Lab Matters Fall 2024 | Page 41

APHL 2024 POSTER ABSTRACTS selected for SARS-CoV-2 amplicon sequencing ( n = 58 ). Negative controls from air samplers placed in empty rooms were also included ( n = 6 ). Fifty-one of 58 ( 87.9 %) air samples were SARS- CoV-2 positive via qPCR . Median SARS-CoV-2 genome coverage for air samplers placed in occupied rooms was 98.3 %. Forty-seven of 58 ( 81.0 %) air samples yielded over 50 % genome coverage and 33 of 58 ( 56.9 %) yielded over 95 % genome coverage . All negative control samples were below 50 % genome coverage . There was a correlation between SARS-CoV-2 Ct and percentage genome coverage ( Spearman r = 0.87 ; p = < 0.05 ), with samples having a Ct below 33 generally yielding over 95 % genome coverage . Multiple SARS-CoV-2 lineages were detected in most air samples , with Pango lineages detected corresponding to lineages reported in contemporaneous clinical specimens .

Conclusions : These preliminary data indicate that pathogen detection via air sampling is technically feasible and could be an important new tool for pathogen genome characterization and viral lineage surveillance . Monitoring of air in healthcare and congregate settings could enable early outbreak detection and enhance citywide surveillance of emerging threats and variants .

Presenter : Sofiya Bobrovska , sofiya _ bobrovska @ rush . edu

Concentration of Nano- and Microplastic Particles From Environmental Samples

D . Alburty , D . Goad , InnovaPrep

Nano- and microplastic particles are ubiquitous in the global environment and are an emerging topic of human health research . These particles have been found in our air , water , soils and foods . The Concentrating Pipette Select is a widely used bioparticle concentrator that can also be used to separate and concentrate nano- and microplastic particles for observation and analysis . This process is accomplished through collection of the particles in the lumen of hollow fiber ultrafilters or submicron filters , passing the liquid matrix to waste . After concentrating the particles in the lumen of the filters , they are swept out using an elution fluid of wet foam . Following elution , the fluid collapses leaving the particles in a very small final volume of fluid . Data are presented showing the concentration from environmental water of spikedin commercially available nano- and microplastic polystyrene particles .

Presenter : David Alburty , dalburty @ innovaprep . com

Development of LC-MS / MS Method for Quantitation of 1,25- and 24,25-Dihydroxyvitamin D Metabolites in Equine Serum Compared to Commercial Radioimmunoassay

G . Serpe , J . Zyskowski , J . Buchweitz , Michigan State Veterinary Diagnostic Laboratory

Serum 25-hydroxyvitamin D ( 25 ( OH ) D ) serves as an indicator of vitamin D status in most animal species . It is metabolized to its bioactive metabolite , 1,25-dihydroxyvitamin D ( 1,25 ( OH ) 2D ) and catabolic product 24,25-dihydroxyvitamin D ( 24,25 ( OH ) 2D ) in the kidney . Most clinical veterinary diagnostic laboratories currently make use of radioimmunoassay ( RIA ) for the quantitation of total 1,25 ( OH ) 2D and interpretation of its clinical significance . Liquid chromatography-tandem mass spectrometry ( LC – MS / MS ), however , offers a far superior method that is more sensitive , specific and accurate in quantitation than immune-based alternatives . Moreover , LC – MS / MS allows for the simultaneous measurement of multiple analytes as compared with the single-target nonspecific binding of antibodies . Accordingly , it has become the gold standard in human clinical diagnostic laboratories . The purpose of this study was to develop and validate an LC – MS / MS method to simultaneously measure the dihydroxyvitamin D metabolites 1,25 ( OH ) 2D3 , 1,25 ( OH ) 2D2 and 24,25 ( OH ) 2D3 in animal serum for veterinary clinical diagnostic laboratory applications . Serum samples were first prepared by supported liquid extraction ( SLE ) with an accompanying deuterated internal standard and the eluate was derivatized with 2-Nitrosopyridine . Derivatized samples were introduced to the LC – MS / MS , ionized by electrospray ionization ( positive-ion mode ) and detected by multiple-reaction monitoring ( MRM ). The assay was linear between 24 to 2400 pmoles / L for 24,25 ( OH ) 2D3 with an R = 0.995 and 12 to 240 pmoles / L for both 1 , 25 ( OH ) 2D3 and 1,25 ( OH ) 2D2 with an R = 0.999 and 0.998 , respectively . The limit of quantitation ( LOQ ) for 24,25 ( OH ) 2D3 was 24 pmoles / L and the LOQ for 1,25 ( OH ) 2D3 and 1,25 ( OH ) 2D2 was 12 pmoles / L each . Percent CV values were less than 15 for all calibrators within the defined diagnostic ranges . Equine serum 1,25 ( OH ) 2D concentrations from 10 animals were comparatively determined by LC-MS / MS summation of 1,25 ( OH ) 2D3 and 1,25 ( OH ) 2D2 and competitive RIA ( DiaSorin ) for total 1,25 ( OH ) 2D . Values obtained by RIA exhibited a mean positive bias of 0.46 pmoles / L by Bland- Altman analysis . Passing-Bablok fit gave a slope of 0.996 and an intercept of -0.646 and an R = 0.939 . This method will assist veterinary clinicians in more clearly understanding the role of vitamin D metabolism through various life-stages and disease processes , as well as providing a more accurate quantitative accounting of dihydroxyvitamin D metabolites .

Presenter : Gianna Serpe , serpegia @ msu . edu

The Development of a High Throughput Solid Phase Extraction Method for PFAS in Human Serum Using an Automated Janus ® Workstation

Z . LI 1 , C . Xu 1 , T . Fan 2 , S . O ’ Leary 1 , D . Mathes 1 , A . Lin 1 , C . Lestician 1 , L . Zhong 1 , New Jersey Public Health Environmental Laboratories 1 , New Jersey Department of Health 2

Per- and polyfluoroalkyl substances ( PFAS ) are a large group of persistent pollutant chemicals considered to be a contaminant of interest in human health . PFAS can be tested in human serum with ultra high-performance liquid chromatography-tandem mass spectrometry ( UHPLC-MS / MS ) after they are isolated by the solid phase extraction ( SPE ). The PFAS method used at the New Jersey Public Health Laboratories ( NJPHL ) employs an automated sample micro-SPE prior to injection and separation . Since these events occur sequentially , sample throughput is a limitation of this approach . We aim to optimize this SPE process and automate the presample preparation steps . To develop this method , we aim to develop a program on the Janus ® for the pre- and sample preparations and validate the method for precision and accuracy . An SPE protocol was created using “ WinPREP ® for Janus ® ” software on Janus ® workstation . The protocol is built by combining pipetting orders on the list provided by the software and run on the Janus ® Application Assistant program . The protocol combines 50 μL human serum sample , 50 μL internal standard and 200 μL acetonitrile . This mixture is centrifuged at 4,000 RPM for 20 minutes . 200 μl of the