International Journal of Scientific Research Engineering & Technology (IJSRET)Volume 2 Issue 8 pp 464-467 November 2013 www.ijsret.org ISSN 2278 – 0882

IJSRET @ 2013

Comprehensive Detection of Human Body Odour in Air MatricesSanjay Kumar Jain, Jyoti Singhai, Shailendra Jain

Sanjay Kumar Jain, Research Scholar, MANIT, Bhopal (e-mail: sanjay@bistbpl.com).Jyoti Singhai, Professor, Department of Electronics and Communication, MANIT, Bhopal (e-mail: j.singhai@gmail.com).Shailendra Jain, Professor, Department of Electrical Engineering, MANIT, Bhopal, (e-mail: sjain68@gmail.com).

Abstract— The Human Body Odour consists ofVolatile Organic Compounds (VOC’s) which areregularly emitted in the environment by the current ofwarm air called raft that surrounds the Human Body.A raft is composed of one or more dead cells carryingapproximately four microbial bacteria and is catalyzedby body secretions. Canine’s can recognize humans bytheir smell. Thus every human should have odourwhich is unique just like fingerprint. In this paper wewill try to detect the VOC’s present in Human BodyOdour by detecting the individual odour in AirMatrices by Head Space Gas Chromatograph and thenwill try to find out the common constituents present inVOC’s so that an artificial machine can be created tobe used in forensic and by law enforcement agenciesthat can depict a trained dog’s nose.

Index Terms— Head Space, Linearity, Odour,Reproducibility, Standard Solution.

I. INTRODUCTIONOdour, which refers to smells, is used to identifysources of air pollution, environmental contamination,disease diagnostics, food analysis and humanidentification in crime investigations using trainedcanines. Odour consists of volatile organiccompounds (VOCs) that typically have relativemolecular masses between 30 and 300 g/mole.Heavier molecules do not occur as VOCs because theygenerally have a vapor pressure at room temperaturethat is too low to be active odorants. The volatility ofmolecules is determined by both their molecularweight and their intermolecular interaction, withnon-polar molecules in general being more volatilethan polar ones. As a consequence the most odorousmolecules tend to have one or two polar functionalgroups. More functional groups in general result inmolecules that are much less volatile [1, 2].There is a limited understanding of how the humanbody creates scent. It is known that the epidermis(outer) layer of the skin constantly sheds epithelialcells into the environment. The surface of the skincontains about two billion cells, and approximately667 cells are shed each second. The average lifespanof an epithelial cell is approximately 36 hours. Deadcells that are shed from the surface of the skin arereferred to as rafts and are approximately 14 microns

in size and weigh approximately 0.07 micrograms. Araft is composed of one or more dead cells carryingapproximately four microbial bacteria and is catalyzedby body secretions. All three components of the raftare characteristic to a person. Each raft is also said tobe surrounded by a minute vapour cloud that resultsfrom the bacteria acting upon the cells [44].Studies conducted at the National Institute forMedical Research in London have shown that there isa current of warm air that surrounds the human body[36]. The current of warm air is approximatelyone-third to one half-inch thick, and it travels up andover the body at a rate of 125 feet each minute.Analysis of the air current indicates that it containsfour to five times as many germs as the air in the restof the sampling room. The germs come from thebacteria that are shed with dead skin cells. Largerflakes of skin fall to the ground, but smaller ones aredrawn up into the current. These currents can also bevisualized through clothing. The warm air currentscarry the rafts from the body into the surrounding areaallowing for the deposit of human scent in theenvironment.

II. HUMAN BODY ODOUR VOC DETECTIONThere are hundreds of VOCs in human odour.However, there are no reports regarding human odourVOC concentrations in the warm current around thehuman body. The human olfactory system is only ableto smell out the human body odour with a sensitivityof 1 ppm to sub ppb level [10]. This is not enough todetect VOC’s present in the Human Body. Wetherefore require some sensitive device which canmimic dog’s nose to detect the VOC’s present in theHuman Body and the surrounding environment.

III. ODOUR MEASUREMENT TECHNIQUESThere are various methods used for the same; whichare listed below –

A. Dilution-to-threshold methodsDilution-to-threshold techniques dilute an odorsample with odorless air at a number of levels and thedilution series is presented in ascending order of odorconcentration. From one level to the next, the dilutiondecreases and the amount of odorous air increases.The first few levels include the sample diluted with alarge amount of odorless air so evaluation can begin

International Journal of Scientific Research Engineering & Technology (IJSRET)Volume 2 Issue 8 pp 464-467 November 2013 www.ijsret.org ISSN 2278 – 0882

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below the threshold of detection. Preferably, multiplepresentations (two odourless air samples and thediluted odour sample) are made at each level ofdilution. When a forced-choice method is used, apanelist, typically trained to conduct theseevaluations, must identify the presentation that isdifferent from the others at each level, even if it is aguess. This permits use of all the data. The thresholdof detection is the dilution level at which the panelistcan determine a difference between the diluted and theodorless samples. After the detection threshold isreached, the panelist continues the evaluation at thenext level or two to be certain the identification wasnot made by chance.

B. OlfactometryIn this method, odor assessment is based on a sensorypanel consisting of a group of selected people(panelists) with a 95% probability of average odorsensitivity. However, physiological differences in thesmelling abilities of the panel members can lead tosubjective results. In addition, the olfactometrymethod is very costly and requires an exactundertaking in an experienced odor laboratory inorder to achieve reliable results.

C. Electronic NosesThe electronic nose is an instrument that consists of anarray of electronic chemical receptor which detectvolatile chemicals or categories of chemicals and thenuses the information to predict sensory-likeproperties. Electronic noses contain an array ofsensors (sintered metal oxides, catalytic metals,conducting polymers, lipid layers, phtholocyanins,organic semi-conductors, and surface acoustic waveor combinations) which respond to a wide variety ofchemical classes [23]. The sensors are based onconducting composites that change resistance onexposure to a vapor [24]. The change in resistance(∆R) of individual sensors from baseline resistance(R) produces a pattern of resistance changes (∆R/R)across the array [25]. The measured response is thenconverted to a signal using a computer processor.

IV. CHALLENGES WITH ABOVE METHODSChallenges with current methodology include the useof humans for assessment. Work has shown that thesame panelist’s response from one day to the next canvary by as much as three-fold, possibly due to healthor mood of the individual. Variability in the sensitivityof the individual conducting the evaluation and odorfatigue are further concerns that are commonlyaddressed in procedural protocol. Odor fatigue is atemporary condition where a person becomesacclimated to an odorant or odor to the point that theyare no longer aware that the odor is present.

V. EMERGING METHODSThe VOC’s present in Human Body Odour areanalyzed by means of Dynamic Headspace- GasChromatography (DHS-GC) [2]. The Headspacesampling system consists of the MASTER DHSDynamic Head Space Sampler equipped with MasterAS Automatic Sampler operated in “purging mode”.The Sample is placed in a sealed vial andthermostatted in a temperature-controlled oven. Aprecise flow of inert gas is purged into the vial throughthe original dual needle; the VOC’s are swept from theliquid sample and concentrated in a sorbent packedtrap kept at low temperature (Fig.1). The trap is thenrapidly heated in backflush and the desorbed analytesare passed through the “Dew Stop” for water removaland introduced directly into the GC system (Fig. 2)The MASTER DHS combined with MASTER ASautomatic Sampler allows sample overlapping andconstant incubation time, increasing sample capacityand maximizing vial processing.

VI. EXPERIMENTAL SAMPLEA volume of 10ml. of a standard solution containing 1ppb of each compound in Human Body Odour isadded to a 20ml. vial.

A. GC Parameters- Instrument : Master GC – Master SHS Column : DN-624 (60m X 0.32 X 1.8µ) Injector : SSL at 2500 C Detector : FID at 2500 C Gain 1 Carrier : Nitrogen at 2.0 ml/min Split Flow : 30 ml/min Ratio: 1:15 Oven : 500 C (5 min), 100 C/min, 2500

C(17mins) Sample : Sweat sample

B. MASTER SHS Oven Temp : 220 0 C Incubation Time : 30 mins Valve Temp : 2500 C Transfer Line Temp : 2500 C Shaking : FAST

FID: This is the most used GC detection method. Inthis method the system measures the ions produced byorganic compounds during combustion. This methodis extremely sensitive with wide dynamic range withseveral orders of magnitude.

VII. TARGET CHEMICAL VAPOURSHuman body odor contains simple or complexcombination of more than 100 volatile organiccompounds (VOCs) belonging several chemical

International Journal of Scientific Research Engineering & Technology (IJSRET)Volume 2 Issue 8 pp 464-467 November 2013 www.ijsret.org ISSN 2278 – 0882

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classes such as aldehydes, ketones, alcohols, acids,amines etc. These chemicals are emitted through bodymetabolic activities in various organs. The metabolicprocesses in individual healthy humans are usuallydissimilar in certain way so that each emits acharacteristic body odor. These variations are mainlyin concentration and combination of several VOCs. Incase diseases, affected organs emit characteristicchemical signature which can be used as a diseasebiomarker for diagnostic purposes. The cessation ofnormal metabolic processes and onset of new bacterialdegradation in a dead body results in new vapormarkers (usually biogenic amines).The design and development of electronic noses fordetection and identification of body odor thereforecould be very useful in a variety of situations such asdisease diagnostics, forensic investigations, personalidentification, search of living and cadavers during innatural calamities etc. In general, the body emissionsare so complex that the identification of individualVOCs does not seem possible by any conventionalinstrument, yet odors (which represent specificcombination of chemicals in vapor phase) can becategorized into separate classes representing variousbody states. Based on VOC emission studies reportedin [14-18], we short listed a set of 14 organic vaporsbelonging to 7 chemical classes found in human bodyodor for the present analysis. The prominent presenceof these represent a range of body conditions; forexample, trimethylamine (TMA) in uremia and otherkidney related diseases, dimethylsulfide in liverinfection, acetone in diabetes, hydrocarbons inoxidative stress [14]. The selected VOCs along withtheir thermodynamical solvation parameters(discussed below) collected from [19] are shown inTable I.

VIII. CONCLUSION:With the solid phase microextraction (SPME), theheadspace GC permits the determination of volatilepresent in a essentially nonvolatile matrix , which mayrequire sample extraction or preparation and theselection of equilibrium conditions mainlytemperature, so that the volatile concentration can bemeasured in the headspace, make the easierdetermination of trace concentration in thesample.[17]The one unknown component in sweat sample atretention time 14.2 min. was obtained, which ispresent in very large amount can be a specificchemical compound produced by subject, the samecan be determined using MS technique for furtherresearch. So identification of such chemicalcompound, may act as individual fingerprints, used asmethod of identifying or characterizing the subjectsand become an important tool in field of forensicscience.Headspace GC a very promising method in theanalysis of volatile components with a reliability andreproducibility. The result provided by technique wassatisfactory with a good resolution, accuracy andprecision of analytes tested.

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International Journal of Scientific Research Engineering & Technology (IJSRET)Volume 2 Issue 8 pp 464-467 November 2013 www.ijsret.org ISSN 2278 – 0882

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