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EPA DESCRIPTION REVISIONS(DATE) COMMENTS introduction(i.e.,direct injection,purge-and-trap,vacuum distillation,automated METHOD static headspace and cartridge desorption),none of which were designed for soil Mamas.D wase new as. For soil as samples,modifications of the introduction step are needed. volatile organic compaaaaw NOGsY N melted amen w s a newad 9 9 P P Ar Collective sped roy-Repered Edldon'or ther'Compendian of Based on surveys conducted by DTSC of fixed and mobile laboratories that Tats CeNstes and Metyaed By Gas 'Second Ef ilbn• M ema is fame Dmermltmdon analyze soil as samples,there are two basic techniques that are current) dein Cbomaagraphy"Ims spectrometry (Jandery 1999) f Toxic Organic Compounds in Y 9 P 9 Y g (comes) AmbientW it Asplmoga employed for soil gas analysis using Method 8260B/C: purge-and-trap and direct Marland TO 14A. injection. Each sample Introduction technique has its own advantages and disadvantages. The advantages and disadvantages of each sample introduction Merhnd TO n ase tgw technique are summarized in Table 2. marled added a me'becand voltage Organic Compounds tunics)bEdilm•of the Yemperidlum d • Tan Ambient Ay hired Aaroe sampling Onto -Second Ealbn Merndds for the beamdabn Table F-2: Advantages and Disadvantages of Sample Introduction Techniques Sabena Tubes lamely 1999) of Toxic Organic compounds In Ambient Air'It is an update of sample ingodums. Advantages Olsadvanlages cammems Mehads TO I and TO-2 from Tac tie the l''vst cmmpendlum r 989). A volume of will gas longer volumes of sial Analytes are rated into e. • N r) omommenmd for sample Is Nkcted gas sempb may be water meed and impar out 1, polarA ater soluble (daces)Nm a Pageamforced Nm ware to Into trap before entering into comiewmars. trepspargerconulnitg achieve lower rapoding GC column.Loss of larger • Surrogates(liquid ..Aaalpas are wharswtunilmiatera. aneMes possible. phased)are used but purged out a apager low sum Antes,Internal Depending on fire type m Introducetl separately too vabma trap us, vanderm and spkes sample conaalnelNesset In Into sperger.Does nag Helium gas.Antras in are added immune which the sample le actually reskim file F-3 MODIFIED GCIMS METHODS the hep ere thermally Vargas before temple collected,sample may meed OMQC thin.to wll gas. descried Ino the GC NfioduUbn and In be vanareaed beret . Ideal for rather column fa separation. WON awthan Imo quarter- cere.nterbn samples. A. EPA Method 8260 soil gas volumes can pmami.I wrize lessor • Nouatommemed fa bar changed by using a oweJor praew. few level pant' smaller syringe or Low recovery of pobrAverer ctrcerwamm samples. EPA Method 8260(Volatile Organic Compounds by Gas Chromatography/Mass teentated sial gas actual.wmpaends. . Recommended for Spectrometry GCIMS Is designed to determine VOCs in a variety of solid and wrmpas can bB cubed c.11badaa cave cot aacemng a mygerams P ry( )) 9 Y in glass bulb before mamntmduad n actino a cblorbatm liquid matrices(SW-846,1996). There are two basic technical modifications made dlaadgirmmnger. standards ane used. compounds due to poor to this analytical method for soil gas sampling. In the first technique,a volume of soil ` size; aBd as sam le is in ected into the s ar a vessel(s ar er containin water and then sand le iia Gcomlumnn gas O ated s mue ple ne dlllth. WeeasaMdld lmitilan bw much Recommended! cre�eni g pumfa 9 P 1 r 9 P 9 ) 9 p ^g "9 dead an VOCs are purged out the sponger with helium gas onto a sorbent trap. VOCs in for s.pere"°" Haulag aIle=not an wmptcwm fo/aaadima (gtwnuaM=mal and the sorbent tri are thermal) deserted into the GC column for separation and he.pmvded samples GC column. aadata monato ng of P Y P mspgd immediately . Loam mucking M,ns may dmul number of known analysis. This is equivalent to EPA Method 5030(Purger-and-Trap for Aqueous wer"60dn. hot has pasalble am ma compounds. Samples). In the second technique,a small volume of the soil as sample is directly Na taawreaaenaiyles may not meet the DOOs fa CeYbabn sandarm P 9 9 P Y from as phase to risk athwarert purave; pa.,.d by wromalan injected into the GC. It analxr(I.e..gas 1. calibaatbn not mama of iquid standards In liquid to gas), meshed. vialsbulb may rot be Can handle high level ameaahle to ea Laboratories employing a modification of EPA Method 8260 to analyze soil gas maeearmed)sampa, caargaunds. samples should adhere to all the basic analytical requirements of the original method including purge time,calibration and Quality Assurance/Quality Control(QA/QC). `Modifications for soil gas samples are outlined in the following sections. 2. Calibration Either EPA 8260B or 8260C is acceptable. 8260C is an updated version of 82608. a. One of the limitations of using EPA Method 82608 for soil gas analysis is Because the California certification program(E LAP)does not currently certify labs to the calibration technique. The current practice in most laboratories is to do 8260C,labs are certified for 82608 only. use liquid-phase standards to prepare the calibration curve. For logistical 1. Sample Introduction and economic reasons,soil gas calibration curves are prepared with liquid-phase standards. The use of liquid-phase standards may create The original EPA Method 8260 outlines five specific methods for sample biases which are undetermined. The chemical dynamics(vapor pressure, solubility,etc.)of each compound is different. The"behavior"of a 12/10/2009 -71 - 12/10/2009 -72-