Spiked Samples Research Articles

Investigation into the linearity of the Roche c 702 carbamazepine assay.

Carbamazepine is an anticonvulsant drug which is monitored in patients due to toxic side effects. At Manchester University NHS Foundation Trust (MFT), carbamazepine is measured using Roche's Kinetic Interaction of Microparticles in Solution (KIMS) method on the c 702 platform. The assay has an upper limit of linearity of 20mg/L. Samples with concentrations above this limit should be identified and manually diluted. However, a poor EQA return from UK NEQAS for Tox and TDM Distribution 456 has highlighted an issue with the Roche KIMS assay. Sample A of the distribution had a carbamazepine concentration of 36mg/L but was underreported by several Roche users. This indicated that the assay was not consistently identifying high concentration samples which required a dilution. In this investigation, fresh frozen plasma was spiked with carbamazepine concentrations ranging from 15 to 40mg/L. The spiked samples and EQA material were analysed at two clinical laboratories using the Roche KIMS assay. Samples spiked with concentrations 20-30mg/L were not consistently identified for dilution by the analyser. This was observed at both hospital sites. Spike samples and EQA with concentrations >30mg/L were correctly identified at both sites. The manual dilution policy has been changed at MFT, so all samples with a carbamazepine level ≥15mg/L will be manually diluted. The problem was reported to Roche who are investigating the issue further. We would suggest that other laboratories look at validating their dilution protocols.

Interference from anti-drug antibodies on the quantification of insulin: a comparison of an LC-MS/MS assay and immunoassays.

Aim: This study aims to compare the anti-drug antibody (ADA) interference in four pharmacokinetic (PK) assays across different platforms (AlphaLISA, Gyrolab, LC-MS/MS) and to devise a strategy for ADA interference mitigation to improve the accuracy of measured drug in total PK assays.Materials & methods: Spiked test samples, created to achieve different ADA concentrations in human serum also containing an insulin analogue, were analyzed alongside pooled clinical samples using four assays.Results & conclusion: Interference was observed in all platforms. A novel approach using the Gyrolab mixing CD, including acid dissociation in the PK assay, significantly reduced interference and thereby improved relative error from >99% to ≤20% yielding measurements well within the acceptance criteria. Clinical sample results reinforced findings from the test samples.

Use of an uncrewed surface vehicle and near infrared hyperspectral imaging for sampling and analysis of aquatic microplastics

Data on MP in aquatic environments have low resolution in space and time. Scaling up sampling and increasing analysis throughput are the main bottlenecks. We combined two approaches: an uncrewed surface vehicle (USV) and near infrared hyperspectral imaging (NIR-HSI) for sampling and analysis of MP > 300 μm. We collected 35 water samples over 4 d in a coastal area. Samples were analyzed using NIR-HSI and Fourier transform infrared spectroscopy (FTIR). Spiked samples were used to determine recovery. We conclude that using a USV can mitigate issues of traditional trawls like scalability, repeatability, and contamination. NIR-HSI detects more polyethylene but less polypropylene than FTIR analysis and reduces analysis time significantly. Highly variable concentrations were found at both sampling locations, with mean MP concentration of 0.28 and 0.01 MP m-3 for location A and B respectively. USV sampling in tandem with NIR-HSI is an effective analytical pipeline for MP monitoring.

Solid-state sensor for direct and real-time assay of p-phenylenediamine in cosmetics and herbal products

p-Phenylenediamine (p-PDA) is a common ingredient in hair dyes, cosmetics and herbal products. The current study used graphene nanoparticles and phosphotungstic acid in a quality-by-design approach to develop and optimize a carbon-paste sensor for p-PDA. Twenty-three sensors with different compositions were tested, and the results were computationally analyzed to generate prediction models. The optimized sensor consisted of graphite, graphene, o-nitrophenyloctylether, and phosphotungstic acid in a 62.83: 4.01: 27.1: 5.34 (wt %) ratio. The optimized sensor displayed a Nernstian slope of 29.1±0.22 mV decade−1, a detection limit of 1.0×10−7 mol L−1, thermal and pH stabilities and a fast equilibration time of 10 s over ten weeks. The sensor accurately measured p-PDA concentrations within a wide linear range (1.0×10−7–1.0×10−3 mol L−1) with high sensitivity and selectivity (even over its isomers o- and m-phenylenediamine). The developed electrochemical method outperformed the commonly used high performance liquid chromatography methods in simplicity, speed, cost-effectiveness, linear range width and enabled real-time detection. The sensor's microstructure, morphology, and particle size were examined using the scanning electron microscope and energy-dispersive X-ray analysis. Spiked samples (3.60×10−3–10.8 % w/w) were analyzed for p-PDA content, including tea, henna, synthetic dye, black pepper, and cosmetics. The work provides quality control laboratories with a validated, fast, and reliable tool to support data-based decisions that can have important implications for health and safety.

The Challenge to Stabilize, Extract and Analyze Urinary Cell-Free DNA (ucfDNA) during Clinical Routine.

The "Liquid Biopsy" has become a powerful tool for cancer research during the last decade. Circulating cell-free DNA (cfDNA) that originates from tumors has emerged as one of the most promising analytes. In contrast to plasma-derived cfDNA, only a few studies have investigated urinary cfDNA. One reason might be rapid degradation and hence inadequate concentrations for downstream analysis. In this study, we examined the stability of cfDNA in urine using different methods of preservation under various storage conditions. To mimic patient samples, a pool of healthy male and female urine donors was spiked with a synthetic cfDNA reference standard (fragment size 170 bp) containing the T790M mutation in the EGFR gene. Spiked samples were preserved with three different buffers and with no buffer over four different storage periods (0 h; 4 h; 12 h; 24 h) at room temperature vs. 4 °C. The preservatives used were Urinary Analyte Stabilizer (UAS, Novosanis, Wijnegem, Belgium), Urine Conditioning Buffer (UCB, Zymo, Freiburg, Germany) and a self-prepared buffer called "AlloU". CfDNA was extracted using the QIAamp MinElute ccfDNA Mini Kit (Qiagen, Hilden, Germany). CfDNA concentration was measured using the Qubit™ 4 fluorometer (Thermo Fisher Scientific, Waltham, MA, USA). Droplet digital PCR (ddPCR) was used for detection and quantification of the T790M mutation. Almost no spiked cfDNA was recoverable from samples with no preservation buffer and the T790M variant was not detectable in these samples. These findings indicate that cfDNA was degraded below the detection limit by urinary nucleases. Stabilizing buffers showed varying efficiency in preventing this degradation. The most effective stabilizing buffer under all storage conditions was the UAS, enabling adequate recovery of the T790M variant using ddPCR. From a technical point of view, stabilizing buffers and adequate storage conditions are a prerequisite for translation of urinary cfDNA diagnostics into clinical routine.

Polyvinyl alcohol electrospun nanofiber membrane based solid-phase extraction for monitoring administered aminoglycoside antibiotics in various animal-derived foods.

This work aims to develop a widely applicable method to monitor administered AGs in various animal-derived food samples to ensure food safety. A polyvinyl alcohol electrospun nanofiber membrane (PVA NFsM) was synthesized and employed as solid-phase extraction (SPE) sorbent, in combination with UPLC-MS/MS, for the simultaneous detection of ten AGs in nine types of animal-derived food samples. PVA NFsM exhibited excellent adsorption performance for the targets (with an adsorption rate of over 91.09%), good matrix purification ability (with a reduction of 7.65%-77.47% in matrix effect after SPE), and good recyclability (can be reused 8 times). The method displayed a linear range of 0.1-25000μg/kg and attained limits of detection for AGs were 0.03-15μg/kg. Spiked samples demonstrated a recovery of 91.72%-100.04% with a precision of<13.66%. The practicality of the developed method was verified by testing multiple actual samples.

A microbial inhibition assay in microplates using Bacillus licheniformis for detection of enrofloxacin and sulfamethazine in chicken spiked kidney, liver and muscle tissues.

The presence of antimicrobial drugs residues in animal products at levels higher than the maximum residue level (MRL) may have adverse effects on consumer health such as allergic reactions and resistance development. Therefore, it is necessary to monitor animal products for the presence of antimicrobial residues. The aim of this study was to evaluate the detection limit of microbial inhibition assay (MIA) in microplate by using of Bacillus licheniformis as indicator microorganism for two antibiotics, enrofloxacin (ENR) and sulfamethazine (SMT), in broiler chicken's kidney, liver and muscle tissue samples. Spiked tissues samples for the two antibiotics were analysed separately by this method. The results of the assay were evaluated by the determination of the absorbance after mean 3.47h of incubation at 45°C. Results showed that the detection limits of MIA for ENR and SMT in kidney (124.03 and 23.21μg/kg, respectively) and liver (90.02 and 62.03μg/kg, respectively) as well as SMT in muscle (46.95μg/kg) were lower than EU (European Union) - MRL, whereas the detection limit for ENR in muscle was slightly higher than MRL (136.3μg/kg compared to 100μg/kg MRL). Furthermore, the MIA in the current study was found to be more sensitive to SMT than ENR (92% and 88% sensitivity rate, respectively). No false-positive was observed in the assay. Based on the results, the MIA investigated in this study had the potential to detect ENR and SMT residues in broiler chicken kidney, liver and muscle tissues at levels below or close to EU - MRL but offered lower capability for the detection of ENR compared with SMT in kidney and muscle tissue samples.

Permeability and diffusion of tritium in bentonite

Abstract. As a part of the Croatian RD&amp;amp;D (research, development, and demonstration) program within the Program for LILW (low- and intermediate-level waste) and SNF (spent nuclear fuel) disposal, research of permeability and the diffusion of tritium in bentonite was organized, as part of the research of the future engineering barriers for repositories of LILW and SNF. Two types of materials were prepared, namely pure sodium bentonite and a mixture of sodium bentonite (12 %) with quartz sand (88 %). Compaction of materials was conducted with a modified Proctor test, and the apparatus was designed and made at the Faculty of Mining, Geology and Petroleum Engineering at the University of Zagreb, utilizing fused deposition modeling 3D printer and PETG (polyethylene terephthalate glycol) material. Water enriched with 3H has been prepared by dilution of the National Institute of Standards and Technology (NIST) 3H standard (4926e) to 6 L. The activity of the prepared enriched water was 49 700±180 TU. One part of the device was filled with 3H-free water and the other with 3H-spiked water (0.6 L volume for each part). In total, five devices with bentonite and five devices with a sand–bentonite mixture were prepared this way. The devices were thoroughly sealed to avoid loss of sample and isotopic exchange with the atmosphere and put horizontally in holders. The water for 3H activity measurements was sampled monthly or bimonthly. A total of 8 mL of the sample was taken by syringe and transferred to a measurement vial. Each vial was additionally filled with 12 mL of a scintillator (Ultima Gold LLT, PerkinElmer) and thoroughly mixed. 3H activity was determined by a liquid scintillation counter (LSC; Quantulus 1220) at the Laboratory for Low-level Radioactivities, Ruđer Bošković Institute, Zagreb. Due to the penetration of bentonite from the barrier into the water samples, tritium-free water has relatively high activity after 2 months of the experiment (average value was 5560±240 TU). In the final sampling, after a 2-month time span, the activity reached 9670±2490 TU. Later, sampling and measurement were not possible due to the high bentonite amount within the samples. Tritium-free samples from the sand–bentonite mixture device were stable, and the first analyses (1 month after the experiment setup) showed an average activity of 533±31 TU, while the final (5-month time span from the first sampling) average activity was 12 800±3430 TU. The increase in the concentration from the beginning to the end of the experiment was almost exponential. Spiked samples from the bentonite device had an average activity of 36 950±2550 TU at the first sampling and 17 580±13 320 TU after a 1-month time leg. Later, sampling was not possible. Spiked samples from sand–bentonite mixture showed a decrease in tritium activity from the first sampling (43 390±1310 TU) to 27 210±285 TU (5 months after the first sampling). Considering the penetration of bentonite material into the water samples, only the sand–bentonite mixture can be considered for further analyses through the calculation of the diffusion.

Ionic liquid-assisted aqueous two-phase system for the enrichment of multiple monosaccharides from jujube

In this study, a simple, high-efficiency and eco-friendly enrichment method using an ionic liquid (IL)-assisted aqueous two-phase system was proposed for the enrichment of multiple monosaccharides. The parameters affecting the enrichment effect were the type of IL, the mass of the IL, the amount of salt, the vortex time, and the pH value of the solution. All of these parameters were optimized using single-factor tests or multifactor experiments. The optimal conditions were as follows: [C4min]Br was 313.49 mg, the mass of K2HPO4 was 4.6 g, the vortex time was 3.18 min, and the pH value was 9. In addition, the established method was verified to have good linearity (r2 ≥ 0.9991) and high sensitivity, with limits of detection ranging from 6.1 to 34.09 ng/mL and limits of quantification ranging from 20.57 ng/mL to 113.63 ng/mL. Spiked samples had recoveries ranging from 85.68 % to 104.83 %. The present work demonstrated that this established method can be successfully used for the extraction and enrichment of various monosaccharides from jujube.

Machine Learning-Mediated Ultrasensitive Detection of Citrinin and Associated Mycotoxins in Real Food Samples Discerned from a Photoluminescent Carbon Dot Barcode Array.

Economically viable remote sensing of foodborne contaminants using minimalistic chemical reagents and simultaneous automation calls for a concrete integration of a chemical detection strategy with artificial intelligence. In a first of its kind, we report the ultrasensitive detection of citrinin and associated mycotoxins like aflatoxin B1 and ochratoxin A using an Alizarin Red S (ARS) and cystamine-derived carbon dot (CD) that aptly amalgamate with machine learning algorithms for automation. The photoluminescence response of the CD as a function of various solvents and pH is used to generate array channels that are further modulated in the presence of the mycotoxins whose digital images were acquired to determine pixelation, essentially creating a barcode. The barcode was fed to machine learning algorithms that actualize and intertwine convoluted databases, demonstrating Extreme Gradient Boosting (XGBoost) as the optimized model out of eight algorithms tested. Spiked samples of wheat, rice, gram, maize, coffee, and milk were used to evaluate the testing model where an exemplary accuracy of 100% even at 10 pmol of mycotoxin concentration was achieved. Most importantly, the coexistence of mycotoxins could also be detected through the CD array and XGBoost synergy hinting toward a broader scope of the developed methodology for smart detection of foodborne contaminants.

The Distinction between Dematiaceous Molds and Non-Dematiaceous Fungi in Clinical and Spiked Samples Treated with Hydrogen Peroxide Using Direct Fluorescence Microscopy

Dematiaceous fungi are pigmented molds with a high content of melanin in their cell walls that can cause fatal infections in immunocompromised hosts. Direct microscopy is the main method for the rapid diagnosis of dematiaceous fungi in clinical specimens. However, it is often difficult to distinguish their hyphae from non-dematiaceous hyphae and yeast pseudohyphae. Our aim was to develop a fluorescence staining method that targets melanin for the detection of dematiaceous molds in clinical specimens. Glass slide smears of clinical samples and sterile bronchoalveolar lavage spiked with dematiaceous and non-dematiaceous fungi were treated with hydrogen peroxide, and digital images were recorded using direct microscopy with different fluorescent filters. The images of fungi were compared for their fluorescence intensity using the NIS-Elements software. The fluorescent signal between dematiaceous and non-dematiaceous fungi demonstrated a markedly increased mean intensity for dematiaceous molds following hydrogen peroxide treatment (7510.3 ± 10,427.6 vs. 0.3 ± 3.1, respectively, p < 0.0001). No fluorescent signal was detected in the absence of hydrogen peroxide. "Staining" fungal clinical specimens with hydrogen peroxide, followed by fluorescence microscopy examination, can differentiate between dematiaceous and non-dematiaceous fungi. This finding can be used for the detection of dematiaceous molds in clinical specimens and enables the early and appropriate treatment of infections.

Laser-induced graphitized electrodes enabled by a 3D printer/diode laser setup for voltammetric detection of hormones

Contraceptive pills have helped to shape modern society and their use has become more popular over the years. β-estradiol, one of the molecules present in this type of medication, is considered an endocrine disrupting compound (EDC), being nowadays commonly found in water resources. Due to their adverse effects on human health and the environment, even at trace levels, low-cost and rapid-detection approaches capable of reliably detecting EDCs such as β-estradiol are highly keen. As an alternative to the classic and well-established analytical methods for hormone detection, here we propose a simple and low-cost strategy that relies on the use of laser-induced graphitization (LIG) to manufacture electrodes for voltammetric detection of hormone in river and tap water. The LIG electrodes were produced by attaching a diode laser to a commercially available Fused Deposition Modelling (FDM) 3D printer, in which the laser promoted the controlled ablation of the polyimide film adhered to the PLA substrates. Specifically, the manufacturing steps included the 3D printing of the substrate followed by laser scribing a double-sided tape made of polyimide glued onto the surface of the substrate. The 3D printer was able to control the laser movement at specifics positions to manufacture the carbon-based three-electrode system (TES) layout. The usability of the electrochemical sensor was evaluated towards β-estradiol detection, which presented a linear response from 0.25 to 10 µmol L−1 and a limit of detection (LOD) = 80 nM. Spiked samples using tap water and river water reached 91 and 110% of recovery respectively. Our results suggest the proposed approach as an innovative and versatile way to produce low-cost, easily customizable, and reliable electrochemical sensors based on laser ablation on polyimide films.

Rapid, novel screening of toxicants in poison baits, and autopsy specimens by ambient mass spectrometry.

Animal poisoning and dissemination of baits in the environment have public health and ethological implications, which can be followed by criminal sanctions for those responsible. The reference methods for the analysis of suspect baits and autopsy specimens are founded on chromatographic-based techniques. They are extremely robust and sensitive, but also very expensive and laborious. For this reason, we developed an ambient mass spectrometry (AMS) method able to screen for 40 toxicants including carbamates, organophosphate and chlorinated pesticides, coumarins, metaldehyde, and strychnine. Spiked samples were firstly purified and extracted by dispersive solid phase extraction (QuEChERS) and then analyzed by direct analysis in real time high-resolution mass spectrometry (DART-HRMS). To verify the performance of this new approach, 115 authentic baits (n = 59) and necropsy specimens (gastrointestinal content and liver, n = 56) were assessed by the official reference methods and combined QuEChERS-DART-HRMS. The agreement between the results allowed evaluation of the performances of the new screening method for a variety of analytes and calculation of the resultant statistical indicators (the new method had overall accuracy 89.57%, sensitivity of 88.24%, and a specificity of 91.49%). Taking into account only the baits, 96.61% of overall accuracy was achieved with 57/59 samples correctly identified (statistical sensitivity 97.50%, statistical specificity 94.74%). Successful identification of the bitter compound, denatonium benzoate, in all the samples that contained rodenticides (28/28) was also achieved. We believe initial screening of suspect poison baits could guide the choice of reference confirmatory methods, reduce the load in official laboratories, and help the early stages of investigations into cases of animal poisoning.

SAMHSA drug panel screening in oral fluid: Development of screening method at 8 seconds per sample using LDTD-MS/MS

In 2019, the US Department of Health and Human Services (via the SAMHSA agency) has established scientific and technical guidelines for federal workplace drug testing programs in oral fluids (Federal Register/Vol. 84, No. 207, 2019). Screening various drug classes requires several different immunoassay reagents or an LC-MS/MS method with a longer analysis time per sample. LDTD-MS/MS technology combines the speed and the analysis of different drug classes with a single method. The goal of this presentation is to use an automated sample preparation method for LDTD-MS/MS screening of all compounds in a single operation. Quantisal collection devices were used in this method. Drug-free oral fluids of different volunteers were collected using the Quantisal device. After the collection of the oral fluid, the pad is transferred into a tube containing an extraction buffer. During this process, oral fluids are diluted by a factor of 3. The SAMHSA drug panel for an Oral fluid screen was spiked in extracts at a concentration around the decision point cut-off (Amphetamine: 50 ng/mL, Methamphetamine: 50 ng/mL, MDA: 50 ng/mL, MDMA: 50 ng/mL, PCP: 100 ng/mL, Morphine: 30 ng/mL, Hydromorphone: 30 ng/mL, Codeine: 30 ng/mL, Hydrocodone: 30 ng/mL, Cocaine: 30 ng/mL, Oxymorphone: 30 ng/mL, Oxycodone: 30 ng/mL, 6-AM: 4 ng/mL and THC: 4 ng/mL). Samples were extracted using the Azeo automated extraction system. The robot scans the barcode of the sample, generates a batch file for the LDTD-MS/MS system, extracts the sample and spots the LazWell plate. Salt assisted liquid-liquid extraction (SALLE) was used as the sample preparation method. LDTD (Phytronix Luxon) uses a carrier gas (air) flow rate of 6 L/min with water infusion at 20 uL/sec. Samples were desorbed from the surface of the plate using a laser ramp of 6 seconds to 65% power and 2 seconds hold at 65% power. Mass spectrometer (Shimadzu 8060) operates in positive MRM mode with a specific transition for the following drugs: Amphetamine, Methamphetamine, MDA, MDMA, PCP, Morphine, Hydromorphone, Codeine, Hydrocodone, Cocaine, Oxymorphone, Oxycodone, 6-AM and THC. Data acquisition systems of mass spectrometers were not designed to deal with signals of only a few seconds per sample. The synchronization sequence adds 6 to more than 15 seconds between each sample. To bypass this, all samples are acquired in a single file. To allow the analysis of such data, Cascade™ software is designed to detect, split, and integrate every sample peak acquired in a single file. Spiked samples around the decision point and blank solutions are used to validate the precision of the method. Each concentration must not exceed 20% CV and the mean concentration ± 2 times the standard deviation must not overlap with other concentrations at the decision point. The peak area against the IS ratio was used to normalize the signal. Replicate extractions are deposited on a LazWell plate and dried before analysis. No overlapping at the decision point is observed for all curves and the CV% was below 15% for within-run experiments. A dry and wet stability of sample extracts were performed. Precision criteria were applied. All results are within the acceptable criteria range. Oral fluids are collected from eight different volunteers. Samples are screened to verify the presence of each analyte (all samples were negative). Drugs are spiked at 50% cut-off (QC-L) and 200% cut-off (QC-H) and screened as unknown to verify the method sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy. A percentage of 100% was obtained for all validation parameters of all drugs. Luxon Ion Source® combined to a Shimadzu 8060 mass spectrometer system allows ultra-fast (8 seconds per sample) screening of a SAMHSA drug panel in oral fluid using a simple and automated sample preparation method.

Application of the US EPA procedure for determining method detection limits to EDXRF measurement of filter-based aerosol samples

ABSTRACT The US Environmental Protection Agency (USEPA) modified its guidance on determining “method detection limits” (MDL) in 2017. The recommended procedures have not yet been applied to the analyses routinely done on filter samples for USEPA’s Chemical Speciation Network (CSN). This paper applies the new USEPA procedure for estimating MDL to Energy Dispersive X-Ray Fluorescence (EDXRF) analysis of atmospheric aerosol samples collected on filters. The procedure involves estimating MDL by two approaches – statistical distributions of unloaded blank sample measurements and lightly loaded, spiked samples – and sets the MDL as the maximum of these two approaches. Spiked samples at low concentrations were developed using an aerosol deposition chamber to follow this approach. The MDL procedure was initially conducted on one EDXRF instrument, and the spike-based MDL was found to be higher than blank-based MDL for 28 of the 31 elements. The blank-based MDL was higher than the spike-based MDL for Si, K and Fe, which are common contaminants present in filter raw media or arising from EDXRF hardware. The annual verification performed using five EDXRF analyzers demonstrated that the MDL estimated following the USEPA procedure was stable over time and analyzers for all elements except K, which yielded a higher MDL. Implications: Lightly loaded reference materials (RM) were developed for Energy Dispersive X-ray Fluorescence (EDXRF) measurements of elemental concentrations in filter-based particulate matter samples using a novel aerosol generation chamber. These RM were then used to estimate method detection limits (MDL) following U.S. Environmental Protection Agency guidance. These new MDL estimates were compared to alternative estimates and, for most elements, are higher. Our work provides EDXRF users with MDL estimates for each element and an assessment of different MDL estimation approaches.

Iron-Doped Bimodal Mesoporous Silica Nanomaterials as Sorbents for Solid-Phase Extraction of Perfluoroalkyl Substances in Environmental Water Samples.

In this work, sorbets based on UVM-7 mesoporous silica doped with Fe were synthesized and applied to solid-phase extraction of perfluoroalkyl substances from environmental water samples. These emerging pollutants were then determined by liquid chromatography coupled with a mass spectrometry detector. Thus, Fe-UVM-7 mesoporous silica materials with different contents of iron, as well as different pore sizes (by using alkyltrimethilamonium bromide surfactants with different organic tail lengths) were synthesized, and their structure was confirmed for the first time by transmission electron microscopy, nitrogen adsorption–desorption, X-ray diffraction, and Raman spectroscopy. After comparison, Fe50-UVM-7-C12 was selected as the best material for analyte retention, and several extraction parameters were optimized regarding the loading and elution step. Once the method was developed and applied to real matrices, extraction efficiencies in the range of 61–110% were obtained for analytes with C8–C14 chain length, both perfluoroalkyl carboxylates, and perfluoroalkyl sulfonates. Likewise, limits of detection in the range of 3.0–8.1 ng L−1 were obtained for all target analytes. In the analysis of real well-water samples, no target compounds were detected. Spiked samples were analyzed in comparison to Oasis WAX cartridges, and statistically comparable results were achieved.

Total observed error, total allowable error, and QC rules for canine serum and urine cortisol achievable with the Immulite 2000 Xpi cortisol immunoassay.

Determining a simple quality control (QC) rule for daily performance monitoring depends on the desired total allowable error (TEa) for the measurand. When no consensus TEa exists, the classical approach of QC rule validation cannot be used. Using the results of previous canine serum and urine cortisol validation studies on the Immulite 2000 Xpi, we applied a reverse engineering approach to QC rule determination, arbitrarily imposing sigma = 5, and determining the resulting TEa for the QC material (QCM; TEaQCM) and the resulting probability of error detection (Ped) for each QC rule. For the simple QC rule 12.5S with Ped = 0.96 and probability of false rejection (Pfr) = 0.03, the associated TEaQCM were 20% and 35% for serum and 28% and 24% for urine QCM1 and QCM2. If these levels of TEaQCM are acceptable for interpretation of patient sample results, then users can internally validate the 12.5S QC rule, provided that their QCM CVs and biases are similar to ours. Otherwise, more stringent QC rules can be validated by using a lower sigma to lower the TEaQCM. With spiked samples (relevant cortisol concentrations in the veterinary patient matrix) at 38.6 and 552 nmol/L of cortisol, TEaQCM at sigma = 5 were much higher (54% and 40% for serum; 90.3% and 42.8% for urine). Spiked samples generate TEa that is probably too high to be suitable for daily QC monitoring; however, it is crucial to verify spiked sample observed total error (TEo; 26% and 18% for serum, 60% and 30% for urine) < TEaQCM, and to use spiked sample TEo for patient result interpretation. In the absence of consensus TEa for cortisol in dogs, we suggest the use of a 12.5S rule, provided that users accept the associated level of TEaQCM also as clinical TEa for results interpretation.

Multi-modality detection of SARS-CoV-2 in faecal donor samples for transplantation and in asymptomatic emergency surgical admissions.

Background: Faecal transplantation is an evidence-based treatment for Clostridioides difficile. Patients infected with SARS-CoV-2 have been shown to shed the virus in stool for up to 33 days, well beyond the average clearance time for upper respiratory tract shedding. We carried out an analytical and clinical validation of reverse-transcriptase quantitative (RT-qPCR) as well as LAMP, LamPORE and droplet digital PCR in the detection of SARS-CoV-2 RNA in stool from donated samples for faecal microbiota transplantation (FMT), spiked samples and asymptomatic inpatients in an acute surgical unit. Methods: Killed SARS-CoV-2 viral lysate and extracted RNA was spiked into donor stool & FMT and a linear dilution series from 10 -1 to 10 -5 and tested via RT-qPCR, LAMP, LamPORE and ddPCR against SARS-CoV-2. Patients admitted to the critical care unit with symptomatic SARS-CoV-2 and sequential asymptomatic patients from acute presentation to an acute surgical unit were also tested. Results: In a linear dilution series, detection of the lowest dilution series was found to be 8 copies per microlitre of sample. Spiked lysate samples down to 10 -2 dilution were detected in FMT samples using RTQPCR, LamPORE and ddPCR and down to 10 -1 with LAMP. In symptomatic patients 5/12 had detectable SARS-CoV-2 in stool via RT-qPCR and 6/12 via LamPORE, and in 1/97 asymptomatic patients via RT-qPCR. Conclusion: RT-qPCR can be detected in FMT donor samples using RT-qPCR, LamPORE and ddPCR to low levels using validated pathways. As previously demonstrated, nearly half of symptomatic and less than one percent of asymptomatic patients had detectable SARS-CoV-2 in stool.

Analysis of Pork Adulteration In Recycled Frying Oils Using Raman Spectroscopy

Abstract Unscrupulous food business operators may use recycled frying oil to save costs. Of particular concern is the recycled frying oil is usually taken from nonhalal food premises which should not be used by halal food premises, and indeed may posing health treats to consumers. Hence, the objective of this paper is to analyse pork adulteration in recycled frying oils by using the combination of Raman spectroscopy and Principal Component Analysis (PCA). Samples of frying oils from homemade fried pork, fried chicken, fried fish and fried banana were analyzed. Spiked samples were prepared by adding frying oil from homemade fried pork ranging from 10% to 50% (v/v) to frying oils from homemade fried chicken, fried fish and fried banana. The results found that Raman spectroscopy and PCA are able to differentiate adulterated frying oil and unadulterated frying oils. However, it could not distinguish the percentage of pork adulteration in the spiked samples. This method would beneficial to ensure food integrity in the frying oils.

Development of surface ionization mass spectrometry for detection of stimulants in human urine.

This paper demonstrates direct detection of stimulants such as amphetamine, methamphetamine and cocaine spiked with untreated urine and a real world sample using surface ionization mass spectrometry. Spiked samples were analyzed without preliminary chromatographic separation and extraction procedure using the developed method. Moreover, in order to check the analytical capabilities of the method non-extracted real world sample was analyzed. After liquid-liquid extraction, the same sample was analyzed using the method for comparative study. Limit of detection of spiked samples was in the range of 10 pg (10 ng/ml) to 100 pg (100 ng/ml). Linear ranges of samples were two orders of magnitude or more than two orders of magnitude. It was revealed these spiked samples and real world sample can be analyzed without preliminary chromatographic separation and preliminary extraction procedure due to high selectivity of the method and the presence of the indicator lines of studied analytes in the mass spectra. The surface ionization mass spectrometry data was attested by the GC/MS analysis of these samples.