Free zone capillary electrophoresis conditions have been improved to allow rapid (2-8 min) separations of grain proteins from several cereals (wheat, oats, rice, barley, and rye) with high resolution and reproducibility. This new method utilized the isoelectric compound iminodiacetic acid (IDA) in conjunction with 20% acetonitrile and 0.05% hydroxypropylmethylcellulose. Cultivars of all cereals tested could be differentiated in 3 min, including wheat, using either prolamin or glutelin protein patterns. Resolution was similar to or higher than that of separations in other acidic buffers. Migration time repeatability was excellent with run-to-run variability <1% RSD, day-to-day <1.4% RSD, and capillary-to-capillary <3.3% RSD. Because larger inner diameter capillaries (50 microm) could be used with this buffer, sensitivity was improved and capillary rinse times could be reduced when compared to smaller capillaries (25 microm i.d.). This also served to reduce total separation time so that the majority of cereal storage protein from several types of cereals could be analyzed with total analysis times of 2-8 min with extremely high resolution and repeatability. This method would allow unattended, high-throughput ( approximately 180-400 samples/24 h) analysis of cereal proteins without the generation of much organic solvent waste as well as automated data analysis and storage.