BACKGROUND: Raman spectroscopy has gained popularity to monitor multiple process indicators simultaneously in biopharmaceutical processes. However, robust and specific model calibration remains a challenge due to insufficient analyte variability to train the models and high cross-correlation of various media components and artifacts throughout the process. MAIN METHODS: A systematic Raman calibration workflow for perfusion processes enabling highly specific and fast model calibration was developed. Harvest libraries consisting of frozen harvest samples from multiple CHO cell culture bioreactors collected at different process times were established. Model calibration was subsequently performed in an offline setup using a flow cell by spiking process harvest with glucose, raffinose, galactose, mannose, and fructose. MAJOR RESULTS: In a screening phase, Raman spectroscopy was proven capable not only to distinguish sugars with similar chemical structures in perfusion harvest but also to quantify them independently in process-relevant concentrations. In a second phase, a robust and highly specific calibration model for simultaneous glucose (root mean square error prediction [RMSEP] = 0.32 g L-1 ) and raffinose (RMSEP = 0.17 g L-1 ) real-time monitoring was generated and verified in a third phase during a perfusion process. IMPLICATION: The proposed novel offline calibration workflow allowed proper Raman peak decoupling, reduced calibration time from months down to days, and can be applied to other analytes of interest including lactate, ammonia, amino acids, or product titer.

• Klíčová slova
• MVDA, Raman spectroscopy, flow cell, harvest library, model calibration, spiking,
• MeSH
• bioreaktory * MeSH
• CHO buňky MeSH
• Cricetulus MeSH
• glukosa metabolismus   MeSH
• kalibrace MeSH
• křečci praví MeSH
• perfuze MeSH
• rafinosa MeSH
• Ramanova spektroskopie * metody   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glukosa MeSH
• rafinosa MeSH

An interlaboratory comparison for European radon calibration facilities was conducted to evaluate the establishment of a harmonized quality level for the activity concentration of radon in air and to demonstrate the performance of the facilities when calibrating measurement instruments for radon. Fifteen calibration facilities from 13 different European countries participated. They represented different levels in the metrological hierarchy: national metrology institutes and designated institutes, national authorities for radiation protection and participants from universities. The interlaboratory comparison was conducted by the German Federal Office for Radiation Protection (BfS) and took place from 2018 to 2020. Participants were requested to measure radon in atmospheres of their own facilities according to their own procedures and requirements for metrological traceability. A measurement device with suitable properties was used to determine the comparison values. The results of the comparison showed that the radon activity concentrations that were determined by European calibration facilities complying with metrological traceability requirements were consistent with each other and had common mean values. The deviations from these values were normally distributed. The range of variation of the common mean value was a measure of the degree of agreement between the participants. For exposures above 1000 Bq/m3, the variation was about 4% for a level of confidence of approximately 95% (k=2). For lower exposure levels, the variation increased to about 6%.

• Klíčová slova
• calibration, interlaboratory comparison, metrological traceability, radon, radon activity concentration,
• MeSH
• kalibrace MeSH
• lidé MeSH
• monitorování radiace * MeSH
• radiační ochrana * MeSH
• radioaktivní látky znečišťující vzduch * analýza   MeSH
• radon * analýza   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• radioaktivní látky znečišťující vzduch * MeSH
• radon * MeSH

Several trials have attempted to identify sources of inter-laboratory variability in comet assay results, aiming at achieving more equal responses. Ionising radiation induces a defined level of DNA single-strand breaks (per dose/base pairs) and is used as a reference when comparing comet results but relies on accurately determined radiation doses. In this ring test we studied the significance of dose calibrations and comet assay protocol differences, with the object of identifying causes of variability and how to deal with them. Eight participating laboratories, using either x-ray or gamma radiation units, measured dose rates using alanine pellet dosimeters that were subsequently sent to a specialised laboratory for analysis. We found substantial deviations between calibrated and nominal (uncalibrated) dose rates, with up to 46% difference comparing highest and lowest values. Three additional dosimetry systems were employed in some laboratories: thermoluminescence detectors and two aqueous chemical dosimeters. Fricke's and Benzoic Acid dosimetry solutions gave reliable quantitative dose estimations using local equipment. Mononuclear cells from fresh human blood or mammalian cell lines were irradiated locally with calibrated (alanine) radiation doses and analysed for DNA damage using a standardised comet assay protocol and a lab-specific protocol. The dose response of eight laboratories, calculated against calibrated radiation doses, was linear with slope variance CV= 29% with the lab-specific protocol, reduced to CV= 16% with the standard protocol. Variation between laboratories indicate post-irradiation repair differences. Intra-laboratory variation was very low judging from the dose response of 8 donors (CV=4%). Electrophoresis conditions were different in the lab-specific protocols explaining some dose response variations which were reduced by systematic corrections for electrophoresis conditions. The study shows that comet assay data obtained in different laboratories can be compared quantitatively using calibrated radiation doses and that systematic corrections for electrophoresis conditions are useful.

• Klíčová slova
• Calibration, Comet assay, Radiation, Ring-trial, Standardisation,
• MeSH
• ionizující záření * MeSH
• kalibrace MeSH
• kometový test metody   MeSH
• lidé MeSH
• poškození DNA * MeSH
• savci MeSH
• vztah dávky záření a odpovědi MeSH
• záření gama MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Semivolatile organic compounds (SVOCs) are mostly man-made chemicals that distribute between the gas and solid phase in the environment. Many of them could pose harm to people and therefore it is important to know their concentrations in the indoor environment to evaluate the related risks. Inhalation exposure can be assessed using passive sampling. In this study, we employed silicone elastomer as a passive sampler for monitoring gaseous polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in indoor air. We performed a sampler calibration study in which samplers consisting of 0.5 mm thick silicone sheets with a total surface area of 300 cm2 were exposed to indoor air in a university lecture theatre for up to 56 days. Uptake kinetics of SVOCs was studied by collecting 2 samplers every week. The results were used to develop a model based on mass transfer theory that can be used to estimate the air sampling rate RS as a function of compound's molecular volume. We examined release kinetics of performance reference compounds that covered a broad range of silicone-air partition coefficient (log KSA 5.95-9.49) and investigated a hypothesis of isotropic exchange kinetics, i.e. equality of rate constants for uptake and release, of SVOCs. PCBs and OCPs concentration in air calculated from contaminant amounts accumulated in passive samplers were in good agreement with those determined by active sampling running simultaneously during the entire study. The use of performance reference compounds is suitable for in situ passive sampler calibration.

• Klíčová slova
• Inhalation exposure, Model, Persistent organic compounds, Sampler calibration,
• MeSH
• kalibrace MeSH
• látky znečišťující vzduch * analýza   MeSH
• lidé MeSH
• monitorování životního prostředí MeSH
• polychlorované bifenyly * analýza   MeSH
• polycyklické aromatické uhlovodíky * analýza   MeSH
• silikony MeSH
• znečištění vzduchu ve vnitřním prostředí * analýza   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• látky znečišťující vzduch * MeSH
• polychlorované bifenyly * MeSH
• polycyklické aromatické uhlovodíky * MeSH
• silikony MeSH

Precise calibration in TOF MS requires suitable and reliable standards, which are not always available for high masses. We evaluated inorganic clusters of the monoisotopic elements gold and phosphorus (Au n+/Au n- and P n+/P n-) as an alternative to peptides or proteins for the external and internal calibration of mass spectra in various experimental and instrumental scenarios. Monoisotopic gold or phosphorus clusters can be easily generated in situ from suitable precursors by laser desorption/ionization (LDI) or matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Their use offers numerous advantages, including simplicity of preparation, biological inertness, and exact mass determination even at lower mass resolution. We used citrate-stabilized gold nanoparticles to generate gold calibration clusters, and red phosphorus powder to generate phosphorus clusters. Both elements can be added to samples to perform internal calibration up to mass-to-charge (m/z) 10-15,000 without significantly interfering with the analyte. We demonstrated the use of the gold and phosphorous clusters in the MS analysis of complex biological samples, including microbial standards and total extracts of mouse embryonic fibroblasts. We believe that clusters of monoisotopic elements could be used as generally applicable calibrants for complex biological samples. Graphical Abstract ᅟ.

• Klíčová slova
• Calibration, Gold clusters, Monoisotopic elements, Phosphorus clusters, TOF mass spectrometry,
• Publikační typ
• časopisecké články MeSH

The future of consumer electronics depends on the capability to reliably fabricate nanostructures with given physical properties. Therefore, techniques to characterize materials and devices with nanoscale resolution are crucial. Among these is magnetic force microscopy (MFM), which transduces the magnetic force between the sample and a magnetic oscillating probe into a phase shift, enabling the locally resolved study of magnetic field patterns down to 10 nm. Here, the progress done toward making quantitative MFM a common tool in nanocharacterization laboratories is shown. The reliability and ease of use of the calibration method based on a magnetic reference sample, with a calculable stray field, and a deconvolution algorithm is demonstrated. This is achieved by comparing two calibration approaches combined with numerical modeling as a quantitative link: measuring the probe's effect on the voltage signal when scanning above a nanosized graphene Hall sensor, and recording the MFM phase shift signal when the probe scans across magnetic fields produced by metallic microcoils. Furthermore, in the case of the deconvolution algorithm, it is shown how it can be applied using the open-source software package Gwyddion. The estimated magnetic dipole approximation for the most common probes currently in the market is also reported.

• Klíčová slova
• Hall nanosensors, calibration, magnetic force microscopy (MFM), magnetic probes, nanoscale,
• Publikační typ
• časopisecké články MeSH

Nuclear Magnetic Resonance (NMR) is an analytical technique extensively used in almost every chemical laboratory for structural identification. This technique provides statistically equivalent signals in spite of using spectrometer with different hardware features and is successfully used for the traceability and quantification of analytes in food samples. Nevertheless, to date only a few internationally agreed guidelines have been reported on the use of NMR for quantitative analysis. The main goal of the present study is to provide a methodological pipeline to assess the reproducibility of NMR data produced for a given matrix by spectrometers from different manufacturers, with different magnetic field strengths, age and hardware configurations. The results have been analyzed through a sequence of chemometric tests to generate a community-built calibration system which was used to verify the performance of the spectrometers and the reproducibility of the predicted sample concentrations.

• Klíčová slova
• Calibration, Food quality control, Interlaboratory comparison, Multiple regression, Validation, qNMR,
• MeSH
• kalibrace MeSH
• magnetická rezonanční spektroskopie MeSH
• ovocné a zeleninové šťávy analýza   MeSH
• Vitis chemie   MeSH
• Publikační typ
• časopisecké články MeSH

The gamma spectrometry is one of the fundamental methods used in nuclear technology with well-established procedures of data acquisition and evaluation. Yet with expanding possibilities of detection and data processing, the question of accurate calibration very often rises, since the traditional approach to calibration might not always be the most efficient. In our work, we focus on field spectrometry and present a way of utilizing an already established and well working calibration facility and expanding its scope for new types of radiation detectors.

• MeSH
• kalibrace MeSH
• metoda Monte Carlo MeSH
• spektrometrie gama * MeSH
• Publikační typ
• časopisecké články MeSH

Current standard EN 50463-2 indicates the tests and the requirements to be satisfied for an energy measurement system of a traction unit for railway applications. Some of these tests are to be done with several harmonics superposed on the rated voltage, respectively current. However, no calibration systems satisfying the standard requirements were available few years ago. The work performed in the EURAMET project "MyRailS" leads to the development of fictive power sources and reference measurement systems described in this paper. Therefore, it is possible to generate distorted 25 kV-50 Hz voltages with harmonics up to 5 kHz and 90° phase-fired currents up to 500 A with harmonics up to 5 kHz. The generated power is measured by developed traceable reference systems with accuracy better than 0.5%.

• Klíčová slova
• calibration procedure, calibration setup, distorted regime, energy measurement, energy measuring system, fictive power source, harmonic waveform, railway system,
• Publikační typ
• časopisecké články MeSH

The thickness of electron transparent samples can be measured in an electron microscope using several imaging techniques like electron energy loss spectroscopy (EELS) or quantitative scanning transmission electron microscopy (STEM). We extrapolate this method for using a back-scattered electron (BSE) detector in the scanning electron microscope (SEM). This brings the opportunity to measure the thickness not just of the electron transparent samples on TEM mesh grids, but, in addition, also the thickness of thin films on substrates. Nevertheless, the geometry of the microscope and the BSE detector poses a problem with precise calibration of the detector. We present a simple method which can be used for such a type of detector calibration that allows absolute (standardless) measurement of thickness, together with a proof of the method on test samples.

• Klíčová slova
• Monte Carlo simulation, SEM, back-scattered electrons, electron mirror, quantitative imaging, sample bias, standardless calibration, thin coating layers,
• Publikační typ
• časopisecké články MeSH