计量科学与技术

Accurate Measurement of Limited Carbonyl Compounds and Heavy Metals Content in E-Liquids

WANG Xiangnan, ZHANG Airui, WANG Meiling, REN Danhua, ZHOU Yan, WANG Hai, CHENG Bin

2024, 68(6): 3-10, 76. doi: 10.12338/j.issn.2096-9015.2023.0247

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Two analytical methods based on high-performance liquid chromatography (HPLC) and hydride generation-atomic fluorescence spectroscopy (HG-AFS) were established to accurately determine four target carbonyl compounds (viz. formaldehyde, acetaldehyde, acrolein, and 2,3-butanedione) and two target heavy metals (viz. arsenic and lead) in e-liquids, respectively. After derivatization with 2,4-dinitrophenylhydrazine hydrochloride, the e-liquid samples were analyzed quantitatively by HPLC. The results showed a detection limit of 0.53-1.2 μg/L, measurement repeatability of 0.26%-2.2%, spike recovery of 90%-103%, and combined uncertainty of 1.6%-4.5%. After microwave digestion, the e-liquid samples were analyzed quantitatively by HG-AFS. The results showed a detection limit of 0.007-0.025 ng/g, measurement repeatability of 2.2%-4.5%, spike recovery of 95%-101%, and combined uncertainty of 2.2%-3.9%. The two established methods have the advantages of simple sample pretreatment, high sensitivity, good repeatability, and high accuracy, making them very suitable for the accurate determination of limited carbonyl compounds and heavy metals content in e-liquids, thereby supporting the implementation of national standards and the regulation of e-cigarettes.

Picosecond-level Precision Measurement of Phase Difference Between Frequency-Multiplied Signals

ZHANG Yang, LIN Pingwei, RU Ning, MA Yanning

2024, 68(6): 11-17. doi: 10.12338/j.issn.2096-9015.2024.0072

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To meet the demand for high-precision timing signals in modern science, using the phase information of sine waves as a fine marker for timing signal measurement is expected to accurately synchronize timing signal errors to the picosecond level. The frequency-multiplied signal with no phase drift relative to the sine wave can be used to characterize the fine phase information within one cycle of a sine wave signal. The prerequisite for calibrating the phase drift between the frequency-multiplied signal and the fundamental sine wave signal is the picosecond-level precision measurement of the phase drift between frequency-multiplied signals. Currently, there is no instrument capable of measuring the phase difference between frequency-multiplied signals with picosecond-level precision. This paper innovatively designs a picosecond-level precision measurement circuit for the phase difference of frequency-multiplied signals. By analyzing the influence of power dividers, amplifiers, mixers, filters, and attenuators used in the circuit on the signal phase, it is demonstrated that the measurement circuit itself causes a phase difference of no more than 3 ps for the measured value, and the stability of the measurement results is in the E-13 level, proving that both the precision and stability of the measurement circuit meet the requirements of picosecond-level high-precision measurement. This creates conditions for further calibrating the phase drift between signals and accurately characterizing the phase information of sine waves to achieve high-precision timing signal synchronization.

Research on Key Technology for Calibrating the Capacity of Spirometer Syringes

GUO Ligong, REN Litai, WANG Jintao, BAO Xuesong, TONG Lin, CHANG Xu

2024, 68(6): 18-24, 17. doi: 10.12338/j.issn.2096-9015.2024.0065

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To better realize the traceability of spirometer syringes used in spirometry, research on the method of calibrating the capacity of the syringes and the development of a calibration device have been conducted. The volume V₂₀ of the syringes at standard temperature is obtained using the developed calibration device, which is calibrated on the negative pressure principle by measuring the mass of pure water inhaled into the weighing cylinder when the piston rod of the syringe is slowly withdrawn to generate negative pressure. The temperature, humidity, and pressure of the atmosphere in the weighing cylinder and calibration cylinder are measured at the beginning and end of the measurement. The volume of pure water drawn in is calculated as V₂₀₁, the volume of air at the beginning and end of the measurement is calculated by applying the van der Waals equation, and the difference in volume is calculated to obtain a correction value ΔV for the volumetric measurement. The sum of V₂₀₁ and ΔV is V₂₀. Volume measurements were carried out on syringes with nominal capacities of 1 L and 3 L. The repeatability of the results of several sets of measurements was less than 0.06%, and the measurement uncertainty was less than 0.1% (k=2). The difference between the volume measurement results and those of the conventional static weighing method was within 0.05%, confirming that the measurements of the calibrated device were equivalent to those of the conventional static weighing method. The calibration method and calibration device in this paper satisfy the requirements for carrying out capacity calibration for syringes with a capacity measurement requirement of 0.05% repeatability and a tolerance of ±0.5%. They will also provide important technical support for the preparation of the calibration specification for the volume of confined cavities.

Research Tatus of CO₂ Detection Methods

PENG Zhixiang, PAN Guanfu, WU Tong, XU Dinghua, QIU Lin, HANG Chenzhe

2024, 68(6): 25-32, 63. doi: 10.12338/j.issn.2096-9015.2024.0079

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CO₂ is an important greenhouse gas that poses multifaceted hazards to the Earth's environment and human health. With the increase in industrialization, urbanization, and energy consumption, the emission of greenhouse gases such as CO₂ in the atmosphere has continued to increase, raising concerns about global climate change. Therefore, the detection of CO₂ concentration has become crucial. Currently, there are two main types of carbon emission measurement methods: testing methods and accounting methods. Testing methods have the advantages of high precision and real-time monitoring, making them more conducive to guiding the low-carbon transformation and operation of the unit compared to accounting methods. This paper mainly introduces the existing primary detection methods for CO₂, which include chemical analysis methods and physical optical analysis methods. Chemical analysis methods mainly include potentiometric titration, chemical absorption, gas-sensitive sensing technology, gas chromatography, and mass spectrometry. Physical optical analysis methods include cavity ring-down spectroscopy (CRDS), off-axis integrated cavity output spectroscopy (OA-ICOS), non-dispersive infrared (NDIR) absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and tunable diode laser absorption spectroscopy (TDLAS). Traditional chemical analysis is more suitable for accurate detection of complex components but is usually not suitable for long-period online detection. With the rapid development of computer technology and optical detection technology, emerging physical optical detection technologies gradually play a greater advantage. This paper summarizes and analyzes various detection methods that can help researchers select suitable CO₂ detection methods and provide data support for related industries. It can also help develop high-sensitivity and high-precision CO₂ metrology and detection equipment, which can aid in implementing the dual-carbon policy and controlling ambient air quality.

Progress in Peptide Purity Measurement Methods and International Comparisons

ZHENG Muhan, LI Ming, GUO Su

2024, 68(6): 33-39, 48. doi: 10.12338/j.issn.2096-9015.2024.0060

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Peptides, amino acid condensation products, have been widely used in various fields such as disease diagnosis, prevention and treatment, nutrition, cosmetics, and personal care. The rapid development of peptide-associated industries has put forward metrological traceability requirements for peptide measurement activities. Peptide purity measurement is an important technical foundation for achieving SI traceability in peptide measurement activities. The primary methods for measuring peptide purity include mass balance, amino acid analysis, quantitative nuclear magnetic resonance (qNMR), and elemental analysis. To achieve accuracy, consistency, and equivalence in peptide purity measurement results, the Protein Analysis Working Group (PAWG) of the Consultative Committee for Amount of Substance (CCQM) has planned a series of international comparisons on purity assessment for peptides. Currently, the International Bureau of Weights and Measures (BIPM), in cooperation with the National Institute of Metrology, China, and the Health Sciences Authority, Singapore, has organized international metrological comparisons on human C-peptide, oxytocin, and glycated hexapeptide, significantly improving the capabilities of participating laboratories from various countries. This review provides detailed principles, uncertainty evaluations, advantages, and disadvantages of peptide purity measurement methods and carefully introduces the international comparisons on peptide purity measurement. The development trends of peptide purity measurement are discussed, aiming to promote scientific and technological research on peptide metrology.

Overview and Comparison of Common Measurement Uncertainty Evaluation Methods

TAO Meng, REN Siyuan, LAO Changjuan

2024, 68(6): 40-48. doi: 10.12338/j.issn.2096-9015.2023.0263

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This article provides a systematic review of the theoretical and applied research on measurement uncertainty since the inception of the theory. Firstly, it gives an overall introduction to the historical development of measurement uncertainty theory. Secondly, the basic principles, latest research applications, and limitations of several mainstream measurement uncertainty evaluation methods are summarized. For example, the earliest published GUM method, which is mainly applicable to linear or approximately linear measurement models, adopts the method based on the propagation of standard uncertainty and is currently the most commonly used evaluation method. The Monte Carlo-based measurement uncertainty evaluation method and its derivatives, the quasi-Monte Carlo method and the adaptive Monte Carlo method, have wider applicability when dealing with complex models. The Bayesian-based measurement uncertainty evaluation method can fully exploit the value of prior data in small-sample measurements and has good performance. In addition, the article discusses some non-statistical methods for measurement uncertainty evaluation, such as the grey evaluation method, fuzzy evaluation method, maximum entropy method, and neural network method. Finally, the article briefly summarizes the various evaluation methods and suggests that with the development of artificial intelligence technology, methods such as support vector machines and neural networks have broad prospects for application in complex measurement models and measurement environments.

Metrological Space of Atomic-Scale Scanning Probe Microscopy under the SI Unit Redefinition

LI Jianqiao, SHI Yushu, WANG Fang, LI Wei

2024, 68(6): 49-54. doi: 10.12338/j.issn.2096-9015.2024.0123

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The 26th General Conference on Weights and Measures (CGPM) in 2018 recommended the silicon {220} lattice spacing as one of the realization methods for the definition of the metre, to meet the demand for atomic-level accuracy measurements as physical dimensions continue to shrink. Currently, the main instruments that can directly characterize the silicon lattice include X-ray diffractometers (XRD), transmission electron microscopes (TEM), and scanning probe microscopes (SPM). This paper briefly introduces the domestic and international application and development status of silicon lattice constant traceability methods under different measurement principles. Focusing on scanning probe microscopy, according to the measurement principles of different types of scanning probe microscopes, the spatial metrological calibration and application prospects of scanning tunneling microscopes (STM), atomic force microscopes (AFM), and qPlus atomic force microscopes (qPlus-AFM) at the atomic scale in both lateral and vertical dimensions are summarized. As an important part of the SI unit redefinition, conducting metrological research on scanning probe microscopy techniques based on the silicon lattice constant will help establish a new generation of nanometrological systems in China and enhance China's international status and voice in the field of nanometrology.

Analysis of Research Hotspots in International Advanced Metrology Institutions in 2023 Based on Bibliometrics

WU Yanchen, SHANG Xueshen, LI Xiaomeng, ZHANG Yu, FAN Wen

2024, 68(6): 55-63. doi: 10.12338/j.issn.2096-9015.2024.0131

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Currently, technological innovation has become the main battleground of international strategic competition, and metrology is an essential foundation for national technological innovation, industrial development, national defense construction, and people's livelihood. Reviewing and analyzing the research status of global metrology science based on scientific literature and identifying relevant research hotspots and trends are of great significance for gaining forward-looking insights and grasping the development direction of international metrology science research. Focusing on eight international advanced metrology institutions, including the National Institute of Standards and Technology (NIST), the National Institute of Metrology, China (NIM), the National Physical Laboratory (NPL), and the Physikalisch-Technische Bundesanstalt (PTB), this article uses bibliometrics, visual knowledge graphs, and other methods to quantitatively analyze the overall research status and hot research content in the global metrology field in 2023 based on the scientific literature data of these institutions on the Web of Science (WOS) platform. The analysis is conducted from multiple dimensions, such as literature output, journal distribution, research topic hotspots, and international cooperation. Quantum information, health, and life sciences are selected as two hot fields for focused analysis, describing their research status and overall development in 2023. Finally, conclusions are drawn to provide insights into global trends in metrology research and to clarify the future research priorities and development directions of metrology science in China.

Uncertainty Analysis of Wavelength Error Calibration for Monochromators Based on Neon Atomic Spectral Lamps

CHE Delu, ZHANG Jiawen, ZHANG Tingting, WANG Gao, LU Xiaofeng, WANG Bingyin, ZHAO Yandong

2024, 68(6): 64-70. doi: 10.12338/j.issn.2096-9015.2023.0239

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As a spectroscopic instrument, the monochromator is used to separate mixed light into monochromatic light in the spectral responsivity calibration system of photoelectric pyrometers. To improve the uncertainty level of temperature scale extension and reproduction for photoelectric pyrometers, it is necessary to calibrate the wavelength accuracy of the monochromator output before the responsivity experiment for three commonly used photoelectric pyrometers with 660 nm, 800 nm, and 900 nm filters. In this paper, a neon atomic spectral lamp is used as a standard light source, and a spectrum analyzer is used to scan its characteristic spectral lines in the range of 600-1200 nm. Thirty-seven suitable characteristic spectral lines are selected to calibrate the wavelength accuracy of the monochromator output. The influence factors of wavelength error, such as ambient temperature, monochromator slit width, wavelength correction method, detector response, nonlinearity, and calibration repeatability, are analyzed based on the calibration results. The results show that the maximum uncertainty of the wavelength error of the monochromator at 900 nm is 0.033 nm. For the photoelectric pyrometer with a commonly used 660 nm filter, when assessing the uncertainty of the monochromator wavelength output, the temperature measurement uncertainties at 1084.62°C and 3000°C are 0.01°C and 0.28°C, respectively.

Domestic Comparison of Standard Metallic Scales (Grade III)

JIANG Yuanlin, LI Jianshuang, MIAO Dongjing, KANG Yao, LI Lianfu

2024, 68(6): 71-76. doi: 10.12338/j.issn.2096-9015.2024.0021

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Standard metallic scales (Grade III) are the third-grade line standards in the Verification Scheme of Line Measuring Instruments and are used for calibrating rigid working line scales, such as steel rulers, in China. To ensure the consistency of the measurement values of standard metallic scales (Grade III) and to scientifically evaluate the Calibration and Measurement Capabilities (CMC) of these scales in China, the National Institute of Metrology, as the pilot laboratory, organized a national measurement comparison of standard metallic scales (Grade III) (project number 2021-B-04), with seven laboratories participating. This paper introduces the basic information, technical scheme, and results of the comparison, analyzes the existing problems in the calibration of standard metallic scales (Grade III), and provides technical suggestions. The comparison results show that the normalized deviations of all participating laboratories are less than 1, indicating satisfactory comparison results.

2024 Vol. 68, No. 6

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