We report on the use of a microcalorimeter X-ray detector with a transition edge sensor in an electron probe to perform quantitative analysis. We analyzed two bulk samples of multielement glasses that have been previously characterized by chemical methods for use as standard reference materials. The spectra were analyzed against standards using three different correction schemes. In one of the standards, the reference line was easily resolved despite its proximity within 45 eV of another line. With the exception of direct measurements of oxygen (a particularly challenging element), the results are in agreement with the certified characterization to better than 1% absolute or 8% relative. This demonstrates the potential of microcalorimeter detectors as replacements for conventional energy dispersive detectors in applications requiring high energy resolution.