How is a blank sample prepared according to NIOSH7400?

A blank sample is prepared to serve as a control in sampling and analysis processes, ensuring that any contamination can be identified. According to NIOSH 7400 protocols, a blank sample is ideally prepared by opening both ends of the cassette and leaving it in a clean area. This method allows for ambient air to pass through the cassette while preventing any specific contaminants from attaching to the filter material.

By exposing the blank cassette under these conditions, it can later be compared to actual samples to determine if there was any contamination during sampling and transport. This procedural step is essential in ensuring the accuracy and reliability of analytical results derived from the actual air samples collected during the monitoring process. Other methods, such as sealing the cassette or submerging it in water, would not facilitate the intended function of a blank sample, which is to represent an uncontaminated baseline measurement for analysis.