Attachment 10 - NIH Isothiazolinone.1714658465277.docx

Attachment 10: NIH Isothizolinone (Gas Chromatography-Mass Spectrometry)

Summary Isothiazolinones are used as non-oxidizing biocides for the control of microorganisms as fungi and bacteria in aqueous-based industrial water. The analysis method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography-mass spectrometry (GC-MS). If needed, derivatization with diazomethane after pre-concentration will be performed to improve its chromatographic performance.

Sample Collection NIH shall collect samples, and the Contractor shall pick up the samples from NIH Bethesda, Building 11. The Contractor shall provide NIH with sampling kits for collecting each sample.

The Contractor’s personnel assigned to pick up the samples shall be trained in sampling procedures, such as wearing gloves and eye protection when collecting samples. The Contractor shall rinse the bottle and cap three times with sample water and fill the bottle to within one to two inches from the top. They shall adhere to the correct procedures for sample collection, sample preservation, sample handling, sample identification, and prompt transfer of the sample to the laboratory. Remove any attachment from the tap such as hoses, filters, screens, or aerators. Flush the water for about 2-3 minutes or until the water temperature reaches a constant temperature.

Sample Preservation and Storage The Contractor shall preserve industrial water samples with sodium azide (NaN3) to promote the stability of the isothiazolines in the solution. Sample storage at 4 C is mandatory to preserve the target biocides.

Method Of Shipping and Duration The Contractor shall lace the sample into a cooler with ice for immediate delivery or shipment to the laboratory. The sample shall be received with a chain of custody (COC). The COC shall have the name of the sample collector, date and time of sample collection, signature or initial of the sample collector, location of the sample and type of sample to be analyzed.

Laboratory Procedure for Analysis The method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography-mass spectrometry (GC-MS). If needed, derivatization with diazomethane after pre-concentration will be performed to improve its chromatographic performance.

Maintenance Plan for The Instrument The Contractor shall perform maintenance on their equipment as outlined per the manufacturer’s instructions.

The maintenance protocol shall be available and be delivered to NIH upon request.

Calibration Procedure Switch on the GC instrument and open the carrier gas cylinders or run your gas mixer if you are using one. Adjust pressure and check the carrier gas flow rate, comparing setpoint to observed flows at different rates.

Analysis Method and Protocol The method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography–mass spectrometry (GC–MS).

Interferences Stability of the isothiazolinones in environmental waters is limited and sample storage at 4C is mandatory to preserve the target biocides

Fate Of Sample (Destruction or Return) If sample arrives at the laboratory past the specified holding time following the collection, the laboratory must reject the samples. NIH CUP shall collect another set of samples and ship back to the lab. Samples collected and sent to the lab without a chain of custody must be rejected. After analysis, the sample shall be discarded.

References https://pubmed.ncbi.nlm.nih.gov/17681349/