Patent ID: 7541190

Claim:
A method of measurement of cellular hemoglobin of a blood sample comprising the steps of: (a) mixing an aliquot of a whole blood sample with a permeation reagent to form a first sample mixture; and incubating said first sample mixture for a first period of time sufficient to permeate the cellular membrane of red blood cells and cause hemoglobin aggregation within said red blood cells; wherein said permeation reagent comprises a N-acyl sarcosine or a salt thereof represented by the following molecular structure: R 1 —CO—N(CH 3 )CH 2 COOX 1 , wherein R 1 is an alkyl or alkylene group having 8 to 18 carbon atoms, and X 1 is H, Na + , or K + ; and said permeation reagent has a pH between 4 and 6 and a low ionic strength defined by conductivity of less than 9 mS/cm; (b) adding a neutralization reagent to said first sample mixture to form a second sample mixture, and incubating said second sample mixture for a second period of time sufficient to inhibit further reactions of said permeation reagent with said red blood cells; (c) performing a cell-by-cell measurement of side scatter signals of said red blood cells in said second sample mixture on a flow cytometer; and (d) obtaining cellular hemoglobin (Hgb cell ) of said red blood cells of said blood sample using said side scatter signals.