Bulletin 922. SPME/GC for Forensic Applications: Explosives, Fire Debris, and Drugs of Abuse. Explosives

Transcription

1 SPME/GC for Forensic Appications: Exposives, Fire Debris, and Drugs of Abuse Soid phase microextraction is a fast, soventess aternative to conventiona sampe extraction techniques. In SPME, anaytes estabish equiibria among the sampe matrix, the headspace above the sampe, and a poymer-coated fused siica fiber, then are desorbed from the fiber to a chromatography coumn. Because anaytes are concentrated on the fiber, and are rapidy deivered to the coumn, minimum detection imits are improved and resoution is maintained. In monitoring exposives, arson sampes, and drugs of abuse, SPME is simper and faster, and produces ceaner extracts, than iquid-iquid or soid phase extraction. This buetin summarizes a few of the procedures that have been reported in the iterature. Key Words: forensics exposives arson fire debris drugs of abuse soid phase microextraction SPME In forensic anayses, sampe preparation usuay invoves removing and concentrating the anaytes of interest through iquidiquid extraction, soid phase extraction, or other techniques. These methods have various drawbacks, incuding excessive preparation time and extravagant use of organic sovents. Soid phase microextraction (SPME)* eiminates most of these drawbacks. SPME is fast, requires no sovents or compicated apparatus, and provides inear resuts over wide concentrations of anaytes (typicay to parts per miion/parts per biion eves). The technique can be used to monitor anaytes in iquid sampes or headspace, and can be used with any GC, GC-mass spectrometer, or HPLC system. In SPME, equiibria are estabished among the concentrations of an anayte in a sampe, in the headspace above the sampe, and in the poymer coating on a fused siica fiber. The amount of anayte adsorbed by the fiber depends on the thickness of the stationary phase coating on the fiber and the distribution constant for the anayte, which generay increases with increasing moecuar weight and boiing point of the anayte. Extraction time is determined by the time required to obtain precise extractions for the anayte with the argest distribution constant. Voatie compounds require a thick poymer coat; a thin coat is most effective for adsorbing/desorbing semivoatie anaytes. Anayte recovery aso is improved, or seectivity atered in favor of more voatie or ess voatie compounds, by agitating or adding sat to the sampe, changing the ph or temperature, or samping the headspace rather than the sampe or vice versa (see Optimizing SPME: Parameters to Contro to Ensure Consistent Resuts on page 5 of this buetin). Exposives With SPME, it is possibe to extract inorganic compounds from an aqueous sampe, and then extract organic components, such as exposives, from the same sampe. Investigators at the Metro- Dade Poice Crime Laboratory in Miami, FL, USA and at the Department of Chemistry at Forida Internationa University (Miami) used SPME for the anaysis of high exposives from soid debris and aqueous sampes (1). They paced their soi and soid sampes in distied water and agitated prior to extraction. To sampe an aqueous mixture of standard exposives, they used an SPME fiber coated with 65µm poydimethysioxane/ divinybenzene (PDMS/DVB). Direct immersion of the SPME fiber was found to be more effective than exposing the fiber to the sampe headspace. Equiibrium time was under 3 minutes for the Figure A. Exposives Samped Without Sovent Sampe: 5ng/mL of each exposive in water SPME Fiber: 65µm poydimethysioxane/divinybenzene : 5731-U Samping: 3 min, immersion Desorption: 5 min GC Coumn: cyanopropy siicone, 3m x.25mm ID,.25µm fim Equivaent: SPB -171 ( 24113) Oven: 95 C (3 min) to 182 C at 8 C/min (4 min) to 25 C at 8 C/min (6 min) Carrier: nitrogen, 6mL/min Det.: ECD, 25 C Inj.: spit/spitess, 18 C 1. Nitrobenzene 2. 2-Nitrotouene 3. 3-Nitrotouene 4. 4-Nitrotouene 5. 2,6-Dinitrotouene 6. 1,3-Dinitrobenzene 7. 2,4-Dinitrotouene 8. Trinitrouene 9. 1,3,5-Trinitrobenzene 1. 4-Amino-2,6-dinitrotouene Amino-4,6-dinitrotouene 12. Tetry G158 Figure courtesy of José Amira, Crime Laboratory Bureau, Metro-Dade Poice Department, Miami, FL, USA, and Grace Bi and Kenneth Furton, Department of Chemistry, Forida Internationa University, Miami. * Technoogy icensed excusivey to Supeco. US patent pending; European patent # T Sigma-Adrich Co.

2 more voatie exposives (peaks 1-4 in Figure A), and onger for the ess voatie exposives. After one-step extraction by SPME, the compounds in Figure A were detected at concentrations ess than 5 parts per biion (ppb). Anaysis by GC proved to be more rapid, sensitive, and reiabe than by HPLC. HMX and RDX exposives, however, must be anayzed by HPLC (1). Arson Furton et a. deveoped what they described as a simpe, inexpensive, rapid, and sensitive method for anayzing gasoine in fire debris, using SPME for headspace samping (2). According to the investigators, current methods for samping fammabe or combustibe iquid residues from fire debris incude static headspace samping (capabe of detecting ~1µL of petroeum product residue) and concentration methods incuding sovent extraction, dynamic headspace concentration, and passive headspace concentration (capabe of detecting ~.1µL of petroeum product residue). A of the concentration methods are cumbersome and time-consuming, and require the anayst to use carbon disufide, a toxic and highy fammabe sovent. In a direct comparison of headspace SPME and passive headspace concentration on activated charcoa strips, SPME was faster, simper, and more economica, and offered greater sensitivity. SPME aso eiminated the need to expose the technician to carbon disufide. Figure B. Headspace Samping of.1µl Gasoine Sampe:.1µL gasoine/1 gaon can, heated 3 min at 4 C SPME Fiber: 1µm poydimethysioxane : 573-U Samping: 2 min, headspace Desorption: 1 sec (spitess mode) Coumn: poydimethysioxane phase, 3m x.25mm ID,.25µm fim Oven: 35 C (2 min) to 22 C at 1 C/min, hod 2 min, to 3 C at 3 C/min, hod 5 min Vots Carrier: heium, 1mL/min (spit 5:1) Det.: FID, 3 C Inj.: spitess (cosed 3 min), 22 C (2mm ID injector iner) Figure courtesy of José Amira, Crime Laboratory Bureau, Metro-Dade Poice Department, Miami, FL, USA, and Kenneth Furton and Juan Bruna, Department of Chemistry, Forida Internationa University, Miami. Reproduced from the Journa of Forensic Sciences. Copyright American Society for Testing and Materias. Reprinted with permission Touene 2. Ethybenzene 3. m-xyene, p-xyene 4. o-xyene 5. 1,2,4-Trimethybenzene 6. 1,2,3-Trimethybenzene 7. n-butybenzene 8. Naphthaene 9. 2-Methynaphthaene 1. 1-Methynaphthaene Tabe 1. Detector Responses for Seected Hydrocarbons in Gasoine Gasoine FID Response Quantity (vots) Response Ratio (µl) SPME Passive SPME/Passive Ethybenzene x = 1. n-butybenzene x = Methynaphthaene x = 11.2 Data from reference 2. After heating various fixed voumes of gasoine at 4 C for 3 minutes, the investigators exposed a 1µm poydimethysioxane-coated SPME fiber to the headspace above the sampe for 2 minutes, then desorbed and anayzed the anaytes under conditions isted with Figure B. They used a Hamiton heated syringe ceaner (12VAC; Supeco 277-U) to cean the fiber assemby between sampes. Athough reativey sma amounts of anaytes were recovered under these conditions, the SPME technique eiminated sampe transfer/ sampe handing osses (the entire extract was introduced onto the GC coumn) and yieded high sensitivity. The investigators cacuated that headspace SPME offered, on average, a 1.-, 3.8-, and 11.2-fod increase in response, reative to passive concentration, for three measured components of the gasoine sampes (Tabe 1). SPME produced acceptabe, identifiabe chromatograms from as itte as.4µl gasoine, a significanty smaer voume than the norma imit for passive headspace samping,.1µl. The forensics experts aso were impressed with the savings in time and cost per sampe offered by SPME (2 minutes or ess, versus 16 hours; ess than haf the cost of passive samping). These anaysts now are appying their headspace SPME technique to anayses of other sampes, incuding acohos and diese fue. Because iquid (immersion) and headspace samping methods differ in kinetics, the two approaches can be considered compementary. For a given samping time, other anaysts found immersion SPME was more sensitive than headspace SPME for anaytes predominanty present in the iquid (3). The reverse was true for anaytes that were primariy in the headspace. These generaizations can be used to advantage to seectivey adsorb more voatie or ess voatie compounds, as a situation warrants. For higher sensitivity from headspace SPME, the sampe headspace shoud be as sma as is practica. A detaied theoretica discussion of headspace SPME is presented in reference 4. The presence of water in a fire debris sampe enhances the concentration of acceerants in the headspace, making extraction by SPME easier than by other methods. Using traditiona extraction methods, acceerants are not easiy extracted from fire debris sampes that contain arge quantities of water, both because of the soubiity of some poar acceerants and because water vapor interferes with the adsorption of the acceerant onto the carbon. Amira et a. used an SPME fiber coated with 65µm PDMS/DVB for a fire debris sampe containing water (5). Equiibrium time was ess than 25 minutes for ow moecuar weight acceerants. High 2

3 moecuar weight acceerants were found at higher concentration on the fiber when the fiber was exposed for a onger time (up to an hour). The investigators found that anaysis of acceerants by GC was simper, faster, and more highy sensitive using SPME, as opposed to the conventiona carbon strip extraction method. Using SPME/GC/FID, they identified 3 potentia acceerants used for arson fires. Drugs of Abuse Amphetamines in Urine Staff members of the Department of Lega Medicine, Hiroshima University Schoo of Medicine and the Department of Lega Medicine, Fukuoka University Schoo of Medicine have deveoped an accurate, simpe, and rapid method for anayzing urine for methamphetamine and its principa metaboite, amphetamine, using heated headspace SPME and capiary GC (6). The investigators sea a 1mL urine sampe in a 12mL via, add interna standard (5µg pentadeuterated methamphetamine, prepared according to reference 7) and.7g potassium carbonate, and heat the sampe at 8 C for 2 minutes on a bock heater. They then expose an SPME fiber coated with 1µm of PDMS to the headspace above the sampe for 5 minutes, then introduce the fiber into the injection port of the chromatograph. In a system equipped with mass spectrometry/chemica ionization seected ion monitoring (GC-MS/CI-SIM), this anaysis was 2 times as sensitive as a method incorporating conventiona headspace extraction (Figure C). Correation coefficients for methamphetamine and amphetamine, based on d 5 -methamphetamine, were.9999 for concentrations of.2 1mg/iter and.997 for concentrations of 5 1mg/iter (Figure D). Coefficients of variation for amphetamine and methamphetamine at 5mg/iter in urine were 7.% and 5.1%, respectivey. Figure C. Methamphetamine and Amphetamine in Urine Figure D. Linear Extraction of Methamphetamine and Amphetamine Sampe: 1mL urine (1µg each anayte, 5µg d 5 -methamphetamine,.7g K 2 CO 3 ) in 12mL via SPME Fiber: 1µm poydimethysioxane : 573-U (manua samping) Extraction: headspace, 8 C, 5 min (sampe incubated 2 min) Desorption: 3 min, 25 C Coumn: poydimethysioxane, 15m x.53mm ID, 2.µm fim Oven: 11 C Carrier: nitrogen, 25mL/min Det.: FID, 25 C Inj.: spitess, 25 C Ratio Ratio mg/iter: r =.9999 Methamphetamine/ d 5 MA µg/botte 5-1mg/iter: r =.997 Methamphetamine/ d 5 MA Amphetamine/ d 5 MA Amphetamine/ d 5 MA Sampe: 1mL urine (1µg each anayte, 5µg d 5 -methamphetamine,.7g K 2 CO 3 ) in 12mL via SPME Fiber: 1µm poydimethysioxane : 573-U (manua samping) Extraction: headspace, 8 C, 5 min (sampe incubated 2 min) Desorption: 3 min, 25 C Coumn: poydimethysioxane, 15m x.53mm ID, 2.µm fim Oven: 11 C Carrier: nitrogen, 25mL/min Det.: FID, 25 C Inj.: spitess, 25 C µg/botte , 598 Heated Headspace SPME 1 2 Conventiona Heated Headspace 1. Amphetamine 2. Methamphetamine Figures C and D provided by M. Yashiki, T. Kojima, T. Miyazaki, N. Nagasawa, and Y. Iwasaki, Dept. Lega Medicine, Hiroshima University Schoo of Medicine, Hiroshima, Japan and K. Hara, Dept. Lega Medicine, Fukuoka University Schoo of Medicine, Fukuoka, Japan , 596 3

4 Subsequenty, these authors deveoped a simiar procedure for monitoring amphetamines in bood (N. Nagasawa, M. Yashiki, Y. Iwasaki, K. Hara, and T. Kojima, Rapid Anaysis of Amphetamines in Bood Using Head Space-Soid Phase Microextraction and Seected Ion Monitoring in Forensic Science Internationa 78 (2), 1996). In pace of potassium carbonate,.5ml 1N sodium hydroxide is used to drive the anaytes into the headspace (see Optimizing SPME: Parameters to Contro to Ensure Consistent Resuts). In anayzing urine sampes for suspected drugs, the New Jersey State Poice Forensic Laboratory used headspace SPME, foowed by headspace derivatization and GC/MS, with positive identification of amphetamines (8). Headspace samping was found to be more effective than direct fiber immersion, due to potentia interferences. The equiibrium time for the compounds was ess than 3 minutes. The anaysts used an SPME fiber coated with 65µm PDMS/DVB. Cocaine in Urine Investigators in the Department of Lega Medicine, Showa University Schoo of Medicine and the Department of Lega Medicine, Hamamatsu University Schoo of Medicine deveoped a method for detecting cocaine in urine, by combining SPME with capiary GC on a poydimethysioxane coumn (3m x.32mm ID,.25µm fim) and a nitrogen-phosphorus detector (9). Because headspace extraction gives poor recovery vaues for cocaine, the anaysts immerse a 1µm PDMS SPME fiber into the sampes. To demonstrate their technique, the anaysts add.5ml urine pus 25ng cocaine and 25ng interna standard (cocapropyene, prepared according to reference 1) to a 1mL via containing 2µL of 2.5% sodium fuoride soution and a sma magnetic stirring bar. They insert the neede on the SPME device through the septum seaing the via, immerse the SPME fiber in the sampe for 3 minutes, then expose the fiber in the heated injection port for 3 minutes to ensure compete desorption of the extracted anayte. Figure E shows chromatograms for cocaine and the interna standard in methano (direct injection, 2ng each on-coumn), the drug and interna standard as extracted from spiked urine, and an extract from a urine bank. The extracts are very cean urine background does not interfere with the anaysis. Recovery vaues for cocaine and the interna standard, determined by comparing peak areas for the extracts to those for the methano soution, were 2% and 3%, respectivey. Extractions were inear from 3ng 25ng/.5mL urine; the detection imit for cocaine was approximatey 6ng/.5mL urine. Figure E. Cocaine in Urine Sampe:.5mL urine (25ng each anayte, 2µL 2.5% NaF) in 1mL via SPME Fiber: 1µm poydimethysioxane : 573-U (manua samping) Extraction: immersion, 3 min Desorption: 3 min, 24 C Coumn: poydimethysioxane, 3m x.32mm ID,.25µm fim Oven: 12 C to 28 C at 1 C/min Carrier: heium, 3mL/min Det.: NPD, 28 C Inj.: spitess (spitter opened after 1 min), 24 C Standards in Methano Spiked Urine 4 Urine Bank Cocaine Cocapropyene C Cocaine Cocapropyene C C , 156, 157 Figure provided by T. Kumazawa and K. Sato, Dept. Lega Medicine, Showa University Schoo of Medicine, Tokyo, Japan and K. Watanabe, H. Seno, A. Ishii, and O. Suzuki, Dept. Lega Medicine, Hamamatsu University Schoo of Medicine, Hamamatsu, Japan. Used with permission of Japanese Journa of Forensic Toxicoogy. 4

5 Optimizing SPME: Parameters to Contro to Ensure Consistent Resuts As these exampes indicate, anaysts using soid phase microextraction routiney obtain consistent resuts and reiabe detection of ow concentrations of anaytes. The poarity and thickness of the coating on the fiber, sampe agitation, the samping method (fiber immersion or headspace samping), the ph, sat content, and voume of the sampe, and other factors affect resuts from SPME. It is important to remember that in SPME neither compete extraction of anaytes nor fu equiibrium are necessary, but consistent samping time, temperature, fiber immersion depth, and headspace voume are crucia to reproducibiity. Fiber Poarity Because the SPME fiber is ony 1cm ong, the coating on the fiber must be either nonpoar or strongy poar in nature. In chromatography, sma changes in the chemica nature of the stationary phase are usefu (a 5% diphenysioxane/95% dimethysioxane phase versus a 1% dimethysioxane phase, for exampe), but such sma differences wi not produce appreciabe seectivity differences in SPME. What is beneficia, however, is the incorporation of an adsorbent materia in the coating. The potentia vaue of incuding various adsorbents, carbons, and siica in SPME coatings is under review at Supeco. Fiber Coating Thickness Diffusion of an anayte from the sampe matrix or headspace into the coating on the fiber is proportiona to the thickness of the coating. A thicker fim retains voatie compounds and transfers them to the GC injection port without oss. For higher boiing compounds, a thin fim ensures fast diffusion and reease of the anayte during therma desorption. A thick fim wi effectivey remove high boiing compounds from the sampe matrix, but the desorption rate wi be proonged, and anaytes coud be carried over to the next extraction. Sampe Agitation Sampe agitation enhances extraction and reduces extraction time, especiay for higher moecuar weight anaytes with high diffusion coefficients. Inconsistent stirring causes poor precision and is worse than no stirring. Sonication promotes anayte adsorption, but can heat the sampe. This might be detrimenta to some heat-sensitive anaytes or, aternativey, coud be usefu for vaporizing anaytes for headspace extraction. Immersion versus Headspace Samping; Effects of Sat and ph Anaytes that exhibit a vapor pressure can be extracted by immersing the fiber into the sampe, or by samping the headspace above the sampe. Anaytes that exhibit no vapor pressure must be extracted by immersion. Adding sat to the sampe or changing the ph prior to extraction can increase the ionic strength of the soution and, in turn, reduce the soubiity of some anaytes. Conversey, sat can increase the soubiity of other anaytes. Consequenty, the effects of adding sat to a sampe shoud be evauated for each specific combination of anaytes and sampe matrix. Changing the ph can minimize soubiity; acidic and basic compounds are more effectivey extracted at acidic and basic ph, respectivey. A combination of sat and ph modification often enhances the extraction of anaytes from the headspace. Equiibration is faster in headspace samping, because in immersion samping the anayte moecues must penetrate a static ayer of water moecues surrounding the fiber. For higher sensitivity from headspace SPME, the sampe headspace shoud be as sma as is practica. A detaied theoretica discussion of headspace SPME is presented in reference 4. Other Factors Less subject to contro, but infuencing the extraction, is anayte concentration. At ow concentrations, changes in sampe voume do not affect response, because equiibrium is concentration-dependent. At higher concentrations, changes in sampe voume become significant. With a arge sampe (>5mL) containing a high concentration of anayte, the amount of anayte removed from the sampe is not sufficient to change the concentration. Therefore, response throughout the caibration curve is exponentia, not inear, especiay for compounds with high distribution constants. Responses may be inear for ow concentrations. Because anayte concentration often is not known, it is best to keep sampe voumes between 1mL and 5mL, and aways use the same voume for sampes and caibration standards. If you anticipate extracting the anaytes by using an immersion samping technique, minimize the headspace in the sampe via. Finay, the desorption parameters injection port temperature, depth of fiber insertion in the injection port, desorption time aso must be optimized for the anaytes invoved. Once estabished, these vaues shoud be used consistenty. Desorption of an anayte from the SPME fiber depends on the boiing point of the anayte, the thickness of the coating on the fiber, and the temperature of the injection port. Some anaytes can take up to 3 seconds to desorb, and cryogenic cooing might be required to focus these compounds at the inet of a capiary GC coumn. Use of an inet iner with a narrow interna diameter (e.g.,.75-1mm) generay provides sharp peaks and can eiminate the need for cooing. As with any other extraction/concentration technique, it is best to use mutipe interna standards in SPME methods, and to treat the standards and the anaytes identicay. References 1. Amira, J.R., G. Bi and K.G. Furton, The Anaysis of High Exposives Residues by Soid-Phase Microextraction Foowed by HPLC, GC/ECD and GC/MS. Paper presented at Academy of Forensic Science, 2/13/ Furton, K.G., J.R. Armira, and J.C. Bruna, J. Forensic Sci., 41: (1996). 3. Yang, X. and T. Peppard, J. Agric. Food Chem., 42: (1994). 4. Zhang, X. and J. Pawiszyn, Ana. Chem. 65: (1993). 5. Furton, K.G., J. Bruna, and J. Amira, J. High Reso. Chromatogr., 18: (1995). 6. Yashiki, M., T. Kojima, T. Miyazaki, N. Nagasawa, Y. Iwasaki, and K. Hara, Forensic Science Internationa 76: (1995). 7. Hara, K., T. Nagata, and K. Kimura, Z. Rechtsmed., 96: (1986). 8. Brette, T., M. Sinibadi, E. McLaughin, and M. Kennedy, Rapid Identification of Amphetamines in Urine Using Headspace Derivatization by Soid-Phase Microextraction and Gas Chromatography/Mass Spectrometry. Paper presented at Eastern Anaytica Symposium, Nov , Kumazawa, T., K. Watanabe, K. Sato, H. Seno, A. Ishii, and O. Suzuki, Japan. J. Forensic Toxico., 13: (1995). 1. Roy, I.M., T.M. Jefferies, M.D. Threadgi, and G.H. Dewar, J. Pharm. Biomed. Ana., 1: (1992). References not avaiabe from Supeco. 5

6 Ordering Information: SPME Fiber Hoder Initiay you must order both hoder and fiber assemby. Hoder is reusabe indefinitey. For manua samping 5733-U For Varian 81/82 autosamper (requires Varian SPME upgrade kit) SPME Fiber Assembies (pk. of 3) 1µm poydimethysioxane coating (best for voatie anaytes) For manua samping 573-U For Varian 81/82 autosamper µm poydimethysioxane/divinybenzene coating For manua samping 5731-U For Varian 81/82 autosamper µm poydimethysioxane/carboxen TM coating (for nonpoar intermediate poarity semivoaties) For manua samping For Varian 81/82 autosamper SPME Fiber Assemby Kit One fiber assemby each: 1µm poydimethysioxane, 65µm poydimethysioxane/divinybenzene, 75µm poydimethysioxane/carboxen For manua samping U For Varian 81/82 autosamper U SPME Samping Stand Hods eight vias whie supporting the SPME syringe for consistent fiber immersion. Accommodates 4mL vias ony. SPME Samping Stand U Heat/Stir Pate Heat or stir sampes when using the SPME samping stand. The pate fits compacty on the base of the stand. Heating range is 4-55 C. Stirring range is 6-12rpm. SPME Portabe Fied Samper This manua-type hoder stores the fiber after samping by seaing it with an interna septum. It is idea for fied work and comes with a PDMS/Carboxen fiber for trace-eve voatie anaysis, or a PDMS fiber for concentrating poar anaytes SPME Portabe Fied Sampers, pk. of 2 75µm PDMS/Carboxen µm PDMS Repacement Septa, pk. of SPME Septum Removing Too Corning Heat/Stir Pate, 12VAC Corning Heat/Stir Pate, 24VAC n Z26,212-9 Z26,2137-1EA Magnetic Stirring Bars Fit 4mL vias. 1 x 3mm, pk. of 3. Magnetic Stirring Bars Z11,8877-3EA Thermometer For monitoring the temperature of sampes when using the SPME samping stand and the heat/stir pate. 5" ong. Thermometer n CE approved. 6

7 Vias and Cosures Pre-Dried Septa for SPME Qty. Screw Top Vias for Varian 81/82 AutoSamper, 12mm OD x 32mm ength Cear, 2mL U Amber, 2mL Headspace Vias, 15mm OD x 45mm ength Cear, 4mL Amber, 4mL Syringe Ceaner Easier neede penetration and high puncture toerance Reduces septum coring that can cause extraneous peaks Conditioned, ready-to-use Extremey ow beed over a wide range of inet temperatures from 1 C to 25 C Rubber formuation excusive to Supeco Qty. Thermogreen TM LB-2 Septa, Pre-Dried 11mm pk. of mm pk. of mm pk. of mm pk. of U Heps rid your chromatograms of ghosts Ceans Hamiton syringes and other syringes with needes up to 18 gauge (.49" OD). Just connect the unit to your water aspirator or other vacuum source, insert the neede through the septum, and in 1-3 seconds, you're ready for a new sampe. A combination of heat (25 C) and vacuum vaporizes and removes contaminating voaties in a singe operation. Qty. Hamiton Syringe Ceaner 12V U Repacement Septa 5mm s Does not have a CE mark. 7

8 SPME Inet Liners Achieve Sharper Peaks with SPME/GC SPME Inserts Using a.75mm ID inet iner in the GC injection port increases inear veocity through the iner, compared to a arger voume 2mm ID iner, and rapidy introduces anaytes onto the coumn in a narrow band. Our proprietary, high-temperature technique thoroughy deactivates these iners to minimize adsorption of active sampe components. Inet Liners for SPME Hewett-Packard (588, 589 series, 689) Each 26375,1 pk. of ,5 pk. of ,25 Varian 175/177 Injectors Each 26358,1 pk. of ,5 pk. of ,25 193/194 SPI Injectors Each 26364,1 pk. of ,5 pk. of ,25 Perkin-Emer (Auto System Spit/Spitess Injector) Each 26312,1 pk. of ,5 pk. of ,25 Shimadzu GC Modes 9A/15A/16 (SPL-G9/15 Injector) Each 26329,1 pk. of ,5 pk. of ,25 GC Modes 14/15A/16 (SPL-14 Injector) Each 26335,1 pk. of ,5 pk. of ,25 GC Modes 17A (SPL-17 Injector) Each 26339,1 pk. of ,5 pk. of ,25 Acknowedgments The procedure for detecting exposives was deveoped by José Amira, Metro- Dade Poice Crime Laboratory, 915 NW 25 St., Miami, FL USA; and Grace Bi and Kenneth G. Furton, Department of Chemistry, Forida Internationa University, Miami, FL USA. The procedure for detecting gasoine in fire debris was deveoped by José Amira, Metro-Dade Poice Crime Laboratory, 915 NW 25 St., Miami, FL USA; and Kenneth G. Furton and Juan Bruna, Department of Chemistry, Forida Internationa University, Miami, FL USA. The procedure for detecting amphetamines in urine was deveoped by Mikio Yashiki, Tohru Kojima, Tetsuji Miyazaki, Nobuyuki Nagasawa, and Yasumasa Iwasaki, Department of Lega Medicine, Hiroshima University Schoo of Medicine, Kasumi, ami-ku, Hiroshima 734, Japan and Kenji Hara, Department of Lega Medicine, Fukuoka University Schoo of Medicine, Nanakuma, Jonan-ku, Fukuoka 814-1, Japan. The procedure for detecting cocaine in urine was deveoped by Takeshi Kumazawa and Keizo Sato, Department of Lega Medicine, Showa University Schoo of Medicine, Hatanodai, Shinagawa-ku, Tokyo 142, Japan and Kanako Watanabe, Hiroshi Seno, Akira Ishii, and Osamu Suzuki, Department of Lega Medicine, Hamamatsu University Schoo of Medicine, 36 Handa-cho, Hamamatsu , Japan. Trademarks Carboxen, SPB, Thermogreen Sigma-Adrich Co. Hamiton Hamiton Co. Hewett-Packard Hewett-Packard Corp. Perkin-Emer Perkin-Emer Corp. Shimadzu Shimadzu Corp. Fash On-Coumn Inserts for Varian SPME Injector pk. of ,5 BULLETIN 922 For more information, or current prices, contact your nearest Supeco subsidiary isted beow. To obtain further contact information, visit our website ( see the Supeco cataog, or contact Supeco, Beefonte, PA USA. ARGENTINA Sigma-Adrich de Argentina, S.A. Buenos Aires 1119 AUSTRALIA Sigma-Adrich Pty. Ltd. Caste Hi NSW 2154 AUSTRIA Sigma-Adrich Handes GmbH A-111 Wien BELGIUM Sigma-Adrich N.V./S.A. B-288 Bornem BRAZIL Sigma-Adrich Quimica Brasi Ltda São Pauo, SP CANADA Sigma-Adrich Canada, Ltd Winston Park Dr., Oakvie, ON L6H 6J8 CZECH REPUBLIC Sigma-Adrich s.r.o. 186 Praha 8 DENMARK Sigma-Adrich Denmark A/S DK-2665 Vaensbaek Strand FINLAND Sigma-Adrich Finand/YA-Kemia Oy FIN-7 Hesinki FRANCE Sigma-Adrich Chimie Saint-Quentin-Faavier Cedex GERMANY Sigma-Adrich Chemie GmbH D-8241 Deisenhofen GREECE Sigma-Adrich (o.m.) Ltd. Iioupoi 16346, Athens HUNGARY Sigma-Adrich Kft. H-167 Budapest INDIA Sigma-Adrich Co. Bangaore IRELAND Sigma-Adrich Ireand Ltd. Dubin 24 ISRAEL Sigma Israe Chemicas Ltd. Rehovot 761 ITALY Sigma-Adrich s.r Miano JAPAN Sigma-Adrich Japan K.K. Chuo-ku, Tokyo 13 KOREA Sigma-Adrich Korea Seou MALAYSIA Sigma-Adrich (M) Sdn. Bhd. Seangor MEXICO Sigma-Adrich Química S.A. de C.V. 52 Touca NETHERLANDS Sigma-Adrich Chemie BV 333 AA Zwijndrecht NORWAY Sigma-Adrich Norway Torshov N-41 Oso POLAND Sigma-Adrich Sp. z o.o Poznañ PORTUGAL Sigma-Adrich Quimica, S.A. Sintra 271 RUSSIA Sigma-Adrich Russia Moscow 1362 SINGAPORE Sigma-Adrich Pte. Ltd. SOUTH AFRICA Sigma-Adrich (pty) Ltd. Jet Park 1459 SPAIN Sigma-Adrich Quimica, S.A. 281 Acobendas, Madrid SWEDEN Sigma-Adrich Sweden AB Stockhom SWITZERLAND Supeco CH-9471 Buchs UNITED KINGDOM Sigma-Adrich Company Ltd. Pooe, Dorset BH12 4QH UNITED STATES Supeco Supeco Park Beefonte, PA Phone or Fax or emai:supeco@sia.com Supeco 8is a member of the Sigma-Adrich famiy. Supeco products are sod through Sigma-Adrich, Inc. Sigma-Adrich warrants that its products conform to the information contained in this and other Sigma-Adrich pubications. Purchaser must determine the suitabiity of the product for a particuar use. Additiona terms and conditions may appy. Pease see the reverse side of the invoice or packing sip. H BQS