APHL 2024 POSTER ABSTRACTS more comprehensive understanding of the PFAS profile within a given sample .
The HRAM PFAS workflow has been developed to be approachable specifically for state and municipality labs that require ease of use , flexibility to sample matrix and both precise mass measurements and high-resolution mass spectrometry , thereby enhancing the accuracy and reliability of PFAS compound annotation . The Compound Discoverer software facilitates efficient data processing and analysis , enabling retrospective review of the PFAS profile as new health concerns arise . Through the integration of HRAM Orbitrap technology and Compound Discoverer software , a faster and more efficient screening method for PFAS compounds is achieved , ultimately contributing to the safeguarding of public health and safety .
Furthermore , an overview of available sample preparation automation technology will be presented , specifically focusing on its application in water , food contact materials and diluted fluorinated firefighting foams . This discussion identifies areas where sample processing times can be improved , thereby streamlining the analytical workflow .
Presenter : Cynthia Grim , cynthia . grim @ thermofisher . com
PFAS Detection in Frozen Water
J . Fennessey , Colorado Department of Public Health and Environment
Per- and polyfluorinated substances ( PFAS ), synthetic chemicals used throughout industry including in numerous nonstick and water resistant products , have been linked to cancer , high cholesterol levels , weakened vaccine response in children and numerous other health problems . Despite increased public awareness of PFAS toxicity , the chemicals remain a major health threat . Since the 1950s , PFAS have contaminated virtually every living thing and ecosystem on the planet . The carbon-fluoride bonds of PFAS render them extremely resistant to destruction , making remediation extremely difficult . Even phased-out PFAS are still being detected in water and blood samples . The presence and concentration of specific PFAS contaminants can be determined by EPA method 537.1 : Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking Water by Solid Phase Extraction and Liquid Chromatography / Tandem Mass Spectrometry ( LC / MS / MS ).
One of the requirements for EPA Method 537.1 is that sample water must not be frozen . The Colorado State Public Health Laboratory will test to what extent this affects PFAS concentration in the sample . Future investigation by the Colorado Department of Public Health and Environment ( CDPHE ) of river or groundwater samples for PFAS may include collection of environmental samples after a thaw . There is also the possibility of customer samples being accidently frozen before shipment . Through the testing of frozen spiked samples , we can determine the actual level of bias introduced by the freezing . Furthermore , we can also take the opportunity to see how hardness and total organic content is affected .
Samples to be tested include five contrived samples — two high samples spiked with PFAS measuring 30 parts per trillion ( ppt ), two low samples spiked with 2 ppt and one unspiked sample — along with the Method Blank and Laboratory Fortified Blank . Samples will be spiked with 300 ppm of calcium and magnesium and 2 ppm of total organic content . All samples will be frozen at -20 ° C . After four days , one high and one low sample will be taken out and thawed . The remaining samples will remain in the freezer for 28 days total . After 28 days , the samples will be removed from the freezer , thawed and analyzed .
By completing this study , the laboratory will be able to assess the effects of freezing a water sample on the concentration of PFAS present and address future concerns related to the biases introduced .
Presenter : John Fennessey , john . fennessey @ state . co . us
Validation of CDC ’ s LN34 Pan-Lyssavirus Multiplex Real -time PCR Assay for Postmortem Diagnosis of Rabies in Animals .
L . Castro , E . Wong , M . Jacinto , G . Masinde , J . Lei , H . Li , San Francisco Public Health Laboratory
Rabies is a preventable viral disease transmitted through the bite of a rabid animal . The gold standard for rabies diagnosis is direct fluorescence antibody ( DFA ). DFA is a rapid and sensitive method that detects the presence of rabies antigens in brain tissue . However , the accuracy of the test depends on the quality of the brain tissue , the availability of the antirabies conjugates and the microscopist experience . Because of the deadly nature of this virus , it is necessary to have standardized , rapid , sensitive , specific , economical and reliable diagnostic tests . We aimed to develop and validate a multiplex RT-PCR assay using the CDC ’ s LN34 pan- Lyssavirus primers and probes that simultaneously detect LN34 and β-actin targets on RNA extracted from animal brain tissue using the Roche Magna Pure 24 instrument . The oligonucleotide primers and probes and synthetic controls were designed according to published sequences ( CDC ’ s LN34 real-time RT-PCR and DOI : 10.1371 / journal . pntd . 0005258 ). We evaluated the assay using 42 DFApositive and 33 DFA-negative animal brain tissue previously tested at SFDPHL and at CDPH ’ s VRDL . We compared the performance of two enzymes : ABI Ag-Path ID One-step RT PCR kit ( CDC ) and ABI TaqPath™ 1-Step Multiplex Master Mix ( No ROX ) ( SFPHL ) and single and multiplexed primers / probes . The analytical sensitivity for the LN34 and β-actin targets was one copies / ml respectively . The sensitivity and specificity were 100 %. The LN34 intra-assay precision ranged from 0.5- 3.8 CV % and inter-assay precision ranged from 1.7-6.9 CV %. The β-actin intra-assay precision ranged from 0.4- 1.9 CV % and inter-assay precision ranged from 0.8-7.2 CV %. We developed a multiplex real-time PCR assay that when used in conjunction with DFA can rapidly and accurately detect rabies virus in animal tissue .
Presenter : Monica Jacinto , monica . jacinto @ sfdph . org
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Fall 2024 LAB MATTERS 43 |