Shah convolution Fourier transform detection: Multiple-sample injection technique

For the direct measurement of electrophoretic mobility, multiple-point (Sha h function) detected, time-domain detector signals were converted into freq uency-domain plots by means of Fourier transformation. Multiple sample plug s (up to a maximum of three) were introduced into the separation channel an d the resultant time-domain signals were then Fourier-transformed. The mult iple-sample injection technique has been successfully demonstrated for a on e-component system and a separation. Though the number of fluorescing zones flowing through the illuminated length of the channel is greater than the number of analytes in the solution, Shah convolution Fourier transform dete ction (SCOFT) is able to identify the number of fluorescent species in the solution based on their migration velocities. The height of the fundamental peak increases as the number of injected sample plugs is increased. More i mportantly, the signal-to-noise ratio (S/N) is found to be proportional to the number of injected sample plugs. With these findings, the multiple-samp le injection technique certainly has got many potential applications in tra ce analysis. The technique would be as equally applicable to other separati on techniques (e.g., high-performance liquid chromatography) and detection methods (e.g., absorption, refractive index).