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We describe a highly accurate and precise method for determination of total cholesterol in serum by isotope dilution/mass spectrometry. The method was developed for a Study Group of the Committee on Standards of the American Association for Clinical Chemistry, for use in establishing the accuracy of a candidate reference method for total cholesterol, and fulfills their criteria for a definitive method. Cholesterol-d7 is added to serum, with the weight ratio of cholesterol-d7 to total serum cholesterol kept near to 1:1. The esters are hydrolyzed and the cholesterol is separated and converted into the trimethylsilyl ether derivative for measurement by combined gas chromatography/mass spectrometry. The intensity ratio of the molecular ions at m/z 465 and 458 is measured for each sample and for two calibration mixtures, according to a prescribed bracketing protocol. A weight ratio for the sample is obtained by linear interpolation of the ion-intensity ratios, and the total cholesterol is then calculated. The method was applied four times over several weeks to each of five serum pools. Statistical analysis involving consideration of both replication error and variability between weeks gave a coefficient of variation for a single measurement of 0.36%. The absence of interferences in the method was demonstrated by measurements at several other masses.
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
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Clinical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
March 1995,
Clinical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
August 1987,
Clinical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
October 1990,
Analytical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
August 1989,
Analytical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
October 1997,
Clinical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
May 1984,
Clinical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
January 1981,
Biomedical mass spectrometry,
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H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
February 2013,
Clinical chemistry,
A Cohen, and
H S Hertz, and
J Mandel, and
R C Paule, and
R Schaffer, and
L T Sniegoski, and
T Sun, and
M J Welch, and
E White
July 1987,
Clinical chemistry,
