This kit allows users to run the assay qualitatively or quantitatively and generally can detect a range from low picogram to the high nanogram concentrations.  For example, qualitative analysis may be useful for initial screening studies on a large number of samples.  The qualitative assay detection levels are as low as 30-60 pg/mL – which is actually far below the negative threshold cut-off values based on COVID-19 negative plasma samples.  For quantitative analysis, the lower level of quantification (LLOQ) is higher, and varies slightly between Ab isotypes.  For example, the linear range for accurate quantification of IgG Abs is between approximately 50 ng/mL down to 300 pg/mL when using the Ab standard included in the kit and preparing a 1:3 serial dilution curve across a row of a 96 well plate or a column of a 384 well plate.