Following an groundbreaking study published last year, journals published by Wiley have moved away from the ±0.4% precision standard for elemental analysis.
First developed in the 18th century, elemental analysis quickly became the gold standard for characterizing chemical compounds, enabling early chemists to accurately determine the relative proportions of different elements in a sample. Even today, with many more modern techniques available, elemental analysis is still a valuable data point, and most journals require this analysis to be within ±0.4% as standard. However, this narrow margin of error has historically caused much frustration within the research community. Most teams have to pay for business analytics, and the high failure rate, combined with the lack of raw data, delays publication.
Curious to explore the truth behind community complaints, in 2022 a team led by Caleb Martin at Baylor University in the United States devised a study to investigate the reliability of business factor analysis and the corresponding validity of the ±0.4% accuracy standard required by journals. “There are rumors that people just keep sending in the same sample until they get the right result as pointed out in a reply from Vincent Lavallo,” says Martin, “We wanted to know how results vary from company to company and if high purity materials from the bottle would pass the 0.4% required by the papers. The results depend on purity and theoretically they could actually claim some samples to be 99.6% pure!’
The team selected five commercial materials containing different proportions of carbon, hydrogen and nitrogen and sent identical samples to 17 commercial companies on four continents. Each sample was also tested on a newly calibrated instrument owned by Saurabh Chitnis’s teammate at Dalhousie University in Canada. Subsequent statistical analysis confirmed the community’s frustration: 10.78% of samples did not meet publication guidelines despite being sufficiently clean.
The team’s analysis couldn’t pinpoint a specific reason for this high failure rate—the results of “failure” were essentially random across all providers—but it does highlight another important issue with the current 0.4% standard. Since most compounds contain very different proportions of carbon, hydrogen, and nitrogen, blanket error limits are oversensitive to the more abundant elements and undersensitive to the less abundant elements. “If you have 50% carbon and 5% hydrogen, obviously 0.4% is a much larger percentage of total hydrogen than total carbon,” explains Jason Dutton, another member of the team from La Trobe University in Australia. “This means that a compound could contain quite a lot of hydrogen impurities and still pass through, while smaller carbon-containing impurities would cause the sample to fail.”
What next for magazines?
Martin’s team concluded that the current ±0.4% standard was simply not scientifically justifiable and hoped their findings would prompt journals to reevaluate their publication requirements.
Wiley was quick to respond to the study, publicly updating its publication guidelines in October, dropping the ±0.4% accuracy requirement. “The data from Kuveke’s study and more suggests that elemental analysis is too unreliable for the necessary routine use,” a spokesman for the publisher said. ‘[It] sparked a debate among chemistry editors who decided in October 2022 to update the notice to authors for the community-owned chemistry journal published by Wiley. The revised guidelines state that “evidence for elemental composition should be provided by adequate elemental analysis, in which case duplicate analyzes should be obtained and an average provided”.
Currently, Wiley remains the only publisher to have changed this standard across all of its chemistry journals, but the Royal Society of Chemistry is working to update the authors’ guidelines on this issue. “We agree that the ±0.4% precision standard for elemental analysis is no longer appropriate and will therefore no longer be specified,” says May Copsey, chief executive at the RSC. “We will place increased emphasis on providing alternative data sources to support uniformity and purity, and encourage authors to provide information on the instrumentation and chromatography of the measurements.”
Other publishers take a more conservative approach, but are aware of the concerns surrounding the current guidelines. The Journal of the American Chemical Society has not changed its publication requirements, stating that “further discussion within the community may be required to reach consensus on a new standard.”
Martin agrees that further investigation is necessary to effectively resolve this issue. “We found problems, but I think in the long term it’s something management should look at.” Analytical experts need to evaluate this and propose a standard that is realistic based on the accuracy of the measuring devices and the required cleanliness,” he says.
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