Abstract：Since there was no standard sample for inner surface residual carbon in copper tube, the instrument was calibrated by synthetic carbon sample. The determination results were verified using reference sample of inner surface carbon of inner grooved copper tube. The content of inner surface residual carbon in inner grooved copper tube was successfully determined by tubular furnace heating-in-frared absorption. Several factors influencing the determination results were tested and discussed, for instance, the sample treatment, the flow selection of oxygen, the temperature constant, the setting of instrumental blank and the calibration of instrument. The results showed that, when the testing temperature was 400-600 ℃ and the flow rate of oxygen was 750 mL/min, the inner surface carbon in copper tube was completely released. The determination results were consistent with those obtained by tubular furnace heatingnonaqueous titration, with relative standard deviation (RSD) of 3.7 %. The synthetic carbon sample was added for recovery test and the recoveries were found as 98 %-103 %.
