Photolytic interface for HPLC-chemiluminescence detection of non volatile N-nitroso compounds

An apparatus, for measuring the amount of N-nitroso compounds including N-nitrosoamides and non-volatile N-nitrosoamines in a sample wherein N-nitroso compound can be cleaved by UV radiation, which comprises a high performance liquid chromatograph communicating with a liquid/gas interface means capable of converting the sample into nitric oxide (NO) for detection in a detector means interfaced therewith, said liquid/gas interface being a photolytic interface apparatus for accepting liquid eluate from a high-pressure liquid chromatograph which contains separated trace amounts of one or more compounds to be detected and analyzed and for converting the said compounds by non-pyrolytic means to a gaseous nitric oxide (NO) which can be detected and analyzed with high selectivity and sensitivity in a detector which comprises:

• a) a high performance liquid chromatograph to separate trace amounts of the N-nitroso compounds in a sample and deliver a liquid eluate containing the separated compounds to a photolytic interface in communication therewith;
• b) a photolytic interface positioned between the chromatograph and a detector for accepting liquid eluate from the chromatograph, said eluate containing separated trace amounts of one or more compounds to be detected and analyzed, for converting the said compounds by non-pyrolytic means to a gaseous product and conveying said gaseous product to a detector communicating with said interface, wherein said photolytic interface comprises:
• (1) a means for combining the liquid eluate from the chromatograph with an inert gas to form a biphasic liquid/gas mixture and for conveying the mixture to a photolytic reactor;
• (2) a photolytic reactor for accepting and irradiating the biphasic liquid/gas mixture without pyrolysis to produce nitric oxide (NO) gas corresponding to the separated trace compounds and for conveying said gas in the gas phase of the biphasic mixture without reaction with the liquid phase to a detector in communication with said reactor;
• wherein said reactor is a coiled tube vertically positioned and concentrically disposed around an irradiation means to allow unobstructed continuous flow of liquid/gas mixture assisted by gravity;
• said coiled tube having a transparent ultraviolet window of from 190 nm to about 430 nm;
• (3) a means for regulating the flow rate of the inert gas and the flow rate of the liquid;
• (4) a means for regulating the temperature of the reactor below the temperature said compounds would pyrolyze or thermally degrade;
• c) a means for separating other components of the liquid/gas mixture exiting the photolytic reactor from the gaseous product to be detected and analyzed;
• d) a detector to detect and analyze the nitric oxide (NO) gaseous product from the separating means.