VDIXXX10.1177/1040638720903115Interlaboratory comparison for heavy metals testingMcGeehan et al.

Overview

This source page is a mechanical bulk-ingest record for a PDF in the methylmercury infant-formula research pull. 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

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• VDIXXX10.1177/1040638720903115Interlaboratory comparison for heavy metals testingMcGeehan et al.
• Interlaboratory comparison of heavy metal 2020, Vol. 32(2) 291­–300
• Steven McGeehan, Timothy Baszler,1 Cynthia Gaskill, Joseph Johnson,
• interlaboratory comparisons. Four laboratories, 1 principal laboratory and 3 collaborating laboratories, conducted instrument
• comparison (limit of detection (LOD), limit of quantification (LOQ), and linear dynamic range (LDR) on 24 data sets), in-
• data sets using Horwitz equation analysis). Matrices tested included 2 types of pet food jerky treats (chicken and sweet potato),
• validation level spike for mercury was 2 µg/g) concentration levels, indicated that ICP-MS can meet U.S. FDA acceptance
• criteria for both accuracy (90–105% recovery) and precision (< 6% coefficient of variation). The interlaboratory comparison
• studies showed that ICP-MS is a reproducible method for the analysis of heavy metals (HorRat value of 0.5–2.0) except for
• Introduction revealed over 50 contamination events nationwide attributed
• new matrices from animal diagnostic specimens. Rapid VetLIRN Report, Sept 2012). Furthermore, animal feed
• veterinary diagnostic laboratories conducted in 2011–2012 Diagnostic Laboratory, Washington State University, Bustad Hall, Room
• by the California Animal Health and Food Safety Laboratory 155N, Pullman, WA 99164-7034. baszlert@wsu.edu
• 292 McGeehan et al.
• ingredients include heavy metals and metalloids such as the method is sufficiently sensitive for diagnostic purposes.8
• arsenic, cadmium, chromium, lead, mercury, and selenium.3 Quantitative evaluation of ILC studies requires calcula-
• mal feeds > 10 ppm are considered highly toxic; for barium, between-laboratory precision (reproducibility). Repeatabil-
• concentrations > 40 ppm are considered toxic.9 (i.e., same analyst with the same instruments in the same
• The evaluation of method performance with a new matrix is the participating laboratories (132 data sets per lab for a total
• intended to ensure that the method will continue to produce of 528 in our study). The AOAC InterLaboratory Workbook
• items by 2 or more laboratories in accordance with predeter- mately 1,000 g of sample material was dried at 50–60°C for
• design used standardized instrumentation (inductively cou- Retsch, Haan, Germany), first to pass a 2.0-mm sieve and
• pled plasma–mass spectrometry (ICP-MS)) and compared then a 0.75-mm sieve.
• ILC levels from data collected by 4 independent laboratories three 6-mo-old Holstein steers being used as normal control
• mal statistical demonstration of similarity, the Horwitz ratio the Retsch mill fitted with a 2-mm ring sieve. The sieved
• analysis, an index of method performance with respect to samples were then dried at 60°C for 24 h. Complete sample
• precision.4 dryness was verified by weighing the entire sample, drying
• An important consideration in assessing the suitability of for an additional 24 h, and reweighing to confirm a constant
• Interlaboratory comparison for heavy metals testing 293
• Table 1. Summary of method parameters used by principal and collaborating laboratories.
• Principal laboratory 0.25 g (dry weight) Concentrated nitric acid; open vessel digestion Agilent 7500 cx ICP-MS, with
• –jerky treats block; 70°C 1 h, ramp to 120°C, hold 6 h; dilute collision cell: He mode for As
• 1.0 g (wet weight) collision cell for Cd, Pb, and Hg
• Collaborating 0.25 g (dry weight) 70% nitric acid + 30% hydrogen peroxide; Agilent 7700 ICP-MS, no
• laboratory 1 –jerky treats microwave digestion (MARS system); 100% collision cell
• 1.0 g (wet weight) ppb Au in type 1 water
• Collaborating 0.25 g (dry weight) Jerky treats and tissue*: Agilent 7900 cx ICP-MS, with
• laboratory 2 –jerky treats concentrated nitric acid; microwave digestion collision cell: He mode for As
• 0.50 g (wet weight) dilute with type 1 water collision cell for Cd, Pb, and Hg
• 1.0 g (wet weight) concentrated nitric acid; TuffTainers in drying
• –whole blood oven, 95°C (100°C for Hg), minimum of 4 h;
• Collaborating 0.25 g (dry weight) Concentrated nitric and HCl acids + 1,000 ppb Au; Agilent 7900 cx ICP-MS, with

Methods (brief)

• Abstract. We compared inductively coupled plasma–mass spectrometry (ICP-MS) test results for the analysis of heavy
• comparison (limit of detection (LOD), limit of quantification (LOQ), and linear dynamic range (LDR) on 24 data sets), in-
• bovine blood, and bovine liver and kidney. The instrument comparison study confirmed that ICP-MS provided the sensitivity
• The “in-house” method comparison samples, spiked at low (0.04 µg/g), medium (0.4 µg/g), and high (8.0 µg/g; note: the high
• validation level spike for mercury was 2 µg/g) concentration levels, indicated that ICP-MS can meet U.S. FDA acceptance
• studies showed that ICP-MS is a reproducible method for the analysis of heavy metals (HorRat value of 0.5–2.0) except for
• mercury in one laboratory, which used a different sample preparation method (open block rather than microwave digestion).
• Overall, our study showed that ICP-MS is a reproducible method for the analysis of heavy metals in spite of minor differences
• Key words: animal diagnostic specimens; animal feeds; heavy metals; inductively coupled plasma–mass spectrometry;
• Sample acquisition and preparation
• and diagnostic specimens by mass spectrometry instrumen- Samples of chicken jerky treats were obtained from a large
• ferences in sample digestion). Thus, the evaluation that we Brands, San Francisco, CA); the sweet potato jerky was pur-
• items by 2 or more laboratories in accordance with predeter- mately 1,000 g of sample material was dried at 50–60°C for
• specified conditions) across multiple active diagnostic labo- placing in a plastic bag and using a hammer to crush. Sample
• pled plasma–mass spectrometry (ICP-MS)) and compared then a 0.75-mm sieve.
• testing performance at the instrument, in-house method, and Samples of bovine liver and kidney were obtained from
• ILC levels from data collected by 4 independent laboratories three 6-mo-old Holstein steers being used as normal control
• using homogeneous and stable samples. Performance param- animals (untreated) on a separate research project that were

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

• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• Mercury
• Cadmium
• Lead
• Arsenic
• Aluminum
• Chromium

Verification notes

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• Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
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• HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

Update history

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