Background: An inductively coupled plasma mass spectrometry (ICP-MS)-based immunoassay has been proposedindependently by Baranov et al. (Anal Chem2002; 74: 1629-36) and our group, but the applicability ofthis method for multianalyte analysis in clinical sampleshas not been fully illustrated. We developed adual-label immunoassay method for the simultaneousdetermination of β-fetoprotein (AFP) and free β-humanchorionic gonadotropin (hCGβ) in human serum.Methods: Monoclonal antibodies immobilized on microtiterplates captured AFP and hCGβ, which weredetected by use of Eu3+-labeled anti-AFP and Sm3+-labeled anti-hCGβmonoclonal antibodies. Eu3+andSm3+were dissociated from the immunocomplex withHNO3 solution (10mL/L) and delivered by peristalticpump to the ICP mass spectrometer.Results: The measurable ranges of AFP and hCG+were4.6-500 and 5.0-170 ug/L, respectively, with detectionlimits of 1.2 and 1.7ug/L (3SD above mean of zerocalibrator), respectively. The intraassay imprecision (CV) for AFP was 8.3%, 4.0%, and 2.7% at 16.3, 86, and 354ug/L, respectively, and the interassay CV was 10%, 5.7%, and 3.5%. For hCGβ, the intraassay CV was 5.4%, 6.4%, and 3.1%, respectively, at 10.5, 45.2, and 105ug/L, and the interassay CV was 7.2%, 8.0%, and 3.7%. Comparisonwith IRMAs for AFP and hCGβyielded correlationcoefficients (r2) of 0.97 and 0.95.Conclusions: Two proteins can be measured simultaneouslyby immunoassays using two rare earth elementaltags (Eu3+and Sm3+) and ICP-MS detection. Themultielement capability and the multiple potential elementallabels make ICP-MS attractive for multianalyteimmunoassays. Implementation of ICP-MS-linked immunoassaysmay be relatively straightforward becausethe labeling and immunoreaction procedures have beenwell developed for clinical time-resolved immunofluorometricassays.

A study was carried out to determine arsenic species in Porphyra seaweed originating from the ChinaSea. Information about arsenic species in Porphyra was provided by HPLC-ICP-MS and ES-MSMS.The total arsenic concentrations of Porphyra samples from five different producing areas rangedfrom 2.1 to 21.6mg/kg. The analysis report also showed that arsenosugars were the only arsenicspecies that could be detected in all of the extracts of samples. Arsenosugar PO4 was the majorcompound in most samples (0.3-13.9mg/kg of dry weight), followed by arsenosugar OH (0.7-6.2mg/kg of dry weight). A further experiment was done to investigate the stability of arsenosugars inthe process of being heated. It was observed that the arsenosugars were stable during a short-termheating at 100℃. Their stability in human ingestion was also studied. A substantial increase ofdimethylarsinic acid (DMA) was detected in urine samples collected from six volunteers after theconsumption of this seaweed. The results obtained indicated that arsenosugars had been metabolizedto DMA, which is more toxic than arsenosugars. From this point of view, consumers should considerthe possible adverse effects of edible Porphyra on human health and choose those Porphyra havinglower arsenic concentrations.

To further expand the range of analytes that can be detected by using ICP-MS coupled with bioanalytical methods, we have employed a new separation system based on the highly active surface streptavidin and biotinylated monoclonal antibody (McAb) in a competitive immunoassay followed by ICP-MS detection. Specifically, we have demonstrated its application for the determination of total thyroxine (T4) in human serum using Eu31 as a label. In this method, streptavidin immobilized to the pre-coated bovine serum albumin (BSA)-biotin on the microwells showed a significantly higher binding capacity for the biotinylated anti-T4 monoclonal antibody. Total T4 was quantified by measuring the Eu31 intensity with ICP-MS after using 1% HNO3 to extract Eu31 from the bound fraction of the immunocomplex. The detection limit was 7.4ng mL-1 with a sample volume of 25

A gas-sensing mode based on chemiluminescence generatedon the surface of nanosized materials is proposed inthe present work. Seven nanosized materials were tested, and chemiluminescence was detected from six of themduring the catalytic oxidation of organic vapors in air. The luminescence characteristics of ethanol and acetonevapors passing through the surface of TiO2 chosen werestudied with a chemiluminescence-based detection system.The linear range of chemiluminescence intensityversus concentration of organic compounds is 40-400µg/mL for ethanol and 20-200µg/mL for acetone dissolvedin water, respectively. X-ray powder diffraction andRaman spectrometry were used to investigate the changesin catalytic activity of TiO2 after a 60-h reaction at 380℃. The results showed that the carbon deposited on thesurface of TiO2, decreasing the catalytic activity, but canbe removed in air by controlling the temperature at 500℃ for 3h. Regenerability and no consumption of sensorsubstrate signify the long lifetime of the gas sensor.

This paper describes a novel aerosol chemiluminescencebaseddetector, which can be coupled to liquid chromatographyfor the determination of the chemicals with weakoptical absorbance in the UV-visible region. This aerosolchemiluminescence (CL)-based detector, in which HPLCeffluent is converted to aerosol and then generated CLemission on the surface of porous alumina, is composedof three main processes: nebuliztion of HPLC effluent, CL emission on surface of porous alumina material, andoptical detection. To demonstrate the utility of the aerosolchemiluminescence detector, some compounds such saccharides, poly (ethylene glycol)s, amino acids, and steroidpharmaceuticals are determined by the present aerosolchemiluminescence detection method. Compared with anevaporative light scattering detector, the proposed detectorshows the following features: (a) extensive CL emissionson porous alumina by many compounds tested, which leads to the potential application for the determinationof volatile and nonvolatile chemicals with or withoutUV-visible absorbance; (b) a CL mechanism based on thecatalytic oxidation of analytes, not on the light scattering,which suggests the present detector be free from theinterference of the inorganic and nonvolatile mobile-phasemodifiers. The CL characteristics and effect of differentparameters, such as temperature and nebulizer gas flowrate, were also discussed in this paper. Furthermore, thisaerosol chemiluminescence-based detector was successfullyapplied to the determination of raffinose, glucose,sucrose, maltose, and r-lactose.