Journal of Chemical Metrology

Year: 2007 Volume: 1 Issue:1

Original Article

1) Rapid and simultaneous determination of 25-OH-vitamin D 2 and D 3 in human serum by LC/MS/MS: Validation and uncertainty assessment

J. Chem. Metrol. (2007) 1:1 ; 1 - 9
by Ahmet C. Gören, Gökhan Bilsel, Mine Bilsel

25-OH Vitamin D3 and 25-OH Vitamin D2 were determined by rapid, simple and validated LC/MS/MS method without using SPE and isotopic standard. The relative standard deviations (RSD) were found to be 3.1 and 2.8 % for 25-OH Vitamin D3 and 25-OH Vitamin D2, respectively. The correlation coefficient was grater than 0.99 for both analytes in the calibration range. The recoveries at 100 μg L-1 concentration averaged to 92 % for 25-OH vitamin D3 and 94 % for 25-OH-vitamin D2. The uncertainty of the measurements for 25-OH vitamin D3 and for 25-OH-vitamin D2 was 7.77 % and 7.24 %, respectively.

Keywords
25-OH Vitamin D3 25-OH Vitamin D2 LC/MS/MS method validation uncertainty
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© 2007 ACG Publications. All rights reserved.
Original Article

2) Uncertainty assessment including sampling for determination of metals in lichen samples using ICP-OES

J. Chem. Metrol. (2007) 1:1 ; 10 - 24
by Serpil Yenisoy Karakaş

The uncertainty arising from the lichen sampling, preparation and analysis was calculated according to a new guide by Eurachem/EUROLAB/CITAC/Nordest/AMC, 2007, using the retrospective lichen data set completed in 2000 in Turkey. ICP-OES was used to determine the elements Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn. The method validation studies included linearity, detection limits, precision and accuracy. Measurement uncertainties were calculated by applying the bottom-up approach. It was observed that the largest contribution to the uncertainty came from the sampling. This approach indicated that, the standard uncertainties of the concentration values could be as large as 31.5%.

Keywords
Uncertainty lichen sampling analysis ICP-OES
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© 2007 ACG Publications. All rights reserved.