The Invitrogen Attune NxT Flow Cytometer has less than 1.0% carryover when the standard rinse cycle is used. Carryover is measured by acquiring a fixed volume of sample, followed by acquiring a fixed volume of a particle-free, buffer-only solution such as phosphate-buffered saline (PBS). The concentration of particles detected in the PBS/buffer blank divided by the concentration of particles in the sample, multiplied by 100, yields the percent carryover (Figure 1).
Figure 1. Analysis of carryover from a tube. (A) A forward scatter (FSC) vs. side scatter (SSC) plot of human lysed whole blood at 106 cells/mL, and (B) analysis of PBS blank with the same gates. The numbers displayed for each population of lymphocytes, monocytes, and granulocytes are the concentrations in cells/µL. (C) Percent carryover of lysed whole blood (LWB) as a function of cell concentration for the three main cell population gates; 50 µL of lysed whole blood was acquired, followed by 50 µL of PBS. Percent carryover = (concentration of PBS subset/concentration of LWB subset) x 100%. In this example, the lymphocyte carryover is (21/12,702) x 100% = 0.17%. The error bars show the standard deviation (n = 3) of the calculated percent carryover at each concentration.
The percent carryover of each of individual subset is calculated as:
Percent carryover = PBS subset/LWB subset x 100
In example shown in figures 1A and 1B, the lymphocyte carryover is calculated at 21/12,702 x 100 = 0.17%
Figure 2. Analysis of carryover using the Attune NxT Autosampler with one rinse and one mix. Carryover is less than 0.40% using only one rinse cycle for each of the three main cell populations of lymphocytes, monocytes, and granulocytes at four different cell concentrations. The error bars show the standard deviation (n = 3) of the calculated percent carryover at each concentration. At 104 cells/mL concentration, the measurement error is higher due to the poor counting statistics (<400 events in each subpopulation).
For Research Use Only. Not for use in diagnostic procedures.