Development of a reference material for mercury in fish: certified

Overview

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uncertainty of 1.8%, while MeHg was 2.9%. Other uncertainty components included long-term stability (2.5%), homogeneity
(1.8%), and short-term stability under transport conditions (0.02%). The CRM was certified with a total Hg mass fraction
of 3.94 mg/kg (relative expanded uncertainty 7.1%, k = 2) and an informative MeHg mass fraction of 3.79 mg/kg (relative
expanded uncertainty 8.3%, k = 2). This CRM is a valuable tool for assessing mercury in similar matrices, supporting com-
30 # 45‑03, 111321 Bogotá, Colombia the atmosphere increased by 20%, with South America, sub-
(FAAST), Department of Chemical Engineering tors. In South America, approximately 80% of total mercury
mercury concentrations, ranging from 0.04 to 0.44 mg/kg, packaged in amber glass bottles containing 15 g of mate-
ments in the Latin American context. content nearing 20 mg/kg; hence, the normalized produc-
separation was achieved using a 5% diphenyl/95% dimethyl
trated, doubly subdistilled nitric acid and 2 mL of 30% diameter, and 0.25 µm film thickness). The temperature pro-
stabilize mercury in the solution, 0.2 mL of a 100 µg/kg gold of 10 °C/min until reaching 240 °C, where it was held for
the extracts were diluted to a final weight of 20 g with deion- in 25% KOH) in a thermostatic bath at 80 °C for 8 h. The
ized water (0.055 µS/cm, Elga, Purelab Flex, UK), and the extracted MeHg was then derivatized using 2% sodium
Isotope monitoring included 74Ge, 199Hg, 200Hg, 201Hg, and urements, a derivatized MeHgCl solution at 1000 mg/kg was
MSresidual indicates the mean square of residuals, and n0 bottles were analyzed under intermediate precision condi-
tively low at 4%. Filleting and deboning incurred the highest Homogeneity
to significant material loss. Moisture content was 4%, with Before estimating the homogeneity uncertainty for the
10%. This increased yield was attributed to a more efficient (ANOVA) in accordance with ISO Guide 33,405, ensuring
reduced to 3.2%, indicating improved process efficiency. determined in the study for different combinations of mer-
3.4%, indicative of a stable and durable material (14, 24). isotopes. This conclusion was supported by smaller mean
The 118–230 μm fraction provided the best balance between the pilot CRM was 3.1%.
for this batch was 1.8%, lower than that of the pilot pro-
kg and an uncertainty of 3.80%, its significantly lower con-
when comparing the normalized material with ERM-CE 60 °C and 80% relative humidity in the pilot material are
3.90%) (13), a similar total mercury concentration is evident; day zero of the study.
uncertainty attributable to the short-term stability of the batch over 730 days, during which total mercury measure-
the pilot material as 0.02% at 30 days under temperature results obtained in the determination of mercury at different
0.02%, demonstrating that the preparation process could be tion because it is the most used model. The uncertainty due
reliably reproduced across different batches and the stability to long-term stability was 2.5%.
comparable to that of the standardized material, a stability estimated at 0.14%, while the standard relative uncertainty
study was conducted using a classic design over 855 days. of the method was 2.6%. The mathematical model used and
that no instabilities occurred in the material over the entire measurement yielded 4.00 ± 0.2 mg/kg, and the second day
period. was 3.99 ± 0.07 mg/kg. The mean and combined uncertainty
were 4.00 ± 0.11 mg/kg (2.63% as relative uncertainty)
The pilot CRM was to assess the preparation conditions and yielding a non-statistically significant of 1.0%.
was not conducted for this batch; total Hg concentration ing calibration, showed stable measurements over 3 days.
was estimated using CV-AAS method obtained a value of The mean value was 3.87 ± 0.079 mg/kg (2.0% as relative
20.88 mg/kg and an RSD of 1.72% with n = 5. uncertainty). When comparing the two methods, CV-AAS
Table 1 Combination of methods for assigning total Hg value process presented in Table 1.
CRM DORM-4 served as a control. The mean measurement
value for MeHg in the fish material was 3.79 ± 0.11 mg/kg
value was 3.82 ± 0.11 mg/kg, and on the second day, it was

Methods (brief)

fasciatum) from the Colombian Amazon. The process involved raw material selection, sample preparation, homogeneity, and
stability, resulting in the CRM INM-039–1. Total Hg was measured using inductively coupled plasma-mass spectrometry
(ICP-MS) and cold vapor atomic absorption spectrometry (CV-AAS), while MeHg was analyzed by gas chromatography-
mass spectrometry (GC–MS). Calibration methods varied: ICP-MS used gravimetric standard addition, CV-AAS employed
(FAAST), Department of Chemical Engineering tors. In South America, approximately 80% of total mercury
Instituto Nacional de Metrología de Colombia, Av Carrera 50 ces requires sophisticated and tailored sample preparation
urement steps (2, 6). Certified reference materials (CRMs) Collection of samples and preparation
determined on a dry basis. In each case, a 0.5 g portion 100 °C and a 500 µL sample loop.
achieved. This sample portion was independent of the one Methyl mercury determination
used for measurement The sample portion in all experiments
the produced fish material. formed using gas chromatography-mass spectrometry
Each subsample (0.5 g) was treated with 3 mL of concen- polysiloxane column (Elite 5, 30 m length, 250 µm inner
ion solution (SMU, Slovakia) was added (21). The samples an additional 3 min. Helium was used as the carrier gas at a
to 20 °C. After digestion, the samples were allowed to cool The sample preparation for MeHg determination involved
plasma mass spectrometry (ICP-MS) and cold vapor atomic ized product with a 9:1 mixture of toluene and isooctane.
absorption spectrometry (CV-AAS). This method was adapted from the procedure described by
ICP‑MS analysis standard correction, was applied using an isotope-enriched
The ICP-MS (NexION300D, Perkin Elmer, MA, USA) For quality control, the certified reference materials

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

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Verification notes

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised