离子色谱-质谱联用技术测定污泥样品中的痕量高氯酸盐

建立了离子色谱-质谱联用技术测定活性污泥样品中高氯酸盐的分析方法。以高容量、强亲水性的IonPacAS20(2mm)阴离子交换柱为分析柱,EGC在线产生等浓度KOH为淋洗液,淋洗液经抑制成水后将样品带入质谱检测。ESI-MS-MS以多元反应监测模式监控100.8/84.9、98.8/66.9、100.8/68.9和98.8/82.9离子对,以98.8/82.9离子对的峰面积进行定量。该方法对高氯酸盐的检出限(S/N=3)为0.01μg/L,高氯酸盐在0.05~100μg/L浓度范围内具有良好的线性,线性相关系数r=0.9988。0.2μg/L的标准溶液重复进样9次,高氯酸盐峰面积的相对标准偏差(RSD)为2.3%。运用该方法测定采自不同地区的活性污泥样品中的高氯酸盐,并对样品加标回收,得回收率在88.5%~102.2%之间。     

离子色谱-质谱联用测定牛奶中的高氯酸盐、溴酸盐和碘离子

以离子色谱-质谱联用同时测定了不同品牌牛奶中的高氯酸盐、溴酸盐和碘离子。以高容量、强亲水性IonPac AS20(2 mm)为分析柱,EGC在线产生KOH为淋洗液,串联质谱检测。ESIMS/MS以多元反应监测(MRM)模式分别监控高氯酸盐的m/z100.8/84.9、98.8/82.9离子对,溴酸盐的m/z126.8/110.9、126.8/95.0离子对和碘离子的m/z126.8/127.0离子对,并分别对高氯酸盐、溴酸盐和碘离子以m/z98.8/82.9、126.8/110.9和126.8/127.0离子对的峰面积进行定量。该方法对高氯酸盐、溴酸盐和碘离子的检出限(S/N=3)分别为0.02、0.1和0.5μg/L,线性相关系数分别是0.999(0.05~50μg/L)、0.999(0.5~100μg/L)、0.998(1~1 000μg/L)。高氯酸盐和碘离子的样品加标回收率分别在102%~108%之间和86%~114%之间。     

淋洗液浓度对痕量低分子量脂肪族胺离子色谱分离度的影响

采用阳离子交换柱分离,以甲基磺酸为淋洗液,建立了检测水体中痕量甲胺和二甲胺的离子色谱法,并分析了淋洗液浓度对被测物分离度的影响.结果表明: 当淋洗液浓度为3 mmol/L,流速为1.1 mL/min,应用电导检测时,甲胺和二甲胺在5.0～100 μg/L浓度范围内具有良好的线性,方法检出限分别低至8.29 ng/L(以峰面积定量)和0.69 μg/L(以峰高定量),平均回收率分别为97.2%和91.6%;3个浓度水平样品(10.0,20.0,和100 μg/L)的精密度均低于2.1%.本方法操作简单,检出限低,适用于检测水体中痕量存在的低分子量脂肪族胺.     

抑制型电导检测离子色谱法测定饮用水中高氯酸盐

建立抑制型电导检测离子色谱法测定饮用水中的高氯酸盐。选用IonPac^?AS19色谱柱(250 mm×4 mm)，柱温为30℃，电导池温度为35℃，用40 mmol/L氢氧化钾溶液作为淋洗液，氢氧化钾淋洗液由淋洗液发生器在线产生，淋洗液流量为1.0 mL/min，淋洗方式为等浓度淋洗。采用AERS 500(4 mm)型抑制器，抑制器电流为99 mA，进样体积为500μL，高氯酸盐的色谱峰面积与质量浓度在0.030～0.200 mg/L范围内的线性关系良好，相关系数为0.999 2，方法检出限为0.002 mg/L，定量限为0.010 mg/L。7次重复测定结果的相对标准偏差为2.49%～3.78%，样品加标回收率为90.0%～101%。该方法适用于饮用水中高氯酸盐的检测。     

超高效液相色谱-电喷雾离子源-串联三重四极杆质谱分析饮用水中的高氯酸盐

建立了超高效液相色谱-电喷雾离子源-串联三重四极杆质谱(UPLC-ESI MS/MS)分析饮用水中高氯酸盐的方法.以300Extend-C18为分析柱,10%甲醇水溶液为流动相,ESI MS/MS串联质谱为检测器,以多重反应监测(MRM)模式监测高氯酸盐m/z 99.5→82.9离子对.方法的线性范围为0.2 ～10 μg/L,相关系数为r2=0.999 9,方法检出限为0.15 μg/L,平均加标回收率为82%,相对标准偏差为4.4%.应用UPLC-ESI MS/MS法测定北京市部分城区饮用水中的高氯酸盐,其中5个水样中检出ClO-4,质量浓度为0.040 ～0.262 μg/L,但在安全阈值范围内,不会对居民健康构成威胁.     

离子色谱-串联质谱法检测茶叶中的高氯酸盐

建立了离子色谱-串联质谱检测茶叶中高氯酸盐的分析方法。选用高容量、强亲水性的IonPac AS20阴离子交换柱（2 mm）进行分离,以淋洗液自动发生器在线产生的70 mmol/L氢氧化钾为淋洗液等浓度淋洗,TSQ Quantiva三重四极杆质谱仪作检测器,采用电喷雾电离源负离子（ESI^-）模式、多反应监测（MRM）模式进行分析,内标法定量。结果表明,高氯酸盐在0.02~10.0 μg/L范围内线性关系良好,相关系数（r）为0.9991,定量限为2 μg/kg。运用该方法测定5种茶叶中的高氯酸盐,加标回收率为87.3%~112.2%。该方法具有操作简单、专属性强、灵敏度高等优点,可满足茶叶中高氯酸盐的检测要求。     

离子色谱-等离子体质谱联用测定热泉水样的砷形态

利用阴离子色谱与六极碰撞等离子体质谱联用的方法,在线同时测定水样的4种砷形态(As(Ⅴ),As(Ⅲ),MMA,DMA),并用于实际样品-热泉水中砷形态的测定.使用K2HPO4-KH2PO4为淋洗液等度淋洗,用Hamilton PRP-X100阴离子色谱柱分离,4种砷形态在7 min之内完全分离.调节淋洗液中K2HPO4与KH2PO4的比例可以优化峰的分离.地下水(含热泉水)基质、样品及淋洗液中的Cl-对砷形态的分离测定没有影响,淋洗液中的盐份在样品锥和截取锥上的积累对测定的影响很小.检出限分别为As(Ⅴ) 0.23 μg/L,As(Ⅲ) 0.30 μg/L,MMA 0.26 μg/L,DMA 0.54 μg/L.     

大体积进样离子色谱法测定环境水样中高氯酸根

采用大体积500μL进样离子色谱法,电导检测测定了几种水体中高氯酸盐的含量。分析柱为容量高、亲水性强的以脂肪族碳骨架为基质的阴离子交换柱IonPac AS20,淋洗液在线发生器自动产生35 mmol/LKOH淋洗液,0.25 mL/m in等浓度淋洗。这种新型的以脂肪族碳骨架为基质的阴离子交换柱的采用,极大的削弱了该色谱柱对对氯苯磺酸的保留,完全消除了现行美国EPA高氯酸盐分析方法中高氯酸根与对氯苯磺酸共淋洗的问题。方法对高氯酸根的检出限(S/N=3)为0.5μg/L,高氯酸根浓度在1~1000μg/L范围内具有良好的线性(r=0.9991)。将本方法应用于自来水、河水和雪水样品中高氯酸盐的检测,实际样品的加标回收率在87%~114%之间;1μg/L高氯酸根连续进样9次,色谱峰面积相对标准偏差(RSD)为6.9%。     

气相色谱-质谱法测定动物组织中三种1,2-二苯乙烯类药物的残留量

建立了动物组织中己烯雌酚(DES)、己二烯雌酚(DIS)和己烷雌酚(HS)残留量的气相色谱-质谱分析方法。动物组织样品在碱性条件下用乙酸乙酯提取,经碳酸钠溶液液-液分配净化,再用硅胶柱固相萃取净化,洗脱液均分成两份后经氮气吹干,分别用双三甲基硅基三氟乙酰氨(BSTFA)和七氟丁酸酐(HFBA)衍生,采用选择离子监测模式(SIM)进行测定,外标法定量。检出限为0.30 μg/kg(cis-DES),0.10 μg/kg(trans-DES和HS)和0.15 μg/kg(DIS)。在0.5~4.0 μg/kg添加水平,回收率为73.0%～86.5%,相对标准偏差(RSD)为1.0%～7.2%。衍生物的峰面积与样品浓度在10～1000 μg/L(DES和DIS) 和5～500 μg/L(HS)范围内呈良好的线性关系,线性回归系数大于0.99。     

离子交换色谱法检测离子液体中阴离子

建立了用阴离子交换分离柱、化学抑制模式、电导检测测定系列离子液体中BF-4阴离子及其他杂阴离子(F-、Cl-、Br-)含量的方法,并用于在线监控离子液体合成工艺中阴离子杂质含量.确定淋洗液组成为1.6 mmol/L Na2CO3+3.9 mmol/L NaHCO3,流速为0.6 mL/min.本方法对所测阴离子检出限分别为50 μg/L(F-、Br-)和80 μg/L(BF-4);线性范围在3个数量级以上;r＞0.999;回收率在98%～102%之间.方法用于对离子液体小试工艺样品分析及过程监控时,结果满意,样品的RSD小于2.6%(n＝6).     

Non-freezing water in protein solutions

Differential scanning calorimetric studies of protein solution provided the freezable water content as a function of concentration. Total water content was obtained by vacuum dehydration. The difference between the two gave the non-freezing water content in protein solutions. The values obtained by these techniques were 2–3 times larger than those obtained on the basis of NMR measurements on the same solutions.     

17O-核磁共振法研究不同处理方法对液态水缔合结构的影响

水作为人类重要的生产要素,参与了卷烟生产的多个环节。水在自然条件下以分子簇的形式存在,多种处理方式可以改变水分子团簇的大小。本文以¹⁷O-核磁共振法为水分子团簇的表征手段,以自来水为水源,考察了氢气、远红外辐射陶瓷球、反渗透、磁场四种处理方法对水分子簇的影响。结果表明:四种处理方式均能使一定量水分子由氢键结合态变为自由态,从而使水分子簇变小。不同处理方法对液态水缔合结构的影响大小排序为氢气处理>远红外陶瓷球处理>反渗透处理>磁场处理。同时,对氢气处理效果的时效性进行了考察,随着放置时间增加,部分自由态水分子再次转变为氢键结合态,水分子簇尺寸变大,但三天后仍保留了一定处理效果。本研究表明氢气处理为四种处理方式中最优的水处理方式,具有提升烟草行业生产用水品质的潜在应用价值。     

Supercooled water. Considerations about the system organization of liquid water

Summary Supercooled water shows increasing values in heat capacity, free energy difference (in relation to ice) and compressibility as the temperature is lowered, whereas the density is decreased. After careful consideration of the boundary conditions, as they are required for the preparation of supercooled water, the reorganizations within the liquid were investigated and the changes in differentiations examined. Different groups of water molecules are distinguished, namely those at the interface, around dissolved gas molecules, around hydrophilic solutes and the vast majority of the remaining water molecules. It is emphasized that all of these groups are required for the existence of liquid water. Their continuous interrelations are described by the introduction of hierarchic levels, as they are characteristic for a system organization.The highest hierarchic level is that of the interface, the forces of which regulate and control the exchange of matter and energy both with the environment and within the liquid phase. Subordinated to this level is that of the dissolved gas molecules and their surrounding water molecules. In both of these levels the dynamic aspects are highly developed. Subordinated to this level is that of the hydrophilic solutes and their surrounding water molecules. Their unavoidable presence in liquid water is evidenced by the self-ionization equilibrium. The lowest level is that of all of the other water molecules, which provides some kind of more static boundary conditions for the exercise of the better developed dynamic features of the higher levels.In order to obtain supercooled water, the dynamic features must be improved in the higher hierarchic levels, whereas in the lower levels the more static features should remain as small as possible. The former is achieved by certain cooling modes, by increased surface area, by hydrophobic environment and by increasing gas concentration in the liquid. On the other hand, the concentration of hydrophilic solutes must be minimized (the purity of water enhanced). The metastable state is dynamically better maintained, the better the system organization is developed. The state of supercooled water approaches that of optimal system organization in the temperature range between –20° and –30°C.

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Unterkühltes Wasser. Betrachtungen über die Systemorganisation von flüssigem Wasser

Zusammenfassung In unterkühltem Wasser nehmen die Wärmekapazität, die Differenz der freien Enthalpie in bezug auf Eis und die Kompressibilität mit sinkender Temperatur zu, während die Dichte abnimmt. Unter Berücksichtigung aller Randbedingungen, unter denen Wasser unterkühlbar ist, wurden die Reorganisationen innerhalb der Flüssigkeit untersucht. Die Eigenschaften von Wassermolekülen an der Phasengrenzfläche, in der Umgebung von Gasmolekülen, in der Umgebung hydrophiler Teilchen und der großen Zahl der übrigen Wassermoleküle sind unterschiedlich. Ihre kontinuierlichen Wechselbeziehungen werden durch Einführung hierarchischer Ebenen beschrieben, wie sie für eine Systemorganisation charakteristisch sind.Die höchste hierarchische Ebene ist diejenige der Moleküle an der Phasengrenzfläche, deren Kräfte den Austausch von Materie und Energie sowohl mit der Umgebung als auch innerhalb der flüssigen Phase regulieren und kontrollieren. Dieser Ebene untergeordnet ist diejenige der gelösten Gasmoleküle und der sie umgebenden Wassermoleküle. In diesen beiden Ebenen sind die dynamischen Aspekte hoch entwickelt. Dieser Ebene nachgeordnet ist diejenige der die hydrophilen Bereiche umgebenden Wassermoleküle. Die niedrigste Ebene ist diejenige aller anderen Wassermoleküle, welche eine Art statischer Randbedingungen für die Ausübung der in den höheren Ebenen besser entwickelten dynamischen Aspekte bieten.Um unterkühltes Wasser zu erhalten, müssen in den höheren hierarchischen Ebenen die dynamischen Eigenschaften verbessert werden, während in den unteren hierarchischen Ebenen die Differenziertheit so klein wie möglich bleiben soll. Ersteres wird durch Vergrößerung der Oberfläche, bestimmte Abkühlungsbedingungen, hydrophobe Umgebung und durch zunehmende Konzentration an gelösten Gasen erreicht, letzteres durch Erhöhung der Reinheit (Minimisierung der Konzentration hydrophiler Teilchen). Der metastabile Zustand wird umso besser dynamisch aufrechterhalten, je besser seine Systemorganisation entwickelt ist. Der Zustand des unterkühlten Wassers kommt der optimalen Systemorganisation im Temperaturbereich zwischen –20° und –30°C am nächsten.

     

单笼形水分子簇中心水分子对类型关系

随机产生单笼形水分子簇(H2O)n(n=8~36),经分类统计后发现,在笼形水分子簇中,其1221,1212,2121和2112四类氢键的个数与水分子和氢键总数之间有定量关系,且1212类氢键的个数与2121类的氢键始终相等.如果笼形水分子簇中某一类氢键数已知,则它的其余三类氢键的个数也随即确定.     

气相色谱法测定饮用水及其源水中灭草松和2,4-滴

采用气相色谱ECD检测器同时分离检测水中灭草松和2,4-滴两种农药.水样中灭草松和2,4-滴在酸性条件下经乙酸乙酯萃取,然后用碘甲烷溶液酯化,生成较易挥发的甲基酯类衍生物,用毛细管气相色谱-电子捕获检测器分离测定.对衍生方式、温度和时间进行了优化,分别使用ECD和FPD检测器测定灭草松,而ECD检测灵敏度高.本法的最低检测质量浓度为灭草松0.15 μg/L,2,4-滴0.050 μg/L.方法灵敏度和精密度均满足分析要求.     

Stability of low levels of perchlorate in drinking water and natural water samples

Perchlorate ion (ClO₄⁻) is an environmental contaminant of growing concern due to its potential human health effects, impact on aquatic and land animals, and widespread occurrence throughout the United States. The determination of perchlorate cannot normally be carried out in the field. As such, water samples for perchlorate analysis are often shipped to a central laboratory, where they may be stored for a significant period before analysis. The stability of perchlorate ion in various types of commonly encountered water samples has not been generally examined—the effect of such storage is thus not known. In the present study, the long-term stability of perchlorate ion in deionized water, tap water, ground water, and surface water was examined. Sample sets containing approximately 1000, 100, 1.0, and 0.5 μg l⁻¹ perchlorate ion in deionized water and also in local tap water were formulated. These samples were analyzed by ion chromatography for perchlorate ion concentration against freshly prepared standards every 24 h for the first 7 days, biweekly for the next 4 weeks, and periodically after that for a total of 400 or 610 days for the two lowest concentrations and a total of 428 or 638 days for the high concentrations. Ground and surface water samples containing perchlorate were collected, held and analyzed for perchlorate concentration periodically over at least 360 days. All samples except for the surface water samples were found to be stable for the duration of the study, allowing for holding times of at least 300 days for ground water samples and at least 90 days for surface water samples.     

Study of water solubilized in AOT/n-decane/water microemulsions

The state of water in AOT-n-decane-water microemulsions has been studied by using Fourier Transform Infrared spectroscopy (FT-IR). The existence of three kinds of water, which correspond to water populations with different degrees of organization, has been observed. Densities of these microemulsions have been measured. From these studies (FT-IR and densities), the apparent molar volumes of the different types of water molecules have been estimated. These apparent molar volumes, as well as their variations with respect to the composition of the microemulsion, depend on the type of water. The volume of the water bound to the ionic heads of the surfactant is lower than that for bulk water and shows a slight dependence on the molar ratio W. In contrast, no dependence on W is found for the volume of water trapped between the tails of the surfactant.     

Determination of freezable water content of beef semimembranous muscle DSC study

The freezable water contents of samples obtained from previously chilled semimembranous muscle of middle-aged beef carcasses after a 24 h cooling period a room at in 5±1C were determined by differential scanning calorimetry (DSC) at –5, –10, –15, –20, –30, –40, –50 and –65C. This was accomplished by freezing the samples at the above-mentioned temperatures, followed by thawing to 35C, and measuring the melting peaks of freezable water. The areas of these peaks were determined by using the peak integration method programs through a computer linked to the DSC, and they were then used to determine the latent heat of melting (H _m) in kJ kg^–1 at each freezing temperature. The resultant latent heat of melting per sample was divided by the latent heat for pure water to determine the amount of freezable water present in these samples. This amount of freezable water was divided by the total water content of the meat sample to determine the percentage of freezable water in the sample. The percentage of freezable water was subtracted from 100 to determine the percentage of bound water present in the sample.     

Sorption and transport of water in nylon-6 films

Sorption and transport properties of water through films of Nylon-6 were obtained at 5, 23, and 40°C. Commercially available films were used and a Cahn electrobalance was employed for measuring the water uptake by the polymer samples. Values of the water sorption isotherms are accurately described by the Langmuir/Flory-Huggins dual-mode sorption model. At water activity values below 0.15, the volume fraction of water described by the Langmuir portion of the model was greater than the Flory-Huggins population. Solubility and diffusion coefficients of water, as well as the diffusion activation energy and enthalpy of dissolution of water for Nylon-6, were determined from the sorption experiments. Values obtained support the hypothesis of a bimodal water sorption mode, and the formation of water clusters. © 1994 John Wiley & Sons, Inc.