Simultaneous speciation analysis of Hg and Se in fish by

Overview

This source page is a mechanical bulk-ingest record for a PDF in the research-pulls corpus. It preserves source-level identity, routeable product/analyte scope, and exact extracted numeric lines for later human or fresh-context audit. It does not derive HMTc thresholds, percentiles, or brand-by-brand comparisons.

Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

28 and a mobile phase consisting of a mixture of methanol 5 % (v/v), 45 mM HNO3, 0.015 % 2-mercaptoethanol
31 by means of the accuracy profile approach by carrying out three series of measurements in duplicate on three
33 0.013 mg/kg wet weight (ww) for all selenium species, except for Se(IV) (0.15 mg/kg ww), while the
34 coefficient of variation in terms of intermediate reproducibility (CV R) was < 7 %. The LOQ for MeHg was
35 0.006 mg/kg ww, while the CVR was 3 %. The method was successfully applied to the analysis of muscle
80 0.14 % (v/v) BME in 50 mM ammonium acetate at pH  4.6 (11).
104 The mobile phases were prepared with MeOH and HNO3 (67 %, v/v) purchased from VWR chemicals
106 (TFA, ≥ 99 %) from Sigma-Aldrich, and the L-cysteine HCl.H2O, (99 %, m/m) from Alfa Aesar (Kandel,
108 Methylmercury chloride (CH3HgCl) standard solution (1001 μg/L) was purchased from VHG Labs (LGC,
109 Molsheim, France) and 1000 mg/L Se standard solutions of the individual Se species were prepared from
110 sodium selenite (≥99 %), Se(IV), sodium selenate (≥95 %), Se(VI), seleno-DL-methionine (≥99 %), SeMet,
111 and Se-methylselenocysteine (≥95 %), SeCys), all being purchased from Sigma-Aldrich.
116 bismuth (Bi), cerium (Ce), cobalt (Co), indium (In), lithium (Li) and uranium (U) at 1.0 μg/L in HNO3 2 %
117 (v/v) and HCl 0.5 % (v/v) and it was purchased from Thermo Fisher Scientific (Courtaboeuf, France).
120 0.0219 ± 0.0027 mg/kg and 0.601 ± 0.030 mg/kg, respectively, and total Se (tSe) certified level of
121 0.113 ± 0.011 mg/kg and 1.33 ± 0.13 mg/kg, respectively. NMIJ 7402-a (codfish tissue) CRM from the
122 National Metrology Institute of Japan (NMIJ) has a certified level of 0.61 ± 0.02 mg/kg for tHg, of
123 0.58 ± 0.02 mg/kg for MeHg and of 1.8 ± 0.2 mg/kg for tSe. Finally DOLT-5 (dogfish liver tissue) from the
124 National Research Council Canada, has a certified levels of 0.44 ± 0.18 mg/kg for tHg, of 0.119 ± 0.058 mg/kg
125 for MeHg and of 8.3 ± 1.8 mg/kg for tSe. The CRMs NMIJ and DOLT-5 were purchased from LGC Standards
127 For the determination of total Hg and Se by ICP-MS, mono-elemental stock standard solutions at 1000 mg/L
129 (Courtaboeuf, France) were used to prepare working solutions daily in 6 % (v/v) HNO3. A solution containing
130 Au at 10 mg/L in 6 % HNO3 (v/v) was used throughout for ICP-MS washing between the analyses to reduce
153 speciation analysis are given in Table 1.
Table 1. ICP-MS and HPLC optimum conditions and instrumental parameters for Se and Hg speciation analysis
160 concentrated HNO3 (67 %, v/v). The digests were diluted with ultrapure water after the addition of internal
169 of BME 10 % (v/v) , ( final volume of 3 mL). The solutions were mechanically shaken by using an overhead
173 suitable for small volumes (maximum final volume of 5.0 mL and maximum sample amount of 0.2 g), allowing
177  7, containing 6.67 g/L of protease XIV and 500 µL of BME 10 % (v/v)) were investigated. Final dilution
206 The simultaneous speciation method was validated by means of the accuracy profile approach, following a
208 The trueness (expressed here by bias, %), the repeatability (expressed here by the coefficients of variation for
210 variation for intermediate reproducibility (CVR), %) were assessed using the accuracy profile approach by
211 means of CRM analysis or by spike recovery experiments.
212 The theoretical validity domain was defined between 0.035 μg/L and the highest concentration used for the
213 calibration curve, namely 2.5 μg/L and 5.0 μg/L in the analysed Hg and Se solutions, respectively, for all
214 species, except for Se(IV), for which the theoretical validity domain was defined from 0.07 μg/L to 5.0 μg/L.
216 quantification (LOQ) of Se species and MeHg by the analysis of solutions of low concentrations of each
222 levels covering the theoretical validity domain, i.e., corresponding to concentrations at ½ × the estimated LOQ,
223 the estimated LOQ, 2 × the estimated LOQ and, also, spiking at concentrations corresponding to various points
225 The final LOQ was determined by the accuracy profile being the intersection point of the acceptance (λ) and
228 The limit of detection (LOD) is equal to 3/10 ×LOQ.
252 samples, the samples were spiked at two levels with Se (0.5 and 1 µg/L) and with Hg species (0.15 and

Methods (brief)

coupled plasma-mass spectrometry following
Se in fish by high-performance liquid chromatography and inductively coupled plasma-mass spectrometry
2 chromatography and inductively coupled plasma-mass spectrometry following microwave
27 separated by HPLC in less than 15 min by using a column with both anion and cation exchange mechanisms
30 by inductively coupled plasma-mass spectrometry (ICP-MS). The speciation analysis method was validated
32 different days over a time-span of three weeks. The limits of quantification (LOQ) are in the range of 0.010-
34 coefficient of variation in terms of intermediate reproducibility (CV R) was < 7 %. The LOQ for MeHg was
36 samples from four different fish species: rainbow trout, tuna, swordfish and dogfish.
38 Keywords: Se speciation, Hg speciation, enzymatic hydrolysis, HPLC-ICP-MS, accuracy profile, fish
48 chromatography (HPLC) coupled to inductively coupled-plasma mass spectrometry (ICP-MS), which are
49 powerful tools for this purpose. The most efficient separation method for Se speciation analysis is HPLC, while
51 there is a growing trend to use HPLC also for Hg species separation due to its simplicity (6, 7).
60 separate procedures for each element species. This involves multiple analyses of the same samples, making
62 development of more advanced multi-elemental speciation analysis methods based on HPLC-ICP-MS is
63 necessary. These methods can significantly improve the sample throughput, minimise the use of reagents and
66 hamper notably their simultaneous extraction but also their efficient (HPLC) separation (9). Ideally, the species
70 It is worth to highlight that simultaneous speciation analysis of Se and Hg by HPLC-ICP-MS has been scarcely
72 water samples (6, 10, 11). Li et al. achieved the separation of four Se species such as

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.

Wiki pages this source may touch

Verification notes

Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
Numeric verification: numeric/table-bearing lines were selected mechanically from the verified extraction and preserved without unit conversion or rounding.
Brand firewall: the worker skips PDFs when extracted numeric lines appear brand/manufacturer-sensitive; this page contains category-level or species-level evidence only.
HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

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