Separation of Methamphetamine from Dimethyl Sulfone by Solubility Differences and Identification, Confirmation by Raman Spectroscopy

Introduction

All opiates have a long history of mixing neutral substances by drug traffickers. In India, Mumbai, the forensic analysis of heroin samples seized most of the samples mixed with paracetamol and caffeine [1].

Paracetamol is a pain relief drug easily available without a doctor’s prescription in any pharmacy. In a few cases, it is found that, Alprazolam a depressant drug added in heroin sample which falls under NDPS act 1985. Despite strict legal provisions, the illegal business of narcotic drugs has been growing day by day and in recent 5 years the increase of narcotic cases has widely increased. But with the increase in the number of cases, the increase in adulterated drugs is also seen in a lot of street samples. In 2015, Mephedrone, a simulant drug added in NDPS Act 1985 is widely seen in narcotic seizures, as soon as its seizure increases a pure sample was adulterated with Aijnomoto a Chinese salt whose appearance is quite similar to Mephedrone [2]. Phenacetin is another popular adulterant in Cocaine sample [3]. On the other hand, similar to this scenario, Methamphetamine another popular stimulant with a famous street name ‘ice drug’ is adulterated with Dimethyl Sulfone, a dietary supplement and it is a common cutting agent for ice drug as its appearance is similar to Methamphetamine hydrochloride. Due to addition of neutral substances identification of samples is not an easy task and forensic experts have to perform a different test to rule out the possibility of said drug. However, the identification of such adulterant, cutting agents and place of seizure, accused or organization involved in crime, such detail profiling of crime can help to establish evidence to track down the criminal organization or traffickers involved in synthetic drug preparation [4]. Detailed analysis of street samples can throw light on a new designer drug that is not controlled in the drug market and is used as a narcotic drug of abuse by a drug cartel to escape from the law, such new psychoactive substances can be included in controlled substances by further study and its illegal use as a drug of abuse can be controlled by legal provisions [5].

Raman Spectroscopy is an easy and reliable technique for different types of drugs. It is a non-destructive technique and for a pure sample there is no special pre-treatment is required hence sample is unchanged [6, 7], and substituted cathinone has been also easily differentiated by Raman spectroscopy [8]. Raman spectroscopy can be successfully employed for narcotic drug identification, even this technique gives the idea of an adulterated sample.

Results and Discussion

Mixed sample shows Raman frequencies of both compound, Methamphetamine hydrochloride and Dimethyl sulfone (Figure 1). when this spectrum compared with Raman spectra of Methamphetamine hydrochloride, characteristic Raman frequency 616nm, 832nm, 998nm, ,1205nm, 1580nm, 1601 nm (Figure 4) in the sample, it gives the idea that sample might contains Methamphetamine and other adulterant. While other Raman frequencies with remarkable presence in the sample are 459nm, 491nm, 696nm, 766nm, 1116nm and 1448 nm which corresponds to dimethyl sulfone (Figures 1 & 3). After precipitation in ether; the separated and dried sample gives spectra which shows absence of Raman frequencies corresponds to Dimethyl sulfone and the spectra is matched with reference spectra of Methamphetamine this confirms presence of Methamphetamine hydrochloride (Figures 3 & 4). All results are tabulated in (Table 2).

Conclusion

Raman spectroscopy is an accurate technique for identification of narcotic drugs, even if sample is adulterated with other substances and if it is Raman active, a powdered sample give the idea of mixture and possible narcotic drugs in the sample. It can be successfully employed for such street samples which are adulterated with different either neutral substances or hazardous pharmaceutical preparation like paracetamol, Lidocaine. Raman spectroscopy is valuable technique for confirmation and identification of narcotic drugs even in mixture and if a sample is separated from mixture, a very small sample quantity is required for Raman spectroscopy to the confirmation of a narcotic drug in adulterated sample.

Acknowledgement

We would like to express our deepest gratitude to Director General (Legal & Technical) Shri. Sandip Bishnoi, for his guidance and support throughout the work.