Carbohydrate-deficient transferrin (CDT) is a reliable biomarker for chronic alc. abuse. We developed a method for CDT anal. by capillary isoelec. focusing, followed by immunodetection directly in the capillary, in an automated fashion and on a single platform. Transferrin glycoforms in serum samples, including disialo-transferrin, were separated and their apparent isoelec. points and relative percentages were determined The relative CDT values (percent of total transferrin) matched expected values for both healthy and alc. samples. Because the method leveraged the sensitivity of an immunoassay, CDT was measured when serum samples were diluted up to 1200-fold, reducing the volume of serum required. Finally, the process is fully automated, with up to 96 samples analyzed per batch. METHOD SUMMARY : Carbohydrate-deficient transferrin is a common biomarker for diagnosing chronic alc. abuse. Here, we developed a technique for the detection of carbohydrate-deficient transferrin by isoelec. focusing followed seamlessly by immunodetection directly in the capillary. The method offers several advantages over existing techniques, including small sample size (15μl), specificity and automation, while also providing a complete charge-based separation profile of transferrin.