Comparison of nicotine and cotine levels in nail samples of people active and passive exposed to cigarette smoke

In the world and partly in our country, there are numerous studies that have been published in the international literature that can detect illicit substances in biological samples such as blood and urine. The increasing use of illicit substances is causing concern in the society and driving analytical developments. Considering the collection and storage conditions of samples such as blood and urine, it is noteworthy that keratinized samples have recently been seen as an advantage. In this study, a method was developed for the simultaneous determination of nicotine, the main active ingredient of cigarette smoking, and its metabolite cotinine in nail samples by GC-MS following a solid phase extraction method. A rapid, reliable, accurate, high recovery, easy extraction method was developed for the simultaneous determination of nicotine and its main metabolite cotinine from nails using n-Docasan as internal standard. Our method was validated and tested for specificity, selectivity, linear working range, limit of detection and limit of quantification (LOD and LOQ), accuracy (recovery and precision). The LOD and LOQ values were 0.15 ng/mL and 0.5 ng/mL for Nicotine, 88.60 ng/mL and 300 ng/mL for Cotinine, respectively. Percent extraction recovery was calculated as 102.44±0.18% for Nicotine and 99.85±14.05% for Cotinine. The results of the precision parameter were obtained from repeatability and reproducibility studies. As a result of the results obtained, our method was found to be within the range of values suitable for forensic toxicology analysis. With this developed method, fingernail and toenail samples obtained from 26 volunteers were analyzed. With the approval of the ethics committee and voluntary participation forms obtained from the participants, they were grouped as active, passive and non-smokers. In the examinations, it was found that compared to other active substances, nicotine accumulation in the hand nails was approximately twice as high as the accumulation in the toenails, and depending on the habit of using the right hand and the left hand, the hand that was mostly used had more accumulation with a significant difference. In our study, for the first time in our country, a method that can determine and quantify nicotine and its metabolite together as the main active substance in nail samples by GC-MS has been developed and the analytical parameters of the method have been successfully performed and evaluated in nail samples obtained from 26 volunteers in three different groups.