Matrix Certified Reference Materials Research Articles

Isotopic spike 190Os as internal standard and empirical coefficient LA-ICP-MS combined with Sb fire assay for the determination of ultra-trace platinum group elements in geochemical samples

In this work, a novel method of antimony fire assay (Sb-FA) enrichment combined with laser ablation ICP-MS (LA-ICP-MS) for the determination of ultra-trace platinum group elements (PGEs) in geological samples was established. The purification and recycling technology of ultra-clean and high-purity fire assay collector Sb2O3 was proposed, in addition, high-purity quartz crucible was developed to replace the usual clay crucible, then the blank values of PGEs were as low as 0.0007–0.0028 ng g−1 (for 20 g sample). 190Os isotopic diluent was used as internal standard (IS) and quantitatively added into the fire assay ingredients, and fully mixed and balanced with the PGEs in the real samples by means of high temperature melting, cupellation and horizontal rotation of crucible and dish. Both 190Os and PGEs in the real sample were pre-concentrated in microgram level Sb granules (100 mg) through Sb-remaining cupellation. After grinding and polishing, 195Pt, 105Pd, 101Ru, 103Rh, 193Ir, total 189Os and 190Os enriched in Sb slices were determined by LA-ICP-MS, 190Os in the internal standard was calculated by isotope dilution equations. The Certified Reference Materials (CRMs) for PGEs were treated by the same procedure to obtain completely matrix matched Sb slices to solve the problem of no internationally recognized uniform PGEs standard materials for LA-ICP-MS determination. Due to the similar distribution trends of different PGEs in Sb slices by LA-ICP-MS imaging, then matrix-matched internal standard calibration strategy was used to reduce the element fractionation effect and improve the determination precision and accuracy of LA-ICP-MS. The laser frequency, energy density, denudation diameter and dwell times were optimized. Under the optimal conditions, empirical coefficient method was used to fit the standard curve and excellent curve fitting of PGEs were obtained with the correlation coefficient between 0.9990 and 0.9999. The method detection limits (LODs) for PGEs ranged from 0.00042 to 0.010 ng g−1. The established method was successfully applied to analyze real geochemical samples and various matrix Certified Reference Materials (CRMs) domestic and international, the determined values were in good agreement with the results of Sb-FA ICP-MS and the certified values.

Green and sensitive method combining ultrasonic solvent extraction, stir bar sorptive extraction and thermal desorption-gas chromatography–tandem mass spectrometry for determination of organotin compounds in sediment

A method integrating ultrasonic solvent extraction (USE) and stir bar sorptive extraction (SBSE) with thermal desorption-gas chromatography–tandem mass spectrometry (TD-GC–MS/MS) was developed and validated for determining critical organotin compounds (OTCs)—tributyltin (TBT) and triphenyltin (TPhT)—in sediment. In preparing a 0.5 g sediment sample, two 1-min cycles of US bath solvent extraction (using equal parts CH3COOH and MeOH), were followed by derivatization with NaBEt4 in the presence of a methanolic-aqueous solution of CH3COONa and SBSE for 1 h, achieving analyte recoveries of 64–94 %. Matrix-matched internal standard calibration and the use of an isotopically labelled recovery standard corrected for analyte losses and matrix effect (ME), ensuring accurate results for triorganotins. However, the method was not suitable for mono- and diorganotins due to low and anomalous recoveries caused by ME. Miniaturizing and optimizing the sample preparation reduced chemicals use and waste, contributing to the method being deemed ’an excellent green analysis’ by the Analytical Eco-Scale assessment. The method achieved a limit of quantification (LOQ) of 0.081 ng g−1 and an expanded uncertainty (U) value of 15 % for TBT, meeting the environmental quality standards (EQS) criteria of the European Union Water Framework Directive. Its applicability was demonstrated through the analysis of actual sediment samples and natural matrix certified reference materials.

Stepping-up accurate quantification of chlorinated paraffins: Successful certification of the first matrix reference material

BackgroundChlorinated paraffins (CPs) are industrial chemicals categorised as persistent organic pollutants because of their toxicity, persistency and tendency to long-range transport, bioaccumulation and biomagnification. Despite having been the subject of environmental attention for decades, analytical methods for CPs still struggle reaching a sufficient degree of accuracy. Among the issues negatively impacting the quantification of CPs, the unavailability of well-characterised standards, both as pure substances and as matrix (certified) reference materials (CRMs), has played a major role. The focus of this study was to provide a matrix CRM as quality control tool to improve the comparability of CPs measurement results. ResultsWe present the process of certification of ERM®-CE100, the first fish reference material assigned with certified values for the mass fraction of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively). The certification was performed in accordance with ISO 17034:2016 and ISO Guide 35:2017, with the value assignment step carried out via an intercomparison of laboratories of demonstrated competence in CPs analysis and applying procedures based on different analytical principles. After confirmation of the homogeneity and stability of the CRM, two certified values were assigned for SCCPs, depending on the calibrants used: 31 ± 9 μg kg−1 and 23 ± 7 μg kg−1. The MCCPs certified value was established as 44 ± 17 μg kg−1. All assigned values are relative to wet weight in the CRM that was produced as a fish paste to enhance similarity to routine biota samples. Significance and noveltyThe fish tissue ERM-CE100 is the first matrix CRM commercially available for the analysis of CPs, enabling analytical laboratories to improve the accuracy and the metrological traceability of their measurements. The certified CPs values are based on results obtained by both gas and liquid chromatography coupled with various mass spectrometric techniques, offering thus a broad validity to laboratories employing different analytical methods and equipment.

Development of a Method for the Determination of Total Selenium in Soil, Maize Plants, and Maize Flour by Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS)

Selenium (Se) is a micronutrient that has multiple biochemical effects ranging from a nutritional deficiency at low levels to toxicity at high levels. Its quantification in environmental systems is vital to protect the health of people and animals. This study developed and validated methods to determine the total selenium (Se) concentration in soil, maize plants, and maize flour. The performance of the methods was ascertained using matrix certified reference materials (CRMs), namely NMIJ CRM 7303-a (trace elements in lake sediments), NIST SRM 1646-a (estuarine sediments), NIST SRM 1570-a (spinach leaves), NIST SRM 1571 (orchard leaves), NCS ZC 73010 (maize flour) and NIST RM 8437 (hard red spring wheat flour). All methods fulfilled the performance requirements of the AOAC International. An acceptable accuracy was achieved with percentage recoveries between 57 and 102% and E n ‐ scores within ±1 limits. Repeatability ( RSD r , % ) and intermediate precision ( RSD R , % ) ranged from 4 to 12%, and 9 to 15%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for soil were 0.024 ng. g−1 and 0.082 ng. g−1, respectively. The LODs and LOQs for maize plants and flour were 0.0036 and 0.0179 ng. g−1, respectively. The performance characteristics of the methods were comparable with previously reported methods, confirming reliability. The measurement uncertainty was evaluated following the guide to the expression of uncertainty in measurement (GUM). Relative expanded uncertainty at a 95% level of confidence ( k = 2 ) was less than 24% for the final measurement results for all the different matrices.

A Study of a New Certified Reference Material for Accurate Determination of the Main Fusarium Mycotoxins in Whole-Wheat Flour.

Matrix certified reference materials (CRMs) play a critical role in analytical method validation and the assurance of reliable measurement results. A certified reference material (GBW(E)100813) for whole-wheat flour was developed to ensure an accurate and reliable measurement of the main Fusarium mycotoxins (deoxynivalenol (DON), nivalenol (NIV), deoxynivalenol-3-glucoside (DON-3G), and zearalenone (ZEN)). CRM candidates were prepared using sun-drying, grinding, sieving, homogenising, packaging, and gamma irradiation. The final produced CRM was packaged at 50 g per unit and stored at 20 °C. Certification was performed using isotope dilution-liquid chromatography-tandem mass spectrometry. CRM characterization was performed in eight laboratories in accordance with the requirements of ISO Guide 35. The certified values and expanded uncertainties (at a confidence of 95%, k = 2) for DON, NIV, DON-3G, and ZEN were determined to be 0.98 ± 0.12 mg/kg, 1.37 ± 0.20 mg/kg, 242 ± 35 μg/g, and 382 ± 50 μg/g. The CRM was sufficiently homogeneous between and within bottles, and remained stable for up to 12 months at 20 °C and 9 days below 40 °C for transportation. Thus, CRM can be used for quality control and method validation to ensure the accurate and reliable quantification of the main Fusarium mycotoxins in whole-wheat flour.

Determination of Ultra-Trace Rhodium in Geological Samples by High Radio Frequency Power Cold Plasma and Kinetic Energy Discrimination Collision Cell-Inductively Coupled Plasma-Mass Spectrometry (KED-ICP-MS)

A novel method was developed for the determination of ultra-trace rhodium (Rh) in geological samples. Using Sb2O3 as fire assay collector, Rh in 10 to 20 g was pre-concentrated in 50 mg Sb granules. After the granules were microwave digested in aqua regia (40%, v/v), 103Rh was determined by high radio-frequency (RF) power cold plasma and kinetic energy discrimination collision cell-inductively coupled plasma-mass spectrometry (KED-ICP-MS). Four methods to eliminate the mass spectral interferences of 206Pb2+ and 40Ar63Cu to 103Rh including standard mode (STD-ICP-MS) hyphenated with equivalent concentration correction of 206Pb2+ and 40Ar63Cu, KED-ICP-MS hyphenated with equivalent concentration correction of 206Pb2+, high RF power cold plasma ICP-MS hyphenated with equivalent concentration correction of 40Ar63Cu, and high RF power cold plasma hyphenated with KED-ICP-MS were compared. The first three methods required equivalent concentration correction so the Pb and Cu content in the sample solutions were determined in advance and subtracted. On the contrary, the interferences were eliminated by high RF power cold plasma hyphenated with KED-ICP-MS. The RF power of cold plasma was studied. Moreover, the He collision gas, nebulizer flow and sampling depth were optimized. Under the optimal conditions, Rh had a linear relationship from 0.001 to 10 ng mL−1 with a correlation coefficient of 0.9999. The detection limit was 0.012 ng g−1. The method was applied to analysis of various matrix certified reference materials (CRMs) and the measured results were in good agreement with the certified values.

Development of a novel certified reference material for the determination of polycyclic aromatic hydrocarbons (PAHs) in whey protein powder

Matrix-based certified reference materials (CRMs) play a central role in the analysis of food contaminants for ensuring measurement accuracy and comparability, as they exhibit the same matrix effects during sample preparation and measurement as the food sample under investigation. However, the availability of such CRMs is still limited. This is also true for matrix CRMs containing polycyclic aromatic hydrocarbons (PAHs), for which maximum levels in food are set in the EU by the Commission Regulation (EU) 2023/915 and in Switzerland by the regulation SR 817.022.15. Therefore, a whey protein powder–based certified reference material (WP-CBR001) was developed according to the requirements of ISO 17034 and the recommendations of ISO Guide 35:2017 containing the four PAHs benz[a]anthracene (BaA), benzo[a]pyrene (BaP), benzo[b]fluoranthene (BbF), and chrysene (Chr). We show that the choice of solvent is of crucial importance to extract the PAHs completely from this matrix. Only polar and protic solvents such as methanol or water provided access for complete extraction of the PAHs. In contrast, nonpolar and polar aprotic solvents, such as n-hexane or ethyl acetate, exhibited only very low extraction efficiencies below 20%. The certified mass fractions and expanded uncertainties (k = 2) were (3.17 ± 0.32) µg/kg BaA, (4.18 ± 0.48) µg/kg BaP, (4.73 ± 0.49) µg/kg BbF, and (2.85 ± 0.33) µg/kg Chr. These values were verified by an interlaboratory comparison study and by the gravimetric mass fractions obtained from production data.Graphical abstract

Development of two new matrix certified reference materials for enrofloxacin and norfloxacin residues in fish meat powder

In this study, two matrix certified reference materials (CRMs) for accurate measurement of enrofloxacin and norfloxacin in fish meat powder were produced, respectively (GBW10167, GBW10168). Raw material was obtained by feeding fish with positive drugs. The homogeneity, stability and certification of two matrix CRMswere stµdied by using a liquid chromatography tandem mass spectrometric with isotope-labeled internal standard method. The certified value of enrofloxacin in fish meat powder was 62.5 µg/kg with an expanded uncertainty of 6.3 µg/kg (coverage factor k = 2, at 95% confidence range). The certified value of norfloxacin in fish meat powder was 41.8 µg/kg with an expanded uncertainty of 5.9 µg/kg (coverage factor k = 2, at 95% confidence range). In addition, homogeneity, long-term stability at −20 °C for a year, and short-term stability at 4 °C, 25 °C, and 50 °C for nine days was assessed in detail. The results showed that the samples were stable under the above conditions.

Development of a new matrix-certified reference material for accurate measurement of PFOA and PFOS in oyster meat powder

Bioaccumulation of PFOA and PFOS in aquatic organisms is increasingly a global environmental problem. The development of biota matrix certified reference materials (CRMs) for PFOA and PFOS is urgently needed to cope with food safety supervision by assuring accurate analysis results. This paper addresses this urgent need by developing a new oyster matrix CRM of PFOA and PFOS; the certified values and expanded uncertainties are 5.63 ± 0.35 and 3.08 ± 0.20 µg/kg. The CRM candidates were prepared by adding PFOA and PFOS into raw oyster meats, followed by freeze-drying, grinding, blending, homogenizing, bottling, and gamma-irradiation. The sample pretreatment strategy of extraction and clean-up was optimized to minimize matrix effects and interferences. The isotope dilution high-performance liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) strategies were employed for certification, homogeneity, and stability assessment. In addition, uncertainties were evaluated by combining the contributions from characterization, homogeneity, and stability.

Determination of inorganic As, DMA and MMA in marine and terrestrial tissue samples: a consensus extraction approach

Environmental context Arsenic can be found in all environmental compartments in a large number of chemical forms of varying toxicity. We performed an inter-laboratory comparison study focusing on quantitation of some of the most toxic arsenic forms in seven different biological materials and found very good agreement among the submitted results. Certification of the studied materials will provide suitable quality control samples for environmentally relevant concentrations of arsenic in food products and biota.Rationale Arsenic (As) speciation analysis in biological matrices has been performed for several decades; however, there are very few matrix certified reference materials available for the validation of analytical methods. The literature data on the mass fractions of As species in the existing certified reference materials are inconsistent and suggest method extraction dependency.Methodology In the present study, an international round-robin study was organised to identify the possible sources of discrepancies in quantitation of several As species in different matrices of biological reference materials: one plant tissue, three marine and three terrestrial biological tissues. Each participating laboratory was provided with a set of identical calibration standard solutions, and analysed the samples by following a common group extraction method as well as using an in-house protocol.Results The results showed that significant biases can be introduced by insufficient verification of the analyte’s mass fractions in the calibration standard solutions. The choice of extraction method seems to have very little impact on the quantitation of As species in the studied plant and terrestrial biological tissues. However, following a prescribed extraction method led to significant reduction of uncertainties in more complex samples such as marine animal tissues.Discussion Some differences in the mass fractions of As species extracted from marine animal tissues in water (with and without H2O2) were observed and should be further investigated. Despite the variety of extraction methods used, very good agreement between reported mass fractions was achieved and the combined consensus values will be published as certified reference values of As species in the studied materials.

Certification of visinin-like protein-1 (VILIP-1) certified reference material by amino acid-based and sulfur-based liquid chromatography isotope dilution mass spectrometry.

As an emerging neurodegenerative disease, Alzheimer's disease (AD) has become a leading cause of dementia in older adults. Visinin-like protein-1 (VILIP-1) is an increasingly used biomarker for AD besides the widely accepted Aβ1-40, Aβ1-42, and tau. However, significant variations exist in the commercial immuno-based assays for VILIP-1 quantification, underlining the necessity to establish a traceability chain. Certified reference materials (CRMs) located at the top of the traceability chain are traceability sources for relevant matrix standard materials. In this work, VILIP-1 solution CRM with a certified value and uncertainty of 39.82±1.52 μg·g-1 was developed and certified using amino acid-based isotope dilution mass spectrometry (AA-ID-MS) and sulfur-based isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). Certified values from both strategies showed great consistency, with traceability to SI units. Moreover, the candidate VILIP-1 CRM shows excellent homogeneity and can be stable for at least 7 days at -20°C and 12 months at -70°C. The VILIP-1 CRM developed can be used in value assignment to secondary calibrators and clinical matrix CRMs, showing prospects in early diagnosis and disease monitoring for AD.

Study of a new matrix certified reference material for accurate measurement of pefloxacin in fish meat powder

Matrix certified reference materials (CRMs) have played a critical role in analytical method validation and assurance of reliable measurement results. A matrix CRM of pefloxacin in fish meat powder was newly studied and developed for fishery food quality and safety monitoring. The CRM candidates were prepared from incurred samples by procedures of freeze-drying, grounding, sieving, homogenizing, secondary freeze-drying, bottling and gamma-irradiating. Isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) was established and applied to value assignment. The certified value was 45.3 μg/kg for mass fraction of pefloxacin in fish meat powder with expanded uncertainty of 3.7 μg/kg (k = 2, at a confidence of 95 %). Homogeneity, long-term stability of six months at −20 °C for storage, and short-term stability of nine days at 4 °C, 20 °C and 40 °C for transportation were investigated. In addition, uncertainty of the certified value originating from value assignment, homogeneity testing and stability monitoring were evaluated.

Digital PCR-Based Characterization of a g10evo-epsps Gene-Specific Matrix Reference Material for Its Food and Feed Detection.

g10evo-epsps is a novel glyphosate herbicide-resistant gene that has been transferred to various crops such as soybean, corn, cotton, and rice. Here, we developed a gene-specific digital Polymerase Chain Reaction (dPCR) detection method for absolute quantitative analysis of g10evo-epsps, and characterized g10evo-epsps certified reference materials (CRM) using ZUTS-33 soybean powder as the candidate material. Stability tests of matrix CRMs demonstrate that these CRMs can be stored stably for 6 months and transported for 10 days at room temperature and withstand summer high temperatures (below 60 °C). CRM characterization is based on the copy number ratio of g10evo-epsps to lectin. Eight qualified laboratories independently validated the CRM using dPCR method, with a measurement of 0.98 (copy/copy) and an extended uncertainty of 0.08 (copy/copy). The g10evo-epsps matrix CRM described here may be used for qualitative and quantitative testing, method evaluation, laboratory quality control, and other related fields.

Non-target analysis and stability assessment of reference materials using liquid chromatography‒high-resolution mass spectrometry

Development and characterization of biological and environmental matrix certified reference materials (CRMs) for organic analytes typically relies heavily on targeted analytical methods, such as liquid chromatography (LC) with triple-quadrupole mass spectrometry detection. LC with high-resolution mass spectrometry (LC‒HRMS) can also provide high quality data for both targeted and non-targeted analytes, with the potential for retrospective data analysis. Here, we demonstrate the utility of non-target analysis (NTA) using LC‒HRMS for profiling and stability assessment of a mussel tissue matrix CRM certified for several classes of marine algal toxins (CRM-FDMT1). First, the NTA method was developed using data-dependent MS/MS acquisition and commercial metabolomics software for data processing. Of 128 toxin analogues previously reported in CRM-FDMT1, 125 were detected by LC-HRMS, with 97 triggered for MS/MS by data dependant acquisition. Automated data processing detected 119 of these compounds and 109 were retained after automated filtering of results for putative toxin analogues. Those analogues not detected were low abundance ions, or poorly resolved isomers. The method was then used to demonstrate new strategies for CRM stability assessment considering the stability of certified analytes, related toxin analogues, and unrelated matrix compounds. Several analogues from each toxin class in CRM-FDMT1 as well as other unrelated matrix compounds were observed to be significantly less stable than the certified toxins. Using this method, no instability was measured for any compounds at conditions ≤4 °C, providing a greater degree of confidence in CRM stability than could be achieved using conventional approaches to stability assessment targeting only the certified analytes. The NTA method and stability assessment approach presented are applicable to future CRM development with other matrices and organic analyte classes.

Determination of Antibiotic Residues in Aquaculture Products by Liquid Chromatography Tandem Mass Spectrometry: Recent Trends and Developments from 2010 to 2020

The issue of antibiotic residues in aquaculture products has aroused much concern over the last decade. The residues can remain in food and enter the human body through the food chain, posing great risks to public health. For the safety of foods and products, many countries have issued maximum residue limits and banned lists for antibiotics in aquaculture products. Liquid chromatography tandem mass spectrometry (LC/MS/MS) has been widely used for the determination of trace antibiotic residues due to its high sensitivity, selectivity and throughput. However, considering its matrix effects during quantitative measurements, it has high requirements for sample pre-treatment, instrument parameters and quantitative method. This review summarized the application of LC/MS/MS in the detection of antibiotic residues in aquaculture products in the past decade (from 2010 to 2020), including sample pre-treatment techniques such as hydrolysis, derivatization, extraction and purification, mass spectrometry techniques such as triple quadrupole mass spectrometry and high-resolution mass spectrometry as well as status of matrix certified reference materials (CRMs) and matrix effect.

New matrix certified reference materials for the measurement of trace elements in swine and chicken compound feed

New animal feed matrix certified reference materials (CRMs) were developed to measure Cu, Fe, Mn, and Zn trace elements in swine and chicken compound feed. The market-obtained raw feed materials were ground, blended, homogenized, bottled, and gamma-irradiated to prepare the CRM candidates. We then employed isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), flame atomic absorption spectroscopy (FAAS), and inductively coupled plasma mass spectrometry (ICP-MS) as reference methods in collaborative characterization program. The certified values and expanded uncertainties (at a confidence level of 95%, k = 2) of Cu, Fe, Mn, and Zn were assigned to be 60.48 ± 1.84, 367.0 ± 14.7, 159.1 ± 6.8, and 335.2 ± 7.7 μg/g in the swine compound feed CRM, respectively, and 39.53 ± 3.08, 332.0 ± 19.9, 111.3 ± 10.4, and 132.1 ± 7.8 μg/g in the chicken compound feed CRM, respectively. The homogeneity, short-term stability at 60˚C for 9 days, long-term stability at − 20˚C and room temperature for 18 months, and uncertainty evaluation were sufficiently studied. Thus, these two CRMs can be used for quality control and method validation to ensure the accurate and reliable measurements of swine and chicken feed for quality and safety monitoring.

Internationally harmonized certified reference materials and proficiency testings for pesticide residue analysis.

Matrix certified reference materials (CRMs) and proficiency testings (PTs) are effective for evaluation of the quality of analytical results. The National Metrology Institute of Japan has developed five kinds of CRMs and has provided eight PTs so far for the quantification of pesticide residues in foods. Target pesticides were sprayed on growing crops, and the harvests were used for the preparation of CRMs and PT samples. In most cases, multiple analytical methods based on isotope dilution mass spectrometry were used to ensure the reliability of certified values (for CRMs) and reference values (for PT samples). These activities were carried out with corresponding to the international standards such as ISO 17034 and ISO/IEC 17043. An overview of the development of CRMs and the implementation of PTs is described, with some examples.

Evaluation of peak-fitting software for magnesium quantification through k0-instrumental neutron activation analysis

The selection and effective utilization of peak-fitting software for conventional gamma-ray spectrum analysis is significant for accurate determination of the mass fraction of elements, particularly in complex peak regions. Majority of the peak-fitting programs can derive similar peak characteristics for singlet peaks, but very few programs can deconvolute multi-peaks in a complex region. The deconvolution of multi-peaks requires special peak-fitting functions, such as left and right-skew distributions. In the this study, 843.76 keV (27Mg) peak area from the complex region (840 keV–850 keV) determined and compared using four different peak-fitting programs, namely, GammaVision, Genie2000, HyperLab, and HyperGam. The 843.76 keV peak interfered with 841.63 keV (152mEu) and 846.81 keV (56Mn). The total Mg concentration was determined through k0-instrumental neutron activation analysis by applying the isotopic interference correction factor 27Al(n,p)27Mg through the simultaneous determination of Al concentration. HyperLab and HyperGam peak-fitting programs reported consistent peak areas, and resultant concentrations agreed with the certified values of matrix-certified reference materials.

Development of a new matrix certified reference material for metronidazole in egg powder

Due to the potential health risks and hazards associated with the intake of metronidazole, several governments and consumers have become increasingly concerned about the quality and safety of food in the recent years. Since it is not possible to avoid the side effects of metronidazole, immense efforts are being taken to appraise and monitor its concentration in feed in order to ensure the safe consumption of food. However, simple certified reference materials (CRMs) for the quality control and quality assurance of metronidazole are still lacking. Thus, the first matrix CRM for metronidazole was developed from egg powder. This paper presents the complete process of the development of a CRM for metronidazole in egg powder, including sample preparation, homogeneity and stability studies, and the uncertainty assessment. The egg samples were taken from hens that took metronidazole orally. The matrix CRM developed was quantified using isotope dilution high-performance liquid chromatography coupled with tandem mass spectrometry. Concurrently, in order to support the certification study, an interlaboratory contrast study involving eight expert laboratories was implemented. The bulk material was bottled in 4 g portions. While the stability of the CRM was monitored at −20 °C for 13 months, at −4°C, 20 °C, and 40 °C for 9 days. During the monitoring period, the matrix CRM candidate was found to be stable at all temperatures.

The importance and availability of marine certified reference materials

Traceability and reliable results are the two pillars of analytical methods; certified reference materials (CRMs) meet this requirement. ISO 17034:2016 credentials provide brief information on general requirements for the competence of Reference Material Producers (RMPs). The different types of CRMs have been produced in recent years for chemical analysis in food, water, soil, and sediment matrices in recent years. This review provides a detailed overview of the development of CRMs in the field of marine environment, as matrix CRMs play an important role in the field of environmental monitoring. COMAR database, EVISA database: materials, LGC standards, and JRC catalogs are very helpful online resources to find various types of CRMs according to the application requirements. Highlights The classification of certified reference materials (CRMs) in the field of marine environment is presented; General information about the production and characteristics of CRMs is discussed; Examples of use of existing marine CRMs are described in detail; Importance of CRMs for QA/QC and CRMs development for chemical analysis is presented; The parameters that characterize the CRMs: representativeness, homogeneity, stability, and certified value are provided.