Perspectives of Three African American Chemists: Reflections on Careers, Experiences, and the Future.

Three African American analytical chemists, whose primary research careers have focused in the respective sectors of academia, government, and industry, have come together to provide personal perspectives on parameters that have impacted their careers as well as to provide their perceptions of the current and future status of African Americans in the overall science, technology, engineering, and mathematics (STEM) enterprise, and the more specific field of analytical chemistry. The authors, having ∼150 years of combined experiences, reflect on the past status and contemplate future advances for African Americans in STEM. The most important factors during their formative years that underpinned their success over the long-term are enumerated. Particularly cited are the distinct features within the Historically Black Colleges and Universities (HBCU) environment that placed them solidly on a path toward successful careers. The Grand Challenge now and for the foreseeable future, reversal of the dysfunctional metropolitan public-school systems, is cited and the only perceived light in the tunnel for addressing this issue is mentioned. Finally, recommendations are made for the future where diversity within the STEM enterprise will be a prerequisite for U.S. competitiveness in our global society.

Improved reproducibility by assuring confidence in measurements in biomedical research.

'Irreproducibility' is symptomatic of a broader challenge in measurement in biomedical research. From the US National Institute of Standards and Technology (NIST) perspective of rigorous metrology, reproducibility is only one aspect of establishing confidence in measurements. Appropriate controls, reference materials, statistics and informatics are required for a robust measurement process. Research is required to establish these tools for biological measurements, which will lead to greater confidence in research results.

Evaluation of Serum Volume Losses During Long-Term Storage.

Aliquots of serum collected in a large case-control study of cervical cancer were stored at -70°C for up to 4 years during implementation of the study. When 500 µL serum aliquots were thawed in preparation for carotenoid and vitamin A assays, volumes were noticeably variable and fell below 500 µL in the majority of the samples. We were concerned about evaporation/sublimation during storage of the samples because loss of water would concentrate the analytes of interest. We evaluated the use of density and sodium ion concentration measurements to confirm its occurrence. We found that serum density was an unreliable indicator of extent of volume loss since the anticipated increases in density due to evaporation were of the same magnitude as inter-individual variation in serum density. In contrast, Na+ concentration is tightly regulated and would rise if water had been lost from the samples. In a representative sample of serum aliquots from the case-control study, 24 of 25 vials contained less than 500 µL of serum. The mean sodium ion concentration (138.1 ± 3.6 mmol/L) was within the normal range for human serum of 136-145 mmol/L, and no correlation was observed between serum volume and Na+ concentration. These results strongly suggest that the observed low volumes were not due to evaporative losses. Instead, the variably low volumes of serum aliquots were probably due to pipetting errors in the initial aliquotting resulting from the use of air-displacement pipettes.