Organophosphorus flame retardants (OPFRs) are widespread environmental contaminants with bioaccumulative potential and associated human health risks. The lack of commercial reference standards for many OPFRs limits the accuracy of their quantification. In this study, a compound-independent calibration (CIC) method using gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) was developed for the simultaneous quantification of seven alkyl OPFRs, with tripropyl phosphate (TnPP) as a single universal calibrant. Key parameters were optimized: a DB-5MS column (15 m × 0.25 mm × 0.10 μm) with pulsed splitless injection (70 psi, 280 °C), and ICP-MS settings including an RF power of 1600 W, sampling depth of 7.5 mm, dilution gas flow rate of 0.5 mL/min, and octopole voltage of − 5 V. The method exhibited excellent linearity (R2 = 0.9994 to 0.9999) over the range of 0.01–1.0 μg/mL. Limits of detection and quantification were 0.22 to 0.91 ng/mL and 0.75 to 3.02 ng/mL, respectively. For six of the seven OPFRs (excluding TEHP), the relative P response ratios compared to TnPP ranged from 0.91 to 1.01, confirming effective structure-independent calibration. The matrix effect in rice was moderate (enhancement factors 1.13–1.35). Quantitative results obtained by the CIC method agreed well with those from an external standard approach, with relative deviations within −8.54

The simultaneous determination of vitamin A and E vitamers in complex matrices presents a significant analytical challenge. To address this, we validated a straightforward method based on a QuEChERS pretreatment coupled with ultrahigh-performance liquid chromatography and diode array detection (QuEChERS-UPLC-DAD). The modified QuEChERS pretreatment procedure integrates saponification and extraction processes into a single step, enabling efficient phase separation, reducing analysis time, and eliminating the need for a salting-out step. Notably, this approach simultaneously accomplishes a recovery of 83.2% to 100.5%, a relative standard deviation of less than 4.6%. The accuracy of the proposed QuEChERS-UPLC-DAD method was confirmed through comparison with a UPLC-IDMS/MS method and analysis of a commercial certified reference material (NIST SRM 1869). Importantly, the approach was successfully applied to analyze various complex dairy products, including infant formula, milk, yogurt, and dairy beverages. Therefore, QuEChERS-UPLC-DAD approach is well-suited for routine quality control and nutritional assessment.

Accurately quantifying vitamin K-1 (VK1) within complex matrixes continues to be both challenging and of great importance. Herein, we develop a certified reference material (CRM GBW10332) for the accurate quantification of VK1 in infant formula using heart-cutting two-dimensional liquid chromatography with ultraviolet detection. An optimized sample pretreatment step based on hydrolysis and the liquid-liquid extraction process was established to efficiently isolate VK1 from the complex matrix. The certified value of VK1 in CRMs was also assigned using ultraperformance liquid chromatography coupled with isotope dilution tandem mass spectrometry. Impressively, two independent analytical approaches demonstrated excellent consistency. Resultantly, the certified value of VK1 in CRM was 643 +/- 60 mu g/kg (k = 2). Moreover, the as-developed CRMs were homogeneous and possessed good stability and were maintained well for 17 months at -80 degrees C and 7 days at 60 degrees C. More importantly, the VK1 CRMs effectively address reliable tools for quality control, method validation, and proficiency testing.

Cetaceans are highly exposed to per- and polyfluoroalkyl substances (PFAS) globally, yet the drivers of their PFAS burdens and associated risks remain poorly understood. Here, we proposed an integrated framework combining targeted/nontargeted analyses with structure-based computational toxicological methods to evaluate the occurrence and estrogenic risk of PFAS in cetaceans. A total of 96 PFAS assigned to 17 classes were discovered in cetaceans from the East China Sea, including 6 classes of fluorotelomer sulfates reported for the first time. Integrating global data, we demonstrate that feeding ecology is the key determinant of PFAS burden in cetaceans, whereas habitat type shapes the unique PFAS signature, reflecting emission sources. In addition, our evidence shows that the transformation of fluorotelomer precursors contributes significantly to the accumulation of perfluoroalkyl carboxylic acids and n:3-fluorotelomer carboxylic acids in cetaceans. On the basis of exposure data and predicted estrogenic activities of PFAS, we revealed that 82.6% of cetacean populations were under potential risks of the estrogenic effect, with about one-quarter facing high risks in coastal regions of Europe, North America, and East Asia. This study provides a comprehensive understanding of the burdens and estrogenic risks of PFAS in cetaceans worldwide, holding significant implications for the conservation of marine mammals from chemical pollution.

Despite growing concern over per- and polyfluoroalkyl substances (PFAS), evidence for packaging-driven dietary exposure under hot-contact scenarios remains limited, especially in China's rapidly expanding takeout market. Here, we conducted a survey of fast foods (n = 150) and corresponding food-contact materials (FCMs, n = 150) across Chinese markets, quantifying 32 legacy and emerging PFAS. PFAS were detected in all foods (range: 0.01-79.4 ng/g; median: 3.45 ng/g) and FCMs (0.01-205 ng/g; 3.88 ng/g). Paper-FCMs showed the highest PFAS levels among different FCM categories and exhibited industry-specific patterns. Food PFAS profiles mirrored those of paired FCMs, with significant correlations for several dominant congeners (p < 0.05), indicating migration contributions. Moreover, migration patterns were jointly influenced by PFAS physicochemical properties (e.g., log KOW, functional moieties), FCM texture, and food composition. Clear differences between leading and smaller brands were observed, with smaller brands exhibiting higher PFAS burdens in fast foods (p < 0.05). Notably higher PFAS concentrations were identified in soup-based instant foods. A controlled experiment demonstrated 3.1-26-fold higher PFAS concentrations in instant foods prepared in original paper packaging than in glass containers, largely driven by 6:2 FTS, which accounted for 88.3% of the total ∑32PFAS increment. Integrated multifactor prioritization revealed several emerging PFAS of particular concern, especially given their expanding use in FCMs. These findings highlight hot-contact packaging as a non-negligible exposure source and call for enhanced surveillance of emerging PFAS in fast-food supply chains.

Global diversity of chemical threats.The booming economy and improving well-being are closely linked to the rapid expansion of chemical manufacture and usage.China,as one of the world's lar-gest chemical producers and consumers,has documented over 47,000 substances in its"Inventory of Existing Chemical Sub-stances",which might drive millions of downstream products.Per-vasive chemical distribution and exposure have raised mounting concerns about the potential ecological and health risks.Of partic-ular concern is a subset of chemicals named as"new pollutants",which can exert significant ecological and public health impacts even at trace levels.New pollutants encompass a wide range of substances,including functional end-products,industrial byprod-ucts,and unintentionally produced contaminants.In recognition of their emerging risks,China launched the"Action Plan on Con-trolling New Pollutants"in 2022,followed by the regional imple-mentation plans across provinces().In 2023,14 types of new pollutants were formally included in the national monitoring list(),10 of which were persistent organic pollutants(POPs)characterized by persistence,bioaccumulation,and toxicity(PBT).

The plutonium in the highly radioactive waste liquid has a long half-life and this persistent radioactivity poses a great challenge to the long-term geological disposal of nuclear waste, making it necessary to separate it from other elements. Herein, three amide functionalized imidazolium ionic liquids (DXZ-1, DXZ-2 and MIMDIDOA) were synthesized for separation of Pu(IV) (Th(IV) used as a surrogate for plutonium) from a high-concentration nitric acid solution. The findings revealed that under the condition of 8 mol/L nitric acid, the kerosene solution with 0.1 mol/L MIMDIDOA has the highest extraction efficiency for Th(IV), with SF Th/U of 5.85, while the extraction of lanthanides (lanthanum and europium) can be ignored. The extraction mechanism was elucidated through Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The extraction process is an anion exchange process between chloride ions and thorium complex anions in solution assisted by N-containing functional groups in ionic liquids. The adsorption recovery rate of Th 4+ / 242 Pu 4+ by the extraction-elution resin impregnated using MIMDIDOA can reach 81 % under experimental conditions.

Rare earth elements have received widespread attention due to their extensive industrial applications. However, the production process of rare earth generates radioactive waste, which poses a threat to the environment. This article develops a safe, efficient, and convenient method to separate Th(IV), U(VI) from radioactive waste leachate to reduce environmental hazards. Bastnaesite is one of the rare earth minerals with the largest reserves in China. This article analyzes the main chemical components of two different types of radioactive residue leachate from bastnaesite. For the first time, TRPO (a mixture of trialkylphosphine oxides) has been used to simultaneously separate Th(IV) and U(VI) in the leachate. The optimal parameters for the separation were determined, including the leachate acidity, extractant concentration, and equilibration time between the aqueous phase and organic phase in extraction, scrubbing, and stripping processes. Based on the optimal parameters, the stage numbers and phase volumetric ratios were obtained using equations based on mass conservation and McCabe–Thiele diagrams. Furthermore, a counter-current extraction-scrubbing-stripping process was developed for the simultaneous separation of Th(IV) and U(VI) in the leachate. The results show that Th(IV) and U(VI) can be selectively and simultaneously separated in the leachate of radioactive waste residues.

The accurate quantification of acrylamide within complex infant formulas remain a significant challenge. This study validates a novel method for analyzing acrylamide in infant formula, which combines the quick, easy, cheap, effective, rugged, safe (QuEChERS) pretreatment approach with the isotope dilution HPLC-MS/MS technique. The optimized QuEChERS procedure effectively eliminates co-extracted matrix interferences and achieves high extraction efficiency. Notably, this approach simultaneously accomplishes a recovery rate of 103 % to 105 %, a relative standard deviation of less than 1.6 %, and a limit of quantification at 0.90 μg/kg. The high accuracy of this proposed method is further confirmed using commercially certified reference material (CRM, No. 108-02-006). Importantly, when 20 real samples were analyzed, five were found to be contaminated with acrylamide. These results demonstrate that the proposed method is rapid and reliable for determining acrylamide levels in infant formula, suggesting its potential as a primary detection method for acrylamide in complex matrices.

Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Development of Gas Chromatography Tandem Mass Spectrometry as a Candidate Reference Method for the Accurate Determination of Fatty Acid Contents in Infant Formula 28 Pages Posted: 27 Feb 2024 See all articles by Mengqian XuMengqian Xuaffiliation not provided to SSRNXiuqin Liaffiliation not provided to SSRNShuyu LiuShanghai University of Engineering ScienceYan Gaoaffiliation not provided to SSRNQing he ZhangNational Institute of Metrology Abstract Analyzing the fatty acid profile is essential for nutritional labeling and contributes to understanding the diversity of fatty acids in infant formula. This study systematically optimizes the complete process of analyzing fatty acids in infant formula using gas chromatography-mass spectrometer (GC-MS), including extraction, derivatization, calibrants, quantitative calibration methods, instrument parameters, matrix effects, and others. Under acetyl chloride derivatization conditions, twenty fatty acids in infant formula are successfully analyzed within 30 minutes using GC-MS equipped with a DB-FastFAMES column (20m×0.18 mm×0.20μm). This method utilizes fatty acid methyl esters as the calibrator and incorporates three glyceryl triacetates as internal standards into infant formula powder samples, employing the internal standard method for quantitative calibration. The validated GC-MS method demonstrates excellent repeatability and reproducibility in analyzing fatty acids of infant formula, with relative standard deviations below 5%. The GC-MS method is applied to measure ten fatty acids in the NIST SRM 1869 infant/adult nutritional formula. The measurement results obtained by the newly developed method align with NIST certified values, indicating that the method can provide accurate measurements for the target fatty acids. It can be employed as a higher-order reference method for assigning values to certified reference materials. Keywords: Fatty acids, Infant formula, Gas chromatography-mass spectrometer, Derivatization, Calibration Suggested Citation: Suggested Citation Xu, Mengqian and Li, Xiuqin and Liu, Shuyu and Gao, Yan and Zhang, Qing he, Development of Gas Chromatography Tandem Mass Spectrometry as a Candidate Reference Method for the Accurate Determination of Fatty Acid Contents in Infant Formula. Available at SSRN: https://ssrn.com/abstract=4740803 Mengqian Xu affiliation not provided to SSRN ( email ) No Address Available Xiuqin Li (Contact Author) affiliation not provided to SSRN ( email ) No Address Available Shuyu Liu Shanghai University of Engineering Science ( email ) shanghai, 201620China Yan Gao affiliation not provided to SSRN ( email ) No Address Available Qing he Zhang National Institute of Metrology ( email ) No.18, Bei San Huan Dong Lu, Chaoyang DistrictBeijingChina Download This Paper Open PDF in Browser Do you have negative results from your research you’d like to share? Submit Negative Results Paper statistics Downloads 0 Abstract Views 4 40 References PlumX Metrics Feedback Feedback to SSRN Feedback (required) Email (required) Submit If you need immediate assistance, call 877-SSRNHelp (877 777 6435) in the United States, or +1 212 448 2500 outside of the United States, 8:30AM to 6:00PM U.S. Eastern, Monday - Friday.

The efficient separation of light hydrocarbons from natural gas is crucial for natural gas purification, yet it remains a challenging and energy-intensive process. Adsorbent-based gas separation methods using metal-organic frameworks (MOFs) offer potential advantages, such as simplicity and energy efficiency. In this study, a pillarlayered MOF, Ni-FDMOF, was constructed by introducing trifluoromethyl (-CF3) groups into the Ni-DMOF framework to modify the pore environment. The C2 and C3 recognition ability and hydrophobicity of NiFDMOF were investigated. Single-component adsorption tests and ideal adsorption solution theory (IAST) calculations confirmed that Ni-FDMOF exhibited higher selectivity for C2/CH4 and C3/CH4 separation than NiDMOF. Notably, Ni-FDMOF achieved an impressive C3/CH4 selectivity of approximately 100, ranking among the top recorded MOFs. Theoretical calculations indicated that multiple attractive interactions between C2-C3 molecules and -CF3 groups play a crucial role in enhancing the adsorption of C2-C3. Moisture stability experiments demonstrated that Ni-FDMOF is a robust MOF with low water vapor capacity, due to the presence of hydrophobic -CF3 groups. Transient breakthrough simulations further verified the excellent separation of C1/ C2/C3 seven-component mixtures by Ni-FDMOF, highlighting its potential for industrial applications.

Chemical contaminants in food has become an issue of wide concern. To protect public health, maximum residue levels for certain contaminants such as mycotoxins, polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs), have been set in food matrix. However, accurate determination of these residue levels faces some technical challenges, for example, the identification of trace targets, the separation of structural analogues, the stability control of standard solutions, and the high accurate measurement of ultra-trace multi-components in complex food matrix. The National Institute of Metrology (NIM), China has developed a series of methods and certified reference materials (CRMs) to build the metrological traceability system for these contaminants in food. (1) Structural analogues and isomers are of great importance in the accurate measurement of PAEs and aflatoxins. Through elucidating the fragmentation mechanism of structural analogues and screening key characteristic fragment ions, we could separate target PAE analytes from coelutes and interferences arising from the sample matrix using LC-MS/MS. Moreover, aflatoxins were also characterized with UHPLC-QE Plus Orbitrap MS. 15 analogues of AFB1 were identified in the reference material candidate. Two degradation pathways have been proposed to evaluate the stability of AFB1 solution CRMs. These findings provide useful guides for the production, storage, and transportation of solution CRMs. (2) Pretreatment methods were innovatively established to enhance the extraction efficiency for multi-components. A facile method to extract PAEs from alcohol, milk powder, edible oil has been developed using polarity-matched mixed solvents. The extraction recovery was over 85% for 16 PAEs in those matrices. Moreover, the complementary liquid-liquid extraction technology was developed to enable simultaneous determination of six brands of regulated mycotoxins. The extraction efficiency was up to 80.8%, and the matrix effect was reduced greatly. External calibration approach verified the good quantification property for each analyte. (3) Due to the ultra-low concentration of analytes and the complexity of various matrices, to accurately determinate analytes in food matrices is very challenging. The synchronous calibration method revealed the effective elimination of isotope internal standard hydrogen-deuterium exchange differences in the PAH quantitation. Standard addition method and isotope dilution mass spectrometry (IDMS) method also revealed effectiveness to eliminate matrix effects of analytes in food matrix. Furthermore, IDMS methods could also correct procedure errors in the pretreatment procedure and presented enhanced precision. Finally, NIM has produced a series of pure, solution and matrix CRMs of these contaminants for commercial applications. A couple of international comparisons have been coordinated by NIM, and the related broad CMCs have been published on the KCDB. Furthermore, NIM has launched international PTs and training programs to promote the improvement and mutual recognition of international contaminant measurement capabilities. With the rapid development of artificial intelligence, big data and advanced manufacturing, new demands for metrology have arisen in order to support non-targeted screening, rapid identification of multiple hazards and food omics etc. A more intelligent food safety measurement system is expected to meet demands of the new era.

Well-characterized solution certified reference materials (CRMs) are necessary for the accurate determination, quality control, instrument calibration, and validation of analytical approach. Simultaneously, a mixed solution CRM of vanillin spices is in high demand because of the accurate measurement and traceability of vanillin spices in various food matrices. In this study, a mixed vanillin spices acetonitrile CRM (issued with GBWE 086557), including methylvanillin, ethylvanillin, vanillin, and coumarin, has been developed using the gravimetric method by the National Institute of Metrology, China. Methylvanillin, ethylvanillin, and vanillin showed poor stability in methanol. The acetalization of the aldehyde group of vanillin was the major step during the degradation process, as elucidated by ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), and exposure to high temperature and light irradiation accelerated the degradation dramatically, whereas the acetonitrile CRMs held sufficient homogeneity, and they were stored stable at 4 °C over 9 months or 50 °C for 7 days. Typically, the certified values for methylvanillin, ethylvanillin, vanillin, and coumarin in CRM were 10.1 ± 0.2, 10.2 ± 0.2, 10.0 ± 0.3, and 10.0 ± 0.2 μg/mL (k = 2), respectively.

The rapid development of nuclear energy has greatly increased the possibility of nuclear leakage, and the rapid detection of radioactive leakage in emergency situations requires rapid analytical methods. Pu(IV) is almost non-existent in nature, so radioactive contamination in the environment is usually analyzed by detecting the radioactivity level of plutonium. Here, the neutral extractant, PyDAM, and the novel functional ionic liquid, PyDAMI, were synthesized by introducing two amide groups into the pyridine for separating Pu(IV). Due to the high radioactivity of Pu, Pu(IV) was replaced by Th(IV) in extraction experiments. It was found that PyDAM in kerosene or [C4mim][NTf2] could not extract Th(IV), U(VI), Eu(III), Ce(IV) and Nd(III) from nitric acid media, while PyDAMI could extract both U(VI) and Th(IV), but hardly extract other metal ions, which indicates that electrostatic interactions play a key role. The distribution coefficients of U(VI) and Th(IV) in PyDAMI/[C4mim][NTf2] increase with an increase in the concentration of nitric acid, while they first increase and then decrease in PyDAMI/kerosene, indicating that PyDAMI has different extraction mechanisms in kerosene and [C4mim][NTf2] and their respective extraction mechanisms were studied through extraction experiments and some characterization techniques. In addition, the separation performance and separation factor of PyDAMI for thorium and uranium are improved in kerosene. Finally, the effect of temperature on PyDAMI's ability to extract uranium and thorium was investigated. It was found that the ability of PyDAMI to extract uranium and thorium decreased with increasing temperature, indicating that the extraction of uranium and thorium by PyDAMI was an exothermic reaction.

Per- and polyfluoroalkyl substances (PFAS) are increasingly detected in agricultural environments, yet national-scale data on PFAS contamination in paired food crops and soils remain scarce. This study presents the first nationwide investigation of legacy and emerging PFAS in paired soil and grain samples (n = 160) from 11 provinces representing China's major rice, wheat, and maize producing regions. PFAS were ubiquitously found in soils (median: 4.96 ng/g; range: 2.28-33.5 ng/g) and grains (7.74 ng/g; 2.40-25.3 ng/g), with short-chain perfluoroalkyl carboxylic acids being the dominant class. The emerging-to-legacy PFAS ratio was 2.16 in soils and 4.26 in grains, and crop PFAS levels were 1.5 times higher than those in corresponding soils, indicating the greater propensity of emerging PFAS to be transported into crops. Paddy soils exhibited significantly higher PFAS concentrations than dryland soils (p < 0.05), likely due to irrigation-driven accumulation. In addition, intensive anthropogenic activities were found positively related to PFAS concentrations in soils (r = 0.54, p < 0.05). Positive Matrix Factorization (PMF) analysis attributed PFAS sources primarily to food packaging, textile processing, and fluorochemical industries. Risk prioritization based on the ToxPi framework highlighted PFPeA, PFOA, PFOS, and HFPO-DA as priority compounds of concern. This study provides essential baseline data on PFAS contamination in Chinese farmland and paired staple crops, supporting regulatory oversight of both legacy and emerging PFAS in agricultural systems.

Organophosphate esters (OPEs) are a class of anthropogenic chemicals that have long been used as plasticizers and flame retardants. Dietary intake is an important OPE exposure pathway for humans. Since OPEs are usually used as industrial additives in food contact materials (FCMs), OPEs can enter foods through contact to FCMs. This paper focused on FCM-related exposure risks in foods, summarizing the presence of OPEs in FCMs and foods, analyzing the migration of the OPEs from FCMs to food, and assessing the dietary exposure risk of the OPEs to humans. Overall, the levels of the OPE in FCMs were at higher levels than those in foods. Processed and packaged foods contained higher levels of OPEs than nonprocessed/fresh foods. The migration investigations revealed that OPEs can be more likely transferred from FCMs to foods under the conditions of higher temperature and longer exposure time. We hope that this work will extend our current knowledge of the apportionment of OPE sources in foods and highlight the existing research gaps.

Despite increasing concerns over the potential hazards of perfluoroalkyl and polyfluoroalkyl substances (PFAS), their characteristics, especially temporal trends, remain largely unexplored in milk. With milk sampled from 2020 to 2024, the temporal trends and cross-country variations of legacy and emerging PFAS were investigated across 15 countries for the first time. Among the 32 PFAS analyzed, 26 were detected in more than 40% of the samples and 18 were present in over 60%, indicating their widespread geographical occurrence. Over the five-year period, concentrations of legacy PFAS declined significantly (p < 0.05), with a reduction rate of 85.9%, whereas emerging PFAS─particularly hexafluoropropylene oxide dimer (HFPO-DA) and 6:2 fluorotelomer sulfonic acids (6:2 FTS)─increased sharply by 251% and 146%. Based on these observed trends, we further projected PFAS concentrations in milk through 2030 using three statistical models, revealing a potential dominance of emerging PFAS in the near future. Notably, spatial differences in PFAS distribution appear to be associated with intensive industrialization and socioeconomic activities. Furthermore, a risk prioritization analysis integrating eight exposure and toxicity domains identified HFPO-DA, perfluorooctanoic acid (PFOA), perfluoropentanoic acid (PFPeA), and perfluorohexanesulfonate (PFHxS) as priority contaminants. These findings provide critical insights into global PFAS regulations, their effectiveness, and the urgent need for continuous monitoring of novel PFAS in future food supply.

Main text The original CCQM-K154.b comparison was coordinated by the Bureau International des Poids et Mesures (BIPM) and the Chinese National Institute of Metrology (NIM) on behalf of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) for National Measurement Institutes (NMIs) and Designated Institutes (DIs) which provide measurement services in organic analysis under the 'Comité International des Poids et Mesures' Mutual Recognition Arrangement (CIPM MRA) and/or have participated in the BIPM's Mycotoxin Metrology Capacity Building and Knowledge Transfer (MMCBKT) project as part of its "Metrology for Safe Food and Feed in Developing Economies" Capacity Building Programme. Gravimetrically-prepared solutions having an assigned mass fraction of specified organic analytes are routinely used to calibrate measurement processes for the quantification of the same analytes in matrix samples. Appropriate assignments of the property value and associated uncertainty of calibration solutions thus underpin the traceability of routine analysis and are critical for accurate measurements. Evidence of successful participation in relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes and designated institutes. In total, eleven NMIs/DIs participated in the Track C, Model II, Key Comparison CCQM-K154.b [Gravimetric preparation and value assignment of aflatoxin B1 (AfB1) in acetonitrile (ACN)] for emerging areas of global interest and innovation. Participants were requested to gravimetrically prepare calibration solutions and value assign the mass fractions, expressed in mg/kg, of aflatoxin B1 (AfB1) in the acetonitrile (ACN) solution. Study samples, with assigned values and associated uncertainties were prepared by the comparison participants and sent to the coordinating laboratory for comparison. The Key Comparison Reference Values (KCRVs), calculated form values measured by the coordinating laboratory based on calibrations obtained from independent gravimetrically prepared calibrant solutions, agreed with participants reported values, within their stated uncertainties. AfB1 was selected to be representative of polar aflatoxins. Aflatoxins are a class of mycotoxins generally produced by fungi of the genus Aspergillus. It was anticipated to provide a challenge representative for the gravimetrical preparation and value assignment of calibration solutions in the mass fraction range of 2 mg/kg to 50 mg/kg of mycotoxins with broadly similar structural characteristics. In the original study CCQM-K154.b, nine participants of the MMCBKT programme were provided with a stock solution having a known AfB1 mass fraction and expanded uncertainty to use to gravimetrically prepare and value assign a calibration solution. Three NMIs/DIs also participated using their own calibration solutions. The use of in-house solutions required an additional capacity to undertake a fit-for-purpose purity assessment. NIM was the only NMI participating using both the MMCBKT based and their own in-house assigned solutions in order to connect the two different groups. It was decided to propose separate KCRVs for each of the two ampoules provided by the participating NMIs/DIs based on the AfB1 mass fraction. This allowed participants to demonstrate the efficacy of their implementation of the approaches used to gravimetrically prepare calibrations solutions and to assess the AfB1 mass fraction. The majority of the AfB1 mass fraction KCRVs (wKCRV) for CCQM-K154.b spanned a mass fraction range of 2.02 mg/kg to 31.57 mg/kg. The relative expanded uncertainties U(wKCRV) ranged from 0.69 % to 2.93 %. Inspection of the degree of equivalence plots for the AfB1 mass fraction assignments in CCQM-K154.b indicated that there was an excellent agreement of results. Solely, the AfB1 mass fraction assignments of the INRAP (Institut National de Recherche et d'Analyse Physico-Chimique, Tunisia) did not agree with the KCRVs. It was found that the samples were altered as a result of an acid contamination. The INRAP has produced a new batch of AfB1 calibration solution using the AfB1 stock solution originally provided to MMCBKT participants to be able to demonstrate the efficacy of their implementation of the approaches used to gravimetrically prepare calibrations solutions and to assess the AfB1 mass fraction. The BIPM organized the present subsequent bilateral comparison CCQM-K154.b.1 to assess the new batch of AfB1 calibration solution of the INRAP. Inspection of the degree of equivalence plots for the AfB1 mass fraction assignments indicated that there is an excellent agreement of the INRAP results for CCQM-K154.b.1. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).