No. Section 4.2.2 of the ASGI describes leak check testing. The intent of leak testing is to demonstrate the integrity of the sampling system. Both gaseous and liquid leak check compounds can accomplish this goal when used properly in the field. Using gaseous leak check compounds in a properly constructed shroud offers the advantage of instantaneously quantifying system leaks in the field with a hand-held instrument prior to sample collection. Thus a shroud provides an opportunity to immediately resolve significant leaks, avoid collecting compromised samples and reducing field time and unnecessary sample analysis. Liquid leak check compounds are equal to gas leak check compounds in their ability to demonstrate the integrity of the sampling system. However, if a mobile laboratory is not being used, then it may be days or weeks before leaks are discovered and that the integrity of the samples were compromised. Thus, soil gas samples will need to be recollected by remobilization of the field crew, and, in some cases, reinstallation of the vapor wells is needed. If a mobile laboratory or field screening is used, leak check compounds can be detected prior to sample collection, and these problems avoided.  With a mobile laboratory, significant leaks in the sampling train can be detected and mitigated prior to sampling. If a mobile laboratory is not employed, a leak check compound screening sample can be taken to a fixed laboratory prior to sampling to ensure no leaks are present. USEPA Methods 8015, 8021, and 8260, when modified pursuant to the recommendations in Appendix F of the ASGI, can be used in risk assessments.