The Special Analytes Sub-Group (SPA) was created in 1999 with the task to deliver CORESTA Recommended Methods (CRMs) for a range of smoke analytes, prioritized by regulators, found in cigarette main­stream smoke.

Considering the need for accredited laboratories, and the expert platform offered by CORESTA, a second objective was added to the SG's remit in January 2016: "To organise and conduct periodically proficiency testing of smoke analytes other than TNCO". 

In January 2017, the Sub-Group changed its name to "Smoke Analytes (SMA)" in order to more clearly indicate that its work is related to combustible products.  In line with this change, reference to "combustible tobacco products" was added to its first objective.

In June 2018, the SMA Sub-Group's revised objectives, as listed above, were approved by the Scientific Commission and the Board.

Tobacco manufacturers and contract and Government laboratories have participated in collaborative studies since 1999 and the large participation has provided robust levels of repeatability (r) and reproducibility (R) under both the ISO 3308 and Health Canada Intense machine smoking regimes. These studies always incorporate reference products.

The CORESTA forum allows valuable insight into both causes and ways to reduce variability. The Sub-Group has found that it is not sufficient to simply take a method described in the literature and use it as a standard method for regular use with high sample throughput. Two significant data mining exercises have been carried out to investigate the yields from reference cigarettes when cigarettes were smoked using preferred methodologies in different laboratories. Significant yield differences were found. Both studies have been published:

• Intorp M., Purkis S., Whittaker M., Wright W.  2009 Determination of “Hoffmann analytes” in Cigarette Mainstream Smoke. The CORESTA 2006 Joint Experiment; Beiträge Tabakforsch. Int. 23(4) 161-202.
• Purkis S., Intorp M.  Analysis of Reference Cigarette Smoke Yield Data from 21 Laboratories for 28 Selected Analytes as a Guide to Selection of New CORESTA Recommended Methods; Beiträge Tabakforsch. Int. 26(2) 57-73.

The Sub-Group has chosen methods pragmatically, based on those most commonly used by and available to laboratories, determined from round-table discussions of members’ experiences and from evaluation of answers to circulated questionnaires. After agreement on a particular method and the writing of a protocol, this has been followed by statistically designed joint experiments to investigate the effects of important method parameters that potentially contribute to variability. This phase allows some training within a laboratory to implement the new method and to generate internal validation data. General methodological aspects to be considered include:

-  Smoke generation and trapping methodology issues
-  Analyte derivatisation (when required), clean up and concentration
-  Analyte reactivity during collection and work-up
-  Calibration errors, use of internal standards
-  Interferences during detection, non-specific detection and poor sensitivity

The results from some joint experiments have been published:

• Intorp M., Purkis, S., Wagstaff, W., 2010a.  Determination of Aromatic Amines in Cigarette Mainstream Smoke - The CORESTA 2007 Joint Experiment; Beiträge Tabakforsch. Int. 24(2) (2010) 78-92.
• Intorp M., Purkis, S., 2010b.  Determination of Selected Volatiles in Cigarette Mainstream Smoke. The CORESTA 2008 Joint Experiment; Beiträge Tabakforsch. Int. 24(4) (2014) 174-186.

When results from joint experiments are received they are discussed and the Sub-Group decides whether there is sufficient harmonisation to move forward to a full collaborative study using a draft CRM. If not, a further joint experiment may be necessary to study other methodological aspects. Finally, a full collaborative study is run to obtain mean, repeatability and reproducibility values involving both commercial and reference cigarettes and as many laboratories as possible (typically up to 20). It should be noted that participation has been increasing annually.

• CRM 58: Determination of benzo[a]pyrene in cigarette mainstream smoke by gas chromatography - mass spectrometry (2004, amended 2013 and 2014, updated 2018 and 2019).
• CRM 63: Determination of tobacco-specific nitrosamines in cigarette mainstream smoke – GC-TEA method (2005, updated 2019).
• CRM 70: Determination of selected volatile organic compounds in the mainstream smoke of cigarettes - Gas Chromatography-Mass Spectrometry Method (2010, amended 2013 and 2014, updated 2018 and 2019).
• CRM 74: Determination of selected carbonyls in the mainstream cigarette smoke by high performance liquid chromatography (2011, amended 2013 and 2014, updated 2018 and 2019).
• CRM 75: Determination of tobacco-specific nitrosamines in cigarette mainstream smoke by LC-MS/MS (2012, amended 2014, updated 2019).
• CRM 78: Determination of Selected Phenolic Compounds in Mainstream Cigarette Smoke by HPLC-FLD (2014, updated 2018).
• CRM 83: Determination of Ammonia in Mainstream Cigarette Smoke by Ion Chromatography (2016)
• CRM 95: Determination of Aromatic Amines in Mainstream Cigarette Smoke by Gas Chromatography Mass Spectrometry with Negative Chemical Ionisation (GC/MS(NCI)) (2021)

CRMs can now be delivered within a two-year time frame and are suitable to be put forward for full ISO standardisation. Any learning gained during CRM development is shared in discussion and provided within the finished CRM with detailed guidance notes; recorded in meeting minutes and often published in more detail in accompanying scientific papers or CORESTA technical reports as listed below:

• Intorp, M., Purkis, S., Wagstaff, W., 2011.  Determination of Selected Volatiles in Cigarette Mainstream Smoke. The CORESTA 2009 Collaborative Study and Recommended Method; Beiträge Tabakforsch. Int. 24(5) 243-251.
• Intorp, M., Purkis, S., Wagstaff, W., 2012.  Determination of Carbonyl Compounds in Cigarette Mainstream Smoke. The CORESTA 2010 Collaborative Study and Recom­mended Method; Beiträge Tabakforsch. Int. 25(2) 361-374.
• Intorp, M., Purkis, S., Wagstaff, W., 2012.  Determination of Tobacco Specific Nitrosamines in Cigarette Mainstream Smoke: The CORESTA 2011 Collaborative Study; Beiträge Tabakforsch. Int. 25(4) 507-519.
• Purkis, S., Intorp, M., Hauleithner, A., 2013.  Updates of CORESTA Recommended Methods after Further Collaborative Studies Carried Out under Both ISO and Health Canada Intense Smoking Regimes; Beiträge Tabakforsch. Int. 25(8) 700-707.
• CORESTA Technical Report: 2013 Collaborative Study for Selected Phenolic Compounds in Mainstream Cigarette Smoke (April 2020)
• CORESTA Technical Report: 2015 Collaborative Study on Ammonia in Mainstream Cigarette Smoke (March 2018)
• CORESTA Technical Report: 2016 Collaborative Study on Aromatic Amines in Mainstream Cigarette Smoke (March 2019)
• CORESTA Technical Report: 2012 Collaborative Study on B[a]P, VOCs, and Carbonyls in Mainstream Cigarette Smoke (August 2019)
• CORESTA Technical Report: 2016 Joint Experiment on Aromatic Amines in Mainstream Cigarette Smoke by LC-MS/MS (November 2019)
• CORESTA Technical Report: 2019 Small Group Collaborative Study on Aromatic Amines in Mainstream Cigarette Smoke (May 2020)

Participation in these collaborative studies has helped Sub-Group participants with their ISO 17025 accreditation and allowed those laboratories whose results deviate significantly from others to improve their methodological processes. This has been shown to improve reproducibility over time.

Some of this data have been presented by CORESTA to the US Food and Drug Administration in a meeting on 21 January 2011 and in an FDA workshop, specifically on tobacco specific nitrosamines and benzo[a]pyrene, on 30-31 July 2013 (further details can be found under the Regulations section of the CORESTA website).

Updated January 2021