Document 6BD2rmq0jEvRMbeKxGKw65kL1

- JSI 'T = J * nu Page 1 of 4 April 12, 1974 : x". Ci- ; t -5 i > VINYL CHLORIDE DETERMINATION-IN AIR BY ADSORPTION ON ACTIVATED \t CHARCOAL AND-ANALYSIS BY GAS CHROMATOGRAPHY ^ PURPOSE AND LIMITATIONS'^Thls paper describes a procedure for ~ r *' ' measuring the exposure, of personnel to vinyl chloride in the working environment. 'The method describes the preparation of standards which.will determine. , vinyl chloride in the range of- 9 to: 90 parts per million by ' volume in air, based on a 4-hour sample at a flow rate of 28 : ml per minute. Lower or higher-ppm~ranges can be determined by preparing additional standards to cover the range^desired.. (Vinyl chloride can be determlned-to atleast 0.05ppa,by . volume in air by this procedure, using more dilute standards.) ta 0 *k 2 PRINCIPLE The sample-is collectedby passing:air through a - glass tube containing activated^charcoal which'. adsorbs any vinyls chloride^vapormpresent. The--.vinyls chloride is then desorbed from? the charcoal by carbon-:disulfide extrac tion and analyzed by gas chromatography. v*-: q ea > ,i>7q9c rsiqosK .--/l . . r.'i . .52..*-' I,r-cl _ INSTRUMENT3 PARAMETERS' o'*1- J rr.lT^iz .o/ C.htro- m*. xaotco.^gra. pvchaqmoO iaDimeriO AID lAnih%ly $t.i*cr al Instvru"'ment s` *i- Din - Development,. Inc. ). Portable^ .v-oonO-^oo'mtt , '.Chromatograph,-lloael '511, or . equivalent chromatograph, with ,, flame ionization detector."* Column Six-foot x 1/8-inch stainless^ steel packed with 10% di(2-ethylhexyl) LB JT YSj ITHJiOc 'A sebacate on Chromasorb Py, 80/100 ,, r*- . .gu'j- r.tiry erl* ^niojsiq v; mesbf,.' NAW.. c * ` " Column; temperature^, - j.00*C isothermal Injection temperature.*"^ ioo*c ' . " Defector. Carrir,c iXJnu S'n t`i * c flame ionization detector js = e helium or nitrogen /^ Hydrogen flow rate 23" cc per minute Air f low, rate-f Sample size Retention time- 4-. - R1Z. 133 cc per minute 2 pi solvent flush technique 0.5 minute (adjust carrier flow :n: jiv j 1 c no: j'os i until vinyl chloride elutes at .-I ' 3 t si 1 n . this' time)'. '1 ; J>.L , ,i: .7. ti :. '^ 2 l c' br J T o? gSV 0005707 p2 of 4. Alternate Column - Better Resolution Instrument Column Detector Column temperature Detector temperature Injector temperature Carrier gas . Air flow Hydrogen flow Sample size Approximate elution time Hewlett-Packard 5750 gas chromato graph-dual column, or equivalent. .25-rfoat x.r/8 inch ^stainless steel ---packe<l-with-25%-by- weight^5% r_C0880/ 25%. Te rg i to l^.B-3 S on 40/60 mesh-rescreened Chromosorb P. flame ionizatioo * at *_ a.. .40 to 100C at 4C per minute 125C /. r 125C. a.,--. , u.i- >. -helium,-30 ml per minute, -r^.. - > ,, - 350 ml per minute ---- -30 ml- per minute^ u 10 Jll : ; * ;r; . ... - 6.5^minutes: ; a^.. ,, ... 4 REAGENTS AND APPARATUS a) Personal sampling pump. USA Model G or Bendix Uicronair. Insert-an in-line orif icemn&de from.a cut-off. and restricted (pinched) hypodermic needle in^the sampling- . - line to the pump in:order to obtain-a 28 ce periminute flow on these pumps. a--'. b) Hypo-vials, 15-ml size, Cat. No. 12911; Neoprene septa, Cat. No. 13233; alumina seals, Cat. No. 13214;.i*nd band crimper. Cat. No. 13212, Pierce Chemical Company, Rockford, Illinois.::; 'u'Tl T-" c) Carbon dihulfide'i spectlrophotometrie grade d) Activated charcoal/Cat." No7"560-26, Barnebey-Cheney, Columbus'/ O'Mb . "t:\ . ' e) Soap film:'-flow meter;* 10^-ml?size f) Stop watch ' ; " .^.'*.."`^'7/ r` 5 PREPARATION OF THE' ACTIVATED^,CARBON ADSORPTION TUBE a) Prepare the activated charcoal by placing the charcoal on a 40-mesh sieve and wash*with demineralized water until no visible fines appear in the washings.* ** b) Dry the carbon in a*drying oven at 110yC until dry and free flowing (overnight).; 'Store in a screw-top, glass bottle un ti 1 needed T r" c) Cut 8-mm O.D. x 6-mm I;D. Pyrex glass tubing into 6-inch lengths and fire polish the ends. d) Insert a Pyrex glass wool plug two-thirds of the distance into the glass tubes'. " The longer section of tubing will be designated as the primary end, while the shorter side of the tubing is the back-up end. e) Pack the tubes with the activated carbon, using a length of 60 mm in the primary section and 35 mm in the back-up section. Retain the carbon with glass wool plugs. f) Seal the tubes with a red rubber septum or parafilm until ready for use. RSV 0005708 p3 of 4 k- . 3 i q 6 SAMPLING PROCEDURE a) Remove the seals from the charcoal tube and attached the back-up section to a portable pump by means of~ a^leog-th: - . of: 1/4-inctr9Tyg <tubingQbii-i;?iL noct*o ;o ic u* by S'eti the^'floir-rate at-28-*l peT, minute througbc$be fubel with a calibrated^ rotratoetbr?. ^(NOTIU^i The IQ-hiI- soap -3bubblei-Tlo# metersvan' be' hsed* to*obtain spmore- precise^ reading of the air flow through the tube if desired); c): Record tbetime. the.air sampling. wam>started; and the time . when? the. sampling! Is obmplefcedw A four-hour. sample may be taken with .this.' system,r.'jsqo* o-qsvgci awe-.r: . d). After-samp ling,recheck--thef lowerste^ and3 resea L. the ends l,c- of the charcoal' tubeuvn Return thej tUbm; te; the laboratory for analysis*, estuq oj *>?>noos3 OX jL- d^ to1 aiiat -/. e) Record the temperature and barometrlcnpressure at.the - . sampling altew. evif'-ys ydsUf-ai:* 9jiiq.;iq-.i .J aj-vO'S'. JTSRfll t9ijj93n 01IJTX 3 C: Oqv A 7 ANALYTICAL PROCEDURE*q sni wo lie bn* isb.nilvs e.-.j no .-a. a 1 Make, a small, hook st Jbhe?ndof^sr piece"of^wire: and remove - the giamSf:*ealoplugiroanhe,/primaJ7 endi of. the^charcoal tube. Make sure that no charcoals particles adhereq-to o the. glasi wool. plug^cni ,aisfv-oqxri aviJoecse't on: b) Pour the charcoal lotansn 10iUnglsms^stoppered^volumetric Yiasfcvpipet 3L*lof9carboitJdisolfidei,:(CS2)'into the ^ 3 3C , flask, and stoppBfrosefchr#lyn^^CAlJTIOI*a'iTCarbo&j disulfide -si Is toxics end should be: ihandledb under- ai hood. ^ ~:,l c)^ Agitate, ^hs. flasks periodically for4, etslasmtn 30 minutes; d) Solvent: Tlnebqlhjection Technique .sSThlsolnjection technique a vdeg dseignedn dps ml A sihate diff icqltioc art sing- from blow- .0; r-o.back ordletiUJanonewiihcthe^needlsoof^ the micro liter yu 1 syringed ef.j oini beliuq ei >5u>iov exm ic o 2*;.. e) Flush a 10 pi syringe with C$2 several^ times 'to* wet the nbarrel*and-ploegearooi oi qi; txn&v ^.-s c;cm,l..j,c - . r-. f) Straw-; 2: pi OIbCS# Awtorithsr. Syringes asdh remove' the tip of i rhe-ueedaeifrom^rheqsolveotq--^Withdraw- the-plunger an-. ~jn addlitlonmloD.Sc plqtoaseparate the eSg-rYrom the sample with a pocket of air. g) -Dip theiSSedie'/datordhes-sampleisolutlon la, the volumetric flask and withdraw the plunger until the air bubble between the solvent and the sample has passed the 2 pi mark on the syringe. _ h> Remove thetip of-ttoe needle from"'-the sample solution and- adjust the volume in the syringe until the meniscus of j . the air-bubble-res~ts on^"the-'2~>ilr'&ark; * 'Remove the excess sample soiution-from the-i tip-'bf*the^needle." ' - i) Pull the plunger back an additional 0.5 pi to prevent the sample solution from evaporating from the tip of the needle. j) Inject the entire contents of the syringe into the chromato graph. k) Measure the peak height and determine the vinyl chloride content from a previously prepared calibration curve. RSv 0005709 5 > ,i p4 of 4 . _L. 8 CALIBRATION CURVE V" a) Pipet 10 ml of carbon disulfide-, (CSg) into, each; of five 15-ml hypo-vials. Cap. the-:; vials with the. Neoprene? septa , and aluminum seals,musing the; hand crimper.Had i. r.: ,* b) Place, the hypo-vialSt. in, wet* ice> ta reduce-the.vapor pressure of CS2.-: ' 11 o :; 2. ri? u &': 1,: A l . a*; c) Cap one of the valves on a. steel sample, cyLinder containing vinyl chloride*with a 1/8-itch Swagelok. tubing nutrwhich has a chromatographic septum Installed^ In" the out.: ' ac d) Insert a hypodermic-needle through the septum, mai thej cylinder, open the valve and allow the vinyl chloride to vent through the needle for about 10 seconds to purge the.-lirfron the system. Remove the needle.= nnr. . * : e) Using the appropriate gas-tight syringe fitted with a number 27 gauge hypodermic needle, insert the needle through the septum on the cylinder and allow the pressure of the. vinyl chloride to displace the volume of the syringe. Flush.the syringe two times to remove.any-air. which mays have been trapped- in the- needleioo~i;i::> on ri.n? rs~..i: f) Into the respective hypo-vials, inject 0.2^c0.a-,0.51.0, and 2L. O co of^ v-iny^ chloride; fronr the syringe.* r .* : oh ; g) Shake the hypo-viala fon one-minute: to pu.t the: vinyL: chloride in. solution^:) These: Standards! wtlir contain 56,82,cl33, 260, 515 ugm of. vinyls ohiorldeopen.mlj' CNOTE^ These calcula- tions.: are corrected^ feet the: dead space; in. the-gas: syringe , needle. :; The. coddLXS2 *o,liLtions in. the hypo-vials are - - under slight- negative^:presstcreuj/.Measurements have shown that the. dead*space:las,the-syringe-needle, amounts to 0.04 cc, and 0.02 cc of this volume is pulled into the hypo-vial by the negativeepressjure^)? c*2C r*; nil- - * h) Allow the standards to warm up to room temperature,then inject these , standards^ into the^ chromatograph using the procedure:describedrin;Sectio*v7.,:paragrapbs d through j. Shake., the- hype^viads eachstime- just prior to withdrawing a sample. i) Plot peak height versuScmierograms. of'vinyl chloride per ml. ^ o/lt iiJ.iu 'i^arvlq t.z 9 CALCULATION. ;-j 2 -'ill - A L x 55^5"^ ^ vinyl chloride, ppm. by volume at 25C and. 760 mm o: - .. ?... ... .- A - ugm per ml ,of; vinyl .chloride read from calibration curve L - total liters of.air,sample- {flow rate x time) - - \~z no - . e- fl/T ` :.^vo "r : . ASV 00057io VINYL CHLORIDE DETERMINATION IN AIR BY GAS CHROMATOGRAPHY 1 PURPOSE AND LIMITATION This method was developed to determine vinyl chloride in air by grab samples taken with a 50-ml hypodermic syringe. Air samples are intro duced directly into the gas chromatograph by means of a 5-cc gas sampling valve. The minimum detectable concentration of vinyl chloride is about 0.1 part per million (ppm) by volume in air using this procedure. The method has been written for use with an Analytical Instrument Development portable chroma tograph but can be used with other suitably equipped gas chromatographs. 2 INSTRUMENT PARAMETERS Chromatograph Column Column temperature Injection temperature Detector Carrier, flow rate Hydrogen flow rate Air flow rate Sample size Retention time AID (Analytical Instrument Development, Inc.) Portable Chromatograph, Model 511, or equivalent chromatograph, with flame ionization detector, eight foot x 1/8-inch stainless steel packed with Poropak Q, 50/80 mesh. 100C, isothermal 100 C flame ionization detector nitrogen, 40 cc per minute 26 cc per minute 120 cc per minute 5-cc gas sampling loop approximately 2.8 min. 3 SAMPLING AND ANALYTICAL PROCEDURE a) Grab samples are taken with a 50-ml hypodermic syringe without needle. After taking samples, cap the opening of the syringe with parafilm or a 7/32 Caplug to prevent diffusion of the vinyl chloride from the syringe. Sample must be analyzed within 30 minutes after taking,as losses of vinyl chloride will occur in the syringe. Samples may also be taken with pre-conditioned Saran plastic bag if desired. -------- b) Turn the gas sampling valve to the load position and connect the 50-ral hypodermic syringe to the inlet. Allow the weight of the plunger to force the contents of the syringe through the 5-cc loop. RSV 0005711 il c) Turn the gas sampling valve to inject position. Measure the peak height and read the concentration of vinyl chloride in ppm by volume in air from a previously prepared calibration curve. 4 CALIBRATION CURVE a) Cap one of the valves on a steel sample cylinder containing vinyl chloride with a 1/8-inch Swagelok tubing nut which has a chromatographic septum installed in the nut. b) Insert a hypodermic needle through the septum on the cylinder, open the valve and allow the vinyl chloride to vent through the needle for about 10 seconds to purge the air from the system. Remove the needle. c) Using the appropriate gas-tight syringe fitted with a number 27 gauge hypodermic needle, insert the needle through the septum on the cylinder and allow the pressure of the vinyl chloride to displace the volume of the syringe. Flush the syringe two times to-.-remove any air which may have been trapped in the needle. d) Prepare a series of vinyl chloride standards in air by measuring 10 liters of purified or cylinder air into each of four Saran bags while injecting 0.0, 0.10, 0.25, and 0.5cc of pure vinyl chloride gas into the respective bags. These standards will contain 0, 10,. 25 and 50 ppm by volume vinyl chloride in air, respectively. If previously unused Saran bags are employed, it is necessary to precondition by filling with air and inject ing 0.5 cc of vinyl chloride. Allow the bags to stand approx imately 30 minutes then deflate. Refill with purified air deflate twice more before making the standards. e) Plot peak height versus concentration of vinyl chloride in parts per million (ppm) by volume in air. 5 CALCULATION Read the concentration of vinyl chloride in the sample, in parts per million by volume in air, directly from the calibration curve. RSV 0005712 V1