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Life without legal metrology is inconceivable, as legal metrology encompasses every sphere of daily life, from eating to safeguarding health to ensuring public safety and the environment. On the other hand, food plays an important role in human life, and the entire civilisation survives on food. Food laws have been developed over the years with the primary objective of providing consumers with safe and nutritious food. Food laws primarily focus on ensuring the safety and quality of consumables, while legal metrology laws govern the accuracy of weights and measures in commercial transactions, including pre-packed food. The intersection of food laws and legal metrology laws in India presents a complex framework that requires careful analysis. This intersection becomes crucial as discrepancies in quantity, labelling, or packaging can impact consumer rights and public health and appropriate declarations on the packaging help the consumer make an informed choice. This comprehensive analysis involves examining how these regulations merge, identifying potential conflicts, and proposing harmonised measures to enhance regulatory efficiency and consumer protection. Balancing the intricacies of both frameworks is essential to creating a robust system that addresses the unique challenges posed by the intersection of food and metrology regulations in India.

Accurate mass determination is vital across scientific, industrial, and technological applications, serving as the cornerstone of measurement quality and reliability. Hydraulic pressure balances are renowned for their precision and play a pivotal role in pressure generation. However, the influence of OIML weights used as reference on mass determination accuracy remains a complex and often overlooked aspect. This article investigates, whether OIML weights when used as a reference in determining the weight of disk masses, have an effect on the pressure generated in hydraulic pressure balances, and tries to shed light on the subtle relationship between the weight determination of disk masses and measurement uncertainty. In this study, a hydraulic pressure balance with a measuring range of 20–1600 bar was employed, focusing on three distinct scenarios utilizing different OIML weights (E1, E2, and F1) as references for mass determination. The results revealed small differences in reference pressure (ranging from 2 to 10 ppm) due to variations in mass values resulting from different OIML weight classes used as reference. Importantly, these discrepancies remained within acceptable measurement uncertainty limits, especially in high-pressure scenarios. The primary contributor to measurement uncertainty was the pressure distortion coefficient, emphasizing its significance in calibration and measurement processes. This research provides valuable insights into the interplay of accuracy of OIML weights used as reference, mass determination, and measurement uncertainty in hydraulic pressure balances. It highlights the robustness of pressure balances in high-pressure settings and suggests that variations in weight accuracy classes used as reference have minimal impact on measurement accuracy. Future research may extend these findings to low-pressure systems, offering opportunities to refine measurement practices in the field of pressure metrology.

The gravimetric method by oven drying is widely used for moisture measurement in solid materials following a drying protocol which includes specific conditions such as drying time and temperature. Although this method is reliable for many types of materials, there are some cases where materials with high moisture content require a pre-drying process at low temperature before performing the final drying. Some examples of such materials are freshly harvested grains which cannot be grounded according to the typical drying protocol. In these cases, the drying process can be applied in several stages to reach a favorable grinding condition. The measurement model for the moisture content determination using N-stages of drying can be derived from the definition of moisture content. Based on this, in this paper, a model to obtain the moisture content in N-stages is presented. The model was applied to samples of corn and wheat by drying in several stages, obtaining comparable results. According to this model, the moisture of the sample only depends on the initial mass and the mass after the final drying stage. The equivalence in the measured results was verified calculating the normalized error. Also, the estimation of the uncertainty was carried out.

The Secondary Standard Dosimetry Laboratories (SSDLs) established through Primary Standard Dosimetry Laboratories are the authorized institutions for calibrating dosimeters used in teletherapy¹ all over the country. These calibrated dosimeters play a pivotal role for treatment planning in accelerator and teletherapy facilities for deciding the amount of dose and exposure to be delivered to the cancer patients during treatment. In India, Radiation Standards Section of Bhabha Atomic Research Centre is the authorized SSDL for providing calibration to teletherapy facilities for around 580 hospitals all over the country. The dosimeters are calibrated as per the standard protocol TRS 398, which is followed by standards laboratories all over the world. The accuracy of setting along with proper functioning of the dosimeters will together contribute for determination of calibration coefficient of the ionization chamber with accuracy. Controlling ambient atmospheric conditions like temperature, pressure and humidity factors within the recommended standard range also plays a major role in deriving calibration coefficient with utmost less uncertainty. A study was carried out on the variation of calibration coefficient of various chambers over a period of 15 years. It was found that variation of calibration coefficient of same chamber over this period varied within the limit measurement uncertainty of ± 1.5% only. Hence based on this study, the period for recalibration of dosimeters can be reviewed for a longer time unless it is subjected to damage or improper handling.

This paper discusses the different methods and instruments followed in India for the estimation of ²²²Rn, ²²⁰Rn, and their progeny. Radon concentration is either directly measured from radon alpha or its progeny alpha emissions. The duration of sampling, necessary information and specific application influence the selection of a particular monitor. In India, we use indigenously developed instruments like scintillation cells, LLRDs, electrostatic collection instruments, electret ion chamber, pulse ionization chamber-based Alpha Guard, electrostatic collection of Radon progeny atoms by RAD7 and Radon Scout Plus for the measurement of these carcinogenic gases. Scintillation cell-based measurement is found to be most reliable for the mine environment whereas highly sensitive instruments like ionization chamber and silicon detector are preferred for continuous radon tracking. Solid-state nuclear track detectors have also been used for long-term radon estimation covering the diurnal and seasonal variations.

The inter-comparison exercise results carried as a part of external quality control helps in establishing the accuracy and uncertainty of the method and the measurement system. The performance evaluation is based on the statistical performance indicators such as precision, trueness, relative bias and z-score. Z-score is used for scaling the difference between a participant’s result and the assigned value for the concentration of the radio-analyte. It allows interpreting the data with different means and standard deviations and placing them on a common scale. This standard scale was used to compare result of the proficiency test made over the years for different radionuclides in matrices such as water, soil, sediment, seaweed, rice grain, having variable mean and standard deviation.

Ambient gamma radiation levels due to natural and anthropogenic sources play an important role in low level gamma spectrometric measurements of different sample matrices. Minimum detection level (MDL) of a high-resolution gamma spectrometry system directly depends on the background radiation levels. The variation of background radiation level due to the location (surface level or below ground level) of the laboratory housing the gamma spectrometric system and the impact of different shielding types is discussed in this study. Relocation of the system to a below ground level laboratory significantly brought down the background induced due to cosmic components. Corresponding reduction in count rates for major gamma emitters ranged from 36 to 59%. Consequently, the MDLs for corresponding peaks improved by 20 to 36%. Improvising the lead bricks-based passive shielding for the gamma spectrometry system to circular lead ring with graded Cu+Sn lining minimised the gamma background due to streaming of gamma rays through lead bricks and reduced the overall background. The combined effect of the location of laboratory below ground level and graded lead shielding resulted in reduction of MDL of the gamma spectrometry system for major gamma peaks by 54 to 80%.

¹⁰⁹Cd is a very important radionuclide and frequently used for calibration of gamma ray spectrometers in low energy region due to its emission of 88 keV photons and long half-life of 461.9 ± 0.4 days. Due to complex decay scheme standardization of ¹⁰⁹Cd is very challenging and was selected for international intercomparison by Bureau International des Poids et Mesures (BIPM) in 2021.¹⁰⁹Cd decays via electron capture to the excited state of ^109mAg which decays mainly with emission of conversion electrons with half-life of 39.6 s. Due to this standardization of ¹⁰⁹Cd using conventional 4πβ-γ coincidence method is extremely difficult. Some of the methods for standardization of ¹⁰⁹Cd were measurement of conversion electron emission rate using liquid scintillation spectrometer and CIEMAT/NIST method. BARC is the designated institute (DI) for ionizing radiation of India. In BARC, RSS, RSSD has been entrusted with the responsibilities related to activities of DI for ionizing radiation and hence develops, establishes, maintains and upgrades the primary and secondary standards for ionizing radiation quantities to provide traceability to the ionizing radiation measurements in the country. To establish the degrees of equivalence with the NMIs/DIs of other countries, BARC participated in international intercomparison of activity measurements of ¹⁰⁹Cd (CCRI(II)-K2.Cd-109 key comparison) piloted by BIPM with support of LNE-LNHB, France. The standardization was carried out by CIEMAT/NIST efficiency tracing using ³H as a tracer and 4π liquid scintillation conversion electron measurements. The activity concentration obtained by CIEMAT/ NIST efficiency tracing has the deviation of 0.59% with respect to the value obtained using 4π liquid scintillation conversion electron measurements which is within uncertainty limits.

An inter-comparison exercise is a quality control tool to standardize a laboratory and was performed between HPU lab at Nuclear Fuel Complex and RPS (NF) lab at Bhabha Atomic Research Centre to determine and compare the concentration of primordial radionuclides in a zircon sample received from Health Physics Unit (HPU), Indian Rare Earth Limited Manavalakurichi weighing 470 g. RPS (NF) lab is annually participating in international inter-comparison exercise conducted by IAEA and is a nodal laboratory for the in-house inter-laboratory comparison exercise. Thus, its values are considered true values. The measured concentrations for ²³⁸U and ²³²Th in zircon sample do not vary considerably as 0.37% variation is observed in true value and measured value of ²³⁸U and 0.32% variation is observed in true value and measured value of ²³²Th. U score is also calculated from the results obtained where it is found to be 0.124 for ²³⁸U and 0.195 for ²³²Th. Trueness and precision tests are also performed, and the laboratory results are found to be “acceptable”. It represents that the laboratory performance is evaluated as satisfactory and does not significantly differ from the expected values as per the statistical tools. This ensures that the analytical measurement results of the laboratory are reliable and traceable to reference standard laboratory.

Gamma spectrometry technique is regularly used for the quantification of different gamma-emitting radionuclides in environmental matrices and other synthetic samples. This is a non-destructive comparative technique which requires the usage of Certified Reference materials from International agencies like IAEA, NIST, etc. Limited availability and high cost of these Certified Reference materials pose a major hindrance in their acquisition by radiometric laboratories, motivating their indigenous preparation. A total of five sets of two types of filter papers and one blank were prepared by spiking with variable activity of ²²⁶Ra by gravimetric and volumetric measurements in a standard geometry. Efficiency of both filter paper standards together, varied from 19.7 to 20.3% in the selected geometry on HPGe-based high-resolution gamma spectrometry system. MDA values were also observed to be suitable for environmental air particulate measurements. The values of efficiencies and MDA obtained indicate that these air filter standards can qualify as candidate reference standards for regular gamma spectrometric counting of air particulates on filter paper media.