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Paper text:
although people think smokeless tobacco is harmless , scientific evidence show that its consumption is a risk factor for blood pressure , dyslipidemia , abortion , low birth weight , exacerbation of asthma , and cancer ( 1 , 2 ) . the smokeless tobacco contains large amounts of carcinogenic compounds among which tobacco specific n - nitrosamines ( tsnas ) is the most important one ( 3 ) .
4-methylnitrosamino-1-(3-pyridyl-1-butanone ) ( nnk ) and n - nitrosonornicotine ( nnn ) are the most important tsnas existing in the smokeless tobacco .
they exist in tobacco leaf in very low concentration and are produced in higher concentration during curing , aging , and tobacco fermentation phases due to the reaction between tobacco alkaloid amines and nitrite ( 4 ) .  
several investigators showed the relationship between snuff consumption and oropharyngeal cancer in the laboratory animals ( 5 ) . according to the researches by hoffman et al . using nnn and
nnk solutions resulted in tumors in mice and hamsters ( 5 , 6 ) . in another study ,
after extensive study on the relative articles published from 1975 , stated that the use of chewing tobacco and moist snuff are associated with low risk for oral cancer , while dry snuff is more risky ( 4 ) .  
. showed that the organic and aqueous extracts of smokeless tobacco are mutagenic or clastogenic ( resulting in breakdown of chromosomes ) ( 8) . regarding the serious threats of smokeless tobacco consumption to human health , different studies were carried out to separate and measure its carcinogenic and toxic substances .
the highest level of nitrosamines was reported in different types of zarda and khaini ( 9 ) . according to brunnemann s study , the level of nnk was from inseparable to 1.9 g / g in the american and danish samples , and the level of nnn ranged from 0.08 to 7.38 g / g in the danish and belgian samples ( 10 ) . in a study by hoffmann ,
the present study was performed due to the following reasons : sistan and baluchetsan is a province neighboring afghanistan and india pakistan through which these products are trafficked and presented in luxurious packages and distributed in the market ; cultural and traditional similarities between the people living in the province , especially the baluch , and those who live in neighboring countries ; the relationship between consumption of smokeless tobacco and oral squamous cell carcinoma ( 11 ) ; and lack of study on identification of smokeless tobacco products , especially the most common type in the province s market .
the current study aimed to analyze , separate , and measure the existing substances in a type of chewing tobacco .
the studied sample was a type of smokeless tobacco known as bt and manufactured in india . to recognize
the sample constituents , 25 g of it was placed in oven at 50c to fully dry it out .
gas chromatography ( gc ) and gas chromatography coupled to mass spectrometry ( gc / ms ) were used to identify the essential oil compounds .
after injection of essential oil into gc apparatus , the essential oil constituents were qualitatively tested using time retention ( tr ) , retention index ( ri ) , and mass spectrum ( ms ) , and these elements were compared with standard compounds or available information in the saturn library ( 12 ) . to measure retention indices ,
normal c6-c30 alkane compounds were injected into gc apparatus . using the information in the carcinogenic library and retention indices , the compounds mass spectra were identified and compared with the standard mass spectra .
the compounds were quantified by means of data processor ( r3 a - chromatepac ) using area normalization method and ignoring the spectra - related response factors .   a gas chromatography apparatus ( shimadzu company , gc-17a ) , equipped with a db-1 type column ( 50 m length , 0.25 mm internal diameter , and 0.25 m thin layer thickness ) was employed for gc analysis .
the temperature was adjusted to start from 70c and increase to 225c with a ratio of 4c / min .
the shimadzu apparatus , qp 505 , equipped with a db-1 column ( 50 m length , 0.25 mm internal diameter , and 0.25 m thin layer thickness ) was used for gc / ms analysis .
the oven temperature increased from 70c to 225c at a speed of 4c / min .
the studied sample was a type of smokeless tobacco known as bt and manufactured in india . to recognize
the sample constituents , 25 g of it was placed in oven at 50c to fully dry it out .
gas chromatography ( gc ) and gas chromatography coupled to mass spectrometry ( gc / ms ) were used to identify the essential oil compounds . after injection of essential oil into gc apparatus , the essential oil constituents were qualitatively tested using time retention ( tr ) , retention index ( ri ) , and mass spectrum ( ms ) , and these elements were compared with standard compounds or available information in the saturn library ( 12 ) .
to measure retention indices , normal c6-c30 alkane compounds were injected into gc apparatus . using the information in the carcinogenic library and retention indices , the compounds mass spectra were identified and compared with the standard mass spectra .
the compounds were quantified by means of data processor ( r3 a - chromatepac ) using area normalization method and ignoring the spectra - related response factors .
a gas chromatography apparatus ( shimadzu company , gc-17a ) , equipped with a db-1 type column ( 50 m length , 0.25 mm internal diameter , and 0.25 m thin layer thickness ) was employed for gc analysis .
the temperature was adjusted to start from 70c and increase to 225c with a ratio of 4c / min .
the shimadzu apparatus , qp 505 , equipped with a db-1 column ( 50 m length , 0.25 mm internal diameter , and 0.25 m thin layer thickness ) was used for gc / ms analysis .
the oven temperature increased from 70c to 225c at a speed of 4c / min .
a gas chromatography apparatus ( shimadzu company , gc-17a ) , equipped with a db-1 type column ( 50 m length , 0.25 mm internal diameter , and 0.25 m thin layer thickness ) was employed for gc analysis .
the temperature was adjusted to start from 70c and increase to 225c with a ratio of 4c / min .
the shimadzu apparatus , qp 505 , equipped with a db-1 column ( 50 m length , 0.25 mm internal diameter , and 0.25 m thin layer thickness ) was used for gc / ms analysis .
the oven temperature increased from 70c to 225c at a speed of 4c / min .
based on the results obtained from the steam distillation and clevenger machine , the existence of different compounds was confirmed .
carcinogenic compounds such as n - nitromethyl vinylamine , n - nitrosonornicotine , and acetaldehyde were recognized .
chemical analysis of the studied sample confirmed the existence of carcinogenic and toxic compounds . in different studies ,
the existence of volatile aldehydes , nitrosamines , nitrosamino acids , tobacco specific nitrosamines ( tsnas ) , and inorganic compounds such as carcinogenic substances are mentioned ( 5 , 6 , 11 , 13 ) . in the current studied sample , tsnas carcinogenic compounds were also recognized .
these compounds are made from precursors of alkaloids , nitrite , or nitrate during curing , aging , and fermentation of the tobacco .
n - nitrosonornicotine ( nnn ) , n - nitrosoanabasine ( nab ) , and n - nitrosoanatabine ( nat ) are created from the second - type amines of nornicotine , anatabine , and anabasin during the early stages of tobacco curing and fermantation , and nnk and some nnn are created from the third - type nicotineamines during the last stages of tobacco curing and fermentation ( 4 , 5 ) .
several factors determine the concentration of tsnas in the tobacco products such as the type of tobacco products , the amount of nitrate and nitrite , the curing technique , and the production methods .
in addition , tsnas have different levels in the various parts of the tobacco plant . based on the analysis of 41 segments of tobacco leaf cured by air , the concentration of nitrosamines was smaller on the tip and the perimeter of tobacco leaf and was greater in the leaf base .
in addition , tsnas concentration was more dependent on the nitrogen and nitrite contents rather than the alkaloid content ( 14 ) . according to the above , due to differences in the product type , production feature , country of origin , and chemical analysis methods , it is difficult to compare the studied sample with the other samples .
this is one of the study limitations , which is also confirmed by a broad range of reported tsnas in the smokeless tobacco products .
the common forms of smokeless tobacco include tobacco with betel quid , lime , and tooth powder .
based on the results of the analysis of these substances in india , the highest tsnas levels were by khaini and zadra , and the lowest were reported in those of gutka and snuff .
the amount of tsnas in the betel and tobacco tooth powder could not be measured ( 5 , 9 ) . in the sample under study ,
6.3 g / g of the nnn compound was identified . in a study by stepanov et al . on new chewing tobacco products , the lowest amount of nnn
was observed in different types of ariva and stone wall ( 0.26 - 0.28 g / g ) , and its highest level was reported in the exalt ( 3.3 g / g ) , which was lower than that of nnn level in bt ( 15 ) .
analyzed five samples of chewing tobacco in america and reported the highest amount of nnn in copenhagen ( 8.73  1.44 g / g ) and the lowest in that of hawken ( 3.07  0.3 g / g ) ( 6 ) .
based on this study , the amount of nnn in copenhagen is greater than in bt , and in hawken is lower than in bt . according to the study by brunnemann
, the level of nnn ranged from 0.08 to 7.38 g / g in danish samples and belgian samples , which was comparable with that of the nnn existing in bt ( 6.3 g / g ) ( 10 ) . according to the study by stepanov et al . on 32 products in india s market ,
the highest level of nnn was in khaini and zadra ( 0.08 - 28.4 g / g ) , which was higher than that of the nnn level in bt ( 9 ) .
the concentration of nnn in bt sample was greater than those of some american , danish , and indian ( khiwam and mishri ) products , while it was lower than those of different types of khaini and zadra ( indian products ) ( 9 , 15 ) .
chemical analysis of a type of chewing tobacco , commercially known as bt and manufactured in india , using gc - ms apparatus proved the existence of carcinogenic and toxic substances in it . therefore , informing people about disadvantages of such substances is essential .  
analysis of chewing tobacco by thermal electrical analyzer ( tea ) , since it produces more powerful signals than gc - ms and is one of the methods to identify nitrosamine .
separation of inorganic material by burning and examination of the sample using atomic absorption device .
background : the use of smokeless tobacco is considered as a risk factor for oral cancer.objectives:the current study aimed to chemically analyze , separate and measure the existing substances in a type of chewing tobacco.materials and methods : in the current descriptive study , the investigated sample was a type of smokeless tobacco , known as bt , manufactured in india . 
 first steam distillation method and clevenger machine were used to separate and extract the essential oil of the sample . 
 the presence of the desired compounds was evaluated in the essential oil , using gas chromatography ( gc ) and then gas chromatography coupled to mass spectrometry ( gc / ms ) analysis.results:based on the results obtained by the applied technique , the presence of carcinogenic compounds , n - nitrosomethyl - vinylamine ( 162 g / g ) , n - nitrosonornicotine ( 6.3 g / g ) , and acetaldehyde ( 117 g / g ) was confirmed in the sample.conclusions:chemical analysis of the sample confirmed the existence of carcinogenic compounds .