基于标准差传递规律的手机比色法测定亚甲基蓝溶液

采用基于误差传递规律的手机比色法测定亚甲基蓝溶液,根据颜色三原色值RGB与灰度值Gr之间的关系,通过标准差传递公式的运算,从理论上证实了间接测量法的可行性。分析了不同光照环境对采集照片质量的影响,将3款不同型号的手机作为采样工具进行对比。结果表明,间接测量法的精密度显著提高,3款手机图片颜色的间接测量值XR、XG、XB与亚甲基蓝质量浓度C之间的变化趋势一致,其中XB与质量浓度C成正比,据此建立了亚甲基蓝质量浓度测定的新方法。该方法对样品测定的相对标准偏差为2.7%~4.8%,加标回收率为91.3%~101%,其稳定性、精密度和准确度均符合测定需求。     

基于智能手机的数字图像比色法快速测定水中氨氮

建立基于智能手机与自制比色装置的数字图像比色法完成对水中氨氮的快速测定。以水杨酸钠为显色剂，三聚氰酸二氯钠为氧化剂，亚硝基铁氰化钠为催化剂，在碱性条件下与水中氨氮反应生成蓝色化合物，通过正交试验对反应条件进行优化。通过自制数字图像比色装置对显色溶液进行手机拍照分析，将经过色彩选择器（color picker）软件获得的RGB值和空白值基础上计算得出的欧氏距离D值应用于图片比色，对氨氮进行定量测定。氨氮质量浓度在0.05～2.0 mg/L与D值呈线性关系，相关系数（r）为0.998，检出限为0.03 mg/L，测定下限为0.12 mg/L。以空白水样为基体进行加标回收试验，氨氮回收率为98.7%～106.0%，测定结果的相对标准偏差为1.1%～7.4%(n=6)。实际样品该法分析结果与分光光度法基本一致。该方法可用于水样中氨氮的现场快速测定。     

卷烟主流烟气pH值测定方法的研究

本实验提出了一种测定每一口主流烟气pH值的新方法。实验以10%PEG-20000/0.1 M氯化钠水溶液在pH复合电极表面形成吸收液膜作为反应介质,以氮气作为载体,与抽吸的主流烟气一起进入测量室,可溶性气体则溶解在吸收液膜中并引起pH复合电极的信号变化,从而测得每一口烟气的pH值。该方法成功测定了5种成品卷烟每一口主流烟气的pH值,相对标准偏差小于2%,操作简便,适用于测定卷烟每一口主流烟气pH值,结果令人满意。     

ICP-OES同时测定矿泉水界限指标中的4种元素

矿泉水界限指标中的四种矿物质元素锌、锂、锶、偏硅酸(以H₂SiO₃计),国标方法需每种元素分别测定且步骤繁琐,本实验采用ICP-OES对矿泉水中这4种元素的含量进行同时测定,四种元素的检出限在0.01~0.10 mg/L,对市售矿泉水进行了检测,加标回收率在83 %~100 %,相对标准偏差为0.31 %~1.96 %,方法简便省时,精密度和准确度较高,可以作为一种鉴别矿泉水品质的方法。     

毛细管电泳-电致化学发光联用技术检测烟草中尼古丁含量

建立了毛细管电泳-电致化学发光联用技术(CE-ECL)检测烟草浸出液中尼古丁含量的方法。考察了检测电位、检测池中Ru(bpy)32+浓度和缓冲液pH值、CE运行缓冲液浓度和pH值、进样时间和电压,以及CE分离电压等实验条件对尼古丁测定的影响。在优化的条件下,尼古丁检测的线性范围为低浓度段:1～100μg/L(r>0.999)、高浓度段:100～1500μg/L(r>0.996),检出限为0.5μg/L(S/N=3)。将本方法用于3种品牌的烟草浸出液中尼古丁含量的测量,测定值均与烟盒上尼古丁的标注值相吻合,样品的加标回收率为95%～106%。     

快速测铝试剂盒的研制

对目视比色法快速测定水中微量Al3+进行了研究,并在此基础上研制出了适用于现场快速检测微量Al3+的试剂盒。对不同实验条件进行了优化。实验结果表明,Al3+、铬天青S(CAS)和十六烷基三甲基溴化铵(CTAB)在pH=5.5的缓冲体系中形成稳定的蓝色三元配合物,其颜色深浅与Al3+含量呈正比,目视极易区分。所研制的试剂盒使用方便,只需加入两种试剂,在室温下显色20min后,通过与标准色阶对照即可得出水中Al3+的含量。方法测定范围是0.01～0.50mg·mL-1,测定结果与国标法及电感耦合等离子体原子发射光谱法(ICP-AES)对照无显著性差异,回收率在87.5%～116.7%之间。     

尼龙6纳米纤维膜固相膜萃取-高效液相色谱法测定塑料瓶装矿泉水中双酚A

采用静电纺丝法制备尼龙6纳米纤维膜,结合固相膜萃取-高效液相色谱法测定了矿泉水中的双酚A。对洗脱溶剂及其体积、进样速度、样品体积、样品pH值、尼龙6纳米纤维膜的用量、及其活化方式和使用次数等影响因素进行了研究。结果表明:10mL样品调至pH8.0后,以3mL/min流速通过1.5mg尼龙6纳米纤维膜,300μL甲醇即可将膜上吸附的双酚A完全洗脱,每张膜至少可重复使用6次。在此最优化条件下,方法的线性范围为0.20～20.0μg/L;检出限为0.15μg/L,膜内和膜间的相对标准偏差均小于4.5%(n=6)。本方法应用于6种不同品牌的矿泉水中双酚A的分析测定,在1.0μg/L加标水平下,测得回收率为95.0%,双酚A测得浓度低于0.30μg/L。与固相萃取方法相比,本方法高效、环保,表明尼龙6纳米纤维膜是极具潜力的萃取介质     

整体柱离子相互作用色谱快速分析无机阴离子

研究了用硅胶整体柱和直接电导检测的离子相互作用色谱快速分析常见无机阴离子的方法。实验采用氢氧化四丁铵和邻苯二甲酸为淋洗液,讨论了包括淋洗液浓度、流速和pH对分离的影响。当以1.5 mmol/L氢氧化四丁铵和1.1 mmol/L邻苯二甲酸为淋洗液(pH 5.5),流速6 mL/min时,可以在1 min内分离Cl-、NO2-、Br-、NO3-、ClO3-、SO42-和I-7种阴离子。方法的检出限为0.3~1.9 mg/L,峰面积、峰高的相对标准偏差(RSD,n=5)分别为0.4%~2.2%和0.1%~1.5%。将该法用于测定矿泉水和地下水中的阴离子,加标回收率在97.9%~100.3%之间。     

手机成像数码比色法测定水样中6价铬

设计了利用手机成像数码比色法测定水样中6价铬的实验,水样中6价铬经二苯碳酰二肼显色后用手机拍摄溶液图像,用Photoshop软件读取图像中显色液绿色通道的亮度值,该亮度值与溶液中铬的质量浓度呈线性关系,从而计算样品中6价铬的含量,对拍摄方式和图像读取方式进行了讨论。样品测定结果与分光光度法一致,加标回收率在98.0%~102.0%之间。该方法不使用专业仪器设备,简便、快速、准确,可实现现场检测。由于只使用学生自带的智能手机为检测设备,可极大地激发学生的实验兴趣和创新、探索精神。     

Top-down法评定EDTA络合滴定法测定海洋沉积物中碳酸钙含量的不确定度

依据Top-down技术中的质控图法对EDTA络合滴定法测定海洋沉积物中碳酸钙含量的不确定度进行评定。利用2021年质控样标准物质GBW 07333、GBW 07314和GBW 07316中CaCO₃测定值的时序数据进行评定,3组时序数据正态统计量A^2*(s)和独立性统计量A^2*(R_M)均小于1,CaCO₃测定值、A_EWMi和移动极差控制图没有失控点,3组时序数据处于受控状态。当CaCO₃质量分数分别为2.05%、6.20%和38.56%时,计算得其扩展不确定度分别为0.08%、0.07%和0.20%。将测量不确定度与对应含量值进行线性拟合建立了不确定度预测模型,GBW 07309和GBW 07334中CaCO₃的测量不确定度预测值分别为0.09%和0.18%,预测值与Top-down技术获取的评定结果较为吻合。     

图像RGB数值衍生的欧氏距离用于手机比色法检测石油类物质

利用手机建立了一套石油类物质浓度的检测系统,将基于RGB值和空白值计算得出的欧氏距离D值应用于图片比色,提高了方法的精密度。分析了不同性能的手机在高照度下的检测效果,结果说明大光圈值(F)手机拍摄得到的图片比色效果更好。考察了不同白平衡模式和光源对D值标准曲线的影响,获得了适宜的条件,即对于偏暖色系的浓度检测,色温2 800 K的白平衡模式和300 W碘钨灯有较好的效果。该方法的线性相关系数在适宜条件下大于0.99,测试范围与分光光度法相当;测定标准样品的相对误差为2.13%,相对标准偏差为3.0%,加标回收率为92.0%～105%。该方法准确方便,成本低,易维护,可实现远程自动化的实时在线检测。     

基于智能手机定量测定蛋白质的方法研究

利用智能手机完成了蛋白质浓度的检测,确定了用于图像比色的参数,方法适用于有颜色反应的分析物浓度检测。利用该法检测的相关系数大于0. 99,检出限为0. 21 g/L。考察了不同品牌手机的检测效果,结果表明,检测效果与手机硬件的配置无明显关联。考察了该方法的重复性,对单个样本检测时,3种质量浓度样本的相对标准偏差(RSD)分别为2. 0%、4. 6%、11. 9%;对4个样本进行同时检测,RSD分别为2. 2%、3. 8%、3. 5%、11. 5%。考察了亮度、色温、拍摄距离的影响,结果显示,亮度与色温对检测结果无影响,而拍摄距离有影响。手机APP与分光光度计对样本检测结果的相关系数(r2)为0. 969。该方法准确、重复性高、便携、操作方便,可实现多种分析物实时现场的快速检测。     

Validation of a new measuring system for water turbidity field measurements

Turbidity is an essential parameter for describing water quality by direct and indirect impacts on fish, invertebrates and aquatic plants. Currently, environmental monitoring measurements are carried out with appropriate quality by accredited testing laboratories, but there is also a need for employing the third sector, i.e. citizens and voluntaries in environmental monitoring. A device called “Secchi3000” was developed as a low-cost and simple-to-operate tool so that water quality measurements can also be carried out by non-experts and citizens. The measurement using the new device is simple: The user fills the container with water and places the measurement structure in the container. The user takes a photograph with the camera on a mobile phone through a hole in the lid. The software sends the photograph to a server, which analyses the photographs automatically. Finally, the results are returned to the user’s mobile phone and stored on a database for further analysis. In this study, the measuring system for turbidity measurements in natural waters was validated. Validation included an estimation of the limit of quantification, investigations of the influence of water colour and illumination conditions on turbidity measurement values and the estimation of measurement uncertainty. A comparison of turbidity results obtained with the new device and laboratory instrument in natural water samples was carried out, and turbidity values obtained with different mobile phones were compared. According to the validation results, the new device was appropriate for the measurement of turbidity lower than 7 FNU (Formazine Nephelometric Unit). An algorithm applied for present turbidity calculations is not fully suitable for higher turbidities. For potential routine use, this is not a major problem, since most Finnish natural waters have turbidities lower than 7 FNU. For official monitoring purposes, the limit of the quantification needs to be lower than presently achieved (1.7 FNU). Although the present configuration of the Secchi3000 device is not yet fully suitable for official environmental monitoring, it will already enable the involvement of the third sector in water quality monitoring, and in this way, citizens’ observations could then serve at least as supplementary information for reporting and surveys.     

Retention of ionizable compounds on HPLC. 6. pH measurements with the glass electrode in methanol-water mixtures

The relationship, delta values, between the two rigorous pH scales, S(S)pH (pH measured in a methanol-water mixture and referred to the same mixture as standard state) and S(W)pH (pH measured in a methanol-water mixture but referred to water as standard state), in several methanol-water mixtures was determined (delta = S(W)pH-S(S)pH). Delta values were measured using a combined glass electrode and a wide set of buffer solutions. The results are consistent with those obtained with the hydrogen electrode. This confirms the aptness of the glass electrode to achieve rigorous pH measurements in methanol-water mixtures. An equation that relates delta and composition of methanol-water mixtures, and allows delta computation at any composition by interpolation, is proposed. Therefore, S(S)pH can be achieved from the experimental S(W)pH value and delta at any mobile phase composition. S(S)pH (or S(W)pH) values are related to the chromatographic retention of ionizable compounds through their thermodynamic acid-base constants in the methanol-water mixture used as mobile phase. These relationships were tested for the retention variation of several acids and bases with the pH of the mobile phase. Therefore, the optimization of the mobile phase acidity for any analyte can be easily reached avoiding the disturbances observed when W(W)pH is used.     

Ion transfer of bromophenol blue across liquid-liquid interfaces

The ion transfer of the acidic dye bromophenol blue (BPB) at the interfaces of water/nitrobenzene (W/NB), water/1,2-dichloroethane (W/1,2-DCE) and water/(nitrobenzene+chlorobenzene) (W/(NB +CB)) was studied in detail by cyclic voltammetry (CV), chronopotentiometry with linear current scanning (CLC), controlled potential electrolysis and UV spectroscopic methods. Using controlled potential electrolysis, we observed successfully the transfer process of BPB across the W/NB interface from the colour changes of BPB in two different phases. The proposed transfer mechanism for BPB is proved to be reasonable using UV spectroscopy of the product of the electrolysis. The standard potential differences Δ^o_w^o and the standard Gibbs energies of the BPB transfer from water to some organic solvents were calculated. The dissociation constants of BPB obtained were quite close to the literature values.     

A Simple Primary Amide for the Selective Recovery of Gold from Secondary Resources

Waste electrical and electronic equipment (WEEE) such as mobile phones contains a plethora of metals of which gold is by far the most valuable. Herein a simple primary amide is described that achieves the selective separation of gold from a mixture of metals typically found in mobile phones by extraction into toluene from an aqueous HCl solution; unlike current processes, reverse phase transfer is achieved simply using water. Phase transfer occurs by dynamic assembly of protonated and neutral amides with [AuCl₄]^? ions through hydrogen bonding in the organic phase, as shown by EXAFS, mass spectrometry measurements, and computational calculations, and supported by distribution coefficient analysis. The fundamental chemical understanding gained herein should be integral to the development of metal‐recovery processes, in particular through the use of dynamic assembly processes to build complexity from simplicity.     

Speciation of As(III), As(V), MMA and DMA in contaminated soil extracts by HPLC-ICP/MS

A method to separate and quantify two inorganic arsenic species As(III) and As(V) and two organic arsenic species, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), by HPLC-ICP/MS has been developed. The separation of arsenic species was achieved on the anionic exchange column IonPac AS11 (Dionex) with NaOH as mobile phase. The technique was successfully applied to analyze extracts of two contaminated soils, sampled at a former tannery site (soil 1) and a former paint production site (soil 2). The soils were extracted at pH values similar to the natural environment. Extractions were performed at different pH values with 0.3 M ammonium oxalate (pH = 3), milli-Q water (pH = 5.8), 0.3 M sodium carbonate (pH = 8) and 0.3 M sodium bicarbonate (pH = 11). No organically bound arsenic was found in the extracts. As(V) was the major component. Only up to 0.04% of the total arsenic contained in soil 1 were mobilized. The highest amount of extracted arsenic was found at the highest pH. In the milli-Q water extract of soil 1 As(III) and As(V) were found. High amounts of As(V) were found in the extracts of soil 2. Up to 20% of the total arsenic bound to soil 2 constituents were released. The results show that the mobilization of arsenic depended on the pH value of the extraction solution and the kind of extracted soil. Dramatic consequences have to be expected for pH changes in the environment especially in cases where soils contain high amounts of mobile arsenic.     

A high-sensitivity LC-MS/MS method for the determination of 4-methyl-piperazine-1-carbodithioc acid 3-cyano-3, 3-diphenylpropyl ester hydrochloride in rat plasma and its application to a pharmacokinetics study

4‐Methyl‐piperazine‐1‐carbodithioc acid 3‐cyano‐3, 3‐diphenylpropyl ester hydrochloride (TM208), a newly synthesized anticancer compound, was quantified using liquid chromatography–tandem mass spectrometry (LC‐MS/MS) for the first time. A simple, rapid and sensitive assay method using propranolol as internal standard (IS) after one‐step precipitation with acetonitrile was developed and validated to determine TM208 in rat plasma. Separation was achieved on a reverse‐phase C₁₈ column with a mobile phase composed of methanol–water (pH4.0) containing 5 m m ammonium acetate in gradient elution mode. A triple quadrupole tandem mass spectrometer with electrospray ionization source was used as detector and operated by multiple reaction monitoring in the positive ion mode. Calibration curves were linear (r > 0.99) between 0.2 and 500 ng/mL. The quantitative limit was 0.2 ng/mL; reliable precision and accuracy were validated by relative standard deviation values in the range 3.44–13.15% and relative error values between ?0.58 and ?9.78%. The method was successfully applied to preclinical pharmacokinetic studies of TM208. Copyright © 2011 John Wiley & Sons, Ltd.     

Speciation of As(III), As(V), MMA and DMA in contaminated soil extracts by HPLC-ICP/MS

A method to separate and quantify two inorganic arsenic species As(III) and As(V) and two organic arsenic species, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), by HPLC-ICP/MS has been developed. The separation of arsenic species was achieved on the anionic exchange column IonPac^®AS11 (Dionex) with NaOH as mobile phase. The technique was successfully applied to analyze extracts of two contaminated soils, sampled at a former tannery site (soil 1) and a former paint production site (soil 2). The soils were extracted at pH values similar to the natural environment. Extractions were performed at different pH values with 0.3 M ammonium oxalate (pH = 3), milli-Q water (pH = 5.8), 0.3 M sodium carbonate (pH = 8) and 0.3 M sodium bicarbonate (pH = 11). No organically bound arsenic was found in the extracts. As(V) was the major component. Only up to 0.04% of the total arsenic contained in soil 1 were mobilized. The highest amount of extracted arsenic was found at the highest pH. In the milli-Q water extract of soil 1 As(III) and As(V) were found. High amounts of As(V) were found in the extracts of soil 2. Up to 20% of the total arsenic bound to soil 2 constituents were released. The results show that the mobilization of arsenic depended on the pH value of the extraction solution and the kind of extracted soil. Dramatic consequences have to be expected for pH changes in the environment especially in cases where soils contain high amounts of mobile arsenic.