Comparison of two isotope dilution/mass spectrometric methods for determination of total serum cholesterol.

1982 ◽  
Vol 28 (1) ◽  
pp. 5-8 ◽  
Author(s):  
R Schaffer ◽  
L T Sniegoski ◽  
M J Welch ◽  
V E White ◽  
A Cohen ◽  
...  
Keyword(s):  
Serum Cholesterol ◽  
Isotope Dilution ◽  
Systematic Difference ◽  
Mass Spectrometric ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
National Bureau ◽  
Average Difference ◽  
Mean Values

Abstract Isotope dilution/mass spectrometric methods for total serum cholesterol, developed separately at the Karolinska Institutet (KI) and the National Bureau of Standards (NBS), were compared by applying them to a common set of serum pools. A search for the cause of a systematic difference of a few percent in results from the two methods revealed that the KI cholesterol standard contained lathosterol, which interfered with the calibration of the method. With NBS Standard Reference Material cholesterol used for new analyses at the KI, the average difference in mean values dropped to 0.2%. The NBS results are more precise. This is attributed to the protocols NBS used for sample preparation and mass spectrometry. However, these protocols make the NBS method more complex and time-consuming. A recent critical article on the use of this technique for total cholesterol is also examined.

Continuous-flow enzymatic determination of total serum cholesterol and method standardization with CDC-calibrated pooled sera.

1980 ◽  
Vol 26 (7) ◽  
pp. 896-902
Author(s):  
M A MacAulay ◽  
C L Jacklyn ◽  
J M Mathers ◽  
V A Storm
Keyword(s):  
Serum Cholesterol ◽  
Continuous Flow ◽  
Cholesterol Content ◽  
Comparison Method ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
Enzymatic Method ◽  
Factors Affecting ◽  
Assigned Value

Abstract We compared Boehringer Mannheim's enzymatic kit for the continuous-flow (AutoAnalyzer II) determination of serum cholesterol with Technicon's N-24a extraction method. Results for patients' samples analyzed by the enzymatic method were higher than those by the comparison method. To evaluate accuracy in the cholesterol determinations, we enrolled the enzymatic method into the Center for Disease Control's (CDC) Lipid Standardization program. We calibrated the method by use of a pooled sera for which cholesterol content was assigned by CDC after analysis by their reference Abell-Kendall procedure. We discuss the difficulties with available calibration material and limitations in the application of some commercial control materials to the enzymatic cholesterol method. The continuous-flow variables, Michaelis-Menton constants, percent ester-hydrolase activity, and other factors affecting the performance of the enzyme-linked cholesterol method are evaluated. We believe pooled sera with an assigned value for cholesterol content is the best calibrator material.

Total serum cholesterol by isotope dilution/mass spectrometry: a candidate definitive method.

1980 ◽  
Vol 26 (7) ◽  
pp. 854-860 ◽  
Author(s):  
A Cohen ◽  
H S Hertz ◽  
J Mandel ◽  
R C Paule ◽  
R Schaffer ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Total Cholesterol ◽  
Serum Cholesterol ◽  
Isotope Dilution ◽  
Isotope Dilution Mass Spectrometry ◽  
Weight Ratio ◽  
Molecular Ions ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
Definitive Method

Abstract 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.

Turbidimetric Determination of Total Serum Cholesterol

1961 ◽  
Vol 33 (4) ◽  
pp. 561-564 ◽  
Author(s):  
G. R. Kingsley ◽  
Ozie. Robnett
Keyword(s):  
Serum Cholesterol ◽  
Total Serum ◽  
Total Serum Cholesterol

Direct Determination of Total Serum Cholesterol by On-Column Gas-Liquid Chromatographic Analysis without Previous Derivatisation Compared with WHO-CDC Reference Method

1983 ◽  
Vol 20 (6) ◽  
pp. 360-363 ◽  
Author(s):  
J W I Brunnekreeft ◽  
G J M Boerma ◽  
B Leijnse
Keyword(s):  
Serum Cholesterol ◽  
Direct Determination ◽  
Reference Method ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
Gas Liquid Chromatography ◽  
Accuracy And Precision ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic

A method for the direct determination of total serum cholesterol by on-column gas-liquid chromatography is described. The French reference method developed by Gambert et al.1 served as a model for our method, which is fast and less laborious than the well-known CDC reference method of Cooper et al.23 based on the Abell-Kendall technique.4 The accuracy and precision of our on-column gas-liquid chromatographic method and the CDC reference method are comparable. The obvious advantage of this proposed gas-liquid chromatographic reference method is its increased analytical speed. The problem of the specificity of our method in relation to cholestanol is discussed.

Enzymatic Determination of Total Serum Cholesterol

1974 ◽  
Vol 20 (4) ◽  
pp. 470-475 ◽  
Author(s):  
Charles C Allain ◽  
Lucy S Poon ◽  
Cicely S G Chan ◽  
W Richmond ◽  
Paul C Fu
Keyword(s):  
Serum Cholesterol ◽  
Free Cholesterol ◽  
Cholesterol Oxidase ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
Enzymatic Method ◽  
Simultaneous Production ◽  
Enzymatic Determination ◽  
Production Of Hydrogen

Abstract An enzymatic method is described for determination of total serum cholesterol by use of a single aqueous reagent. The method requires no prior treatment of sample and the calibration curve is linear to 600 mg/dl. Cholesterol esters are hydrolyzed to free cholesterol by cholesterol ester hydrolase (EC 3.1.1.13). The free cholesterol produced is oxidized by cholesterol oxidase to cholest-4-en-3-one with the simultaneous production of hydrogen peroxide, which oxidatively couples with 4-aminoantipyrine and phenol in the presence of peroxidase to yield a chromogen with maximum absorption at 500 nm. The method is reproducible, and the results correlate well with those obtained by automated Liebermann—Burchard procedures (AA-2 and SMA 12/60) and the method of Abell et al. The present method affords better specificity than those previously reported and has excellent precision.

Continuous-flow enzymatic determination of total serum cholesterol and method standardization with CDC-calibrated pooled sera.

1980 ◽  
Vol 26 (7) ◽  
pp. 896-902 ◽  
Author(s):  
M A MacAulay ◽  
C L Jacklyn ◽  
J M Mathers ◽  
V A Storm
Keyword(s):  
Serum Cholesterol ◽  
Continuous Flow ◽  
Cholesterol Content ◽  
Comparison Method ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
Enzymatic Method ◽  
Factors Affecting ◽  
Assigned Value

Abstract We compared Boehringer Mannheim's enzymatic kit for the continuous-flow (AutoAnalyzer II) determination of serum cholesterol with Technicon's N-24a extraction method. Results for patients' samples analyzed by the enzymatic method were higher than those by the comparison method. To evaluate accuracy in the cholesterol determinations, we enrolled the enzymatic method into the Center for Disease Control's (CDC) Lipid Standardization program. We calibrated the method by use of a pooled sera for which cholesterol content was assigned by CDC after analysis by their reference Abell-Kendall procedure. We discuss the difficulties with available calibration material and limitations in the application of some commercial control materials to the enzymatic cholesterol method. The continuous-flow variables, Michaelis-Menton constants, percent ester-hydrolase activity, and other factors affecting the performance of the enzyme-linked cholesterol method are evaluated. We believe pooled sera with an assigned value for cholesterol content is the best calibrator material.

Fluorometric Enzymatic Determination of Total Cholesterol in Serum

1975 ◽  
Vol 21 (11) ◽  
pp. 1605-1608 ◽  
Author(s):  
Hua-shan Huang ◽  
Jui-chang W Kuan ◽  
George G Guilbault
Keyword(s):  
Serum Cholesterol ◽  
Free Cholesterol ◽  
Cholesterol Oxidase ◽  
Correlation Coefficients ◽  
Total Serum ◽  
Total Serum Cholesterol ◽  
Enzymatic Method ◽  
Enzymatic Determination ◽  
Production Of Hydrogen

Abstract We describe a fluorometric enzymatic method for determining total serum cholesterol, based on hydrolysis of cholesterol esters to free cholesterol by cholesterol ester hydrolase (EC 3.1.1.13). The free cholesterol formed, as well as that initially present, is then oxidized by cholesterol oxidase (EC 1.1.3.6) to cholest-4-en-3-one with simultaneous production of hydrogen peroxide. The latter catalytically oxidizes homovanillic acid in the presence of peroxidase (EC 1.11.1.7) to form the highly fluorescent 2,2'-dihydroxy-3,3'-dimethoxy-biphenyl-5,5'-diacetic acid. A calibration curve is constructed from data on a series of standard cholesterol solutions vs. the corresponding fluorescence change (Δf/5 min). This curve is linear up to 4.0 g of total serum cholesterol per liter of serum. The method is specific, precise, accurate, rapid, and simple, and results correlate well with those obtained by both the Liebermann-Burchard procedure and the colorimetric enzymatic method (correlation coefficients, 0.984 and 0.981, respectively)

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