Commercial instruments

The quadrupole ion trap traps ions in an electric field generally in the presence of a buffer gas (He). The theory and some of its uses have been discussed by March (26). Ion molecule reactions in ion traps have been reviewed (27). The quadrupole ion trap is a relatively new instrument commercialized <20 years ago and the new generation of instruments has only been available since 1995. Thus gas-phase inorganic chemistry using a quadrupole ion trap is as yet relatively hard to find, but on the increase. 

The volume of sample which can be applied to the resin column will vary for the different instruments commercially available. With progressive refinements in instrumentation the tendency has been towards a decreased sample volume, of 50 1 or less. Correct sample preparation is very important if reproducible results are to be obtained along with trouble-free operation. This will vary according to the nature of the sample and its constituents but the fluid... 

There are many barriers to and challenges for instrumentation commercialization. It seems that most often, the parties involved are working at crosspurposes. The (often academic) inventor is never satisfied and always wants to continue to improve his or her invention. The instrument company only wants to build and sell the product. They would also like to have planned obsolescence to guarantee future sales. The salesperson has to sell what he has now, while convincing the customer that it will meet all his needs. The customer wants a product that is inexpensive and will last forever. 

A. Simple COTS instrument (commercial Balance, pH meter, digital thermometer... 

Because this detector is found to be universal, have a broad dynamic range, good sensitivity, and a wide choice of carrier gases it is gaining in acceptance. Today there is an instrument commercially available (Figure 5.24)(40). In this detector, sound waves are propagated at one transducer and received at another,... 

If the thermal desorption unit is able to provide inverted (back-flush) gas flow during trap desorption (Figure 1.2), the same technique described for tubes can also be used for the cold trap. A multi-bed trap can considerably extend the analytical window of the instruments. Commercial cold-traps packed with quartz beads, quartz wool and Tenax TA are reported to cover a substance range from C6 to C40. 

There are a few liquid chromatography/Fourier transform infrared spectroscopy (LC/FT1R) instruments commercially available, but there are so far no published applications on the analysis of chemicals... 

The PatchXpress, the QPatch (Sophion Biosciences) and the Patchliner (Nanion Technologies) also use planar substrates, but recording from individual cells occurs in asynchronous fashion, limiting the throughput of these instruments. Commercially available instruments use 16-well or 48-well disposable cartridges. High-resistance seals between the cells and the substrate... 

Circular dichroism has been well understood and estabhshed in the ultra-violet, visible, near- and mid-infrared frequency range as an integral part of contemporary biophysics with numerous, excellent, turnkey instruments commercially available. However, there have been no documented measurements of terahertz circular dichroism. We have developed a simple physical model of circular dichroism in the terahertz frequency range, and build upon our broad band absorption spectrometer to explore the terahertz circular dichroism signatures of prototypical proteins in aqueous solutiom... 

Summarizing the results of our discussion of the practice of Fourier transform spectroscopy, we start with the presumption that the equipment for most routine spectroscopic investigations consists of a Fourier spectrometer with a Michelson interferometer and a digital computer. In other words, the advantages of the lamellar grating used as a two-beam interferometer, and of phase modulation, for example, have been utilized only for certain special applications in the extreme far-infrared. All commercial Fourier spectrometers are available with a computer attached, which in most cases not only performs the Fourier transform but is also programmed to control the instrument. Commercial instruments have a remote switch for the selection of the different spectral ranges, and the filters and beams... 

The instruments commercially available to perform mass spectrometry are a reflection of the technique itself, very diversified. No matter what their degree of complexity is, they are all composed of similar basic components that can be described as follows a sample introduction inlet, an ion source, a mass analyser, and a detector. 

In MAE and particularly PLE, few parameters have to be optimized. PLE instruments commercially available at present are more automated than MAE instruments, but also more expensive. Considering economical and practical aspects, the investment of MAE is lower but this technique requires manual operations, such as loading the solvent into the cell, and filtration or centrifugation to separate the extract from the matrix. The possibility to directly inject the extracts into chromatographic systems (on-line or off-line) makes SFE methods simple with less manual steps. On the other hand, SFE requires more experience to handle and is not that straightforward to operate as MAE and PLE. 

Virtually every optical Instrument commercially available at present accommodates a microprocessor which, through a small keyboard, allows the user to select the different instrumental variables and programming the Instrument s functioning during the analyses. More recent and sophisticated Instruments have no keyboard and are controlled via a screen on which the working modes and parameters are selected by means of a mouse . 

The automated ISE-based (glass and valinomycin) instruments commercially available for the determination of sodium and potassium compete advantageously with flame photometers for the same purpose. Representative examples of this type of potentlometrlc Instrument are the KNAI sodium-potassium analyser from Radiometer, the Electrolyte II (In semi- and fully automatic versions) from Beckman and the Nova 1 from Biomedical Laboratories. 

Table I gives a summary of the instrumentation commercially available for re-fractometric HPLC detection.

This list is not inclusive or comprehensive, but is meant to give the student a feeling for the types of instruments commercially available at the present time. Typical detection limits for elements determined by ICP emission spectrometry can be found in Appendix... 

It would be possible to scan the RF and measure the magnimde of the image current at each m/z value to obtain the mass spectral information but the process would be very slow. Instead, an RF pulse is used that contains a range of frequencies. The range of frequencies is chosen to excite the desired m/z range. When the pulse is off, all of the exited ions induce image currents in the receiver plates as they rotate. The output current, which contains all of the frequency and magnitude information from all of the ions present can be converted mathematically to a mass spectmm by application of the Fourier transform (FT). The use of an ICR ion trap and Fourier transformation is called Fourier transform ion-cyclotron resonance mass spectrometry (FTICRMS) or just FTMS. As of early 2003, this was the only type of FTMS instrument commercially available. 

The majority of CE instruments commercially available today are equipped with UV—visible absorbance detectors because of their wide range of... 

Providing lists of commercial manufacturers and types of instruments is a dangerous business, as instrument company takeovers, sell-offs, and the usual yearly introduction of new instruments, sometimes with only minor changes but with new names, occur on a frequent basis. The instrument company websites should be consulted for current details. There are also many companies who manufacturer instruments with limited geographic distribution who are not included in the discussion. This list is not inclusive or comprehensive, but is meant to give the student a feeling for the types of instruments commercially available at the present time. 

A relative newcomer to the atomic emission instruments commercially available, LIBS has some significant advantages over the other emission techniques and over ICP-MS and XRF. It is virtually nondestructive and often can be used with no sample preparation. It has the ability to detect all of the elements in virtually any sample type. Versions are available that are field-portable, and versions are available for remote/standoff analysis. Instrumentation is relatively inexpensive. The major disadvantage is the lack of LIBS spectral libraries for easy fingerprint matching, but that is being remedied as the instrumentation becomes more common. 

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