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2.7.5 Holding Time: All soil gas samples(e.g., samples of VOCs, methane, fixed gases, or biogenic gases),with the exception of hydrogen sulfide samples, should be analyzed within 30 minutes by an on-site mobile laboratory. Hydrogen sulfide samples should be analyzed as specified in Section 2.7.9.B.2. Under the following conditions, holding times may be extended and analyses performed off-site: A Soil gas samples collected in glass bulbs with surrogates added within 15 minutes of collection may be analyzed within 4 hours after collection; B. Soil gas samples collected in Summalm canisters may be analyzed within 72 hours after collection; and C. Methane samples may be analyzed as specified in Section 2.7.9.A.2. 2.7.6 Analytical Methods A VOC Samples: All VOC samples should be analyzed using only a Gas Chromatograph/Mass Spectrometer(GC/MS) method (e.g., EPA Method 826013, used for analysis of soil gas samples, EPA Method TO-14A or TO-15, or equivalent), except at well- characterized sites (e.g., VOCs are known to be present and confirmed based on previous GC/MS analyses). A non-GC/MS method (e.g., EPA Method 8021 B, used for analysis of soil gas samples) may be used only for routine monitoring of VOC contamination at well-characterized sites. If during routine monitoring, new VOC(s)were detected by a non- GC/MS method, then at least 10 percent of the samples with each newly identified VOC should be confirmed by a GC/MS method. Thereafter, routine monitoring can resume with the non-GC/MS method, including the new analyte(s). B. Methane and Hydrogen Sulfide Samples: These gas samples should be analyzed using methods specified in Section 2.7.9. 2.7.7 Auto samplers may be used if: A One(1) sample is introduced ata time, B. The sample vials are gas-tight and never opened after the sample is added; C. Proper holding times are maintained (see Section 2.7.5); and D. All samples are secured and under proper custody. 01/28/2003 - 17-