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目的探讨哮喘儿童呼出气冷凝液(EBC)pH测定的影响因素,建立规范、准确的哮喘儿童EBC pH测定方法。方法哮喘儿童EBC采用Rtube采集,pH测定采用微电极电位分析法。结果采样时冷凝管的温度(-18℃~4℃)、采样时间(10~30 min)对EBC pH测定结果无显著影响,高纯氩气吹扫4 min后pH达到稳定;对不同pH的实际样品测定的日间精密度(以相对标准差RSD表示)范围为0.74%~1.01%;对pH分别为4.01、6.86、9.18的NIST pH标准缓冲液的测定值与理论值的相对偏差范围为0.11%~0.75%;用于pH测定的EBC样品可以保存6个月。结论通过规范EBC pH测定影响因素建立的测定方法,简单快捷,准确度高,重现性好,可以用于哮喘儿童EBC pH测定。
Objective To investigate the influencing factors of pH value determination of exhaled breath condensate (EBC) in children with asthma and to establish a standardized and accurate method for the determination of EBC pH in children with asthma. Methods EBC of asthmatic children were collected by Rtube, and the pH was measured by microelectrode potentiometry. Results The temperature of the condenser (-18 ℃ ~ 4 ℃) and the sampling time (10 ~ 30 min) did not affect the pH value of the EBC at the time of sampling. The pH of the EBC was stable after being purged with argon for 4 min. The daytime precision (relative standard deviation RSD) of the actual samples ranged from 0.74% to 1.01%. The relative deviation between the measured and theoretical values of NIST pH standard buffers at pH 4.01, 6.86, and 9.18 was 0.11% ~ 0.75%; EBC samples for pH measurement can be stored for 6 months. Conclusion The method established by standardizing the influencing factors of EBC pH determination is simple, rapid, accurate and reproducible. It can be used for the determination of EBC pH in asthmatic children.