Passive Samplers Research Articles

Building an eDNA surveillance toolkit for invasive rodents on islands: can we detect wild-type and gene drive Mus musculus?

Invasive management strategies range from preventing new invasive species incursions to eliminating established populations, with all requiring effective monitoring to guide action. The use of DNA sampled from the environment (eDNA) is one such tool that provides the ability to surveille and monitor target invasive species through passive sampling. Technology being developed to eliminate invasive species includes genetic biocontrol in the form of gene drive. This approach would drive a trait through a population and could be used to eliminate or modify a target population. Once a gene drive organism is released into a population then monitoring changes in density of the target species and the spread of the drive in the population would be critical. In this paper, we use invasive Mus musculus as a model for development of an eDNA assay that detects wild-type M. musculus and gene drive M. musculus. We demonstrate successful development of an assay where environmental samples could be used to detect wild-type invasive M. musculus and the relative density of wild-type to gene drive M. musculus. The development of a method that detects both wild-type M. musculus and a gene drive M. musculus (tCRISPR) from environmental samples expands the utility of environmental DNA. This method provides a tool that can immediately be deployed for invasive wild M. musculus management across the world. This is a proof-of-concept that a genetic biocontrol construct could be monitored using environmental samples.

From Trophic Magnification Factors to Multimedia Activity Ratios: Chemometers as Versatile Tools to Study the Fate of Hydrophobic Organic Compounds in Aquatic Ecosystems.

We applied passive equilibrium sampling using silicone-based chemometers to nine biota species, sediment, and water in a multimedia aquatic ecosystem. They allowed for direct comparison of the concentration of regulated and emerging hydrophobic organic compounds in the silicone across species as well as the comparison of biota with sediments and water. We derived chemometer-based trophic magnification factors (TMFs) of diverse compounds that agreed with the traditionally derived TMFs. Our exploratory work in water demonstrated that equilibrium with newly designed chemometers can be achieved in few days for compounds with a log KOW up to 6. We calculated activity ratios, dividing the concentrations in the silicone equilibrated with biota by those equilibrated with the abiotic exposure media (sediments and water), assessing the thermodynamics of bioaccumulation and the equilibrium state between the ecosystem compartments. They confirmed that the biota were below equilibrium partitioning relative to sediments and water, as other studies have described. Silicone-based chemometers open up new opportunities and applicability in multimedia aquatic ecosystems for studies that rely on equilibrium partitioning of the in-situ mixtures of chemicals, such as multimedia assessments or application of effect-based methods.

Field monitoring of copepodamides using a new application for solid phase adsorption toxin tracking

AbstractChemical signaling is ubiquitous in the marine environment. Plankton rely on chemical signals to find mates, hunt prey, and respond to threats, and these small‐scale interactions can propagate into community‐wide cascades and large‐scale ecological changes. The chemical signaling exchange in the open ocean is poorly understood, and fundamental information about concentrations and spatiotemporal variability is lacking. Passive sampling has been used to monitor a wide range of dissolved chemicals, including anthropogenic pollutants and harmful algal toxins, but it is not generally applied to the study of marine chemical ecology. Here we test the compatibility of two resins commonly used for passive sampling via solid phase adsorption toxin tracking (SPATT), Diaion® HP20 and Sepabeads® SP207, with copepodamides, a group of polar lipid signaling compounds produced by copepods. We developed extraction and analysis methods that align with current SPATT practices for algal toxins and show the first measurements of copepodamides from Monterey Bay in California. In lab trials, mean copepodamide recovery from HP20 resin was approximately 240% greater than SP207. In addition, copepodamides were found to have a mean half‐life of 34 h in seawater. Adsorption to HP20 stabilized dissolved copepodamides, increasing the mean recovery after 168 h from 0.62% in seawater to 65.2% from SPATT. Results suggest that SPATT is a sensitive and effective tool for obtaining integrated copepodamide concentrations, spotlighting a novel method to include information from copepod mesozooplankton in time series and field studies.

Microplastics in indoor and outdoor environments in China: characteristic and human exposure risk assessment

Human exposure to microplastics (MPs) has led to global health concerns, but our knowledge of the characteristics and human exposure of airborne MPs is limited. Adults may have different exposure patterns and lifestyles from other age groups. Therefore, this study aims to determine the MPs exposure among adults at various locations and during different time periods. MPs were collected and detected through passive sampling and laser direct infrared (LDIR) imaging (Agilent 8700) at five locations including: dormitory, dining hall, office, library, and outdoor; the sampling lasted for 3 months. The highest concentration of indoor MPs was detected in the dining hall (193 ± 8 MPs/m2/day), whereas the lowest was detected in the library (113 ± 4 MPs/m2/day). Among all sampling points, the outdoor locations had the lowest MPs concentrations (92 ± 4 MPs/m2/day). The length of the MPs ranged from 10 μm－760 μm. Pellets (54.6%), fibres (21.6%), and fragments (23.8%) were the shapes identified in this research. Polyamide (51.7%) was the most prevalent polymer type at all sampling points. This article conducted respiratory exposure assessments of MPs for males and females of different ages (age ranges: 18－21; 21－30; 31－40; 41－60) in different environments and at different times. For both weekends and weekdays, dormitories contributed the most to MPs respiratory exposure. Males aged 31－40 years had the highest exposure with an average of 266 particles/day, whereas females aged 18－21 (157 particles/day) had the lowest exposure. Differences in respiratory rate according to age and gender may be the main reason for these results. These findings indicate that further research into the adult MPs inhalation exposure under indoor and outdoor conditions is crucial.

Mycological analysis in three schools over four seasons using passive air sedimentation

The aim of the study is the isolation and identification of fungi using passive air sedimentation. This study analyzed 540 mycological samples from three primary schools in Zenica, collected in September, December, February, and May. Each season, 135 samples were taken from five rooms (two classrooms, a gym, a locker room, and a library) in each school. Samples were collected three times daily at three different heights with 15-minute exposure times. Samples were refrigerated and transported in sterile bags, incubated for 24 hours, and inoculated on specific agars with and without additives. Plates were incubated at 37°C and 25°C for up to 7 days, followed by examinations. Petri dishes were used for passive air sampling, and colonies were counted after incubation. The average number of microorganisms (CFU/m³) was calculated using Omeliansky’s method. Statistical methods included the Chi-squared test and p-value. Colony appearance was assessed visually and microscopically using a light microscope. Growth rate, size, structure, and color changes were monitored. In September, the highest mold concentrations were at H. Kikić Primary School (796 CFU/m³, not significant), M. Dizdar Primary School (1260 CFU/m³, not significant), and A. Šantić Primary School (3980 CFU/m³, significant). Penicillium spp. and Alternaria spp. were most prevalent, with Alternaria spp. significant at H. Kikić Primary School. In December, the highest mold/yeast concentrations were at H. Kikić Primary School (4578 CFU/m³, not significant), M. Dizdar Primary School (1924 CFU/m³, significant), and A. Šantić Primary School (2587 CFU/m³, not significant). Penicillium spp. was most prevalent. In February, the highest mold concentrations were at H. Kikić Primary School (4578 CFU/m³, not significant), M. Dizdar Primary School (2786 CFU/m³, not significant), and A. Šantić Primary School (5838 CFU/m³, significant). Aspergillus spp. and Penicillium spp. were equally prevalent. In May, the highest mold/yeast concentrations were at H. Kikić Primary School (6568 CFU/m³, significant), M. Dizdar Primary School (3516 CFU/m³, significant), and A. Šantić Primary School (7431 CFU/m³, significant). Aspergillus spp. was most prevalent. These findings highlight the importance of regular monitoring and implementing appropriate ventilation measures to manage air quality and health concerns in schools.

Assessment of residual pesticides and other organic pollutants using passive samplers in Can Tho River, Vietnam, and Cagayan de Oro River Basin, Philippines

Agriculture-dependent developing Southeast Asian countries need to assess residual pesticides in receiving water from agricultural runoff as one of the basis for the establishment of baseline data. Monitoring residual pesticides in surface water is challenging due to pesticides’ irregular/intermittent emission and low solubility in water. To address the challenge of pesticide assessment, passive samplers composed of silicon rubber sheets (SR) and speedisk (SD) were used to capture hydrophobic and hydrophilic organic pesticides and other organic pollutants, respectively. Samplers were submerged uninterruptedly for at least 30 days in three selected sites in Can Tho River, Mekong Delta, Vietnam, and Cagayan de Oro River Basin, Philippines, for 2 years. Passive samplers (SR spiked with 232 pesticides) captured 83 and 69 residual pesticides at concentrations of ng/L levels in Vietnam and the Philippines, respectively, which is unattainable through conventional grab sampling methods. Trace concentrations of banned compounds such as OCPs, PCBs, and PAHs were also detected at pg./L levels. The success of this alternative methodology can be attributed to the combination of passive samplers tailored for nonpolar (water-insoluble) and polar (water-soluble) organic contaminants coupled with sensitive analytical instruments, including GCMSMS and LCMSMS.

How far should adjacent pan traps be placed for bee sampling?

AbstractAmong several methods of active and passive sampling bees (Hymenoptera: Apoidea), pan traps, also known as bee bowls, are commonly utilized for their efficiency and as a means of avoiding collector bias. When comparing pan‐trap samples using traditional statistical methods, the assumption of independence among samples needs to be met. To determine the necessary distance between pan traps to obtain independent samples, we investigated spatial dependence in bee catches using pan traps at four sites. At each site, a regular grid of pan traps was laid out, with each sample having two colors of fluorescent trap (i.e. blue and yellow). These trap pairs were separated by 10 m, with 100–109 points in the grid. In addition, five points within the grid were chosen randomly, and an additional 40 traps were placed at 2 m and 4 m from the five sample points to sample bees at a minimum 2 m trap distance. Traps collected bees for five consecutive days and bees were counted for each point and each trap color. Bee count data were analyzed using geostatistics to determine the spatial dependency in trap catches for yellow traps, blue traps, and both colors combined. The highest value of the range parameter of the semivariogram found across the four sites and pan trap colors was 17 m for blue traps. From this, we recommend a conservative minimum distance of 17 m between adjacent pan traps to obtain spatially independent samples for optimizing sampling plans when independent samples are necessary.

Are passive collectors effective samplers of microbes in natural aquatic systems?

Biodiversity surveys of aquatic systems often include DNA metabarcoding analyses of environmental samples that are collected through filtration of large volumes of water. The standard practice of sterile collection and filtration in or near the field sites is challenging to implement in remote locations, and filtration of large volumes is a limiting step, especially for water from highly productive systems or with high suspended sediment loads. Recent trials have shown that passive samplers can be effective for aquatic metabarcoding to document metazoan diversity, but that this approach needs to be trialed under a wider variety of conditions and across more diverse taxa. Here we assess the utility of passive sampling for documenting the diversity of bacteria in six tropical aquatic environments (one lake, one reservoir, two mountain streams and two blackwater rivers). We find that passive collectors generally recover significantly higher diversity of Bacteria compared to filtered samples, despite capturing significantly less overall DNA than active water filtering. However, the communities captured by the two methods show significant differences within sites, with only 26% of the Bacteria ASVs recovered by both methods. These differences were largely driven by relative abundances of taxa within Actinobacteriota, Campilobacterota, Desulfobacterota, and Proteobacteria. Our results demonstrate that passive collectors can be a cost-effective solution for monitoring aquatic microbial diversity but that the two methods are not interchangeable. Additional work is necessary to understand the selectivity of both passive collectors and active water filtering for eDNA studies.

Deodorising Garlic Body Odour by Ingesting Natural Food Additives Containing Phenolic Compounds and Polyphenol Oxidase

Garlic consumption is a well-known cause of unpleasant breath and body odour, with volatile organosulfur compounds, such as diallyl disulfide (DADS) and allyl methyl sulfide (AMS) responsible for the characteristic odour. Certain foods that are rich in polyphenols (PPs) and polyphenol oxidase (PPO) are known to deodorise garlic breath. However, no study into garlic body odour has been reported owing to the very low amounts of emitted volatile organosulfur compounds. Herein, we aimed to demonstrate the effects of ingesting natural food additives rich in both PPs and PPO on the emissions of skin-derived DADS and AMS using a passive flux sampler in conjunction with gas chromatography–mass spectrometry. Three healthy male subjects were subjected to garlic-consumption testing, with all subjects commonly observed to exhibit remarkably higher dermal DADS- and AMS-emission fluxes after consuming 45 g of cooked garlic, which then gradually decreased toward their initial baseline levels. In comparison, remarkably lower emission fluxes of both organosulfur compounds were observed after consuming a natural food additive following garlic consumption in a dose-dependent manner. The optimal amount of ingested natural food additive required to reduce garlic body odour was found to be 1–2 g. Considering the metabolic pathway associated with garlic-derived sulfur compounds and elimination reactions involving PPs and PPO, allyl mercaptan is likely to be a key substance involved in reducing garlic body odour through the ingestion of natural food additives.

Intensive, Real-Time Data Collection of Psychological and Physiological Stress During a 96-Hour Field Training Exercise at a Senior Military College: Feasibility and Acceptability Cohort Study.

Poor physical fitness, stress, and fatigue are factors impacting military readiness, national security, and economic burden for the United States Department of Defense. Improved accuracy of wearable biosensors and remote field biologic sample collection strategies could make critical contributions to understanding how physical readiness and occupational stressors result in on-the-job and environment-related injury, sleep impairments, diagnosis of mental health disorders, and reductions in performance in war-fighters. This study aimed to evaluate the feasibility and acceptability of intensive biomarker and biometric data collection to understand physiological and psychological stress in Army Reserved Officer Training Corps cadets before, during, and after a 96-hour field training exercise (FTX). A prospective pilot study evaluated the feasibility and acceptability of multimodal field data collection using passive drool saliva sampling, sweat sensors, accelerometry, actigraphy, and photoplethysmography. In addition, physical fitness (Army Combat Fitness Test), self-reported injury, and psychological resilience (Brief Resilience Scale) were measured. A total of 22 cadets were included. Two were lost to follow-up due to injury during FTX, for a retention rate of 91%. Assessments of performance and psychological resilience were completed for all remaining participants, resulting in 100% testing adherence. All participants provided saliva samples before the FTX, with 98% adherence at the second time point and 91% at the third. For sweat, data collection was not possible. Average daily wear time for photoplethysmography devices was good to excellent, meeting a 70% threshold with data collected for ≥80% of person-days at all time points. Of the participants who completed the FTX and 12 completed a post-FTX acceptability survey for a response rate of 60%. Overall, participant acceptance was high (≥80%) for all metrics and devices. This study demonstrates that wearable biosensors and remote field biologic sample collection strategies during a military FTX have the potential to be used in higher stakes tactical environments in the future for some, but not all, of the strategies. Overall, real-time biometric and biomarker sampling is feasible and acceptable during field-based training and provides insights and strategies for future interventions on military cadet and active-duty readiness, environmental stress, and recovery.

Lessons learnt from the use of passive samplers to measure ammonia emissions in multi-plot experiments

Lessons learnt from the use of passive samplers to measure ammonia emissions in multi-plot experiments

Potential health risks of inhaling hazardous chemical exposures at fuel stations: a pilot study in a hot, arid environment

In recent years, there has been a growing focus on the issue of exposure to hazardous chemical compounds and the potential health risks associated with them. Fuel stations play a critical role in society, supporting the transportation industry and serving the general public. However, the routine activities at these stations expose workers and customers to dangerous chemical compounds, posing potential health risks. As part of a pilot study, the exposure of workers and customers to hazardous chemical compounds at fuel stations in Kuwait, characterized by its hot and arid environment, was investigated. The study specifically looked at volatile organic compounds (VOC) concentration and their effects on human health. Three hundred-eight air samples were collected in a hot, arid environment, focusing on fuel stations. Two sampling methods were used in this pilot study: personal inhalation exposure using active sampling and workplace air sampling using passive sampling. Samples were collected in fuel filling areas, indoor control rooms, and through personal exposures, adhering to ISO procedures (EPA TO-17). The study also assessed the non-carcinogenic and carcinogenic risks to human health to potential exposure to hazardous hazardous chemicals. The findings revealed that hazardous chemicals levels in the pump area were lower than those in the indoor control rooms. Workers’ inhalation exposure to hazardous chemicals remained below the international occupational exposure limit (OEL). However, the study identified unsafe inhalation exposure levels to Benzene, which could have adverse carcinogenic effects. In contrast, exposure to ethylbenzene was found to be within safe limits, with no associated carcinogenic effects. This study underscores the importance of identifying the risks associated with exposure to hazardous chemical compounds to minimize human health risks and promote a safe working environment.

Archetypes of Spatial Concentration Variability of Organic Contaminants in the Atmosphere: Implications for Identifying Sources and Mapping the Gaseous Outdoor Inhalation Exposome.

Whereas inhalation exposure to organic contaminants can negatively impact human health, knowledge of their spatial variability in the ambient atmosphere remains limited. We analyzed the extracts of passive air samplers deployed at 119 unique sites in Southern Canada between 2019 and 2022 for 353 organic vapors. Hierarchical clustering of the obtained data set revealed four archetypes of spatial concentration variability in the outdoor atmosphere, which are indicative of common sources and similar atmospheric dispersion behavior. "Point Source" signatures are characterized by elevated concentration in the vicinity of major release locations. A "Population" signature applies to compounds whose air concentrations are highly correlated with population density, and is associated with emissions from consumer products. The "Water Source" signature applies to substances with elevated levels in the vicinity of water bodies from which they evaporate. Another group of compounds displays a "Uniform" signature, indicative of a lack of major sources within the study area. We illustrate how such a data set, and the derived spatial patterns, can be applied to support the identification of sources, the quantification of atmospheric emissions, the modeling of air quality, and the investigation of potential inequities in inhalation exposure.

Passive sampling of polycyclic aromatic hydrocarbons with low-density polyethylene: Equilibration limitations in aqueous suspensions

Polyethylene (PE) and other polymers are widely and successfully used as passive samplers for organic pollutants in the environment. This study provides high-resolution experimental data from batch shaking tests on the uptake, reversibility, and linear equilibrium partitioning of polycyclic aromatic hydrocarbons (PAHs) using two different PE sheets of 30 µm and 80 µm thickness. Kinetics for phenanthrene are well described by a mechanistic first-order model with mass transfer limited by an aqueous boundary layer (with a mean thickness of 170 µm). Equilibration in laboratory batch systems during uptake and desorption is very rapid with characteristic times of 1–2 h but this depends on the boundary condition, e.g., the ratio of PE mass to water volume. Therefore, equilibration of PE in other setups, e.g., in soil slurries or sediment suspensions, may take orders of magnitude longer because the boundary condition for PE changes from finite to infinite bath conditions (soil or sediment particles may keep the concentration in water almost constant). Solid precipitates for high molecular weight PAHs explain partition coefficients below expected values because of kinetic limitations in such a system. Nevertheless, passive sampling can be employed safely if such limitations are considered; furthermore, partition coefficients can be estimated accurately by empirical relationships (e.g., within 0.1 log unit) based on molecular weight, octanol/water partition coefficients, or subcooled liquid solubilities.

Airborne microplastic monitoring: Developing a simplified outdoor sampling approach using pollen monitoring equipment

A novel, yet simple, airborne microplastic (MP) sampling approach using global pollen monitoring equipment was applied to identify, characterise and quantify outdoor airborne MPs for the first time. Modification of Burkard spore trap tape adhesive provided particle capture and facilitated downstream spectroscopy analysis. 36 polymer types were identified from a total of 21 days sampling using Burkard spore traps at two locations (United Kingdom and South Africa). MPs were detected in 95 % of daily samples. Mean MP particle levels were 2.0 ± 0.9 MP m-3 (11 polymer types) in Hull (U.K.), during March, 2.9 ± 2.0 MP m-3 (16 types) in Hull in July, and 11.0 ± 5.7 MP m-3 (29 types) in Gqeberha, (S.A.) in August 2023. The most abundant polymer type was nylon (Gqeberha). The approach was compared with two passive sampling methods whereby 27 polymer types were identified and of these, 6 types were above the limit of quantification (LOQ), with poly(methacrolein:styrene) (PMA/PS) the most abundant. Irregularly shaped MPs < 100 µm in length were predominant from all sampling approaches. For the first time, airborne MPs were chemically characterised and quantified using volumetric pollen sampling equipment, representing a viable approach for future airborne MP monitoring.

Analysis of emission of volatile organic compounds and thermal degradation in investment casting using fused deposition modeling (FDM) and three-dimensional printing (3DP) made of various thermoplastic polymers.

The study examined the degradation process of various types of polymers used to form models using the fused deposition modeling (FDM) and three-dimensional printing (3DP) methods and used in the investment casting method. Commercial filaments made of polylactide (PLA), acrylonitrile butadiene styrene terpolymer (ABS), high-impact polystyrene (HIPS), polyamide 12 (PA12), poly(methyl methacrylate) (PMMA), and polypropylene (PP) were used to produce gypsum molds. The assessment included organic volatile compounds (VOCs) released during mold heating and model degradation, which is characteristic of this technological process. The screening qualitative chromatographic analysis of decomposition products sampled from various points of the production hall made it possible to define potential threats related to the processing of selected polymers and the necessary preventive measures. Furthermore, passive diffusion-type samplers were used at the sampling stage of VOCs emitted to the gaseous phase to reduce nuisance and user interference. Studies have been completed to characterize the thermoplastic polymer degradation process. The coupled thermogravimetry (TGA) with analysis of gaseous products by infrared spectroscopy with Fourier transformation (FT-IR) has been used. The presented results are the first to compare and rate the use of this still-developing novel aspect of castings by the method of fused models.

Fast On-Site Speciation and High Spatial Resolution Imaging of Labile Arsenic in Freshwater and Sediment Using the DGT-SERS Sensor.

Diffusive gradients in thin films (DGT) technique is renowned for in situ passive sampling but not for rapid on-site analysis, whereas surface-enhanced Raman spectroscopy (SERS) excels in ultrasensitive on-site detection but is limited by substrate contamination from complex matrices. Here, a hierarchical nanostructure of silver (Ag) mirror-supported large Ag nanoparticles (∼120 nm) was grown in situ in polyacrylamide hydrogel with a restricted pore size (PAM/Ag mirror/AgNPs) to serve as both the DGT binding phase and the SERS substrate. The substrate exhibited a maximum electric field enhancement factor of 9.9 × 108 and a signal relative standard error of 4.8%. Using the DGT-SERS sensor, As(III) and As(V) in freshwater were simultaneously detected at limits of 0.9 and 0.8 μg L-1, respectively, applicable across a wide range of environmental conditions. The DGT-SERS effectively mitigated the interfacial reduction of As(V) caused by humic acid by excluding it from plasmonic hotspots through size exclusion of the diffusive layer. The Raman analysis of a DGT sample in the field requires only 2 s using a portable spectrometer without DGT device disassembly. More importantly, the DGT-SERS captured the first two-dimensional image of As(III) and As(V) in one DGT at the micron scale resolution, revealing their spatially supplementary distribution patterns at the sediment-water interface. This study paves the way for next-generation speciation imaging DGT and the application of SERS in complex environments.

Assessment of VOCs emission inventory in Seoul through spatiotemporal observations using passive and online PAMS measurements

We have conducted a quantitative analysis of volatile organic compounds (VOCs) in Seoul from September 2022 to June 2023, employing passive air samplers (PAS) at 25 sites and continuous monitoring at five photochemical assessment monitoring stations (PAMS). Comparing VOCs concentrations and compositions from PAS and PAMS during the same time periods, we found that most VOCs showed no significant difference (p-value >0.05) between the methods, except for olefins, which were overestimated by 24 % in passive sampling, confirming PAS as an effective tool for assessing the spatial distribution of VOCs species over large areas. Throughout Seoul, median values of total volatile organic compounds (TVOCs) concentrations collected with passive samplers remained stable with a standard deviation of 1.22 ppbv, typically ranging from 11 to 13 ppbv, except for an increase during winter in the southwestern regions of the city, where intense industrial and vehicular emissions are reported in the current Clean Air Policy Support System (CAPSS) emissions inventory. Positive matrix factorization (PMF) analysis using the passive data revealed general consistency in the spatial distribution of area and road emissions when compared with CAPSS emission inventory, although localized discrepancies were observed. In quantitative assessments of TVOCs comparing PAS observations with emission-based models, modeled values were within 1.5 times the interquartile range of observed PAS concentrations over Seoul. However, the lack of detection of emission hotspots in southeastern Seoul in the PAS data, coupled with the omission of photochemical loss in our dispersion-only models, indicates that the current CAPSS emission inventory may significantly underestimate actual ambient VOCs levels, especially in summer.

9296 A Novel LC-MS/MS Salivary Fludrocortisone Method With Potential for Monitoring in Adrenal Insufficiency Patients

Abstract Disclosure: M. Dolan: None. D. Marshall: None. J. Hawley: None. N. Reisch: None. B.G. Keevil: None. Fludrocortisone (FC) is a fluorinated exogenous mineralocorticoid used to treat conditions associated with adrenal insufficiency including Addison’s disease and classic congenital adrenal hyperplasia (CAH). The mineralocorticoid action of FC allows the drug to compensate for aldosterone deficiency, thus helping to maintain blood pressure and other homeostatic mechanisms. Optimising FC replacement is vital as under-replacement can cause dizziness and hypotension, whereas over-replacement can lead to cardiometabolic disturbances. Treatment in classic CAH patients, who are typically diagnosed as new-borns, is even more complex as the requirement for mineralocorticoid replacement decreases with age. Endocrine Society guidelines recommend that FC monitoring should involve the clinical assessment of symptoms, which can be non-specific, and regular blood pressure measurements. Plasma renin activity (PRA) should be measured if clinical changes occur, aiming towards the upper end of the reference range. The utility of PRA is debated due to methodological issues and the inherent variability of the analyte itself, which may not always represent FC replacement status. Therefore, investigation into alternative biochemical markers of FC replacement is required. Here we aimed to facilitate this by developing an LC-MS/MS method for the measurement of salivary FC. Method: A salivary FC LC-MS/MS assay has been developed and validated for use according to FDA and EMA guidelines. Passive drool samples from 10 clinical trial patients with classic CAH were collected on two separate occasions at select time points throughout the day (0800, 1200, 1600, 2000 and 2300h). In most patients the 0800h sample was taken pre-FC dose. Once in the laboratory the patient samples were extracted and analysed using the FC method to produce a FC concentration day curve. Results: The method analysis time was 2.1 minutes, with a mean recovery of 102% and limit of quantification of 5 pmol/L (2.1 pg/mL). No analytical interference was identified. Analysis of patient samples using the method showed the presence of FC allowing the production of day curves. In most patients, the pre-dose sample contained no FC, with the subsequent samples showing a peak FC concentration corresponding to the Cmax. After this the FC concentration gradually tapered off throughout the remainder of the day. Conclusions: We have developed a novel assay for the measurement of salivary FC, which may allow the calculation of the area under the curve. As an optimal FC dose has yet to be determined this method may facilitate more in-depth pharmacokinetic studies into FC metabolism and blood pressure control. Thereby identifying patients that are fast metabolisers or poor absorbers of the medication, enabling a non-invasive strategy to optimise patient care. Presentation: 6/1/2024

12260 Assessing The Impact Of Saliva Collection Devices On Analyte Recovery

Abstract Disclosure: D. Marshall: None. M. Dolan: None. M. Mctaggart: None. B.G. Keevil: None. Introduction: Analysis of saliva is gathering momentum, often conveying advantages over regular venepuncture, offering a convenient way of collecting multiple samples throughout the day with relative ease from the comfort of a patient’s home or workplace. The advent of more sensitive mass spectrometry equipment has opened the possibility of measuring analytes previously unsuitable, offering a multitude of steroid hormones for diagnosis and monitoring of a range of endocrine disorders. Traditionally, samples are collected onto a Sarstedt Salivette device comprising of a synthetic swab enclosed within a polypropylene tube. For certain analytes, the Salivette device is known to impede analyte recovery, resulting in the requirement for a passive drool sample which can be difficult and unpleasant to collect for some patients. Methods Previous work has been undertaken showing the SalivaBio Oral Swab (SOS) to have less of an impact on analyte recovery. Here, through addition of low, medium and high spikes and subsequent LC-MS/MS analysis of 19 different steroid hormones (11-dehydrocorticosterone, 11-deoxycorticosterone, 11-deoxycortisol, 11-hydroxyandrostenedione, 11-hydroxytestosterone, 11-ketoandrostenedione, 11-ketotestosterone, 17-hydroxyprogesterone, 18-hydroxycortisol, 18-oxocortisol, 21-deoxycortisol, aldosterone, androstenedione, corticosterone, cortisol, cortisone, dexamethasone, testosterone and tetrahydro11-deoxycortisol) we aimed to assess a broader repertoire of analytes and whether saliva collection devices impact on analyte recovery. Results With an acceptability criterion of 10% difference from baseline passive drool samples, Salivette devices were acceptable for 12 out of 18 analytes, SOS were acceptable for 16 analytes. Both devices were unacceptable for measurement of androstenedione, testosterone and 11-deoxycorticosterone. When 10% is deemed as an acceptable difference, the SOS performs better than the Salivette device for the steroid hormones investigated in this study. This may have implications for research studies, patient diagnosis and monitoring of endocrine disorders where saliva collection devices were previously deemed unacceptable due to issues with analyte recovery. Presentation: 6/2/2024