Trace Analysis — Challenges and Problems

Namieśnik, Jacek

doi:10.1080/10408340290765579

Cited by 47 publications

(20 citation statements)

References 172 publications

(2 reference statements)

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“…The variation in the literature K OC values has been attributed to measurement uncertainty due to different analytical methods, temperature differences, lack of equilibrium, impurities of test compounds, photolysis, oxidation, reduction, and chemical transformations (Linkov et al, 2005; Namiesnik, 2000, 2002). However, one process that damages sample integrity before analysis is analyte adsorption onto the walls of samplers and vessels.…”

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confidence: 99%

Use of Mixed Solvent Systems to Eliminate Sorption of Strongly Hydrophobic Organic Chemicals on Container Walls

et al. 2009

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Strongly hydrophobic organic chemicals (SHOCs) can be defined as neutral organic chemicals that have soil organic carbon (OC) normalized sorption coefficient (K(OC)) >10,000. Sorption isotherms of SHOCs are normally measured in aqueous systems to determine K(OC). Since SHOCs can adsorb on container walls leading to overestimation of K(OC), we used mixed solvent systems to characterize this potential error. Sorption coefficient (K(M)) and percent recovery (%R(M)) of anthracene, DDT, and dieldrin during sorption on centrifuge tubes made of polytetrafluoroethylene (PTFE), polycarbonate (PC), polypropylene copolymer (PPCO), and glass high pressure liquid chromatography vials (HPLCV) were measured in volume ratio-varied methanol-water mixtures until 100% recovery of the sorbate was achieved. The data were evaluated using the Solvophobic theory. The K(M) values of the entire test SHOCs decreased exponentially with increasing fraction of methanol (f(c)). For sorption on PTFE, 100% recovery of the three chemicals was at f(c) > 0.45. However, 100% recovery of DDT and anthracene from PC and PPCO was at f(c) > 0.90. The 100% recovery of dieldrin from HPLC vials was at f(c) > 0.70. In water the calculated recoveries of DDT, dieldrin, and anthracene from PTFE were 32, 43, and 48%, respectively. However, the recoveries of dieldrin from HPLC vials and DDT and anthracene from PC and PPCO ranged from 2 to 14%. The data demonstrate that sorption on container walls is a source of error that can reduce the integrity of the analyte and might be one of the causes for the large variability in literature K(OC) values for SHOCs.

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confidence: 99%

Use of Mixed Solvent Systems to Eliminate Sorption of Strongly Hydrophobic Organic Chemicals on Container Walls

et al. 2009

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“…In combination with standards, QCs, and appropriate internal standard, the technology assured the delivery of reliable concentration results to clients. We believe the approach may be applied to most bioanalytical projects and removes an important risk factor12, 13 from the bioanlytical process.…”

Section: Discussionmentioning

confidence: 99%

A novel approach for in‐process monitoring and managing cross‐contamination in a high‐throughput high‐performance liquid chromatography assay with tandem mass spectrometric detection

Chang

Kim

El-Shourbagy

2006

Rapid Comm Mass Spectrometry

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Cross-contamination among wells of a high-throughput, high-density assay is a risk that cannot be detected or controlled by the performance of calibration standards and quality control samples. In the current practice, carryover and cross-contamination is detected only when analytes are detected in blank, zero, placebo, pre-dose samples, in a low standard or low quality control sample. There is no mechanism that allows bioanalytical scientists to determine if cross-contamination has occurred among other samples. As a result, erroneous results can be released to clients even though a batch meets the acceptance criteria. We tested a new approach that quantifies the cross-contamination of each sample and allows the scientist to make quality decisions with documentation. The approach will also detect carryover in over 90% of the wells. Briefly, two additional analytes were added as contamination markers. The markers were added to a multi-well plate alternatively creating a pattern of a checkerboard. The spiked multi-well plate was then used to perform the assay. If both markers were detected in a well, the sample was considered contaminated. The amount of the unexpected marker detected in a well measures the degree of contamination and may be used to make deactivation decisions. Depending on the relative impact of the contamination, a scientist can choose to tolerate the bias, reject the sample, reject the batch or raise the lower limit of quantitation for the batch. A guideline for rejection decisions is presented for discussion.

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“…Accuracy is often still a problem in contemporary inorganic trace analysis [5,6]. In a world-wide intercomparison aimed at certification of trace elements in Oriental Tobacco Leaves, 60 laboratories supplied results for Fe [7].…”

Section: Introductionmentioning

confidence: 99%

Ratio primary reference measurement procedure (RPRMP) for the determination of iron in biological materials by RNAA

Dybczyński¹,

Danko

Pyszynska

et al. 2012

Radiochimica Acta

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Ratio primary reference measurement procedure (RPRMP) / NAA / RNAA / Definitive method / Iron / Anomalous sorption / Tobacco leaves CRM Summary.A new ratio primary reference measurement procedure (RPRMP), i.e. a definitive method for the determination of iron in biological materials, was devised. It is based on a combination of neutron activation with selective and quantitative post-irradiation separation of 59 Fe from all accompanying radionuclides followed by γ -ray spectrometric measurement. The novel separation scheme, involving the use of column chromatography on two (anion and cation) exchange columns, was extensively checked using radioactive tracers and was shown to be very selective and truly quantitative. High selectivity of the separation scheme was achieved by exploiting the "anomalous" sorption of Fe(III) on medium cross-linked sulfonic cation exchanger from concentrated hydrobromic acid solution. The accuracy of the RPRMP was demonstrated by the analysis of several certified reference materials. The method was used for the analysis of the three INCT CRMs based on tobacco leaves in which Fe was originally not certified, because widely discordant results by different analytical techniques were obtained in world-wide intercomparisons. The results by RPRMP in those materials were in a very good agreement with our own results by INAA. Tentative certified values (TCV) for Fe were proposed as a combination of RPRMP and INAA results. Some possible sources of systematic errors in other analytical methods were discussed.

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Trace Analysis — Challenges and Problems

Cited by 47 publications

References 172 publications

Use of Mixed Solvent Systems to Eliminate Sorption of Strongly Hydrophobic Organic Chemicals on Container Walls

Use of Mixed Solvent Systems to Eliminate Sorption of Strongly Hydrophobic Organic Chemicals on Container Walls

A novel approach for in‐process monitoring and managing cross‐contamination in a high‐throughput high‐performance liquid chromatography assay with tandem mass spectrometric detection

Ratio primary reference measurement procedure (RPRMP) for the determination of iron in biological materials by RNAA

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