Patent ID: 6941005

Claim:
A method for sorting particles in a stream of a sample in a flow cytometer, comprising: (a) producing from a stable sort having desirable sort characteristics multiple images of a portion of said stream; (b) generating from said multiple images an averaged numerical reference standard representative of said stable sort; (c) continuously collecting during the sorting multiple running images of said portion of said stream; (d) generating from said multiple running images (c) at least one numerical sample average representative of the sample sort of each collection of said multiple running images, comprising the steps of: (1) converting said image (d) into a sample histogram having a downstream and upstream direction on the X axis, at least one neck region, and at least one undulation downstream of said neck region, said undulation comprising a positive slope nd a negative slope; (2) determining from each histogram a selected numerical value corresponding to the reference standard, wherein said numerical value is selected from the group consisting of: i. the slope of the upstream edge of an undulation appearing downstream of the neck region of each histogram; ii. the slope of the downstream edge of the undulation appearing upstream of the neck region of each histogram; iii. the average of the sum of the absolute values of the slopes (i) and (ii) for each histogram; iv. the midpoint of the segment defining the slope of the downstream undulation of each histogram; v. the integral of the area of the histogram between the lower of the slope values of slopes (i) and (ii); and vi. combinations thereof; and (3) averaging said selected numerical values from the multiple sample histograms of the multiple sample images (d) to create at least one numerical sample average of the sort of each collection of multiple running images; and (e) comparing each numerical sample average (d) to said numerical reference standard (b) and determining whether average (d) exhibits a deviation from said reference standard that requires an adjustment of said sort.