PDCA循环又称质量环,是进行全面质量管理的一种科学化、标准化的循环体系[1].PDCA代表的是PLAN(计划)、DO(执行)、CHECK(检查)、ACTION(行动)四个步骤.冷冻切片在术中快速、准确诊断中起到关键作用,其结果对临床医生及时制定手术方案、缩短手术时间极为重要,也为疾病的治疗提供了重要依据.因此,加强冷冻切片的质量控制、注重环节和过程,在冷冻切片的主动、持续和全过程质量管理中,具有非常实际的意义.我院病理科每个月的冷冻切片质量检查总能够发现一些问题,如切片完整性、刀痕、褶皱、冰晶、气泡、染色欠佳等.针对发现的问题,我科运用PDCA循环持续对冷冻切片的质量进行精细化管理,取得了较好效果.现探讨如下.

蔬菜中VC含量是评价其品质和耐贮性的一个重要指标.据文献报道, VC 含量测定方法有高效液相色谱法[1]、荧光分析法[2]、紫外分光光度法[3]、电位滴定法[4]等.目前,食品安全国家标准规定了食品中抗坏血酸的测定方法有高效液相色谱法、荧光法、2 ,6-二氯靛酚滴定法.笔者提出的两点电位滴定法已被推广应用于VC含量的测定[5-7].本试验以两点电位滴定法为基础,提出等电位间隔—电位滴定法,只需按等电位间隔(一般20～30 mV)记录化学计量点前的3～5组滴定数据,通过计算确定滴定终点Ve ,不需要滴定到达终点,节省了时间和药品,简便快速,并且准确.

Objective:To establish a simple,rapid,environmental-friendly method of determining vitamin C content in fruit juice.Methods:Two-point potentiometric titration based on indirect iodine quantity method was used.Quantitative KIO3 standard substance with an excess of KI reacted quantitatively to I2,the sample was added to the reaction system,and finally the remaining I2 was titrated by Na2S2O3 standard solution.Results:The relative standard deviations of the sample were between 0.47％ to 1.2％ and the recovery ratios were between 101.0％ ～ 102.9％.Conclusion:It is an effective and environment-friendly method of determining vitamin C content in fruit juice,which is accurate,fast-speed,safe and non-pollution.The instrument is simple and this method will be widely used in local level agricultural and forestry institute.

[目的]建立茶叶中茶多酚含量测定的新方法。[方法]根据茶多酚与重铬酸钾的定量反应,设计重铬酸钾电位滴定法测定茶多酚的检测方法。[结果]该方法的相对标准偏差为0.1%~0.8%（n=6）,标准样品回收率为99.4%~100.6%,适用于任意茶多酚含量的茶叶样品检测。[结论]采用该方法测定茶多酚含量所需仪器设备简单,操作简便,重现性好,准确度高,试剂稳定性好,适合各种茶叶中茶多酚含量的测定。

A new method for detecting iodine content in salt by two-point potentiometeric titration is established.The titrimetric chemical measuring point can be calculated only by recording the titration data twice near the terminal with this method.The experimental results show that this method is con-venient to operate and handle the data with higher precision and accuracy,and the analytical speed is greatly improved compared with that of the national standard method.

Objective:To establish a method for determination of free sulfur dioxide in wine by the equal potential interval potentiometric titration.Methods: According to indirect iodimetry,the end-point of titration could be judged with the equal potential interval potentiometric titration.Results: The RSD was 0.3%～0.5%,the recovery rate for free sulfur dioxide was 94.50%～103.7%.Compared with automatic potentiometric titration,the relative deviation for free sulfur dioxide was less than 1.0%.Conclusion: The indirect iodimetry is simple,accurate without iodine standard solution.The equal potential interval potentiometric titration is accurate,reliable with good repeatability.It is suitable for determination of free sulfur dioxid in wine.

The equal potential interval-potentiometric titration was used for the determination of acid content in the soy.Based on the two-point potentiometric titration theory,by recording a small amount group of titration data before the titration end-point with approximately equal potential interval,the potentiometric titration end point can be quickly identified with this method according to the equal potential interval titration's data processing program.In a comparative study of the proposed method with the GB 5009.39-2003,no significant difference was found between them.

在两点电位滴定法理论基础上,提出了等电位间隔法处理电位滴定数据。经对文献和实验数据处理,结果与二阶微分法一致。