Study On Determination Of Sulfur Using Inductively Coupled Plasma Mass Spectrometry

Sulfur element is of great importance in nature and human life, andit plays a great role in the fields of environmental science, quantitativeproteomics, geology, food safety and metrology. Environmental concernsabout sulfur containing pollution increases the need to develop methodsfor sulfur analysis, and routine technologies cannot meet the demand onaccurate determination of trace sulfur in a variety of matrices. InductivelyCoupled Plasma Mass Spectrometry （ICP MS） is commonly used ininorganic chemistry for trace analysis, hence, the study of developing themethod on sulfur determination by ICP MS is of utmost importance.Contents in this work can be listed as follows,（1） Optimization ofinstrument: Instrumental parameters such as RF power, Sample gas,Torch position were adjusted to get maximum sensitivity by combiningthe orthogonal test with single factor test, and then the optimalinstrumental parameters of ICP MS for determination of sulfur were obtained.（2） Comparisons of sulfur determination by two kinds ofICP MS: Sensitivity, background noise and Limit of Detection （LOD）during determination of sulfur, using both Quadrupole InductivelyCoupled Plasma Mass Spectrometry （Q ICP MS） and Sector FieldInductively Coupled Plasma Mass Spectrometry （SF ICP MS）, werestudied in this work. SF ICP MS was applied to the further study becauseof its distinct advantages.（3） SF ICP MS was used to determine sulfurwith different species (S^2-, S₂O₃^2-, SO₃^2-, SO₄^2-) in two different matrices,and effect of matrix and sulfur species during determination of sulfur bySF ICP MS was presented. In addition, the mechanism on it wasdiscussed.（4） Measurement of sulfur in diesel by Isotope Dilution MassSpectrometry （ID MS）:（a） Studied and optimized pre treatmenttechnologies which were including digestion and reduction evaporationof diesel sample.（b） Prepared³⁴S enriched isotope spike solution andcalculated sulfur concentration in it.（c） Converted sulfur in34S enrichedisotope spike solution to As2S3using reduction evaporation technology,and then, Thermal Ionization Mass Spectrometer （TIMS） was used tomeasure sulfur isotopic abundances.（d） Firstly, mixed some diesel（weighed to0.01mg） with³⁴S enriched isotope spike in accordance withthe optimal isotope ratio. Secondly, digested the mixture usingmicrowave digestion with optimal procedures and collected sulfur usingevaporation reduction method. Finally, measured sulfur isotopic ratio by SF ICP MS and sulfur content in diesel was obtained.Procedures for determination of sulfur by combining microwavedigestion reduction purification with ID SF ICP MS were established inthis work which was supported by a great number of experiments. Then,its evaluation by measurement of sulfur in diesel fuel oil （standardreference material2723a） was presented. It showed that this method wassuitable for sulfur determination in sample with complex matrix such asdiesel, it was an accurate and precise method for determination of sulfur.