Sample preparation 3.4.1. Open the styrene cassette and place the coated glass fiber filter in a 4-mL vial so that the filter is flat against the inside of the vial. Do not fold or crumple it. Seal the vials with PTFE-lined septa and allow them to extract for one hour. Shake the vials by hand periodically during this extraction time.
Any compound having a similar retention time to the analyte is a potential interference.
Generally, chromategraphic conditions can be altered to separate an interference from the analyte. Retention time on a single column is not proof of chemical identity. A calibration curve is constructed by plotting detector response versus standard concentration. The concentration of IPDI in a sample is determined from the calibration curve. The total IPDI concentration is then determined by the following formula.