Objective To investigate the effect of conventional preseratives on the stability of carboxyhemoglobin(HbCO)in the stored blood samples.Methods Blood samples with 30%～40% and 60%～70% of HbCO were established,respectiviely.The samples were stored with the commomly used preseratives including formaldehyde,sodium fluoride,EDTA-Na_2,sodium nitrite,potassium oxalate,heparin sodium,sodium citrate and the mixture of sodium fluoride and sodium citrate(1:3).Saturation of HbCO in the preserved blood samples were determined at 0h,2h,8h,24h,3d,and 7d after treatment with the addictives,respectively.The data were evaluated statistically.Results The stability of HbCO was significantly affected in the formaldehyde and sodium nitrite-treated samples,but no significant effects of the other preseratives on the blood samples were detected.Conclusion The stability of HbCO in the blood samples conserved varies with the type of the preseratives used.The samples taken from cases with suspected death from carbon monoxide poisoning should be kept with proper preseratives.Blood samples preserved with formaldehyde and sodium nitrite are not suitable for HbCO determination.

Objective To obtain methamphetamine concentration profiles in saliva and urine samples of drug addicts and to screen the colloidal gold strip. Methods Methamphetamine concentration in saliva and urine samples of drug addicts was determined by liquid chromatography tandem mass spectrometry. The initial screening was obtained by colloidal gold strip test. The results were compared and analyzed. Results using the method of protein and fluid MRM scan method to detect direct precipitation, saliva is linear in the range of 1~100ng/mL, the linear correlation coefficient is 0.9987, the detection limit is 0.1ng/mL, the limit of quantification was 1ng/mL, the urine is linear in the range of 1~100ng/mL, the linear correlation coefficient is 0.9943, the detection limit is 0.5ng/mL, the limit of quantification was 1ng/mL. Saliva and urine samples diluted, the concentration in the linear range. Saliva and urine samples of four types of methamphetamine colloidal gold reagent strip were screened directly, and the results were judged visually. Conclusion the detection rate of colloidal gold strip is about 79%, the detection rate of saliva is about 81%, and the detection rate can be increased to more than 93% by using two reagent strips. Combined with the initial screening results and the instrument confirmation concentration, it can be found that the gray zone setting and sensitivity setting have certain influence on the detection rate, and it is suggested to improve the sensitivity to meet the needs of screening.