isoton u00ae 3e then 403 u03bcl of a lytic reagent composition of formula c was mixed manually with the prediluted sample the absorption spectrum of the sample mixture was measured immediately on a beckman du 7500 spectrophotometer fig1 shows a total of 12 spectra of the blood samples treated according to above procedure using formula c the spectra were acquired from 12 seconds after the addition of the lytic reagent composition with an interval of 10 seconds 111 blood samples their hemoglobin concentration ranging from 6 to 17 g dl and white blood cell count ranging from 1 000 u03bcl to 40 000 u03bcl were analyzed on a calibrated coulter u00ae lh750 instrument under standard instrument configuration except for the lytic reagent being replaced by formula a these sample were also analyzed on another reference lh750 instrument which used lyse s u00ae iii diff as the lytic reagent more than 50 percent of the samples were clinical samples including various clinical conditions fig2 shows the correlation of the hemoglobin concentration between the results obtained using formula a and the results obtained on the reference instrument fig3 shows the correlation of the numbers of white blood cells reported as wbc in 10 3 u03bcl between the results obtained using formula a and the results obtained on the reference instrument fig4 a and 4b show the white blood cell distribution histograms of one blood sample obtained on the instrument using formula a and the reference instrument respectively as shown using formula a similar to the white blood cell distribution obtained using the reference reagent lyse s u00ae iii diff the white blood cells were differentiated into lymphocytes monocytes and granulocytes while the present invention has been described in detail and.