Synthesis of an IS and Steviol Glycoside Analysis by a Validated Internal Standard Method

The internal standard (IS) method is the best method for the analysis of samples, as it is independent of errors in injection volume, changes in sample volumes, and changes in sensitivity of the detector, etc. Use of an internal standard allows for the correction of losses due to sample clean-up of complex samples. An ideal IS is a compound that has properties very similar to, and that behaves as the compounds to be analysed. Ideally, only in the last step of analysis (HPLC), the IS should be well separated from the compounds of the mixture to be analysed. After testing several existing compounds with negative results, we decided to synthesise the 19-O-β-D-galactopyranosyl-13-O-β-D-glucopyranosyl-steviol as IS. This is the 19-galactosyl ester of steviolmonoside (13-O-β-D-glucopyranosyl-steviol). The IS was made according to published methods. Steviolmonoside (SM) was made from purified commercial rubusoside (Rub) by refluxing it in 10% KOH for 2 h. SM was precipitated and crystallized from MeOH. The hydroxyls of the glucose unit of SM were protected by acetylation. The acetylated SM was crystallized from acetone and dissolved in 1,2-dichloroethane. Then Ag2CO3 on Celite and tetra-acetylated galactopyranosyl bromide were added and the mixture was refluxed for 2 h. After cooling, BaO in MeOH was added to remove the acetyl groups. The 1,2-dichloroethane fraction was then extracted three times with equal volumes of water and the water fraction containing the IS was further purified on a C18 flash chromatography column. Traces of unreacted SM were removed by preparative HPLC on an Alltima C18 column (250 mm × 22 mm, particle size 10 μm) with AcCN:water (35:65, 20 ml/min). Detection was at 210 nm (KNAUER, “Smartline” UV detector 2500). The collected IS fraction from the HPLC was completely dried. Mixtures of steviol glycosides (SVglys) containing IS could be purified over SPE cartridges without change of the SVgly over IS ratio. The calibration curves for rebaudioside A (RebA) and stevioside (ST) were linear between 0.012 and 0.95 and between 0.013 and 1.13 mM for RebA and ST, respectively. The accuracy was checked by the standard addition method. It was concluded that the IS method gives an excellent precision and accuracy.

Inspiration of Foreign Innovative Drug Pricing Methods and Medical Insurance Payment Standards to China

Objective To study the innovative drug pricing methods and medical insurance payment standards in foreign countries and to provide reference for China’s government.Methods The official websites were searched for information and related literature,and literature review was used.Results and Conclusion In foreign countries,the clinical value of innovative drugs and their impact on medical insurance funds were comprehensively evaluated based on factors such as quality-adjusted life years,clinical benefit,and improvement of clinical benefit.Then,the evaluation results were taken as an important basis for whether innovative drugs were admitted to the medical insurance catalog and establishing medical insurance payment standards.By using international experience for reference,innovative drug pricing methods and medical insurance payment standards for China’s national conditions can be improved by establishing a basic database of clinical value and drug economic evaluation of innovative drugs,as well as innovative drug payment models based on decision thresholds.

Quantitative Determination of Tetrachlorantraniliprole by(1)^H NMR Spectroscopy with Internal Standard Method

[Objective]This study was to establish a rapid,specific and simple method for quantitative determination of tetrachlorantraniliprole by 1H NMR.[Method]1H NMR spectroscopy was acquired with deuterium DMSO as the solvent and maleic acid as internal standard under the conditions of temperature 25℃,pulses width 8.0μs,delay time 5 s,and scanning times 8.[Result]The hydrogen proton peaks of tetrachlorantraniliprole(δ=10.55)and maleic acid(δ=6.27)were taken as quantitative peaks.The peak area ratio y(As/Ar)and mass ratio x(ms/mr)were linearly regressed,and the correlation coefficient was 0.9999.The RSD value of repeatability test was 0.38%,and the RSD value of stability test was 0.77%.The content of tetrachlorantraniliprole was determined as 99.6%.[Conclusion]1H NMR spectroscopy can be used for quantitative determination of tetrachlorantraniliprole without standard reference,which is rapid,accurate and simple.

LA-ICP-MS Calibrations for Intact Rock Samples with Internal Standard and Modified Constant-Sum Methods

Laser ablation coupled with inductively coupled plasma-mass spectrometry (LA-ICP-MS) calibration was conducted with multiple spot analyses on eleven intact rock samples using both an internal standard (IS) method and a modified constant-sum (MCS) method. Methods were then compared for reported bulk elemental composition of the rocks. The MCS method was based on the sum of eight major elements, which is spatially more stable than one single major ele-ment as used in the IS method, and is quite constant among different rock samples. Calibrations were performed with standard reference materials NIST SRM 610, 612, 614, and 616. Little difference was found between using a single standard and a set of standards, because of the good linearity shown by the reference materials. Comparison of the two calibration methods shows that the MCS method produced better and more stable results than the IS method for heterogeneous samples. With the MCS method, approximately 94% to 95% of the total measurements are within the range of ±100% relative deviation, compared with 82% to 86% with the IS method. The IS method resulted insubstantial overestimations for some rock samples (e.g., 648% for Basalt BCR-2 using NIST SRM 610 as the calibration standard), while the largest deviation with the MCS method was 216% for U in Eagle Ford shale #80 sample. For Quartz latite QLO-1, a relative homogeneous sample, the IS method generated slightly better results than the MCS method. Regardless of method, spatially heterogeneous distribution of elements in the intact rock at the scale of the laser spot is considered to be the main reason for the large relative deviations seen in our work compared to published results.

高效液相色谱内标法测定海水叶绿素a浓度

叶绿素a浓度是海水水质监测和海洋赤潮预警的重要指标,高效液相色谱法作为叶绿素a浓度最准确的测量方法之一被广泛应用。本文选用β-阿朴-8’-胡萝卜素醛(β-Apocarotena-8’-carotenal,Apocarotenal)为内标物,建立了一种基于液相色谱内标法的海水叶绿素a浓度分析方法,在实验检测范围内,方法相关性良好,相关系数为0.9998,检出限为0.05μg/L,回收率为97.0%~100%,相对标准偏差为0.38%~0.55%,精密度良好。同时,利用实验室培养的小球藻藻液和现场海水样品对内标法和外标法进行了显著性差异评估。结果表明:两种方法不存在显著性差异,12组现场海水样品内标法和外标法的测定结果相关性良好,相关系数为0.92,平均相对误差为6.21%。液相色谱内标法测定海水叶绿素a浓度分离效果好、准确度高,能对实验室叶绿素a浓度的测量进行较为准确的质量控制。

基于标准火灾曲线和热释放率的衬砌温度分布数值计算研究

为探明火灾下衬砌温度的分布特性,基于隧道火灾-衬砌辐射对流传热数学模型建立了衬砌温度数值计算方法,并对HC标准火灾曲线和30 MW火灾热释放率火灾工况进行计算分析。结果表明,标准火灾曲线最高温度普遍大于目前我国规范的要求。采用火灾温度作为衬砌壁面边界条件将显著增大衬砌温度荷载,2小时HC火灾曲线和30 MW火灾工况衬砌最高温度分别为778℃和351℃。标准火灾曲线工况衬砌内部的高温影响范围和高温值均显著大于30 MW火灾工况。

一测多评法测定莲芝消炎胶囊中4种二萜内酯

目的:建立一测多评法测定莲芝消炎胶囊中新穿心莲内酯等4种二萜内酯成分的含量。方法:色谱柱为Shimadzu Shim-pack C_(18)(250 mm×4.6 mm,5μm);流动相乙腈-0.1%磷酸水溶液,梯度洗脱;流速1.0 mL•min^(-1);检测波长为203 nm。以穿心莲内酯为参照,计算其他3种二萜内酯成分的相对校正因子,并测定其含量。结果:4种二萜内酯成分在各自范围内线性关系良好(r≥0.9999),平均加样回收率为100.0%~102.8%,RSD为1.1%~2.2%。一测多评法与外标法所得结果接近。结论:该方法快速准确,重复性好,可用于莲芝消炎胶囊的质量控制。

UPLC-FLD法测定全血中原卟啉和锌原卟啉

目的建立全血中原卟啉和锌原卟啉的超高效液相色谱-荧光测定方法。方法全血加入间卟啉Ⅸ-二盐酸盐内标,经纯水稀释后,采用二甲基亚砜-丙酮液液萃取进行净化,经C_(18)色谱柱分离,双通道荧光检测器检测,内标法定量。结果原卟啉和锌原卟啉的线性范围均为0.1~5.0μmol/L,相关系数均为0.9995;方法的检出限分别为0.02μmol/L和0.03μmol/L,定量限分别为0.06μmol/L和0.09μmol/L;原卟啉和锌原卟啉在低、中、高三个浓度加标时,方法的加标回收率分别为85.2%~94.7%和84.8%~92.8%;批内精密度(RSD)分别为2.8%~5.3%和2.7%~6.1%,批间精密度(RSD)分别为3.4%~6.3%和3.2%~7.1%;对30份血样中原卟啉与锌原卟啉检测结果分别为:0.1~0.5μmol/L与0.4~1.2μmol/L。结论本方法适用于全血中的原卟啉和锌原卟啉的同时测定。

微信结合CBL在中医经典住培带教中的应用

目的探讨以微信为载体结合基于案例的学习(Case-based learning,CBL)在中医经典教学中的应用效果。方法于2020年9月—2021年7月,以2019年10月在北京中医药大学各临床医学院参加中医住院医师规范化培训的59名中医内科专业住院医师为研究对象,按随机数字表法分为实验组和对照组,实验组30名,对照组29名。实验组采用微信公众号平台联合CBL教学,对照组采用单纯CBL教学,分别讲解《黄帝内经》《伤寒论》《金匮要略》及《温病条辨》经典条文理解及方药运用,每门课程20学时,比较两组学习效果。结果实验组住院医师中医经典测试成绩显著优于对照组,差异有统计学意义(P<0.05)。两组住院医师对教学模式各方面的满意度差异均具有统计学意义(P<0.05)。结论在中医经典教学中,应用以微信为载体结合CBL的教学法能够提高住院医师综合能力,有助于培养住院医师中医临床思维。

Quantitative Analysis of Fe Content in Iron Ore via External Calibration in Conjunction with Internal Standardization Method Coupled with LIBS

The external calibration in conjunction with internal standardization（ECIS） coupled with laser-induced breakdown spectroscopic（LIBS） technique was proposed to perform the quantitative analysis of Fe content in iron ore The plasma temperature and the electron number density were calculated to prove that the plasma was under local thermodynamic equilibrium（LTE） conditions and to ensure that the integral intensities of Fe I lines were reasonable. In addition, the result of the quantitative analysis shows a content of （20.26±0.59）% by mass of Fe in the iron ore. It was determined by four calibration curves, drawn for four emission lines of Fe I（373.48, 373.71,404.58 and 438.35 nm） normalized by Mn I line, base on the ECIS method which can eliminate the influence of matrix effect and improve the accuracy of quantitative analysis, compared with the standard addition method. Both the results of these two analytical methods were compared with that listed in the Standard Substance Certificate. The percentage content of Fe in the same sample of iron ore by the ECIS method was （20.17±0.08）% by mass, which shows a good performance to analyze the Fe content of iron ore in combination with LIBS.

气相色谱内标法对糟烧白酒中甲醇含量的检测与应用

建立气相色谱内标法,检测糟烧白酒中的甲醇含量,此方法精确度、灵敏度、回收率均良好;对半成品和成品糟烧白酒中的甲醇含量作了比较,发现半成品糟烧白酒中甲醇含量较高,需作进一步的抽样检测,以指导生产,改良工艺。

基于XRD内标法测定LiF-BeF_2熔盐体系中UF_3含量

在氟化物熔盐相直接将UF6中转化为UF_4是熔盐堆燃料盐的合成及重构的候选工艺之一。其中,UF_(3)是该工艺过程的重要中间产物,其含量是开展工艺研究的关键参数之一。本文采用X射线衍射(X-ray Diffraction,XRD)内标法测量氟化物体系中的UF_(3)含量,分析了不同组分的固态熔盐样品,建立了UF_(3)含量的测量分析方法。首先以刚玉(α-Al_(2)O_(3))为内标,获得了UF_(3)在1.00~10.00 wt%含量范围时,LiF-BeF_(2)-UF_(3)熔盐的XRD峰高度内标曲线(R=0.986)和峰面积内标曲线(R=0.995)。然后应用这两条内标曲线测量已知含量的LiUF_(5)和UF_(3)固体混合样品,结果表明峰面积内标曲线具有更好的准确度,测量相对误差不大于8.7%。最后分别对快速冷却的LiF-BeF_(2)-UF_(3)固态熔盐样品和自然冷却的LiF-BeF_(2)-UF_(3)-LiUF_(5)固态熔盐样品进行测量,测量结果的相对误差不大于5.4%。以上结果表明:本文建立的XRD内标法可以用于混合氟盐样品的UF_(3)分析,并具有较好的测量精度和重复性。

基于LIBS-GD联用技术定量检测黄河水中Cu元素

针对目前定量检测液体中重金属元素含量方法存在的缺陷,引入了激光诱导击穿光谱-辉光放电联用(LIBS-GD)技术,并用于黄河水中铜(Cu)元素的检测。通过对不同质量浓度Cu标准溶液的测定,采用内标法建立了Cu的标准曲线,并得出Cu的检出限为0.045 mg/L。实验测量了不同采样点黄河水中Cu的质量浓度,并与火焰原子吸收光谱(AAS)方法进行了对比,结果显示,两种方法的测量结果一致性良好。LIBS-GD联用技术在Cu元素检测方面表现出良好的性能,为水体中重金属元素的检测提供了更简便高效的选择。

Application of internal standard method in recombinant luminescent bacteria test

Mercury and its organic compounds have been of severe concern worldwide due to their damage to the ecosystem and human health. The development of effective and affordable technology to monitor and signal the presence of bioavailable mercury is an urgent need.The Mer gene is a mercury-responsive resistant gene, and a mercury-sensing recombinant luminescent bacterium using the Mer gene was constructed in this study. The mer operon from marine Pseudomonas putida strain SP1 was amplified and fused with prompterless lux CDABE in the p UCD615 plasmid within Escherichia coli cells, resulting in p THE30–E. coli.The recombinant strain showed high sensitivity and specificity. The detection limit of Hg^2＋was 5 nmol/L, and distinct luminescence could be detected in 30 min. Cd^2＋, Cu^2＋, Zn^2＋, Ca^2＋,Pb^2＋, Mg^2＋, Mn^2＋, and Al^3＋did not interfere with the detection over a range of 10-5–1 m M.Application of recombinant luminescent bacteria testing in environmental samples has been a controversial issue： especially for metal-sensing recombinant strains, false negatives caused by high cytotoxicity are one of the most important issues when applying recombinant luminescent bacteria in biomonitoring of heavy metals. In this study, by establishing an internal standard approach, the false negative problem was overcome;furthermore, the method can also help to estimate the suspected mercury concentration,which ensures high detection sensitivity of bioavailable Hg2＋.

六种香精化合物核磁共振法纯度定值

建立了核磁共振氢谱法(1HNMR)测定6种香精化合物(香豆素、香兰素、甲基香兰素、乙基香兰素、麦芽酚、乙基麦芽酚)纯度的定值方法。选择合适的溶剂、内标,通过测定样品的定量信号的纵向弛豫时间(T 1)来计算准确定量所需的理论弛豫时间(D 1),比较样品在不同弛豫时间下测得的实际纯度来对D 1进行优化的数据,实验结果显示两种D 1优化方法结果一致。分析样品中每个合适的定量信号所得到的定值结果并找到定值结果差异的原因。最终6种样品的纯度结果分别为99.79%、99.80%、99.78%、99.82%、99.86%、99.53%,扩展不确定度(k=2)分别为0.16%、0.10%、0.22%、0.18%、0.14%、0.14%。其不仅适用于香豆素等香精化合物的含量测定,在弛豫时间及定量峰的确定方面也适用于其他化合物,以确保更精确的定值。

明渠非标准断面法测流水位流量关系的率定及影响因素分析

为探究明渠非标准断面法测流的水位流量关系曲线的率定问题,以新疆第三师某团场25处渠道量水断面为研究对象,利用FlowTracker 2手持式声学多普勒流速仪进行了水位流量关系率定工作.根据实测结果,率定了各渠道量水断面的水位流量关系曲线,并对所率定出的曲线进行了符号检验、适线检验和偏离数值检验及误差分析,在此基础上,对流量拟合参数的影响因素进行了分析.结果表明:所率定的25处渠道量水断面中,14处具有稳定的水位流量关系,5处受回水影响、6处受渠道淤积影响为不稳定的水位流量关系;在渠道粗糙系数Ra、边坡系数m及坡降i相同的条件下,流量拟合参数与渠道底宽b总体上呈正相关;在渠道粗糙系数Ra、边坡系数m及底宽b相同的条件下,流量拟合参数与渠道坡降i总体上呈负相关.研究结果可以为灌区自动化量水设备测流准确性的校核提供参考依据.

气相色谱-串联质谱法测定火锅底料中邻苯二甲酸酯类塑化剂含量

目的建立气相色谱-串联质谱法(gas chromatography-tandem mass spectrometry,GC-MS/MS)测定火锅底料中邻苯二甲酸酯类塑化剂[邻苯二甲酸二正丁酯(dibutyl phthalate,DBP)和邻苯二甲酸(2-乙基)己酯(di(2-ethylhexyl)phthalate,DEHP)]的分析方法。方法样品加入少量正己烷溶解,经乙腈超声提取,低温离心,取乙腈层浓缩干正己烷定容,通过HP-5MS UI色谱柱(30.0 m×0.25 mm,0.25μm)分离,多反应监测(multiple reaction monitoring,MRM)模式扫描,同位素内标法定量。结果在0~1.00μg/mL质量浓度间,DBP和DEHP线性良好(r>0.999),定量限分别为0.05 mg/kg、0.04 mg/kg,在低、中、高的0.20、0.30、0.50、1.00和2.00 mg/kg5种浓度下的加标回收率均在95.5%~108.1%,相对标准偏差均在0.43%~3.70%,满足相关检测要求。结论本研究在国家标准的基础上优化前处理过程,采用三重四极杆串联质谱法,提升仪器的特异性,建立了一种简单、操作性强且适用于基质复杂的火锅底料的DEHP和DBP塑化剂的定量分析方法,同时发现塑化剂在火锅底料这类油脂类食品中存在明显的污染。

液相色谱—质谱法测定食用盐中的丙烯酰胺

应用液相色谱—质谱法测定食用盐中的丙烯酰胺残留量。将乙腈作为食用盐中丙烯酰胺的提取溶液,用正己烷除脂,取下层清液旋蒸浓缩至近干,加1 mL水复溶,经0.45μm水系滤膜过滤得到待测液。采用液相色谱—质谱的多反应离子监测模式测定,内标法定量。结果显示,丙烯酰胺在5~1000 ng/mL范围内有良好的线性关系,且方法的精密度和回收率符合相关标准要求。该方法操作过程简单,重现性好,可满足实验室日常测定食用盐中丙烯酰胺的任务要求。

紫外标准曲线法测定对乙酰氨基酚片的不确定度评定

采用紫外标准曲线法测定对乙酰氨基酚片含量,评估测定结果的不确定度。通过不确定度来源分析,建立数学模型,量化不确定度分量,计算出测定值的不确定度结果及各分量的贡献率。不确定度的主要来源为系列标准溶液的配制及样品处理过程,其次为紫外仪器和标准工作溶液的配制。当k=2时,按置信区间为95%,对乙酰氨基酚片百分标示量含量测定值为(99.55±2.48)%。不确定度评估可以用于分析和优化紫外标准曲线法测定药品含量的过程,对药品的质量控制和方法改进有重要的指导意义。

顶空-气相色谱法测定南极磷虾油中有机溶剂残留量

目的基于顶空-气相色谱法(headspace-gas chromatography,HS-GC),建立同时测定南极磷虾油中甲醇、丙酮、异丙醇、正己烷和乙酸乙酯5种有机溶剂残留的方法。方法样品溶解于苯甲醇,顶空进样器80℃平衡10 min,有机溶剂经DB-624毛细管色谱柱(60 m×0.32 mm,1.8μm)分离,氢火焰离子化检测器(flame ionization detector,FID)检测。对该方法进行了方法学验证,并实际应用于样品的分析测定。结果HS-GC可以将5种待测溶剂以及内标物很好地进行分离。标准曲线在所考察的浓度范围内线性良好,相关系数为0.9992~1.0000,检出限为0.6~9.0 mg/kg,定量限为1.2~15.0 mg/kg。方法日内精密度和日间精密度良好,在3个不同添加水平下,平均加标回收率为80.5%~105.0%,符合测定需求。结论该方法简单快捷,无需复杂前处理过程,结果可靠,可用于南极磷虾油中有机溶剂残留量的大规模快速检测。