Immunoassays have become invaluable in the generation of data for preclinical and clinical studies, process development/optimization and manufacture of biotherapeutics, and also for new applications such as determining viral titer in cell and gene therapy. Having confidence in the data based on the accurate and precise determination of analytes in complex matrices means overcoming many challenges. These can include interference that reduces robustness, selectivity and specificity, the poor performance of cross-reacting antibody reagents, and time-consuming methods that threaten time plans. Such challenges can be overcome by choosing the right reagents, using the right approach on the right immunoassay platform to deliver reliable data as quickly as possible.