氢化可的松纯度标准物质的研制

介绍纯度标准物质氢化可的松的研制方法.采用高效液相色谱法对该标准物质进行了定值及均匀性、稳定性检验.该标准物质定值结果为99.5%,扩展不确定度为0.2%,其均匀性和稳定性检验结果表明,该标准物质符合国家一级标准物质的技术要求.     

液相色谱-同位素稀释质谱法测定婴幼儿配方奶粉中黄曲霉毒素M1

建立液相色谱–同位素稀释质谱法测定婴幼儿配方奶粉中黄曲霉毒素M_1基体标准物质研制的定值方法。采用单点逼近法,以~(13) C_(17)–AFTM_1为内标,乙腈为溶剂,经免疫亲和柱净化,采用单点逼近法测定婴幼儿配方奶粉中黄曲霉毒素M_1的含量。黄曲霉毒素M_1的质量浓度在0.05～5.0 ng/mL范围内与色谱峰面积线性关系良好,线性相关系数为0.999 3,平均回收率为102.0%。该方法稳定性好,操作简单,可以作为婴幼儿配方奶粉中黄曲霉毒素M1基体标准物质研制的定值方法。     

丙酮中除虫脲溶液标准物质研制

采用重量-容量法制备丙酮中除虫脲溶液标准物质。准确称量国家二级标准物质除虫脲溶解到色谱纯丙酮中,通过A级容量瓶定容至500 mL,摇匀后分装到2 mL安瓿瓶内共460瓶,每瓶为1 mL,保持低温迅速封口,配制过程中室温保持在(20±2)℃。采用液相色谱法进行均匀性、稳定性检验和定值结果验证。从样品中随机抽取16瓶进行均匀性检验,经F检验表明,在95%的置信区间范围内该标准物质均匀性良好;采用t检验对标准物质稳定性进行检验,标准物质在12月内稳定性良好。对该标准物质的不确定度进行了评定,研制的丙酮中除虫脲溶液标准物质定值结果为100μg/mL,相对扩展不确定度为2%(k=2)。结果表明,该标准物质均匀性与稳定性良好,量值准确,可用于日常分析检测中的方法评价和仪器校准。     

低温封接玻璃成分分析标准物质的研制

研制了低温封接玻璃成分分析标准物质,对标准物质的制备技术进行了研究。分别用F检验和t检验法对研制的标准物质进行了均匀性和稳定性检验,结果表明,研制的低温封接玻璃标准物质具有良好的均匀性和稳定性。采用6家实验室进行协作定值,对定值结果的不确定度进行了评定。各组分定值结果的相对扩展不确定度均小于5%(k=2)。     

空气中偏二甲肼气体标准物质的研制

采用称量法制备空气中偏二甲肼气体标准物质,分别用F检验和回归曲线法对研制的标准物质进行均匀性和稳定性检验。结果表明,研制的空气中偏二甲肼气体标准物质具有良好的均匀性和稳定性,定值结果分别为10,500μmol/mol,定值结果的相对扩展不确定度为2%(k=2)。该标准物质可用于偏二甲肼报警器的检定或校准。     

电力变压器油中溶解气体分析用标准物质的研制

采用称量法制备了电力变压器油中溶解气体分析用气体标准物质,分别用F检验和回归曲线法对研制的标准物质进行了均匀性和稳定性检验。结果表明,研制的电力变压器油中溶解气体分析用标准物质具有良好的均匀性和稳定性,标准物质定值结果为5 000μmol/mol,定值结果的相对扩展不确定度为1%(k=2)。该标准物质可用于电力部门变压器油中溶解气体的分析及测试。     

激光玻璃成分分析标准物质的研制

采用高温熔融方法制备了激光玻璃成分分析标准物质。对该标准物质的均匀性、稳电性进行了检验。结果表明,研制的标准物质具有良好的均匀性和稳定性。采用6家实验室进行协作定值,各组分：芑值结果的相对扩展不确定度均小于5％（k=2）。     

血液中乙醇含量检测用标准物质的研制

制备8种不同浓度的血液中乙醇含量检测用水中乙醇标准物质。采用重量–容量法配制水中乙醇溶液标准物质,以配制值作为定值结果。采用气相色谱法对标准样品进行了均匀性和稳定性检验,并对定值结果进行验证。对定值结果的不确定度进行了评估。结果表明,水中乙醇标准物质的均匀性和稳定性良好,可稳定12个月。该系列标准物质已获批为国家二级标准物质,编号为GBW(E) 083145～GBW(E) 083152。     

液相色谱仪检定用甲醇中胆固醇标准物质的研制

采用重量–容量法制备了液相色谱检定用200μg/m L的甲醇中胆固醇标准物质,分别用F检验和回归曲线法对研制的标准物质进行了均匀性和稳定性检验,对定值结果的不确定度进行了评定。结果表明,研制的甲醇中胆固醇标准物质具有良好的均匀性和稳定性,定值结果的相对扩展不确定度为2%(k=2)。该标准物质可用于液相色谱仪示差折光检测器、蒸发光散射检测器的检定。     

甲基对硫磷溶液标准物质的研制

采用重量–容量法研制了1.00 ng/μL甲基对硫磷农药标准物质,对研制的甲醇中甲基对硫磷溶液标准物质量值进行了均匀性和稳定性检验,对定值结果的不确定度进行了评定。结果表明,该标准物质均匀性良好,在一年内量值没有显著性变化,具有良好的稳定性,定值结果的相对扩展不确定度为3%(k=2)。该标准物质可用于农药残留测量结果的准确性评价。     

Immunoaffinity column cleanup with liquid chromatography for determination of aflatoxin M1 in liquid milk: collaborative study

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatographic method for determination of aflatoxin M1 in milk at proposed European regulatory limits. The test portion of liquid milk was centrifuged, filtered, and applied to an immunoaffinity column. The column was washed with water, and aflatoxin was eluted with pure acetonitrile. Aflatoxin M1 was separated by reversed-phase liquid chromatography (LC) with fluorescence detection. Frozen liquid milk samples both naturally contaminated with aflatoxin M1 and blank samples for spiking, were sent to 12 collaborators in 12 different European countries. Test portions of samples were spiked at 0.05 ng aflatoxin M1 per mL. After removal of 2 noncompliant sets of results, the mean recovery of aflatoxin M1 was 74%. Based on results for spiked samples (blind pairs at 1 level) and naturally contaminated samples (blind pairs at 3 levels) the relative standard deviation for repeatability (RSDr) ranged from 8 to 18%. The relative standard deviation for reproducibility (RSDR) ranged from 21 to 31%. The method showed acceptable within- and between-laboratory precision data for liquid milk, as evidenced by HORRAT values at the low level of aflatoxin M1 contamination.     

Determination of Aflatoxin M1 in Milk by a Magnetic Nanoparticle-Based Fluorescent Immunoassay

A sensitive and rapid magnetic nanoparticle-based fluorescent immunoassay for the determination of aflatoxin M1 in raw milk was developed. Aflatoxin M1 was converted to aflatoxin M1-o-carboxymethyl oxime. The aflatoxin M1-oxime was used for the preparation of aflatoxin M1-oxime-fluoresceinamine conjugate through the carbodiimide reaction. The aflatoxin M1-oxime-fluoresceinamine conjugate was characterized by ultraviolet–visible and infrared spectroscopy. Magnetic nanoparticles (Fe₃O₄) were synthesized and modified by 3-(aminopropyl)triethoxysilane. The size of initial (139?nm) and functionalized magnetic nanoparticles (147?nm) was determined by particle analysis. The optimal mass of immobilized antibody (25?µg) and optimal concentration of aflatoxin M1-oxime-fluoresceinamine conjugate (15?µg?mL^?1) for magnetic nanoparticle-based fluorescent immunoassay were determined. The developed immunoassay provided a linear aflatoxin M1 concentration range from 3.0 to 100?pg?mL^?1 in bovine milk. The detection limit was 2.9?pg?mL^?1. The results of aflatoxin M1 magnetic nanoparticle-based fluorescent immunoassay in heat-treated milk and phosphate-buffered saline at pH 6.6 were compared. The influence of the somatic cell count, pH, and fat concentration in bovine milk on the aflatoxin M1 immunoassay was investigated. The influence of the milk species on the immunoassay was also characterized. The high fat concentration ovine milk depressed the sensitivity of the aflatoxin M1 immunoassay.     

氮中磷化氢气体标准物质的制备

用称量法配制磷化氢气体标准物质,以配制值作为标准值,研制出浓度为10~4 000μmol/mol的氮中磷化氢气体标准物质,其量值相对扩展不确定度U_(rel)=2%(k=2),其均匀性满足FF_α,稳定性满足|b_1|t_(0.95,n-2)·s(b_1)。试验测试和应用结果表明,该标准物质量值准确可靠,均匀性、稳定性和不确定度符合项目任务书的要求,可用于磷化氢气体报警器的检定、校准以及环境监测和化工企业等领域的质量控制、方法确认。     

High-performance liquid chromatography with post-column derivatisation and fluorescence detection for sensitive determination of aflatoxin M1 in milk and cheese

A new HPLC method with fluorescence detection using pyridinium hydrobromide perbromide as a post-column derivatising agent has been developed to determine aflatoxin M1 in milk and cheese. The detection limits were 1 ng/kg for milk and 5 ng/kg for cheese. The calibration curve was linear from 0.001 to 0.1 ng injected. The method includes a preliminary C18-SPE clean-up and the average recoveries of Aflatoxin M1 from milk and cheese, spiked at levels of 25-75 ng/kg and 100-300 ng/kg, respectively, were 90 and 76%; the precision (RSDr) ranged from 1.7 to 2.6% for milk and from 3.5 to 6.5% for cheese. The method is rapid, easily automatable and therefore useful for accurate and precise screening of aflatoxin M1 in milk and cheese.     

Molecular Recognition of Aflatoxin M1 in Water and Milk Samples

Two stochastic microsensors based on diamond paste modified with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) were proposed for the molecular recognition of aflatoxin M1 in water and milk samples. Two types of diamond were used: a monocrystalline diamond powder (1 μm) (DP) and a nanopowder of monocrystalline diamond (10 nm) (nDP) for the design of the stochastic microsensors. The microsensors were incorporated as combined stochastic microsensors (a microcell containing the stochastic microsensor and the Pt wire, and a Ag/AgCl sensor) in a platform used for monitoring of waste waters and milk samples. The platforms were used for the fast screening of water and milk samples for the qualitative and quantitative analysis of aflatoxin M1 at very low concentration levels (up to 0.001 fg/L). The linear concentration ranges were wide, being able to cover concentrations between 0.001 fg/L to 20 μg/L. The highest sensitive microsensor (sensitivity of 4.74×10¹⁰ s mg^?1 L) was the one based on nDP. The results provided by the platforms were in agreement with those obtained by utilization of standard method (ISO certified methods (HPLC/fluorescence method)), recoveries being higher than 99.00 % and RSD lower than 1.00 % proving that the method can be reliable used for molecular recognition of aflatoxin M1 in water and milk samples.     

Testing the suitability of different high-performance liquid chromatographic methods to determine aflatoxin M1 in a soft fresh Italian cheese

Aflatoxin M1 (AFM1) is a toxic undesirable compound in milk. AFM1 affinity for caseins causes a concentration effect during milk process for dairy transformation. In spite of this, no official method of analysis, nor maximum tolerance level for aflatoxin M1 in cheese have been established. Thus, the aim of this work was to test the suitability of different HPLC methods for the AFM1 quantification in soft cheese samples at three different contamination levels (low, medium and high, at respectively nearly 30, 100 and 250 ng/kg). Nine participants were selected among Italian laboratories accredited by the Italian accreditation body (ACCREDIA) for HPLC toxin analysis. They were asked to analyze samples applying the method routinely used. The different applied methods were compared, and precision and accuracy parameters were evaluated. The main differences among HPLC procedures were registered at the level of extraction step. The use of an enzymatic digestion for the extraction of the toxin from cheese seemed to be particularly advantageous and the use of immunoaffinity columns seemed to be determinant for the improvement of sensitivity at low contamination levels. In general, the applied methods well discriminated the 3 levels of contamination, even though they performed better at the medium and high concentration levels (100 and 250 ng/kg) than at the low one (30 ng/kg). In fact relative standard deviation for reproducibility at low level was higher (60.1%) than the same value at medium and high levels (22.8% and 28.9%, respectively).     

磷酸三(2-氯乙基)酯标准物质的研制

研制了有机磷阻燃剂磷酸三(2-氯乙基)酯(TCEP)标准物质。采用硅胶柱层析法对TCEP原料进行纯化,得到纯度大于99%的TCEP纯品。通过红外光谱和气相色谱–质谱准确定性分析后,利用气相色谱法和气相色谱–质谱法结合热重分析法分别对TCEP纯物质进行纯度定值。将制备的50 g TCEP纯品分装到100个小瓶中,每瓶0.5g,从中随机选取10瓶,进行均匀性和稳定性实验,结果表明,研制的TCEP标准物质均匀性良好,在半年内是稳定的。研制的有机磷阻燃剂磷酸三(2-氯乙基)酯标准物质的纯度定值为99.56%,扩展不确定度为1.18%(k=2)。研制的磷酸三(2-氯乙基)酯标准物质满足国家二级标准物质标准的要求。     

Determination of aflatoxin B1 in baby food (infant formula) by immunoaffinity column cleanup liquid chromatography with postcolumn bromination: collaborative study

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for determination of aflatoxin B, in a milk powder based infant formula at a possible future European regulatory limit (0.1 ng/g). The test portion was extracted with methanol-water (8 + 2 [v + v]), filtered, diluted with water, and applied to an immunoaffinity column. The column was washed with water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. The separation and determination of the aflatoxin B1 was performed by reversed-phase LC and detected by fluorescence after postcolumn derivatization (PCD) involving bromination. PCD was achieved with either pyridinum hydrobromide perbromide (PBPB) or an electrochemical (Kobra) cell by addition of bromide to the mobile phase. The baby food (infant formula) test samples, both spiked and naturally contaminated with aflatoxin B1, were sent to 14 laboratories in 13 different European countries. Test portions were spiked at levels of 0.1 and 0.2 ng/g for aflatoxin B1. Recoveries ranged from 101 to 92%. Based on results for spiked test samples (blind pairs at 2 levels) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 3.5 to 14%. The relative standard deviation for reproducibility (RSDR) ranged from 9 to 23%. Nine participants used PBPB derivatization, and     

氮中丙烯腈气体标准物质的研制

以高纯丙烯腈和高纯氮气为原料,采用称量法配制氮中丙烯腈气体标准物质。对配制的气体标准物质分别进行机械混匀试验、压力均匀性和时间稳定性试验。经F检验,2.00μmol/mol及5.00μmol/mol两种浓度的样品在0.5~10 MPa范围内标准值无显著变化,具有较好的压力均匀性;在–20℃和40℃条件下保存7 d,其量值无显著变化,可满足运输环节量值稳定;在常温下贮存9个月量值无显著变化,表明其稳定性良好,满足国家二级标准物质对有效期的要求。对定值结果的不确定度进行评定。配制的氮中丙烯腈气体标准物质标准值为(2~5)×10~(–6)mol/mol,相对扩展不确定度为9%(k=2)。该标准物质达到国家二级标准物质的相关技术要求,可用于对丙烯腈气体报警器的校准。