scholarly journals Human C-peptide Quantitation by LC-MS Isotope-Dilution Assay in Serum or Urine Samples

Author(s):  
Alexander V Stoyanov
1977 ◽  
Vol 53 (5) ◽  
pp. 453-457 ◽  
Author(s):  
C. A. Hall

1. After fractionation of the vitamin B12-binding proteins of ten normal sera the components containing transcobalamin II and R-type binders of vitamin B12 respectively were studied for endogenous vitamin B12 content by two distinct systems of vitamin B12 assay. 2. The measurements of total serum vitamin B12 by either bioassay with Euglena gracilis or a radioisotope dilution assay agreed closely. 3. The native vitamin B12 carried by transcobalamin II was higher as measured by bioassay than by isotope dilution assay. 4. The presence of the transcobalamin II fraction of human serum altered the key reaction between the binding reagent of the isotope dilution assay, so that this assay failed to measure vitamin B12 quantitatively. 5. Probably, the mean fraction of plasma vitamin B12 carried by transcobalamin II is in the range 20–30%.


2017 ◽  
Vol 65 (24) ◽  
pp. 5026-5033 ◽  
Author(s):  
Akira Nakanishi ◽  
Yusuke Fukushima ◽  
Norio Miyazawa ◽  
Keisuke Yoshikawa ◽  
Tomoko Maeda ◽  
...  

1996 ◽  
Vol 79 (2) ◽  
pp. 583-586 ◽  
Author(s):  
Bettina Dollmann ◽  
Dominicus Wichmann ◽  
Alfred Schmitt ◽  
Hans Koehler ◽  
Peter Schreier

Abstract Isotope dilution analysis was used to quantitate 2- aminoacetophenone in wines exhibiting the so- called untypical aging off-flavor. d3-Aminoacetophe- none was synthesized and used as isotopomeric internal standard. The method of quantitation was verified by several model experiments. In the off-flavored wines studied, amounts of 2-aminoacetophe none ranging from 0.7 to 12.8 μg/L were determined.


2002 ◽  
Vol 60 (2) ◽  
pp. 88-96 ◽  
Author(s):  
Jean-Pierre Dufour ◽  
Rana Wierda ◽  
Michelle Leus ◽  
Geert Lissens ◽  
Freddy Delvaux ◽  
...  

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