Concerning analytical sensitivity of a genetic analyzer

The article considers the effect of reflection and scattering of fluorescence radiation in a capillary array on the analytical sensitivity of a genetic analyzer. Reflected and scattered radiation creates background illumination, which in some cases can exceed the intensity of the informative fluorescence signal. It is shown that the main contribution to the background illumination of a capillary array is made by reflection of radiation from neighboring capillaries with a high concentration of fluorophores and, accordingly, high fluorescence intensity. An experimental test of the proposed model for the formation of background illumination was carried out on a standard capillary array with 8 capillaries, in which one of the capillaries was filled with a colloidal solution of quantum dots. The experimentally obtained dependences of the intensity of fluorescence radiation reflected by the capillaries are quite correctly described by the proposed model. If the fluorescence intensity in different capillaries of the array differs insignificantly, then the capillaries do not have a significant effect on each other. With a 1000-fold difference in fluorescence intensity, the effective analytical sensitivity drops approximately 100 times. The results show that to achieve high analytical sensitivity in genomic sequencing, the fluorophore concentration should be approximately the same in all capillaries in the array. The feasibility of using arrays of capillaries with a large number of capillaries and measures to reduce the mutual influence of capillaries in the array of capillaries in the genetic analyzer are discussed.