• Analytical Science and Technology
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• v.27 no.3
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• pp.140-146
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• 2014

An internal standard was used in PCID (post column isotope dilution) to improve the accuracy and precision in quantification of various chemical species. The error occurring in the column was the largest in HPLC-ICP/MS (high performance liquid chromatography-inductively coupled plasma/mass spectrometry) when PCID and other traditional quantification methods were compared with each other. Internal standard was effective in correcting the loss of sample in the column to improve accuracy and precision. When applied to SeMet, using MeSecys or $Se^{4+}$ as an internal standard, relative errors were reduced from 31% and 13% to less than 1%, while standard deviations were reduced from 5.1% and 6.9% to 1.5% and 0.2%, respectively. Positive aspects of using an internal standard in PCID were compared with other quantitative techniques and discussed in detail.

• Analytical Science and Technology
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• v.27 no.6
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• pp.269-276
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• 2014

A short study for the uncertainty of post column isotope dilution method has been performed for the analysis of Selenomethionine in HPLC-ICP/MS. Major error sources studied were concentration and the flow rate of Se isotope solution, atomic weights of Se in spike and sample, and isotope ratio measured for the spiked sample. Uncertainties were obtained for each factor and the contribution for the total concentration uncertainty was 54.4% and 0.61%, 0.0072% and 0.018%, and 45.0%, respectively. The biggest contribution factor was concentration of the spike solution and the second was the isotopic ratio measured for the spiked sample solution. The mass flow rate of spike and atomic weights did not show much contribution. The calculated total uncertainty was $1.46ng{\cdot}g^{-1}$ for the standard SeMet ($126.30ng{\cdot}g^{-1}$). The experimental result was $127.09{\pm}1.46ng{\cdot}g^{-1}$ and the relative uncertainty was 1.20%.