We report a spectrophotometic method for the determination of cyanogen chloride (CNCl) in air pollution.Experimental parameters for the stability and absorbility of CNCl gas in the different media were studied.The experimental conditions were optimized for CNCI as follows:absorbent:1%isonicotinic acid-barbituric acid;reaction acidity:pH 5.8 in phosphate buffer at room temperature;masking agent:0.01mol/L EDTA;λmax:598nm. The apparent molar absorptivity was found to be 1.17×105L·mol-1·cm-1,the linear range was within 0～5μg of CNCl in 25 mL solution; the regression equation of the curve has given by A=-0.0040+1.935C(r=0.9999).The method has been applied to the determination of CNCl in chimney gas,workshop air and production area air of the cyanuric trichloride plant,chemical works and pharmaceutical factory air.The relative standard deviation was below 2.7%(n=4)for the cyanogen chloride amount within 13～64mg/m3,and when CNCl amounts were within 0.1～1.0mg/m3,RSD was below 6.9%(n=6).The recovery was 98.7%.

Objective To study the diagnostic value of relative parameters and time-relative-intensity curve(TRIC) in malignant and benign liver tumors with contrast-enhanced ultrasound(CEUS). Methods Fifty-nine focal liver lesions were examined with CEUS and drawed time-intensity curve(TIC) with QLAB software. The relative parameters of malignant and benign liver tumors were calculated and analysed. The relative intensity equaled the echo intensity of lesion substracted the encho intensity of liver. TRIC were drawed with time as abscissa and relative intensity as the ordinate. The types of TIRC were analysed comparatively in different groups (benign and malignant). Results There were significant differences in relative peak time, relative peak intensity, relative enhancement time and relative decline slope between malignant and benign lesions( P ＜0. 05). TRIC appeared quick-ascending and quick-descending types in the malignant lesions,the decline curve of TRIC droped down to 0 dB at (28.24 ± 8. 14)s and down to lowest - 8 dB continually, meanwhile fluctuated slightly. While TRIC appeared slow-ascending and slow-descending types in the benign lesions, the decline curve of TRIC droped down to the lowest 4 dB continually, meanwhile fluctuated slightly. Conclusions The relative parameters and TRIC are new quantitative indicators of CEUS for diagnosis of malignant and benign liver tumors.