为评定气相色谱-串联质谱法(gas chromatography-tandem mass spectrometry,GC-MS/MS)测定果汁中α-六六六、β-六六六、γ-六六六、δ-六六六残留量的不确定度。采用GB 23200.113—2018《食品安全国家标准植物源性食品中208种农药及其...为评定气相色谱-串联质谱法(gas chromatography-tandem mass spectrometry,GC-MS/MS)测定果汁中α-六六六、β-六六六、γ-六六六、δ-六六六残留量的不确定度。采用GB 23200.113—2018《食品安全国家标准植物源性食品中208种农药及其代谢物残留量的测定气相色谱-质谱联用法》测定果汁中六六六的残留量,建立不确定度数学模型,分析测定过程中各种因素(包括样品溶液、分析仪器、方法回收率、标准系列工作溶液和标准曲线拟合)引入的不确定度。该法测定α-六六六、β-六六六、γ-六六六、δ-六六六的扩展不确定度分别为0.0086、0.0088、0.0090、0.0100 mg/kg。标准曲线拟合和标准系列工作溶液的配制是影响GC-MS/MS法测定果汁中六六六残留量不确定度的主要因素。拟合标准曲线时调整标准曲线的权重可以提高低浓度点的定量准确性。配制标准溶液时,应该选择合适的稀释方法,规范使用各类量具。展开更多
为保证实验室电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)法测定白酒中铅含量方法的有效性,建立不确定度的数学模型,分析测定流程,确定不确定度来源,计算各分量并合成,评定该过程中的不确定度,旨在更...为保证实验室电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)法测定白酒中铅含量方法的有效性,建立不确定度的数学模型,分析测定流程,确定不确定度来源,计算各分量并合成,评定该过程中的不确定度,旨在更加合理、科学地表示检测结果。结果显示,ICP-MS测定白酒中铅的含量为14.949μg/kg,不确定度表示为X=(14.949±0.28)μg/kg,包含因子k=2。标准曲线拟合、标准溶液配制和测量重复性对结果不确定度的贡献度分别为51.84%、24.97%和21.44%,该方法的不确定度主要来源于标准曲线拟合。展开更多
Five multiparameter empirical criteria were exclusively evaluated by comparing them with the strength data covering various stress conditions to find out which failure criterion best fits the test data and describes t...Five multiparameter empirical criteria were exclusively evaluated by comparing them with the strength data covering various stress conditions to find out which failure criterion best fits the test data and describes the mechanical behavior of the salt rock sequence (halite,bedded composite specimens and anhydrite interlayers).Full-scale comparison of all criteria for the three rock types was conducted based on five standard statistics calculated from least squares curve-fitting,which measures both the goodness of fitting and the quality of future prediction.The results indicate that all five nonlinear criteria with a basic power form are efficient in predicting the strength trend in the low tension area as well as in the high compression area of the soft rocks.The parameters obtained for the bedded rock salt are somewhat in the ones for the "pure" rocks and are even closer to those obtained for the halite.The generalized Hoek-Brown criterion is proven to perform best to two rock strength data followed by one for the Bieniawski empirical criterion,thus is the best candidate for the analysis of the salt rock.The Sheorey empirical criterion consistently achieves an intermediate performance for all the three rocks.It seems that the superiority of the poly-axial criteria (the Mogi 1967 criterion and the N-type criterion) over the former three triaxial criteria no longer exists when applied to the conventional triaxial strength data.Besides,the method of tension cut-off was proposed to solve the ambiguity problem of the two poly-axial criteria in the tension field in the plane of the major (σ1) andminor principal stress (σ3).展开更多
文摘为保证实验室电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)法测定白酒中铅含量方法的有效性,建立不确定度的数学模型,分析测定流程,确定不确定度来源,计算各分量并合成,评定该过程中的不确定度,旨在更加合理、科学地表示检测结果。结果显示,ICP-MS测定白酒中铅的含量为14.949μg/kg,不确定度表示为X=(14.949±0.28)μg/kg,包含因子k=2。标准曲线拟合、标准溶液配制和测量重复性对结果不确定度的贡献度分别为51.84%、24.97%和21.44%,该方法的不确定度主要来源于标准曲线拟合。
基金Project(2009CB724608) supported by the National Basic Research Program of China
文摘Five multiparameter empirical criteria were exclusively evaluated by comparing them with the strength data covering various stress conditions to find out which failure criterion best fits the test data and describes the mechanical behavior of the salt rock sequence (halite,bedded composite specimens and anhydrite interlayers).Full-scale comparison of all criteria for the three rock types was conducted based on five standard statistics calculated from least squares curve-fitting,which measures both the goodness of fitting and the quality of future prediction.The results indicate that all five nonlinear criteria with a basic power form are efficient in predicting the strength trend in the low tension area as well as in the high compression area of the soft rocks.The parameters obtained for the bedded rock salt are somewhat in the ones for the "pure" rocks and are even closer to those obtained for the halite.The generalized Hoek-Brown criterion is proven to perform best to two rock strength data followed by one for the Bieniawski empirical criterion,thus is the best candidate for the analysis of the salt rock.The Sheorey empirical criterion consistently achieves an intermediate performance for all the three rocks.It seems that the superiority of the poly-axial criteria (the Mogi 1967 criterion and the N-type criterion) over the former three triaxial criteria no longer exists when applied to the conventional triaxial strength data.Besides,the method of tension cut-off was proposed to solve the ambiguity problem of the two poly-axial criteria in the tension field in the plane of the major (σ1) andminor principal stress (σ3).
