Multiple sector analysers

ABSTRACT Analysis of accident reports has been a useful tool in occupational safety research. Important variables related to main circumstances of accidents are being gathered in Europe according to European Statistics on Accidents at Work framework (ESAW). This paper present a method for the identification of possible public safety programs based on the application of Multiple Correspondence Analyses (MCA) and the introduction of the concepts of task and accident mechanism. The method is presented using the accidents notified in the manufacturing sector of Andalusia. This method can help policy makers in the identification of areas of public intervention. 

Instruments that incorporate two or three mass analysers in a series have been developed to study ion fragmentation. Several of the same type of mass analyser can constitute a tandem mass spectrometer, or they can be constructed using different mass analysers (hybrids). Hybrid spectrometers include the combination of magnetic sector followed by quadrupole, multiple quadrupole, quadrupole TOF, etc. In these instruments, a collision cell is placed between each analyser (Fig. 16.23). Tandem instruments have different scanning modes. 

TIMS analysis was performed on a fully automated VG Sector 54 mass spectrometer with eight adjustable faraday cups and a Daly ion-counting photomultiplier system. Analysis was performed in static mode. Each sample was analyzed 50 times to ensure acceptable precision. The TIMS analysis was standardized by use of the NIST SRM981 common lead standard. Multiple analyses of the SRM981 standard were used to determine a fractionation correction of 0.12% per amu and an overall error 0.06% per amu. Errors between runs of the same sample were below 0.01% per amu. This level of precision is comparable to the archaeometry database for lead isotopes (8). 

Fig. 5 Statistical evaluation of LC-MS-based methods for tropane alkaloids referred in this chapter. (a) Relative frequency of ionization methods. +APCI positive atmospheric pressure chemical ionization, +ESI positive electrospray ionization, FAB fast atom bombardment, +TSP positive thermospray, (b) Relative frequency of scan modes used. MS full scan MS, MS/MS tandem mass spectrometry (product ion scan), MRM multiple reaction monitoring, SIM selected ion monitoring, (c) Relative frequency of mass analysers used. EBQtQ2 double focusing sector field mass spectrometer, IT ion trap, QqQ triple quadrupole, SQ single quadrupole. Considered publications were found by PubMed data-based search and references cited in these articles...

The modern TIMS instrument consists of an ion-source chamber, flight-tube, sector magnet, and ion-collector chamber. Depending upon the manufacturer and age of the instrument as many as 20 samples can be mounted together in the ion-source chamber and analysed sequentially. The ion-collector chamber may include an array of up to 9 multiple Faraday collectors as well as secondary electron amplification devices allowing ion currents from 1 x 10 A to less than 1 X 10 A to be measured. Since these instruments are designed to measure isotope abundance ratios with high accuracy and precision, the mass spectrum is well-resolved and the spectral peaks are broad with flat tops. 

B, Li, Cl, Cu, and Fe isotope analyses have been carried out by a variety of gas-source and solid-source isotope ratio mass spectrometry techniques and, more recently, by plasma-source magnetic-sector multiple-collector mass spectrometry. The reader is referred to the cited references for specifics. 

The potential of the most commonly used mass spectrometers (quadrupoles and magnetic sector-field single collectors) for elemental analysis has been discussed in detail in Parts 2.1 and 2.2.1 of this chapter. However, some intrinsic limitations still remain with these sequentially scanned systems, particularly when transient or time-dependent signals (such as those produced by laser ablation (LA), electrothermal vaporisation (ETV), flow injection (FI) and chromatography) are used to analyse a large number of isotopes. These scan-based systems can measure only a single m/z at a unit of time. Hence, truly simultaneous determination of multiple isotopes, particularly when fast transient signals are analysed, is not possible without the introduction of spectral skew . ... 

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