General purpose instrumentation

Like the QIT, ionization in the FT-ICR maybe performed either internally or externally to the cell. For several reasons, external ionization has become the technique of choice. External ionization allows the use of virtually any ionization method, and commercially available instruments are typically designed as general purpose instruments incorporating interchangeable ion sources. All three major suppliers of FT-ICR instruments (lonSpec, Bruker Daltonics, and Finnigan) offer external sources. 

While most HPLCs are general-purpose instruments, many are dedicated analysis systems packaged with specific columns and reagents. They often come with guaranteed performance from the vendor. Examples are systems for the analysis of amino acids (Figure 4.15c), carbamate pesticides, or sugars (see Chapter 7). 

Parker IntraFlow substrate fittings have been developed specifically for analytical, lab and other complex general purpose instrumentation flow control systems. ISA/ANSI SP76.00.02 compliant,... 

Hitachi Ltd. (Instrument Div., Shin Maru Bid. 5-1, Marunouchi Chiyoda-Ku, Tokyo, Japan 100). The company offers a laboratory instrument for serial assays of industrial samples in a single unit. The carrier stream is propelled by a piston pump, samples are aspirated into the injector by means of a peristaltic pump. A sophisticated 16-port valve allows combination of sample and reagent solutions to be introduced by the merging zone technique. General purpose instrument for industrial and environmental analysis. Detector systems have to be acquired separately. 

Of course, the electron-impact source cannot be used if nonvolatile inorganic samples such as metal alloys or ionic residues are to be analyzed. These substances can be investigated using a different kind of ionization chamber called a spark source, similar to the excitation sources used in emission spectroscopy (Chap. 11). The other parts of the spectrometer can be the same as a general-purpose instrument however, a Mattauch-Herzog double-focusing instrument is preferred (Fig. 16.7 below), because the spark source produces ions with a wide spread of kinetic energies. The entire device is known as a spark-source mass spectrometer (SSMS). 

GAO U.S. General Accounting Office GPIA general purpose instrumentation... 

For general purpose instruments (scenario 2), the most important parameters are resolution and accurate mass measurement for the identification and characterization of unknowns. Typical are MS/MS systems based on TOE or FT (orbitrap or ICR). The major categories here are TOF/TOF, QTOF, LT-TOF, LT-orbitrap, and LT-FT-ICR. For analytes of >1 kDa, TOF/TOF systems in combination with MALDI sources are straightforward and should be evaluated where multiple users are involved. QTOF, LT-TOF, and LT-orbitrap are all suited to LC operation at regular or nanoflow rates. The resolution of orbitraps is much higher (250,000) than that of TOF instruments (20,000 to 60,000), although available resolution on the former is subject to duty cycle limitations. Table 3.13 lists representative examples of the types of instruments one might consider for common applications. 

Table 3.4 compares detection limits with secondary fluorescers to the results with the RMF method and 15-kV broadband excitation [16,17]. Four different fluorescence analyzers were tested (units A, B, C, and D), and the results were corrected for differences in performance for the energy-dispersive spectrometers employed on each unit. Unit A used a chromium anode tube, and unit B used a tungsten anode tube. Unit A was a commercial, general-purpose instrument. Unit B was specifically designed for atmospheric aerosol analysis, where closer coupling between the tube, fluorescer, sample, and detector could be employed with some sacrifice of insensitivity to specimen-positioning errors. Table 3.5 lists the x-ray tube operating conditions required for Table 3.4. For medium- to high-atomic-number elements, the secondary fluorescer method provides detection limits equivalent to the RMF element, but requires much higher x-ray tube power. For light elements.

Figure 10.1 Details of general purpose instrument for GC determination of water and...

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