Preparation of specimens for external quality control of urinary biological monitoring

将未接触有机溶剂的正常人尿液和含有人类尿液主要成分的人工尿液作为质量控制调查的样本。将不同浓度的马尿酸、甲基马尿酸和扁桃酸加入正常尿和人工尿中。一些标本被冷冻干燥并用于质量控制研究。然后，将样品在30、4、-20三种温度下分别保存1、2、4周，用高效液相色谱法分析三种酸在保存过程中的浓度变化。在人工尿液中加入三种酸的情况下，在30°C（1周）、1°C（2周）和-20°C（4周）的条件下，每种酸在储存后的平均浓度是储存前的97%或更多。三种酸在低温下均保持稳定，其中扁桃酸最稳定。在30℃和4℃的贮藏条件下，cr . More etinine的稳定性较差。在正常尿液中加入高浓度和低浓度的三种酸的情况下，每种酸在储存后的平均浓度是储存前的99%或更多，在30 C条件下储存1周，4 C和-20 C条件下储存4周。当人工尿液和正常尿液中加入三种不同浓度的酸后，冷冻干燥后，每种酸在25‰的温度下的平均浓度大约是在干燥人工尿液中储存前的100%，是在干燥人类尿液中储存前的99%或更多。接触低浓度混合甲苯和二甲苯的工人尿液中的马尿酸和甲基马尿酸在-20℃冷冻条件下可保持6个月无变化。体外质控标本中所含溶剂的尿液代谢物经低温邮寄后是稳定的。少

Urines from normal human subjects who had not been exposed to organic solvents and artficial urines containing major components of human urine were prepared as specimens for the survey of quality control. Various concentrations of the hippuric acid, methylhippuric acid and mandelic acid were spiked into the normal and artificial urines. Some of specimens were freeze-dried and used for quality control studies.Thereafter, the specimens were kept at 30ﾟC,4ﾟC and -20ﾟC for 1,2 and 4 weeks, and the changes in concentrations of above described three acids during storage were analyzed by high performance liquid chromatography.In the case of artificial urines spiked with the three acids, the average concentration of each acid after storage was 97 per cent or more of that before storage under the condition at 30ﾟC for 1 week, 1ﾟC for 2 week and -20ﾟC for 4 weeks. The three acids were stable when they were kept at lower temperature and the mandelic acid was the most stable one among them. The cr … More eatinine was less stable compared to the three acids under the storing condition at 30ﾟC and 4ﾟC.In the case of normal urine spiked with three acids at high and low concentrations, the average concentration of each acid after storage was 99 per cent or more of that before storage under the condition at 30ﾟC for 1 week and 4ﾟC and -20ﾟC for 4 weeks.When artificial and normal urines spiked with three acids at high and low concentrations were freezedried, the average concentration of each acid after storage at 25ﾟC was approximately 100 per cent of that before storage in dried artificial urine and was 99 per cent or more of those before storage in dried human urine. The hippuric acid and methylhippuric acid in the urine of workers exposed to low concentrations of mixed toluene and xylenes could be kept without change for 6 months under the freezing condition at -20ﾟC.Urinaly metabolites of solvents contained in the specimens prepared for external quality control were proved to be stable after mailing at low temperature. Less