酱油总酸含量测定的不确定度评定

本文根据国家计量技术规范JJF1059-1999<测量不确定度评定与表示>、依据GB/T5009.39-2003<酱油卫生标准的分析方法>,并结合了实际中的工作经验,对酱油总酸含量测定的不确定度进行评定.     

白酒中总酸含量测量不确定度的评定

酸碱滴定法测量白酒中总酸含量不确定度的影响,对测量不确定度的各个因素的评定,得到白酒中总酸测定结果的合成不确定度为4.36×10-3(g/L)。     

水中总硬度测定结果的不确定度评定

对EDTA滴定法测定水中总硬度的不确定度来源及测量不确定度的影响进行分析,建立有效的数学式,利用相对标准不确定度分量进行测量不确定度的评定。     

洗涤剂中总活性物含量测定的不确定度评定

本文对洗涤剂中总活性物含量（A法）的测定结果进行了不确定度评定，给出了国家标准GB/T 13173.2-2000所规定测试方法的测量准确度。     

邻苯二甲酸酐总酸度的测定不确定度评定

本文对邻苯二甲酸酐总酸度测定的不确定度进行了评估,分析了测量过程中存在A类和B类不确定度的来源以及它们对总不确定度的影响程度,建立测定过程的数学模型和不确定度的传播率,量化合并不确定度分量,求出合成不确定度和扩展不确定度,最终给出测定结果的表示式。     

邻苯二甲酸酐总酸度的测定不确定度评定

本文对邻苯二甲酸酐总酸度测定的不确定度进行了评估,分析了测量过程中存在A类和B类不确定度的来源以及它们对总不确定度的影响程度,建立测定过程的数学模型和不确定度的传播率,量化合并不确定度分量,求出合成不确定度和扩展不确定度,最终给出测定结果的表示式.     

酿造白醋总酸度测定不确定度评定

采用酸碱滴定法测量酿造白醋的总酸度,根据化学分析项目建立数学模型,分析氢氧化钠标准溶液浓度标定、白醋测定过程中相关参数对白醋中总酸度的不确定度影响,给出测量不确定度结果。     

食醋中总酸测量结果的不确定度评估

目的:找到容量法测定食醋中总酸的不确定度的评估方法:通过不确定度的分析,对方法的改进,实验中控制点给出建议;当测定结果在限量值附近时,帮助对结果的适用性给出合理的建议.方法:依据JJF-1059-1999,找出测景过程中影响不确定度的因素,进行评估合成.结果:对容量法测定食醋中总酸给出了测定不确定度.结论:通过对使用容量法测量方式中不确定度的评估,找到工作中的关键步骤,对提高测量的质量有指导意义.     

密度瓶法测定葡萄酒中酒精体积分数的不确定度评定

根据标准GB/T 15038-2006《葡萄酒、果酒通用分析方法》中密度瓶法测定葡萄酒中酒精度的不确定度,建立密度瓶法测定葡萄酒中酒精度的不确定度分析方法,以评定测定结果的质量,找出主要影响因素.     

三级总光通量标准白炽灯的测量不确定度评定

三级总光通量标准白炽灯是通过球形光度计来检定白炽灯泡总光通量的标准器。本文通过对三级总光通量标准白炽灯的校准,分析其各不确定度分量的来源,并对三级总光通量标准白炽灯不确定度进行评定。一、概述依据JJG247-1991《总光通量标准白炽灯》检定规程,对三级总光通量标准白炽灯在球形光度计内用比较法进行测量,标准器为二级总光通量标准白炽灯。由于二级总光通量标准白炽灯是由一组不同功率的标准灯组成的,所以总不确定度用相对不确定度来表示。二、数学模型φ=φ0(I/I0)6式中:φ0——二级总光通量标准白炽灯总光通量标准值;φ——三级…     

Measurement uncertainty in the determination of total petroleum hydrocarbons (TPH) in soil by GC-FID

In this investigation two methods were used for estimating the measurement uncertainty due to sampling and analysis of petroleum hydrocarbon contaminated soil. Analysis of variance (ANOVA) was used for type A evaluation of the measurement uncertainty. The results showed that the statistical evaluation of measurement uncertainty can be complicated by the log-normality and heteroscedasticity of the data. Although mathematical transformation of raw data is widely suggested for overcoming the discrepancy between data and ANOVA assumptions, its use results in problems with the interpretation of the ANOVA results at the original scale.

The measurement uncertainty was also estimated from the calculated precision equations for sampling and analysis. Comparison of measurement uncertainty values with the equivalent values obtained with ANOVA revealed that ANOVA overestimates the expanded uncertainty at both low and high TPH concentrations. Consequently, correct selection of the statistical analysis method needs comprehensive knowledge of the assumptions and limitations of statistical methods and careful consideration of the special characteristics (distribution, constancy of measurement variance) of the raw data as these may affect the validity of the estimated uncertainty. The expanded uncertainty obtained in this study for the results of TPH determinations with linear measurement precision modelling was moderate, ranging from 21% at a TPH concentration of 895 mg/kg to 9% at a TPH concentration of 10 019 mg/kg. If a single sample taken in a survey is analyzed only once, then the analytical variance contributes the most to the measurement variance, ranging from 68– 80% at a TPH concentration of 100–10 000 mg/kg.     

小麦粉中偶氮甲酰胺含量测量的不确定度评定

分析了高效液相色谱法测定小麦粉中偶氮甲酰胺含量不确定度的各分量,对其测量不确定度进行合理的评定,结果表明:小麦粉样品中偶氮甲酰胺的含量为43.1mg/kg时,其扩展不确定度为2.6 mg/kg(k=2),不确定度主要是最小二乘法拟合标准工作曲线求得样品浓度过程引入的。     

大米中镉含量的测量不确定度评定

分析了石墨炉原子吸收光谱法测定大米中镉含量不确定度的各分量,对其测量不确定度进行合理的评定,结果表明:大米样品中镉的含量为0.18 mg/kg时,其扩展不确定度为0.01 mg/kg(k=2),不确定度主要是最小二乘法拟合标准工作曲线求得样品浓度过程和测试过程随机效应引入的。     

盐酸溶液标定分析结果的不确定度评定

本文列出影响容量分析中盐酸溶液标定的影响因素,依据不确定度的评定规范,对盐酸标定结果进行不确定度评定。     

食品中山梨酸、苯甲酸测定方法的改进

[目的]建立一种准确测定食品中山梨酸、苯甲酸的方法。[方法]采用乙酸锌和亚铁氰化钾处理样品,除去样品中脂肪以及蛋白质成分。[结果]该方法回收试验相对偏差为2.51%~3.52%。[结论]该方法能有效的除去食品中的脂肪及蛋白质成分,确保试验准确可靠。     

Evaluation of an ultrasonic acid digestion procedure for total heavy metals determination in environmental and biological samples

In this study, a sample preparation method based on ultrasonic assisted acid digestion (UAD) has been evaluated for total heavy metals (Cd, Cr, Ni and Pb) determination in different environmental (soil, sediment and sewage sludge), and biological (fish muscles, vegetables and grains) samples, using electrothermal atomic absorption spectrometry (ETAAS). The investigated parameters influencing UAD such as presonication time, sonication time, temperature of ultrasonic bath, and different acid mixtures were fully optimized, whereas power was maintained constant at 100% of nominal power of ultrasonic bath. Six different sets of above parameters were applied on six certified reference materials (CRMs) having different matrices. The accuracy of the method was also tested by comparing the results with those obtained from conventional hot plate assisted acid digestion method on same CRMs. Analytical results for HMs by both methods showed no significant difference at 95% confidence limit (p<0.05). Recoveries of HMs ranging from 96.2% to 102% and 96.3% to 98.6% were obtained from biological and environmental samples, respectively. The average relative standard deviation of UAD method varied between 3.5% and 8.2%, depending on the analyte.     

Detonation zone width determination based on uncertainty principle

A phenomenological approach to describing detonation phenomena in high explosives is proposed, according to which the zone of relaxation processes (detonation zone) is treated as an excited quantum-mechanical system in the coherent state. The corresponding definition of the detonation zone width is not related to the kinematic parameters of the detonation wave.     

Analysis of total uncertainty in spectral peak measurements for plasmonic nanoparticle-based biosensors

One goal of recent research on plasmonic nanoparticle-based sensors is maximizing nanoparticle sensitivity or shift of resonance peak wavelength per refractive index change. Equally important is a measurement system's peak location uncertainty or shift resolution. We provide systematic analyses and discuss optimization of factors that determine peak location uncertainty, reporting values as low as 0.3 nm for the presented scheme. This type of analysis is important, in part, because it provides a means of evaluating detection thresholds for biosensor applications such as analyte binding. We estimate thresholds of 310 streptavidin molecules for the presented scheme and 20 molecules with system improvements.     

气相色谱法测定蔬菜中氧化乐果农药残留量的测量不确定度评定

本文通过对气相色谱法测定蔬菜中氧化乐果残留量的测定过程的分析,合理选择评定方法,简化并计算了测试过程中的不确定度分量,计算出了相对合成标准不确定度和相对扩展不确定度,达到了对其测量不确定度的合理评定的目的,反映了实验室的技术和设备水平.     

LC-MS/MS测定猪尿中盐酸克伦特罗不确定度的评定

建立了液相色谱-串联质谱法(LC-MS/MS)测定猪尿中盐酸克伦特罗残留量的不确定度评定数学模型,分析了影响样品测定结果的不确定度的主要来源,并计算出了各影响因素的不确定度分量.当猪尿中盐酸克伦特罗残留量的测定结果为3.6ng/mL时,其扩展不确定度为0.4ng/mL.