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T L Liem

Publications and source records attributed to T L Liem.

6 recordsLinked to original sources
PubMed1990

The Reflotron Total Cholesterol assay in heparinized venous and capillary blood.

We recently evaluated the Reflotron Total Cholesterol dry chemistry assay by examining the calibration and the accuracy of the assay in serum, whole venous EDTA-blood and capillary EDTA blood. We now describe a study on the analysis in heparinized venous and heparinized finger stick blood. Cholesterol assays in venous serum and plasma, and in finger capillary blood and plasma (all with heparin) were compared. Finger capillary blood was obtained in two ways: 1. in heparinized capillaries; 2. in a Becton Dickinson microtainer that could be centrifuged for separation of the plasma. Venous blood was obtained in plain tubes (for serum) and heparinized tubes to obtain venous whole blood and also venous plasma. We did not, on average, find large differences between the concentrations of cholesterol in the various materials. The regression equations for finger capillary whole blood and venous whole blood however show higher slopes than the others. Inaccuracy due to the sampling technique appears to be no greater for finger capillary samples than for venous samples.

Capillaries↗
PubMed1988

Revised calibration of the Reflotron cholesterol assay evaluated.

We evaluated the Boehringer Mannheim (B.M.) Reflotron Total Cholesterol "dry-chemistry" method after its recalibration in 1987. Reports in the literature up to 1986-1987 of a negative bias (up to -10%) in the method prompted a revision of the factory-set calibration of the Reflotron. For this, B.M. prepared a new set of calibrators with 12 different concentrations of cholesterol. We checked in two ways whether accuracy had been achieved: (a) The values assigned to the calibrators by B.M. were checked with the manual Abell-Kendall Reference Method (MAK) performed in an official Reference Center. These were shown to be correct. (b) Concurrently, a direct comparison was made by analyzing 200 fresh samples of human serum. Reflotron cholesterol values obtained for these samples proved to be accurate, meeting the current World Health Organization/Centers for Disease Control criterion of maximum bias less than or equal to 5%. Orthogonal regression analysis yielded the following correlation: Reflotron = 0.985 MAK + 0.238 mmol/L (y = ax + b). Reflotron mean = 6.26 mmol/L; MAK mean = 6.09 mmol/L. SDa = 0.015 mmol/L; SDb = 0.120 mmol/L, and r = 0.989.

Autoanalysis↗
PubMed1977

A simple automated method for the fluorometric titration of calcium in biological fluids,.

A new automatic device has been developed for the determination of the calcium content in biological fluids. The method is based on a fluorometric titration technique, in which calcium is titrated with ethyleneglycolbis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA). The end-point of the titration is indicated by quenching of the fluorescence of a calcium-calcein complex, in which calcein is the fluorescein-complexone indicator. To obtain proper results we found it necessary to use a 1 molar potassium hydroxide solution as titration medium. The results are printed out directly in concentration units (mmol/l). In order to carry out these determinations, several electronic and mechanical devices, including a sample-changer, titration cabinet with built-in fluorometer, control unit and electron titrator, were developed. Together they form the new calcium automatic device of which several qualitites such as precision, recovery and correlation have been studied. The disturbing influence of bilirubin has been minimized by using an excitation wavelength of 492 nm, at which there is nearly no absorption by bilirubin. At a concentration of bilirubin of as much as 500 micronmol/l, the recovery of calcium is still about 96%.

Autoanalysis↗