Denitrosation photolytic

Quantification of total /V-nitroso compounds in urine and gastric juice is achieved by combining photolytic denitrosation with TEA. Nitrite interference is effectively eliminated with sulfamic acid (H2NSO3H)605. 

The choice of the proper stationary and mobile phases for the foregoing purpose would depend on several factors, such as the nature (polarity, stability in mobile phase) of the NOC analyzed and the availability/compatibility of the detector used. For example, if only a TEA is available as a detector, the use of an ion-exchange or a reversed-phase system is ruled out, because both require aqueous mobile phase for proper operation. Moisture in the mobile phase causes freeze-up of the cold traps in the TEA and also results in noisy response due to interference during chemiluminescence detection. Similarly, if one is using, as the detector the newly developed Hi-catalyzed denitrosation-TEA (62) or the photolytic cleavage-TEA (58), a reversed-phase system using aqueous mobile phase would be the method of choice. These detectors, however, have not been demonstrated to work in the normal-phase system. The use of an electrochemical detector will also be incompatible with an organic solvent as the mobile phase. 

The nitrite ion can be detected spectrophotometrically after the separation of nitrosamines by HPLC followed by photolytic or chemical denitrosation. Postcolumn formation of an azo dye by the reaction of nitrite with a Griess-type reagent allows its spectrophotometric detection at 546 The kinetics and mechanisms of the Griess reaction have been extensively... 

These methods are in general based on their photolytic or chemical denitrosation, and the subsequent derivatization of the resulting nitrite ion or the corresponding amine. 

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