Sector field analyzers spectrometers

A Thermo Finnigan Element 2 Inductively Coupled Plasma Sector-Field Mass Spectrometer (ICP-SF-MS) with guard electrode was employed for trace element analyses. RSD values derived from internal check standard never exceeded 10%. Accuracy was better than 15% for all elements as determined by analyzing the certified reference standard NWRI TM-RAIN 95 trace metal fortified rainwater, every 5 to 8 samples. 

The ions formed are extracted by the extraction lens, EL, perpendicular to the electron beam. Due to the low energy spread of ions formed in an electron ionization source (< 1 eV) one single-focusing magnetic sector field mass spectrometer or quadrupole analyzer is sufficient for... 

Sector field analyzers are magnetic or electric sector fields or a combination of the two with ion focusing and separation properties used in static mass spectrometers. 

At present GDMS164 165 is one of the most powerful solid-state analytical methods for the direct determination of trace impurities and depth profiling of solids. The positively charged ions formed in the low pressure argon plasma of the glow discharge are extracted and accelerated into the double-focusing sector field mass spectrometer, quadrupole, ion trap or ToF mass analyzer. 

Elemental analysis by mass spectrometiy was performed using a Perkin-Elmer Sciex ELAN 6000 Inductively Coupled Plasma—Mass Spectrometer (ICP-MS) and a ThermoFinnigan Element 2 Inductively Coupled Plasma Sector Field Mass Spectrometer. The iron oxide colored fibers (Table III, 16, 17) were weighed into the following aliquots (1) 1 mg rabbit hair (RH), (2) 5 mg RH, (3) 1 mg of milkweed (MW), (4) 5 mg MW and (5) a mixture of 2.5 mg RH and MW each. These samples were combined with concentrated nitric acid. Wanning the mixture to just below boiling temperature for 5 to 7 minutes did not result in total digestion. Hence, the incubation time in the water bath was increased to 30 minutes. Afterward, these samples were analyzed in the spectrometer. 

An even more powerful way to cope with spectral overlap is the use of an ICPMS instrument equipped with a double-focusing sector field mass spectrometer (inductively coupled plasma sector field mass spectrometry, ICP-SF-MS) instead of a quadrupole filter. By operating such a mass analyzer at higher mass resolution, the signal of analyte and interfering ions can be resolved in the majority of cases [33,34]. 

As in inductively coupled plasma optical emission (ICP-OES) spectra, in addition to atomic lines, intense ionic lines are also observed, the use of an ICP as an ion source for MS seemed logical, but overcoming the difference in pressure between the ICP (generated at atmospheric pressure) and the mass spectrometer (10 —10 mbar) proved difficult and had to be accomplished via the use of a two-cone interface. Despite the advantages that double-focusing sector field mass spectrometers (higher mass resolution) and TOP analyzers (high data acquisition speed) can offer, approximately 90% of the ICP-MS units used worldwide are equipped with a quadrupole filter for mass analysis. 

The first protein quantification based on sulfur monitoring and species-unspecific isotope dilution was carried out by Schaumloffel et al. using a CE unit coupled to a sector field mass spectrometer operated at a mass resolution of 3000 and aimed at analyzing metallothionein fractions of a rabbit liver [110]. 

By analyzing a solution of three standard proteins (lysozyme, ovalbumin, and bovine serum albumin), and also two certified protein reference materials (BCR CRM 393 human apolipoprotein A-1 and BCR CRM 486 a-fetoprotein), the accuracy but also possible limitations of absolute protein quantification via species-unspecific isotope dilution were demonstrated. A micro-HPLC system coupled to a sector field mass spectrometer, operated at a mass resolution of... 

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