A Method for Determination of Particle Magneic Susceptibility with Analytical Magnetapheresis

摘要

We recently developed a new method for simple deter-mination of particle magnetic susceptibility using analyti-cal magnetapheresis. This new method does not require laborious calibration plots and trial susceptibility values as do previous analytical magnetapheresis methods. The new method is based on balancing channel flow rates and magnetically induced flow rates for particle deposition in analytical magnetapheresis. The maximal flow rate for complete particle deposition was determined experimen-tally and set to equal the magnetically induced flow rate for determining particle magnetic susceptibility. This magnetic susceptibility determination generally takes less than 20 mm. Several magnetically susceptible and ion-labeled particles were tested using this new method. The carrier magnetic susceptibilities were varied, and erbium ion-labeled particles were studied experimentally, result-ing in successful susceptibility determinations of erbium ion-labeled particles and yeasts. The precision of each measurement was generally —.10%. Experimental deter-mination of particle magnetic susceptibilities differed by less than 10% from reference measurements taken using a superconducting quantum interference device magne-tometer. This method can dete~-mine minimal suscepti-bilities on the order of 10-s cgs. The minimum number of erbium labeling ions per particle required for complete deposition of silicas and yeasts was found to be 6.7 x 10g. Analytical magnetapheresis shows good potential for use in simple determination of particle magnetic susceptibili-ties and should become a useful technique.