Filter tandem

A triple quadrupole instrument (QqQ) is a combination of two mass quadrupole mass filters (tandem mass spectrometry) separated by a collision cell which is also a quadrupole operating in RE-only mode (Pig. 1.18). A common nomencla-... 

A single magnetic sector can be used as a mass filter for other apparatus. However, much more infonnation of the simple mass spectrum of a species can be obtained using the tandem mass spectrometer. 

Another approach to mass analysis is based on stable ion trajectories in quadnipole fields. The two most prominent members of this family of mass spectrometers are the quadnipole mass filter and the quadnipole ion trap. Quadnipole mass filters are one of the most connnon mass spectrometers, being extensively used as detectors in analytical instnunents, especially gas clnomatographs. The quadnipole ion trap (which also goes by the name quadnipole ion store, QUISTOR , Paul trap, or just ion trap) is fairly new to the physical chemistry laboratory. Its early development was due to its use as an inexpensive alternative to tandem magnetic sector and quadnipole filter instnunents for analytical analysis. It has, however, staned to be used more in die chemical physics and physical chemistry domains, and so it will be described in some detail in this section. 

Aside from the smgle mass filter, the most connnon configuration for quadnipole mass spectrometers is the triple-quadnipole instrument. This is the simplest tandem mass spectrometer using quadnipole mass filters. Typically, the... 

Filters have a time constant r = R x C which increases the damping of the measuring instrument. The time constant depends on the required attenuation and the interfering frequency, but not on the internal resistance of the measuring instrument. The time constants of the shielding filter are in the same range as those of the electrochemical polarization, so that errors in the off potential are increased. Since the time constants of attenuation filters connected in tandem are added, but the attenuation factors are multiplied, it is better to have several small filters connected in series rather than one large filter. 

A second sampling program in Southern California sampled for polychlorinated dioxins and polychlorinated dibenzofurans at seven locations (9). Because of the semivolatile nature of these compounds, a tandem sampler was used with a glass fiber filter to collect the particulate-associated compo-... 

Different mass analysers can be combined with the electrospray ionization source to effect analysis. These include magnetic sector analysers, quadrupole filter (Q), quadrupole ion trap (QIT), time of flight (TOF), and more recently the Fourrier transform ion cyclotron resonance (FTICR) mass analysers. Tandem mass spectrometry can also be effected by combining one or more mass analysers in tandem, as in a triple quadrupole or a QTOF. The first analyzer is usually used as a mass filter to select parent ions that can be fragmented and analyzed by subsequent analysers. 

The instrumental analysis for the identification of UV filters degradation products formed during the fungal treatment process was performed by means of HPLC coupled to tandem mass spectrometry using a hybrid quadrupole-time-of-flight mass spectrometer (HPLC-QqTOF-MS/MS). Chromatographic separation was achieved on a Hibar Purospher STAR HR R-18 ec. (50 mm x 2.0 mm, 5 pm, from Merck). In the optimized method, the mobile phase consisted of a mixture of HPLC grade water and acetonitrile, both with 0.15% formic acid. The injection volume was set to 10 pL and the mobile phase flow-rate to 0.3 mL/min. 

In tandem-based AMS systems, analysis on both low and high energy sides is typically performed by coupling al least two of the described filters. The reason can be easily understood by looking at Figure 16.2, where the loci of values of j vs as determined by different beam analysers are represented. 

Fig. 11.16. Representation of three tandem mass spectrometry (MS/MS) scan modes illustrated for a triple quadrupole instrument configuration. The top panel shows the attributes of the popular and prevalent product ion CID experiment. The first mass filter is held at a constant m/z value transmitting only ions of a single mlz value into the collision region. Conversion of a portion of translational energy into internal energy in the collision event results in excitation of the mass-selected ions, followed by unimolecular dissociation. The spectrum of product ions is recorded by scanning the second mass filter (commonly referred to as Q3 ). The center panel illustrates the precursor ion CID experiment. Ions of all mlz values are transmitted sequentially into the collision region as the first analyzer (Ql) is scanned. Only dissociation processes that generate product ions of a specific mlz ratio are transmitted by Q3 to the detector. The lower panel shows the constant neutral loss CID experiment. Both mass analyzers are scanned simultaneously, at the same rate, and at a constant mlz offset. The mlz offset is selected on the basis of known neutral elimination products (e.g., H20, NH3, CH3COOH, etc.) that may be particularly diagnostic of one or more compound classes that may be present in a sample mixture. The utility of the two compound class-specific scans (precursor ion and neutral loss) is illustrated in Fig. 11.17.

Gas chromatography coupled to tandem mass spectrometry (GC-MS/MS [49]) prior to analysis of the three primary active components of cannabis (THC, cannabidiol and cannabinol) by this technique, airborne particulates were extracted in an ultrasonic bath with chloroform. The extracts were combined and concentrated under a stream of nitrogen. The residue was filtered through pre-washed disposable PTFE membranes, dried and finally reconstituted with cyclohexane. After separation and solvent partitioning, the extracts were analysed by GC-MS/MS. 

DehnuUe, B., De Saeger, S., Adams, A., De Kimpe, N., and Van Peteghem, C., Development of a hquid chromatography/tandem mass spectrometry method for the simultaneous determination of 16 myco-toxins on cellulose filters and in fungal cultures, Rapid Communications in Mass Spectrometry 20(5), 771-776, 2006. 

FDA Guidance The specific bulk product solution filtration processes, including tandem filter units, prefilters, and bacterial retentive filters, should be described. A summary should be provided containing information and data concerning the validation of the retention of microbes and compatibility of the filter used for the specific product. Any effects of the filter on the product formulation should be described (e.g., adsorption of preservatives or active drug substance, or extractable). 

Ito T, van Kuilenburg ABP, Bootsma AH, Haasnoot AJ, van Cruchten AG, Wada Y, van Gen-nip AH (2000) Rapid screening of high-risk patients for disorders of purine and pyrimidine metabolism using HPLC-electrospray tandem mass spectrometry of liquid urine or urine-soaked filter paper strips. Clin Chem 46 445-452... 

Van Kuilenburg ABP, van Lenthe, Loffler M, van Gennip AH (2004) Analysis of pyrimidine synthesis de novo intermediates in urine and dried urine filter paper strips with HPLC-elec-trospray tandem mass spectrometry. Clin Chem 50 2117-2124... 

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