Using Elemental Analysis Techniques to Detect Metals in Counterfeit Cigarettes and Water Samples and Promote Environmental Education

The analysis of metals using inductively coupled plasma–mass spectrometry (ICP-MS), ICP-atomic emission spectroscopy (ICP-AES), and atomic absorption can serve many purposes in environmental, health, and forensic studies. Yi He, a chemistry professor at John Jay College of Criminal Justice at The City University of New York, has been using these elemental analysis techniques for fingerprinting and provenance of counterfeit cigarettes and as an educational tool. Here, she discusses some of that work.

In a recent paper (1), you discuss a method for the investigation of lead and cadmium in counterfeit cigarettes using microwave digestion followed by ICP-MS analysis. What benefits does this method offer compared to others?

Microwave digestion is a well-accepted sample preparation technique for dissolving solid samples to perform elemental analysis. Compared with conventional hot plate digestion, microwave digestion is faster and more user friendly. The loss of volatile components in sample solutions can be prevented and contamination to both sample solutions and the ambient environment can be significantly reduced by using the microwave technique. This method works very well with tobacco samples. Commercial microwave digestion systems allow us to treat the samples in a batch mode to improve analysis throughput. 

ICP-MS is a good choice for the determination of multiple elements at the trace level because of the fast speed, excellent sensitivity, and wide linear range offered by the instrument. Using yttrium (Y) as an internal standard, the method detection limits (MDL) for lead (Pb) and cadmium (Cd) were estimated to be 0.02 mg/kg and 0.06 mg/kg, respectively.  

The toxicity of Pb and Cd to human beings has been well documented. We used this method to investigate Pb and Cd in counterfeit cigarettes seized by various law enforcement agencies in the United States. Our work revealed that both Pb and Cd concentrations in counterfeit cigarettes were markedly higher than those in their genuine equivalents, and exhibited greater sample to sample variability. Such information offers insight on the potential public health impact of consuming counterfeit cigarettes, the linkage of a product to its geographical origin, and the technology used by counterfeiters in the illicit cigarette trade.

You’ve also done some work with ICP–AES to detect the elemental profile of tobacco used in counterfeit cigarettes (2). Why did you choose ICP-AES over the microwave digestion ICP-MS method for this study?

This work is an effort of our collaboration with scientists at the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS). ICP-AES uses an optical detector, which is less expensive than MS, yet provides the capability to perform multielement analysis. Our methods showed that both ICP-MS and ICP-AES work well for the determination of toxic elements in tobacco samples. We also compared the dry ashing sample preparation technique and the microwave digestion method. Experimental data generated by both methods were acceptable, but the microwave digestion process in general has better analysis recoveries.

The procedure demonstrated in this work provides an alternative choice for laboratories that don’t have access to microwave digestion and ICP-MS to treat and analyze a large batch of tobacco samples in an efficient and accurate manner.

You also recently presented some work on detecting cadmium in environmental water samples using atomic absorption spectroscopy (3). Can you please describe the method used in that research? What are the primary sources of cadmium found in environmental water samples? What were your findings and how will those findings impact future research in this area?

Our work on investigation of Cd in Superfund sites in New York City is an educational project funded by the National Science Foundation (NSF) to promote student learning and to cultivate the younger generation’s environmental and social responsibility. This work also got support from the Program for Research Initiatives in Science and Math (PRISM) at John Jay College. Students were engaged in learning science through a project that investigates pollutants in an urban environment relevant to their daily life. The analytical procedure and sample preservation methods were developed by a group of undergraduate students. The quality of analysis was ensured by frequently analyzing National Institute of Standards and Technology (NIST) SRM 1640a: Trace Elements in Natural Water and comparing the results with the certified value.

Once used for industrial purposes in the production of batteries, paints, and plastics, cadmium is now widely dispersed in the environment. Some water bodies in New York were historically contaminated by Cd from the industrial activities in this area. We measured Cd in water collected from three Superfund locations in New York City: the Hudson River in midtown Manhattan, Newtown Creek, and Gowanus Canal. The Cd concentration was found to be 2 µg/L in Hudson River surface water, 3 µg/L in the Gowanus Canal, and 18 µg/L in the Newtown Creek in our 2015 survey. Based on Environmental Protection Agency (EPA) 2016 aquatic life ambient water quality criteria for Cd, catch-and-release fishing should be used in these areas because the fish or crab are considered to be harmful for human consumption.    

In addition to providing scientific data that are meaningful to the community, our students’ learning has been greatly enhanced through participating in this project, which can be used as an authentic learning model and shared with researchers and educators in the field of science education.

What are the next steps in your research?

We will continue our work on the investigation of elemental profiles, especially toxic elements, in counterfeit or poor quality cigarettes. The development of a method to identify counterfeit cigarettes and an investigation of their chemical signature are a territory yet to be explored. Our work will provide useful tools and information for researchers in the field of criminology and public health to study the distribution of counterfeit cigarettes and the social and health impact of using these illicit products. In addition, I am dedicated to science education and will work more on this aspect to help young students to thrive in the science, technology, engineering, and math (STEM) fields.

References

• Y. He, K. von Lampe, L. Wood, and Marin Kurti, Food and Chemical Toxicology81, 40–45 (2015).

• Y. He, C. Green, R. Chaney, F. Tan, H. Ye, V. Mei, M. Kurti, and K.V. Lampe, “Elemental Profile of Tobacco Used in Counterfeit Cigarettes,” presented at Pittcon 2016, Atlanta, Georgia.

• Y. He et al., “Determination of Cadmium in Environmental Water Samples Collected in Superfund Sites in New York City,” presented at Pittcon 2016, Atlanta, Georgia.