Paola Luraschi

10% CV concentration for the fourth generation Roche cardiac troponin T assay derived from Internal Quality Control data

December 2005 8 1 11.7 0.035 January 2006 18 1 7.6 0.038 February 2006 15 1 9.1 0.037 March 2006 22 2 11.0 0.042 April 2006 20 2 10.9 0.043 May 2006 15 3 5.6 0.048 June 2006 18 3 11.5 0.043 July 2006 20 3 10.7 0.044 Alberto Dolci, Roberto Dominici, Paola Luraschi and Mauro Panteghini* 1 Laboratorio Analisi Chimico-Cliniche, Azienda Ospedaliera ‘‘Luigi Sacco’’, Milan, Italy 2 Cattedra di Biochimica Clinica e Biologia Molecolare Clinica, Dipartimento di Scienze Cliniche ‘‘Luigi Sacco’’, Università degli Studi di Milano, Milan, Italy

Precision and long-term stability of capillary electrophoresis measurement of serum protein zones.

BACKGROUND Analytical evaluations of an available system for capillary zone electrophoresis (CZE) of serum protein have been reported. However, data concerning long-term precision and stability of the system, operated under routine conditions, are lacking. We report data from an internal quality control (QC) scheme, obtained over a 1-year period. METHODS Measurements were done with a pair of instruments (Beckman Paragon CZE 2000 system), each equipped with seven capillaries. After preliminary (1 month) assessment of possible inter-capillary and inter-instrument variations, the QC material (a home prepared serum pool stored in the frozen state) was assayed daily over a 1-year period. RESULTS Maximum inter-capillary and inter-instrument differences were 3.1% and 2.4%. No significant trend was observed for daily values (205 measurements over 1 year); in the same period overall imprecision values (CV) were in the interval 1.2% (albumin) to 3.2-6.1% (globulin zones). Mean monthly imprecision (CV) values were in the interval 1.1% (albumin) to 5.2% (globulin zones). There was no significant trend of monthly means with time. The observed imprecision values were within the biological variation-derived goals for imprecision. CONCLUSIONS It is concluded that the assessed analytical instruments, operated in routine conditions, show long-term stability and imprecision consistent with the clinical use of the results produced.

A HEMOGLOBIN VARIANT FOUND DURING GLYCOHEMOGLOBIN MEASUREMENT, IDENTIFIED AS Hb TOULON [α77(EF6)Pro→His] BY TANDEM MASS SPECTROMETRY

Structural hemoglobin (Hb) variants are typically based on a point mutation in a globin gene that produces a single amino acid substitution in a globin chain. Although most of these are of limited clinical significance because they are asymptomatic or mildly symptomatic, diagnosis may be important for genetic counseling. In this paper we describe the first Italian case of Hb Toulon [a77(EF6)Pro!His], and report the analysis of the variant peptide sequences by electrospray ionization mass-mass spectrometry (ESI-MS=MS). The patient, a 59-year-old woman of Northern Italian descent, suffered from multiple benign pathologies, and venous thrombosis. She was obese and reported to have diabetic brothers. No significantly abnormal data resulted from routine clinical chemistry and hematology tests: Hb 13.1 g=dL; RBC 4.3610=L; MCV 91 fL; WBC 7.9610=L. Because of obesity and familial diabetes, glycohemoglobin (Hb A1c) measurement was ordered. By ion exchange high performance liquid chromatography (HPLC) assay (L-9100; Hitachi, Maidenhead, Kent, UK) using a 3-minute program, the Hb A1c was 3.0% (a rather low value); no additional peak was evident in the short chromatogram, but a marked abnormality of the baseline was shown. Whole blood HPLC analysis with a variant Hb dedicated program