Determination of carbohydrate‐deficient transferrin in human serum by capillary zone electrophoresis: Evaluation of assay performance and quality assurance over a 10‐year period in the routine arena

Abstract

The performance of high-resolution CZE for determination of carbohydrate-deficient transferrin (CDT) in human serum based on internal and external quality data gathered over a 10-year period is reported. The assay comprises mixing of serum with a Fe(III) ion-containing solution prior to analysis of the iron saturated mixture in a dynamically double-coated capillary using a commercial buffer at alkaline pH. CDT values obtained with a human serum of a healthy individual and commercial quality control sera are shown to vary less than 10%. Values of a control from a specific lot were found to slowly decrease as function of time (less than 10% per year). Furthermore, due to unknown reasons, gradual changes in the monitored pattern around pentasialo-transferrin were detected, which limit the use of commercial control sera of the same lot to less than 2 years. Analysis of external quality control sera revealed correct classification of the samples over the entire 10-year period. Data obtained compare well with those of HPLC and CZE assays of other laboratories. The data gathered over a 10-year period demonstrate the robustness of the high-resolution CZE assay. This is the first account of a CZE-based CDT assay with complete internal and external quality assessment over an extended time period.

Monitoring of transferrin isoforms in biological samples by capillary electrophoresis

“…The CEofix assays are characterized with a high precision performance [29,30,83] and were routinely used in our laboratory since 2002. Assay performance and stringent quality assurance over a 10-year period were assessed and reported [104]. The robustness of the HR-CEofix assays was thereby documented with data obtained by analysis of the serum of a healthy individual, of commercial QC sera, and by participation at external QC schemes.…”

Recent advances in capillary electrophoretic migration techniques for pharmaceutical analysis

“…CE techniques demonstrated successful applications for analysis of small analytes from biological matrices usually using proper IS without tedious sample preparation . However, in order to guarantee the accuracy of a main assay and to reliably control all degradation products of pharmaceuticals or biopharmaceuticals, orthogonal assays with different separation efficiency are indispensable .…”

On‐line immunoaffinity solid‐phase extraction capillary electrophoresis mass spectrometry for the analysis of large biomolecules: A preliminary report

“…Saturated Tf solution (1500 g/mL) was prepared to avoid the heterogeneity in glycoform charge caused by incomplete iron saturation by dissolving the protein in an aqueous solution containing 0.27 mM FeCl 3 and 18.7 mM NaHCO 3 [17,[23][24][25][26][27][28]. Saturated Tf solution (1500 g/mL) was prepared to avoid the heterogeneity in glycoform charge caused by incomplete iron saturation by dissolving the protein in an aqueous solution containing 0.27 mM FeCl 3 and 18.7 mM NaHCO 3 [17,[23][24][25][26][27][28].…”

“…The BGE (25 mM ammonium acetate) was adjusted to pH 8.5 with ammonia, while applying a separation voltage of 5 kV. No improvements were obtained either with decreasing the sample injection volume or analyzing Tf after saturation with Fe to ensure a constant metal content in Tf [17,[23][24][25][26][27][28]. 1A can be observed that S3, S4, S5 and S6 Tf sialoforms were poorly resolved after the negative dip indicating the EOF [23].…”

“…Sialoforms S0, S1 and S2, which are practically nonexistent in the serum of healthy individuals, are biomarkers for carbohydrate-deficient transferrin (CDT) and chronic alcoholism [17,[22][23][24][25][26][27][28]. Tf (approximately 80 kDa) is an iron transporting glycoprotein containing carbohydrates that differ in the number and composition of sugar antennas terminating in sialic acid residues (S0-S6).…”