ammonium acetate separation buffer at pH 6.9 is used to analyze TNT, TNB, RDX, HMX, and CL-20 [199]. CE coupled to a mass spectrometer with ESI enables better resolution than LC separation and thus enhanced identification of moderate polarity nitra-mine explosives and their degradation products from soil and water samples. 

Bruker Esquire 3000 plus ion trap MS (scan from m/z = 200 to 1500,... 

Example I The positive-ion electtospray tandem mass spectrum of the [M+2ir ion of the P-casein tryptic phosphopeptide FQpSEEQQQTEDELQDK was obtained on a Bruker Esquire 3000 quadrupole ion trap (Fig. 9.21) [98]. Sequential amino acid residue losses from lx)th terminal ends of the peptide are labeled according to the b- and y-ion nomenclature. Due to the phosphoserine, the C- and N-terminal peptide ions (bs- bis and y - y ) exhibit an increase of 80 u in mass as compared to the unphosphorylated form. In addition, most ions are accompanied by the corresponding fragments from H3PO4 loss (98 u). 

The control of the hyphenated system, comprised of an Agilent 1100 HPLC, a Bruker Avance 600 MHz NMR spectrometer and a Bruker Daltonics Esquire ion-trap mass spectrometer, was achieved by using HYSTAR software from Bruker Analytik. Peaks were selected for analysis using both UV and mass detection and were stored in the Bruker BPSU-36 loop storage unit prior to NMR analysis. A schematic diagram of the system is shown in Figure 4.9. 

An ESI mass spectrometer equipped with a standard or a nanospray source and with the option for MSn may be used (Q-TOF, Ion Trap, etc.) as well as appropriate software. Ion Trap mass spectrometer (Esquire-LC, Bruker) equipped with a nanospray source was used. 

For ion traps interfaced to HPLC via ESI, external sources are absolutely essential because the electrospray process cannot be carried out inside the trap. The Thermo Finnigan LCQ series ion traps and the Bruker Daltonics Esquire are examples of such instruments. 

Mass spectra were recorded with the Esquire-LC 00084 and with MALDl-TOF MS Bruker Biflex IV. DSC and TGA measurements were carried out using a TA instruments DSC 2920. The DSC as well as the TGA measurements were performed at a sean rate of 5 K/min under nitrogen atmosphere. 

HPLC-ESI-MST Analyses were done on an Esquire Ion Trap LC-MS system (Bruker, Germany). Equipment and chromatographic conditions were the same as previously published 10,12). Alternatively, the sample solution was delivered directly by a syringe pump 74900 (Cole-Parmer, USA) into the ESI source at a flow rate of 300 pL/h. ESI-spectra were measured in positive mode. MS parameters dry gas N2, 4.0 L/min, dry temperature 300°C, nebulizer 10 psi, capillary -3500 V, end plate offset ... 

The FIA-MS system was controlled by a PC using Esquire Control 5.1 and HyStar 2.3 data evaluation was done with DataAnalysis 3.1 (all Bruker Dal-tonics, Bremen, Germany). 

Fig. 6. A comparison of the absorbance of fractions eluting off an HPLC column (UV/VIS) with the total molecular ion intensities of the fractions (TIC). Separation C-18 reverse phase colrnnn with 90 10 v/v water/acetonitrile (both containing 0.1% HAC) to 10 90 v/v over 20 min. Detection UV absorbance at 254 nm total ion coimts (TIC) with ESI source, m/z scanned 350-2000 in positive ion mode (Esquire LC/MS Ion Trap Mass Spectrometer/ Bruker)...

Electrospray (ESI) mass spectrometry was performed on an Esquire 3000+ ion trap spectrometer (Bruker Daltonik, Bremen, Germany) at the following conditions capillary temperature 250°C, nebulizer gas 20 psi (Ar), drying gas 9 L/min (N2), potential difference 4 kV (positive ion mode), end plate offset 500 V, skimmer 40 V, and capillary exit 136 V. The ion trap was locked on automatic gain control, and six microscans were collected for each full MS scan with a maximum accumulation time of 200 ms for each ion (Table 15.1). 

Several laboratories successfidly coupled the ESI source to a QIT mass spectrometer in the 1990s.Van Berkel, Ghsh, and McLuckey at Oak Ridge National Laboratory were the first to couple an ESI ion source to a QIT in 1990. In 1992, Mordehai and co-workers at Cornell University coupled their own ESI source to the first bench-top QIT (Saturn II , Varian Instruments, Palo Alto, CA, USA) for use in LC and CE studies. Bruker-Franzen of Germany also introduced an ESI/QIT instmment (ESQUIRE ) at that time. ThermoFisher Corporation introduced an ESI/QIT mass spectrometer (LCQ ) in 1995. In 2002, Hager at MDS Sciex described the first ESI LQIT system. ... 

FIGURE 10 Diagram of the Bruker orthogonal electrospray LC/MS interface. [Reprinted by permission from the Bruker-HP Esquire LC Operations Manual, Version 3.1.)... 

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