ABSTRACT
Although analysis of metals and metalloids, such as arsenic, is widely spread in many different fields, their analysis in gas and liquefied gas samples is still a challenge. A new GC-ICP-MS set up has been developed for their simultaneous total and speciation analysis in gas and liquefied gas samples without the need of a preconcentration step. An arsine in nitrogen standard was used for optimization and evaluation of the system. Good linearity and detection limits in the very low ppt level for both total and speciation analyses were found. Liquefied butane pressurized under nitrogen and doped with arsine and a propylene real sample from a cracker plant were analyzed using both external calibration and standard additions methods. The good match between both quantifying approaches demonstrated almost negligible matrix effects, even for the total analysis. Application of the approach to check repartition of volatile elements or species between gas and liquid phases was performed in the real propylene sample. Finally, its potential applicability for the simultaneous total and speciation analysis of other elements, such as Hg, was also proved.
ABSTRACT
A method based on CZE coupled to quadrupole TOF MS (Q-TOF MS), which is suitable to analyze seven common melamine impurities is presented. MS compatible formic acid based BGEs with various concentrations of organic modifiers were investigated using UV detection to determine the best separation system regarding resolution and speed. The optimized BGE consisted of 350 mM formic acid with 10% ACN and migration times were <6 min. The detection limits were considerably improved when ESI MS was applied instead of UV detection. In addition the instrument allows quantification with good linearity and repeatability in the relevant concentration range. The analytical characteristics of the method were evaluated for melamine, guanylurea, diaminotriazine, ureidomelamine, guanlymelamine, melam, methylmelamine, and dimethylmelamine both with UV and MS detection. Several different melamine samples were analyzed und the determined impurity levels were in the range from 0.02 to 2.3%.
