傅里叶红外光谱法分析密胺餐具、脲醛餐具及其表面涂层

采用衰减全反射ATR傅里叶红外光谱法分析密胺餐具、脲醛餐具及其表面涂层。利用功能团的位置及强度区分密胺树脂和脲醛树脂。经3%乙酸浸泡后,密胺树脂红外谱图结构基本无变化,而纯密胺树脂或密胺–脲素混合树脂的红外谱图强度降低,呈现毛刺现象。采用红外光谱仪分析了密胺餐具、脲醛餐具的外涂层,结果显示,涂层的主要成分为高纯度甲醛–三聚氰胺树脂,经3%乙酸多次浸泡后,涂层逐渐被破坏,餐具内部的有毒物质开始溢出。实验表明,ATR傅里叶红外光谱法可以快速区分密胺餐具、脲醛餐具的材质。     

极谱吸附催化波连续测定痕量铅镉

本文研究了在溴化钾乳酸-CTMAB体系中痕量铅、镉催化电流的极谱行为。从底液组成发现了铅、镉均能形成三元络合物,获得灵敏的吸附催化波,从而提高了铅、镉的测定灵敏度,测定下限铅为6 ppb、镉为0.6ppb,试验了多种共存离子的影响。方法用于高纯锌中痕量铅、镉的测定,其结果与标准值一致.     

ICP-AES法同时测定搪瓷餐具中铅镉锑镍的溶出量

采用ICP-AES法同时测定搪瓷餐具中铅、镉、锑、镍的溶出量,并对ICP-AES法测定乙酸（4％）浸泡液时分析线的选择,入射功率、护套气流量、载气压力的影响,以及基体和共存离子的干扰等进行研究。方法简便快速,回收率为100．8-104．0%,相对标准偏差为0．66％～1．75％。     

分离富集-原子吸收光谱法测定锌锰电池中铅和镉

对用原子吸收光谱法测定锌锰电池中铅和镉结果的可靠性进行了研究。对于典型的4R25电池,试液中主要成分锌和锰总量超过40 g.L-1,直接用普通稀释法得不到准确的结果。采用CL-7301萃淋树脂微色谱柱将电池试液中铅和镉与基体快速分离,用火焰原子吸收光谱法测定铅和镉,当铅和镉的含量较高时,可以将样品预稀释后采用在线稀释技术直接测定铅和镉。     

阻抑动力学光度法同时测定痕量铅和镉

基于氨水溶液介质中,痕量镉和铅阻抑过氧化氢氧化偶氮胂Ⅰ褪色的作用,建立了动力学光度法同时测定痕量铅和镉的新方法。方法测定铅、镉的线性范围分别为0.005~0.50μg/mL和0.002~0.80μg/mL。用于实际样品中铅、镉同时测定。     

二乙胺荒酸钠–四氯化碳萃取连续光源原子吸收法测定磷酸一二钙中的痕量铅、镉

建立连续光源原子吸收分光光度法同时测定磷酸一二钙(MDCP)中铅、镉的方法。MDCP经盐酸消解后,以氢氧化钠溶液调节p H为11,加入KCN作为掩蔽剂,用二乙氨荒酸钠–四氯化碳络合铅、镉离子,再经CCl_4进一步萃取浓缩,采用连续光源原子吸收分光光度法测定铅、镉的含量。该方法铅、镉的检出限为1,0.5 mg/kg;用于不同批次MDCP产品测定,铅、镉测定结果的相对标准偏差分别为3.58%,6.91%(n=11);铅、镉的加标回收率分别为88.9%~104.7%,91.0%~106.4%。该法可用于MDCP中痕量铅、镉的同时测定。     

微量铅,镉极谱法连续测定

１　引　言铅镉催化极谱单项测定均已有报道，但对于微量铅镉连续测定尚未得到很好的解决。作者在实验中发现Ｗ．Ｃｈｒｉｓｍａｎｎ提出的仅用于测定铅的Ｐｂ－ＫＩ－Ｖ（Ⅳ）－Ｖｃ－ＨＡｃ体系中，用于铅镉连续测定，则镉波太小，只能查见。当加入少量ＯＰ试剂，可使镉波大幅度增高，同时加入少量吡啶，更有利于铅镉波形稳定，并且底液有适宜乙醇，可以抑制底液波及残余电流，提高铅铜的检出限，从而很好地解决了微量铅、锅的连续测定问题。本文建立了连续测定的适宜条件，详细研究了共存离子的干扰情况。该法具有简便、快速、灵敏度高、…     

示波极谱法同时测定尿中铅和镉

研究示波极谱法同时测定尿中铅和镉的方法.运用正交试验选择底液的组成为碘化钾-抗坏血酸-浓盐酸-磷酸.用硝酸、高氯酸、盐酸混合酸消化尿样,消化液在酸性介质中,置极谱仪的三电极系统,样品溶液在滴汞电极上产生还原电流,分别于-480 mV和-620 mV处测量铅和镉的峰电流,对尿样中铅和镉进行测定,铅、镉的质量浓度在100 μg·L-1以内与峰电流呈线性关系.铅、镉的相对标准偏差分别为6.91%,6.45%,检出限(3S/N)分别为2.0,1.0 μg·L-1,回收率分别为88.4%～101.4%,83.1%～103.5%.     

电感耦合等离子体发射光谱(ICP－OES)法测定聚碳酸酯中重金属铅、镉、汞、铬

采用微波消解法对聚碳酸酯(PC)样品进行前处理,使用电感耦合等离子体发射光谱(ICPOES)法测定聚碳酸酯中重金属铅、镉、汞、铬元素,通过对消解方式和消解试剂的研究,建立了ICP-OES法测定聚碳酸酯中重金属铅、镉、汞、铬元素的方法。结果表明,铅、镉、汞、铬加标回收率均在94.0%～105%,相对标准偏差(RSD)均小于4%,样品处理时间短,测定速度快,污染小,环保,有较高的加标回收率和精密度,适用于聚碳酸酯中重金属铅、镉、汞、铬的测定。     

巯基棉分离富集-电感耦合等离子体原子发射光谱法(ICP-AES)测定高盐体系中痕量的铅、镉

采用巯基棉富集分离,电感耦合等离子体原子发射光谱法(ICP-AES)测定了高盐水样中痕量的铅、镉。研究表明,pH值为7时,巯基棉同时富集铅、镉的效果最好,可成功分离基体元素,以盐酸(1.5mol/L)溶液洗脱,铅、镉的加标回收率在95.0%~105.0%,相对标准偏差RSD为3.8%~9.7%。     

密胺餐具中三聚氰胺的迁移规律

密胺餐具样品用乙酸溶液浸泡后,采用高效液相色谱法测定其中三聚氰胺的迁移量。考察了浸泡液的种类、浸泡温度、浸泡时间、样品尺寸、浸泡次数等参数对三聚氰胺迁移量的影响。试验结果表明:三聚氰胺的迁移量随溶液酸性、浸泡温度、浸泡时间的增加及样品尺寸的减小而增大;随浸泡次数的增多,每次浸出量递减。     

Determination of Melamine in Dairy Products and Melamine Tableware by Inhibition Electrochemiluminescent Method

An electrochemiluminescent (ECL) method has been developed for the determination of melamine based on the inhibition of luminol ECL. A significant luminol ECL can be found at 1.47 V in the phosphate buffer solution at high pHs and low potential scan rates, this ECL signal can be inhibited obviously by melamine. The decrease of ECL intensity was linearly proportional to the logarithm of melamine concentration in the range of 1–100 ng/mL (R²=0.9911) and with the detection limit of 0.1 ng/mL. The method has been applied successfully to determine melamine in dairy products and melamine tableware, the recoveries were in the range of 98.5%–103.7% and 95.5%–106.0%, respectively. The mechanism of the inhibition effect was also proposed, the active oxygen (O₂^{· −}) generated from the electrooxidation of OH⁻ reacted with luminol anion (L^{· −}) to generate light emission, and the present of melamine can eliminate the active oxygen, which cause the decrease of the ECL intensity.     

Hydrogen-bonding recognition-induced aggregation of gold nanoparticles for the determination of the migration of melamine monomers using dynamic light scattering

The migration of melamine monomers from food contact materials has aroused particular attention since the 2008 melamine-tainted milk scandal in China. However, the determination of melamine monomer’s migratory quantity (MMMQ) has remained an open question because of the complex sample pretreatment and the low sensitivity. Based on the hydrogen bonding interaction between DNA thymine and melamine, this paper described a simple and rapid method focusing on the measurement of MMMQ from melamine tableware by gold nanoparticles (GNPs) and dynamic light scattering (DLS). With the presence of probe DNA (p-DNA), the GNPs were stable in NaCl solution (0.06 M), whereas they became aggregated when the p-DNA hybridized with melamine. The change in the hydrodynamic diameter of GNPs could be detected by DLS technology. Under the optimal conditions, the average diameter increased linearly with the concentration of melamine over the range from 5.0 to 320.0 μg L⁻¹, and showed a detection limit of 2.0 μg  L⁻¹ (3σ/slope). The MMMQ was investigated within a range from 6.00 × 10⁻⁴ to 2.58 × 10⁻¹ mg dm⁻² (n ≥ 3) in four different food simulants at different temperatures and time points. The results suggest that the DLS method has great potential in the analysis of the migration of melamine monomers.     

“浙八味”药材中重金属铅、镉、铜含量分析

为对"浙八味"药材质量控制和安全用药提供可靠的依据,采用灰化法处理样品,火焰原子吸收分光光度法测定了其铅、镉、铜含量。结果表明,8种药材中的铅含量为0.828 1~1.747 3 mg.kg-1,镉含量为0.116 9~0.295 0mg.kg-1,铜含量为2.519 5~8.286 4 mg.kg-1。8种药材均检出一定量的有害重金属,但含量较低,未超出国家限量标准,符合《药用植物及制剂进出口绿色行业标准》的有关规定。     

UPLC-MRM法测定饲料中的三聚氰胺

提出了一种UPLC-MRM测定饲料中微量三聚氰胺的分析方法. 饲料经10 g/L三氯乙酸溶液提取和22 g/L乙酸铅溶液沉淀蛋白质, 过混合型阳离子交换柱(MCX)纯化, 离心后用0.45 μm滤膜过滤, 用超高效液相色谱-质谱-质谱联用仪(UPLC-MS-MS)分析测定, 以三聚氰胺母离子126.9 (m/z)和子离子67.5与84.6 (m/z)定性、定量目标物. 饲料样品加标回收率(n=6)为84.5%, 检测限0.01 μg/L, 相对偏差(RSD) 6.5%.     

Synthesis of magnetic polyphosphazene-Ag composite particles as surface enhanced Raman spectroscopy substrates for the detection of melamine

Magnetic polyphosphazene(MPZS) particles coated by Ag nanoparticles(MPZS-Ag) have been developed as surface enhanced Raman spectroscopy(SERS) substrates for sensitive detection of melamine in aqueous solutions and milk samples.5,5'-Dithiobis-(2-nitrobenzoic acid)(DTNB) was used as model analyte to test the SERS activity of the MPZS-Ag particles.The prepared MPZS-Ag particles possess both magnetic responsiveness and excellent SERS properties.SERS detection of different concentrations of melamine aqueous solutions and spiked milk samples were performed by the MPZS-Ag particles.The limit of detection(LOD) of the melamine in aqueous solutions was 10-7 mol/L(0.0126 mg/L) and 0.6 mg/L in real milk samples using the MPZS-Ag particles as SERS substrates.The LOD of the melamine are much lower than the safety values of Food and Drug Administration and Codex Alimentarius Commission.These results indicate that the MPZS-Ag particles have promising application prospect for SERS analysis in food safety fields.     

Rapid coprecipitation-separation and flame atomic absorption spectrometric determination of lead and cadmium in water with cobalt (II) and ammonium pyrrolidine dithiocarbamate

A coprecipitation technique which does not require complete collection of the precipitate was proposed for the determination of trace lead and cadmium in water with flame atomic absorption spectrometry (FAAS) after preconcentration of lead and cadmium by using cobalt (II) and ammonium pyrrolidine dithiocarbamate (Co-APDC) as coprecipitant and known amount of cobalt as an internal standard. Since lead, cadmium and cobalt were well distributed in the homogeneous precipitate, the concentration ratio of lead to cobalt, and cadmium to cobalt remained unchanged in any part of the precipitate. The amount of lead and cadmium in the original sample solution can be calculated respectively from the ratio of the absorbance values of lead and cadmium to cobalt in the final sample solution that is measured by FAAS and the known amount of the lead and cadmium in the standard series solutions. The optimum pH range for quantitative coprecipitation of lead and cadmium is from 3.0 to 4.5. The 16 diverse ions tested gave no significant interferences in the lead and cadmium determination. Under optimised conditions, lead ranging from 0 to 40?µg and cadmium ranging from 0 to 8?µg were quantitatively coprecipitated with Co-APDC from 100?mL sample solution (pH?～?3.5). This coprecipitation technique coupled with FAAS was applied to the determination of lead and cadmium in water samples with satisfactory results (recoveries in the range of 94.0–108%, relative standard deviations <6.0%).     

Electrochemical Detection of Trace Concentrations of Cadmium and Lead with a Boron‐Doped Diamond Electrode: Effect of KCl and KNO3 Electrolytes,Interferences and Measurement in River Water

Parts‐per‐billion levels of cadmium and lead were detected using square‐wave anodic stripping voltammetry with a boron‐doped diamond electrode. Calibration plots (10‐minute deposition time) in KCl and KNO₃ were non‐linear at low concentrations (1–5 ppb) due to the deposition mechanism of these metals. The preferred electrolyte for cadmium was KCl, while lead could be measured in either electrolyte. The lowest concentrations included in the linear portion of the calibration plot (5 minute deposition time) for cadmium were 10 ppb and 50 ppb in KCl and KNO₃, respectively, and 10 ppb for lead in KNO₃. The presence of either lead or copper suppressed the cadmium stripping peak, but the lead stripping peak was unaffected by cadmium, and enhanced by the addition of copper. A river water sample was analyzed for cadmium and lead, and the cadmium results were confirmed using ICP‐AES spectrometry. It was determined electrochemically that a fraction of lead in the river sample was bound by complexing material in the sample.     

螯合树脂在线富集火焰原子吸收法测定痕量铅和镉

在pH=4.88的乙酸-乙酸钠缓冲溶液中,用螯合离子交换树脂富集铅和镉,以1.50mol/L HNO3作洗脱液,火焰原子吸收法测定洗脱液中痕量铅和镉。该方法对铅和镉的线性范围分别是4.0～80.0μg/L和2.0～30.0μg/L,检出限分别为1.3μg/L和0.7μg/L。该方法用于地表水中痕量铅和镉的测定,分析结果满意。     

气相色谱-质谱法测定鸡蛋中三聚氰胺

建立了气相色谱-质谱法测定鸡蛋中三聚氰胺的方法. 鸡蛋样品经三氯乙酸提取,乙酸铅沉淀蛋白后,过MCX阳离子交换固相萃取小柱除去样品基质干扰,用N,O-双三甲基硅基三氟乙酰胺(BSTFA)+三甲基氯硅烷(TMCS)(99+1)衍生,进行气相色谱-质谱分析. 在0.010~2.00 mg/L浓度范围内,线性关系良好(r=0.9996),检出限为0.01 mg/kg. 方法回收率为90.1%~94.7%,RSD为1.7%~5.3%. 方法准确、灵敏,适用于鸡蛋中三聚氰胺的检测.