A vaporizer (100, 200, 300, 400, 500) for vaporizing a multi component hydrocarbon containing liquid mixture, comprising: a generally elongated tubular body having a first segment defining a first end and a second segment defining a second end; a liquid sample port connected to a liquid passage formed integrally in the first segment, where said first liquid sample port provides for liquid input; a liquid channel disposed generally longitudinally along a central axis of the vaporizer (100, 200, 300, 400, 500) and extending substantially in the direction of elongation of said tubular body, said liquid channel having a first end and a second end, said first end of said liquid channel intersecting with said liquid passage to provide a flow path for liquid from said liquid sample port therethrough along its length; a liquid flow control element disposed in said first segment of said tubular body and configured to intersect the liquid channel; a vaporizer core disposed in said second segment internal to and extending from said second end of said tubular body to said second end of said liquid channel; a heating assembly (131, 132, 133) dimensioned for insertion into the vaporizer core and sealingly securable to said tubular body, said heating assembly (131, 132, 133) having a flash vaporizing heating element that vaporizes liquid introduced from said liquid channel; and a vapor discharge outlet port formed in said tubular body in said second segment spaced from said second end of the tubular body and intersecting with said vaporizer core; and a thermal isolation gap integrally formed in the body and axially disposed between the liquid sample port and the vaporizer core to form said first segment of the body above the gap and said second segment of the body below the thermal isolation gap, wherein said thermal isolation gap is formed in and extending from an exterior surface of the tubular body, wherein said thermal isolation gap is defined by upper and lower non-parallel surfaces tapered inwardly toward the liquid channel and disposed along the length of the liquid channel below said liquid flow control element, wherein said upper and lower non-parallel surfaces are configured to change the angle of heat radiation incidence and improve the reflective loss. a generally elongated tubular body having a first segment defining a first end and a second segment defining a second end; a liquid sample port connected to a liquid passage formed integrally in the first segment, where said first liquid sample port provides for liquid input; a liquid channel disposed generally longitudinally along a central axis of the vaporizer (100, 200, 300, 400, 500) and extending substantially in the direction of elongation of said tubular body, said liquid channel having a first end and a second end, said first end of said liquid channel intersecting with said liquid passage to provide a flow path for liquid from said liquid sample port therethrough along its length; a liquid flow control element disposed in said first segment of said tubular body and configured to intersect the liquid channel; a vaporizer core disposed in said second segment internal to and extending from said second end of said tubular body to said second end of said liquid channel; a heating assembly (131, 132, 133) dimensioned for insertion into the vaporizer core and sealingly securable to said tubular body, said heating assembly (131, 132, 133) having a flash vaporizing heating element that vaporizes liquid introduced from said liquid channel; and a vapor discharge outlet port formed in said tubular body in said second segment spaced from said second end of the tubular body and intersecting with said vaporizer core; and a thermal isolation gap integrally formed in the body and axially disposed between the liquid sample port and the vaporizer core to form said first segment of the body above the gap and said second segment of the body below the thermal isolation gap, wherein said thermal isolation gap is formed in and extending from an exterior surface of the tubular body, wherein said thermal isolation gap is defined by upper and lower non-parallel surfaces tapered inwardly toward the liquid channel and disposed along the length of the liquid channel below said liquid flow control element, wherein said upper and lower non-parallel surfaces are configured to change the angle of heat radiation incidence and improve the reflective loss.