Suppression of matrix-related ions using cyclodextrin in MALDI mass spectrometry.

Anal Sci. 2008;24(11):1497-500.
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Suppression of matrix-related ions using cyclodextrin in MALDI mass spectrometry.

Yamaguchi S, Fujita T, Fujino T, Korenaga T.

Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.An effective technique for the suppression of matrix-related ions in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry have been developed. Using typical organic matrices such as THAP (2,4,6-trihydroxyacetophenone) and CHCA (alpha-cyano-4-hydroxycinnamic acid) in a cyclodextrin cavity, we successfully measured the mass peaks of only protonated matrix ions and significantly suppressed their intensities and fragmentation. In addition, it became possible to analyze the mass peak of the analyte molecules (substance P and adenosine) without any interference from the matrix. We believe that this technique could be a powerful tool for MALDI mass spectrometry, particularly for low-molecular-weight compounds.

Publication Types:
Research Support, Non-U.S. Gov't

PMID: 18997382 [PubMed - indexed for MEDLINE]

Flame Atomic Absorption Spectrometric Determination

Abstract
An atomic absorption spectrometric method for the determination of trace amounts of lead after
adsorption of its 1-(2-pyridylazo)-2-naphthol (PAN) complex on microcrystalline naphthalene
has been developed. This complex was adsorbed on microcrystalline naphthalene in the
pH range 8.4–11.5 from large volumes of aqueous solutions of various alloys and biological
samples. After filtration, the solid mass consisting of the complex and naphthalene was dissolved
with 5 ml of dimethylformamide and the metal was determined by flame atomic absorption
spectrometry. Lead was alternatively quantitatively adsorbed on
1-(2-pyridylazo)-2-naphthol-naphthalene adsorbent packed in a column and determined similarly. In this case, 0.5 g of lead was concentrated in a column from 500 ml of aqueous sample, where its concentration
was as low as 1.0 ng ml–1. Eight replicate determinations of 4.0 g ml–1 of lead gave a mean
absorbance of 0.200 with a relative standard deviation of 1.5 %. The sensitivity for 1 % absorption was 88 ng ml–1. The interference of a large number of anions and cations was studied
and the optimized conditions developed were utilized for the trace determination of lead in various standard samples.

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Flame Atomic Absorption Spectrometric Determination of Trace Lead

ANALYTICAL METHODS FOR DETERMINATION OF MAJOR, MINOR, AND TRACE ELEMENTS IN COAL

Summary

The analytical work performed on coal samples received in the U.S. Geological Survey laboratories is outlined in figure 1. An undried 600 g (about 1 qt) split of samples representative of the set collected is sent to the U.S. Bureau of Mines at Pittsburgh, Pa., for the routine coal analysis. This analysis sequence includes (1) proximate analysis (percent ash, moisture, fixed carbon, and volatile matter), (2) ultimate analysis (percent carbon, hydrogen, oxygen, nitrogen, and sulfur), (3) Btu determination, and (4) sulfur analysis (percent organic sulfur, pyrite sulfur, and sulfate sulfur). The analytical methods used by the Bureau of Mines have been described in U.S. Bureau of Mines Bulletin 638 (Staff Office of the Director of Coal Research 1967) and will not be described in this report. The remainder of all analytical work and sample preparation shown in the analysis sequence flow diagram (fig. 1) is performed by the U.S. Geological Survey laboratories.

Articles

Trace chemical analysis of high-purity glass

Summary
Trace-element impurities in high-purity silica (Corning Code 7940 fused silica and J. T. Baker Ultrex silicon dioxide), 96% silica glass (Corning Code 7913), borosilicate glasses (Corning Code 7740 and Owens-Illinois KG-33) and doped optical waveguide glass have been determined by spark-source mass-spectrometry, optical-emission spectrography, neutron-activation analysis, atomic-absorption and plasma emission spectrometry, spectrophotometry, voltammetry and chemical methods. Particular care was taken to prepare samples and carry out analyses in a clean environment with ultrapure reagents. In most cases some 30 elements as well as water were determined by two or more of the techniques indicated. The impurity level for many elements in the high-purity silica and optical waveguide glass is in the ng/g range and in themgrg/g range for the other glasses. Spark-source mass-spectrometry and neutron-activation analyses were carried out not only on samples prepared by a hydrofluoric acid dissolution-evaporation procedure but also on undissolved samples for volatile elements such as B, P, S, As and Hg. Results obtained are discussed with respect to application of the materials as well as to the analytical methods developed


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