The ionic composition of interstitial and intravascular fluids is the same. Proteins, however, are kept with the vascular compartment, at least to a degree, by the vascular wall, which is a semi-permeable membrane. The concentration of proteins is much higher in the plasma sector than in the interstitial sector.
Detection of marijuana using swab drug test can vary from person to person taking into account the different conditions like general health, different fluid intake, metabolism, etc.
Second-hand marijuana smoke can leave traces of the chemical tetrahydrocannabinol (THC) in your urine. ChaCha! [ Source: http://www.chacha.com/question/does-second-hand-smoke-from-marijuana-show-up-in-a-drug-test ]. More Answers to  Does second hand smoke from marijuana show up in a drug test .