Development of certified reference materials of lithium chloride solution for water activity.

Water activity (a) is used to assess the microbiological stability, shelf life, and safety of food. Water activity meters using electric humidity sensors can measure water activity conveniently. To calibrate water activity meters, certified reference materials (CRMs) of lithium chloride (LiCl) solution for water acidity were prepared by using the gravimetric method.

Electronic Noses: From Gas-Sensitive Components and Practical Applications to Data Processing.

Artificial olfaction, also known as an electronic nose, is a gas identification device that replicates the human olfactory organ. This system integrates sensor arrays to detect gases, data acquisition for signal processing, and data analysis for precise identification, enabling it to assess gases both qualitatively and quantitatively in complex settings. This article provides a brief overview of the research progress in electronic nose technology, which is divided into three main elements, focusing on gas-sensitive materials, electronic nose applications, and data analysis methods.

Design, preparation, and property analysis of metal/dielectric multilayer film with wavelength selectivity.

Metal/dielectric multilayer films have important applications in energy-saving glass, stealth materials, solar energy utilization and other fields. In the current study, the thickness of each layer of TiO/Ag/TiO/Ag/TiOfilm is optimized. The effects of the number of metal/dielectric multilayer films and the incident light angle on their optical properties were investigated.

Intercomparison of neutron personal dose equivalent measured by thermoluminescence dosimeters.

An intercomparison of neutron personal dose equivalent measured by the Harshaw thermoluminescence neutron dosimeters (TLDs) between the National Institute of Metrology of China (NIM) and the Institute for Nuclear Science and Technology of Vietnam (INST) was performed. Three sets of TLDs (each set consisting of five TLDs) were prepared for each laboratory. Each set was then irradiated to the corresponding same nominal standard value of neutron personal dose equivalent, H(10), of 1.

Development and Application of Certified Reference Materials of Light Crude Oil for Water Content.

The water content of the crude oil needs to be measured accurately. The analytical methods that are used, including distillation and Karl Fischer coulometric titration (KFCT), require verification using certified reference materials (CRMs) of crude oil for the water content. In the present study, five CRMs of light crude oil with large volumes and various certified water contents (1-10 mg/g) were developed using the gravimetric method.

Compact Fluorescence Spectrometer with Built-In In-Line Calibration: Application to Detect Dissolved Organic Matter in Water.

Fluorescence spectrometer (FS) is widely used for component analysis because each fluorescing material has its own characteristic spectrum. However, the spectral calibration is complicated and bulky. Herein, an in-line spectral calibration sheet (ISCS) was proposed in which a narrow band-pass filter and a linear variable filter (LVF) were integrated on a metal plate.

A novel photochemical conversion technique for reliable calibration of peroxyacetyl nitrate (PAN) analyzers.

Photochemical synthesis of peroxyacetyl nitrate (PAN) through irradiating air mixtures of NO and acetone is prevailingly adopted for calibrating PAN analyzers, but few users of PAN analyzers provide evidence to certify the calibration reliability. Here we report a nonnegligible variation (up to ~50 %) of PAN synthesized in the calibration unit of a commercial PAN analyzer, whereas PAN synthesized in the two custom-made reactors could achieve stable values with variations of <2.5 %.

Improved impurity determination of pure organic substances by differential scanning calorimetry with a dynamic method.

Differential scanning calorimetry can be used to measure the impurity contents of pure organic substances on the principle of freezing-point depression. Impurity determination by differential scanning calorimetry with a dynamic method, which has the advantages of speediness and convenience, remains to be explored. Here, a series of acetanilide and dibenzothiophene samples with various purities was prepared through zone melting, and the samples were then analyzed by gas chromatography-mass spectrometry.

High-Acceleration Vibration Calibration System Based on Phase-Locked Resonance Control.

In order to ensure the measurement accuracy of high-acceleration vibration sensors used in engineering applications, it is necessary to calibrate their key performance parameters at high acceleration. The high-acceleration vibration calibration system produces high-acceleration vibration by utilizing the resonance amplification principle; however, the resonance frequency of the resonant beam changes with increasing amplitude, affected by the influences of nonlinear and other factors. In this study, a phase-locked resonance tracking control method based on the phase resonance principle is proposed to accurately and quickly track the resonance frequency of the resonant beam, which can improve the accuracy and stability of resonance control.

Determination of water content of crude oil by azeotropic distillation Karl Fischer coulometric titration.

The determination of water content in crude oil is important for oil transportation, refining, and trade. However, the sensitivity and accuracy of the conventional azeotropic distillation (AD) method are inadequate. Karl Fischer titration methods may give false high results because of the reducing sulfur compounds in crude oil.

Ultrasensitive Electrochemical DNA Biosensor Based on a Label-Free Assembling Strategy Using a Triblock polyA DNA Probe.

Multiblock DNA probe attracted a large amount of scientific attention, for the development of multitarget biosensor and improved specificity/sensitivity. However, the development of multiblock DNA probes highly relied on the chemical synthesis of organic linkers or nanomaterials, which limited their practicability and biological compatibility. In this work, we developed a label-free assembling strategy using a triblock DNA capture probe, which connects two DNA probes with its intrinsic polyA fragment (probe-PolyA-probe, PAP).

Half-life determination and comparison of activity standards of Pa.

The results of an international comparison of activity measurements of a solution of Pa are reported and analysed. Prior to this, no known standardisation of Pa by activity measurement had been carried out. The comparison was run in 2017-2018 involving eight laboratories, and returned results with no identifiable inconsistencies between methods or laboratories.

Testing of a MEMS Dynamic Inclinometer Using the Stewart Platform.

The micro-electro-mechanical system (MEMS) dynamic inclinometer integrates a tri-axis gyroscope and a tri-axis accelerometer for real-time tilt measurement. The Stewart platform has the ability to generate six degrees of freedom of spatial orbits. The method of applying spatial orbits to the testing of MEMS inclinometers is investigated.

Determination of Water Content of Nitrogen Containing Hydrogen Sulfide by Karl Fischer Coulometric Titration.

Measuring the water content in natural gas is important for safety; however, complex matrixes make the results inaccurate. Natural gas contains hydrogen sulfide (HS), which react with iodine (I), causing Karl Fischer coulometric titration (KFCT) to give higher results. The KFCT method for the determination of water content of nitrogen containing HS was investigated.

Certification of the reference material of water content in water saturated 1-octanol by Karl Fischer coulometry, Karl Fischer volumetry and quantitative nuclear magnetic resonance.

Certified reference materials (CRMs) of water content are widely used in the calibration and validation of Karl Fischer coulometry and volumetry. In this study, the water content of the water saturated 1-octanol (WSO) CRM was certified by Karl Fischer coulometry, volumetry and quantitative nuclear magnetic resonance (Q NMR). The water content recovery by coulometry was 99.

Accurate analysis of trace earthy-musty odorants in water by headspace solid phase microextraction gas chromatography-mass spectrometry.

A simple and sensitive method was developed for the simultaneous separation and determination of trace earthy-musty compounds including geosmin, 2-methylisoborneol, 2-isobutyl-3-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,3,4-trichloroanisole, 2,4,6-trichloroanisole, and 2,3,6-trichloroanisole in water samples. This method combined headspace solid-phase microextraction (HS-SPME) with gas chromatography-mass spectrometry and used naphthalene-d(8) as internal standard. A divinylbenzene/carboxen/polydimethylsiloxane fiber exposing at 90°C for 30 min provided effective sample enrichment in HS-SPME.

Accurate analysis of trace pentachlorophenol in textiles by isotope dilution liquid chromatography-mass spectrometry.

A highly accurate method for measuring pentachlorophenol (PCP) concentrations in textile samples was developed. This highly accurate method for the analysis of textile samples is valuable, given the inherent challenges associated with the complexity of the sample matrix. This method can be applied to certify the concentration of pentachlorophenol in textile CRMs.