Inductively coupled plasma mass interface system

A novel interface to connect a ce system with an inductively coupled plasma mass spectrometric (icpms) detector has been developed (88). The interface was built using a direct injection nebulizer (din) system. The ce/din/icpms system was evaluated using samples containing selected alkah, alkaline earths, and heavy-metal ions, as well as selenium (Se(IV) and Se(VI)), and various inorganic and organic arsenic species. The preliminary results show that the system can be used to determine metal species at ppt to ppb level. 

To optimize the applicability of the electrothermal vaporization technique, the most critical requirement is the design of the sample transport mechanism. The sample must be fully vaporized without any decomposition, after desolvation and matrix degradation, and transferred into the plasma. Condensation on the vessel walls or tubing must be avoided and the flow must be slow enough for elements to be atomized efficiently in the plasma itself. A commercial electrothermal vaporizer should provide flexibility and allow the necessary sample pretreatment to introduce a clean sample into the plasma. Several commercial systems are now available, primarily for the newer technique of inductively coupled plasma mass spectroscopy. These are often extremely expensive, so home built or cheaper systems may initially seem attractive. However, the cost of any software and hardware interfacing to couple to the existing instrument should not be underestimated. 

This experiment presents the measurement of uranium with an inductively coupled plasma mass spectrometer (ICP-MS). In this system, a nebulizer converts the aqueous sample to an aerosol carried with argon gas. A torch heats the aerosol to vaporize and atomize the contents in quartz tubes. The atoms are ionized with an efficiency of about 95% by an RF (radiofrequency) coil. The plasma expands at a differentially-pumped air-vacuum interface into a vacuum chamber. The positive ions are focused and injected into the MS while the rest of the gas is removed by the pump. The ions are then accelerated, collected, and measured as a function of their mass. Losses at various stages, notably the vacuum interface, result in a detection efficiency of about 0.1 %, which is still sufficient to provide great sensitivity. The amounts of uranium isotopes in the sample are determined by comparisons to standards. Because different laboratories have different instruments, the instructor will provide instrument operating instmctions. Do not use the instrument until the instructor has checked the instrument and approved its use. 

J.-H. Wang, E.H. Hansen, Interfacing sequential injection on-line preconcentration using a renewable micro-column incorporated in a Tab-on-valve system with direct injection nebulization inductively coupled plasma mass spectrometry, J. Anal. At. Spectrom. 16 (2001) 1349. 

Mass Spectrometric Detection. The very small volumetric flow rates of less than 1 pi,/min from electrophoresis capillaries make it feasible to couple the effluent directly to the Ionization source of a mass spectrometer. The most common sample-introduction and ionization interface for this purpose is currently electrospray (Section 20B-4), although fast atom bombardment, matrix-assisted laser desorption-ionization (MALDI) spectrometry, and inductively coupled plasma mass spectrometry (ICPMS) have also been used. Because the liquid sample must be vaporized before entering the mass spectrometry (MS) system. 

Forthcoming books in the Techniques in Analytical Chemistry Series will cover a variety of techniques including chemometric methods, biosensors, surface and interface analysis, measurements in biological systems, inductively coupled plasma-mass spectrometry, gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, and other significant topics. The editors welcome your comments and suggestions regarding current and future titles, and hope you find the series useful. 

In recent years, a remarkable trend can be observed i.e. the utilization of inductively coupled plasma-mass spectrometry (ICP-MS) as an attractive complement for protein quantification. If the heteroatom-containing proteins are known and the standards are available, the absolute quantification of proteins can be easily obtained via element analysis by ICP-MS. However, when ICP-MS is interfaced to a separation system, such as HPLC, the organic solution and inorganic salts introduced into ICP-MS usually decrease the instrumental stability and detection limits. To overcome the problems, isotope dilution analysis is introduced to an ICP-MS-based linked system. ... 

Kumagai, H.,Yamanaka, M., Sakai,T., andYokoyama.T. (1998). Determination of trace metals in sea-water by inductively coupled plasma mass spectrometry interfaced with an ion chromatographic separation system Effectiveness of nitrilotriacetate chelating resin as the column stationary phase for preconcentration and elimination of matrix effects. Anal. At. Spectrom. 13(6), 579. 

McLaren, J.W., Lam,J. W., and Gustavsson, A. (1990). Evaluation of a membrane interface sample introduction system for inductively coupled plasma mass spectrometry. Spec-trochim.Acta, Part B 45(9), 1091. 

Although originally FIA was conceived as a special technique for delivery of a sample segment into the instrument, the combination of flow injection as a sample pretreatment tool with atomic spectrometry has been shown to be of great potential for enhancing the selectivity and sensitivity of the measurements. Moreover, contamination problems are reduced due to the closed system used, making this interface suitable for ultratrace determination of metal species. Hyphenated techniques such as FIA/ SIA with flame atomic absorption spectrometry, inductively coupled plasma (ICP)-optical emission spectrometry, and ICP-mass spectrometry (MS) have been exploited extensively in recent years. The major attraction of FIA-ICP-MS is its exceptional multi-elemental sensitivity combined with high speed of analysis. In addition, the possibility of... 

Luminescence molecular detectors have also been used for online monitoring of dissolution tests and the characterization of toxic residues using bioluminescence assays. Atomic (atomic absorption spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES)) detectors have been coupled to robotic stations either through a continuous system acting as interface or by direct aspiration into an instrument from a sample vial following treatment by the robot. Mass spectrometric and nuclear magnetic resonance (NMR) detectors... 

The MC-ICP-MS consists of four main parts 1) a sample introduction system that inlets the sample into the instrument as either a liquid (most common), gas, or solid (e.g., laser ablation), 2) an inductively coupled Ar plasma in which the sample is evaporated, vaporized, atomized, and ionized, 3) an ion transfer mechanism (the mass spectrometer interface) that separates the atmospheric pressure of the plasma from the vacuum of the analyzer, and 4) a mass analyzer that deals with the ion kinetic energy spread and produces a mass spectrum with flat topped peaks suitable for isotope ratio measurements. 

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