MW-RN-2020 (1)

Protocol for the Collection, Transfer and ANSI/AARST MW-RN 2020 Measurement of Radon in Water 31 11.2 Transfer Methods 11.2.1 Sample extraction Extraction of a water sample from the collection bottle shall be conducted using either an airtight graduated syringe or transfer pipet. The identity of the transfer device shall be documented. The following pertains to extracting 5-10 mL of water; if a laboratory uses a different volume the procedure shall be adjusted accordingly. Informative advisory —Water samples are often collected in glass VOC-type bottles and transported back to the laboratory before an aliquot of the water is extracted from the collection bottle for analysis. This approach eliminates the need to carry glass vials containing an organic-based scintillation fluid into the field and is recommended when conducting sample transport by mail (the postal service and package- shipping companies discourage the mailing of organic liquids in glass containers). 11.2.2 Syringe options Two types of syringes can be used to transfer a water sample from a collection bottle to a liquid scintillation vial. Both types shall be graduated and airtight. Informative advisory —A syringe with a large diameter tubing is recommended over the use of a hypodermic-needle syringe (6-10 gauge diameter), since the latter forces the extracted water through a constriction that produces sufficient pressure to enable dissolved gases to come out of solution from the water. If a needle syringe is used to pierce the septum of a ring-capped bottle, insert another needle or use a purge transfer needle ( Fig. 11.2.2 ) to allow air back into the capped bottle while extracting water. Figure 11.2.2 Example of purge transfer needle use to extract water from a capped collection bottle Single-port Hypodermic Needle If a needle syringe is used, the needle diameter shall be 10 gauge or larger. Both the use of a single- port hypodermic-needle syringe and the diameter (gauge) of the needle shall be documented. The cap shall be removed, or another needle shall be inserted through the septum to allow air into a capped bottle. Informative advisory —A single-port hypodermic-needle syringe ( Fig. ) should be avoided but is permitted for use in the laboratory to transfer a water sample. Figure Example of a single-port hypodermic needle syringe