<p>The present invention relates to a method for separating a plurality of proteins which method comprises providing a labeled proteinaceous sample or more than one proteinaceous samples which are distinguishably labelled; providing a proteinaceous standard which is distinguishable from said label of said proteinaceous sample(s); subjecting said proteinaceous sample(s) to isoelectric focusing in a pH gradient gel; subjecting the standard to stacked gel electrophoresis; subjecting said proteinaceous sample(s) and said standard to resolving gel electrophoresis; and comparing the separated proteinaceous entities and the separated internal standard. The inventions methods may also be used for identifying the presence of one or more proteins contained in a proteinaceous sample, or for determining the allergenic carcinogenic, contamination or infection potential of a proteinaceous sample. A gel suitable for gel electrophoresis of proteins comprising (from top to down) a stacking gel; a predetermined pH gradient gel; and a resolving gel is also disclosed.</p>
