在线固相萃取-离子色谱法测定4种芳环磺酸盐中的硫酸根离子

建立一种在线固相萃取-离子色谱测定4种芳环磺酸盐中硫酸根离子含量的新方法。将自装填的多孔石墨化碳固相萃取柱应用于离子色谱系统,对样品进行在线前处理。样品经过多孔石墨化碳固相萃取柱基体消除后进入收集环,通过阀切换方式使待测硫酸根离子转入阴离子分析柱和检测系统。固相萃取流路用1.5 mmol/L碳酸钠以0.8 mL/min的流速对基体在线富集,进样量为20μL,分析柱为SH-AC-3(250 mm×4.0 mm)+SH-AG-3(50 mm×4.0 mm)色谱柱,柱温为35℃,在6 mmol/L碳酸钠-4 mmol/L碳酸氢钠条件下等度洗脱,流速为0.8 mL/min。结果表明:硫酸根离子在0.50~20.00 mg/L范围内呈良好的线性关系,线性相关系数为0.998 3,保留时间、峰高和峰面积的相对标准偏差均在0.28%~2.86%之间,方法检出限为0.010 6 mg/L,回收率为91.01%~109.3%,具有良好的线性关系和重复性。整个在线分析过程在25 min之内完成。该方法进样量少、快速、高效。     

二维液相色谱法在线检测哈茨木霉发酵液中2460A含量

建立了在线检测哈茨木霉发酵液中微量2460A的二维液相色谱方法。利用Ultimate 3000双三元液相色谱仪,采用阀切换二维色谱技术,组合3根色谱柱实现2460A的在线净化、富集和含量检测。净化柱采用资生堂MF C8柱(10 mm×4.6 mm,5.0μm),富集柱采用资生堂MGC18柱(20 mm×4.6 mm,5.0μm),以水-甲醇为流动相,梯度洗脱,流速2.0 m L/min;二维分析柱采用Thermo Hypersil GOLD C18柱(250 mm×4.6 mm,5.0μm),以水-甲醇为流动相,梯度洗脱,流速1.0 m L/min;进样量1.0 m L;柱温40℃;检测波长424 nm。方法验证结果显示,2460A的线性范围为0.0025~10.0 mg/L(r=0.9981,n=8),检出限为1.2μg/L;定量限为2.5μg/L;方法回收率为88.0%~104.4%。     

离子色谱法测定饱和卤水中痕量碘离子

建立了一种在线样品预处理、脉冲安培检测饱和卤水中痕量I-的离子色谱新方法。进样体积为50μL,选用Cryptand C1浓缩柱富集I-,并用10 mmol/L NaOH洗脱样品中的基体Cl-。用0.5 mmol/L NaOH将I-从浓缩柱转移到保护柱柱端。用IonPac AS20阴离子交换柱,25 mmol/L NaOH淋洗分离,结合脉冲安培银工作电极检测。I-检出限为0.07μg/L(3倍基线噪音);I-在5~1000μg/L范围内具有良好的线性关系(r=0.9995)。50μg/L的I-溶液连续进样9次,峰高相对标准偏差(RSD)为1.0%。     

全自动在线固相萃取-二维高效液相色谱与质谱联用测定辣椒油中苏丹红

建立了全自动在线固相萃取-二维高效液相色谱与质谱联用快速测定辣椒油中的苏丹红Ⅰ,Ⅱ,Ⅲ,Ⅳ的方法。样品经乙腈和二氯甲烷萃取后,在一维色谱柱(Acclaim PAⅡ,150 mm×3.0 mm×3μm)上分离出苏丹红,通过阀的分段切换,依次富集在SPE柱(Acclaim 120 C18,10 mm×4.6 mm×5μm)上,在线完成净化和萃取富集;再通过阀切换将它们转移至二维色谱流路,在Acclaim 120 C18色谱柱(100 mm×2.1 mm×2.2μm)上分离检测。一维色谱以水-乙腈-甲醇/四氢呋喃(1∶1,V/V)为流动相,进样体积20μL,0.6 mL/min流速梯度洗脱和紫外-可见检测器(λ=254 nm)监测分离状况;二维色谱以水-乙腈-甲酸/乙腈(1∶1000,V/V)为流动相,0.3 mL/min流速梯度洗脱,采用单四极质谱仪,选择离子方式检测。整个分析流程27 min即可完成。4种苏丹红的保留时间的相对标准偏差均小于0.1%,色谱峰面积的相对标准偏差均小于2%(n=7);在0.6～60μg/L范围内峰面积与进样质量浓度的线性相关系数均大于0.9958;加标回收率为50%～97%;方法检出限均小于0.2μg/L(S/N=3)。测定结果令人满意。     

高效阴离子交换-脉冲安培检测同时分析单糖和糖醛酸

建立了高效阴离子交换-脉冲安培检测(HPAE-PAD)同时分离测定8种单糖和2种糖醛酸的分析方法。以CarboPacPA20阴离子交换柱为分离柱,以2mmol/LNaOH溶液将8种单糖从分离柱上洗脱,而后用NaAc(50~200mmol/L)梯度淋洗2种糖醛酸,淋洗液流速为0.5mL/min,总分析时间为30min。在优化的分离测定条件下,8种单糖和2种糖醛酸的检出限为2.5~14.4μg/L(进样体积25μL,峰面积定量)。5mg/L的10种化合物的混合标准溶液连续7次进样,峰面积的相对标准偏差为0.3%~1.5%。用所建立的方法测定了多糖水解液和木材半纤维素水解液中的单糖和糖醛酸含量。     

OPA-FMOC在线柱前衍生化HPLC法测定甘露聚糖肽中氨基酸组成及含量

建立了OPA-FMOC在线柱前衍生化高效液相色谱法测定甘露聚糖肽中氨基酸组成及含量的方法,采用色谱柱为Agilent ZORBAX Eclipse XDB-C18柱(250 mm×4.6 mm,5μm),流动相A为40 mmol/L Na_2HPO_4缓冲溶液(pH 7.8);流动相B为甲醇:乙腈:水(45∶45∶10,V/V/V);梯度洗脱;流速:1.5 m L/min;柱温:40℃;检测波长:338,262 nm。20种氨基酸在53 min内得到较好地分离,各氨基酸在5~500μg/m L范围内线性关系良好,相关系数在0.9941~0.9999之间;平均加标回收率在85.6%~102.6%之间;检出限在0.56~8.33 ng(进样量1μL)范围内。甘露聚糖肽样品中含有16种氨基酸,氨基酸总量平均为3.56%(n=3)。     

在线固相萃取-高效液相色谱法测定水体中的多环芳烃

建立了在线固相萃取-液相色谱测定水体残留的多环芳烃的方法,用于测定自来水中的20种多环芳烃( PAHs)。直接进样1 mL经过过滤的水体样品,其中的被测组分富集在SPE柱( Acclaim PA II,50 mm×4.6 mm,3μm)上,在线完成净化和萃取富集;再通过阀切换将它们转移至分析流路,在Hypersil Green PAH色谱柱(150 mm ×3 mm,3μm)上分离检测。在线固相萃取流路以水和乙腈为流动相,0.4和0.6 mL/min流速梯度富集/萃取和洗脱;分析流路亦以水和乙腈为流动相,0.8 mL/min流速梯度洗脱,采用紫外254 nm检测无荧光效应的苊烯和弱荧光效应的萘,其它的多环芳烃化合物则于不同的荧光检测通道里,在其对应的最大激发/发射波长下灵敏测定。整个分析流程32 min即可完成。20种PAHs的保留时间的相对标准偏差均小于0.2％,色谱峰面积的相对标准偏差均小于1.3％(n=7);在3个浓度数量级范围内峰面积与进样质量浓度的线性相关系数均大于0.9910,0.05μg/L的自来水加标样品的回收率为57％~140％,5μg/L的自来水加标样品的回收率为85％~116％;多数有荧光响应的PAHs的方法检出限均小于0.02μg/L (S/N=3)。     

双抑制在线基体去除-离子色谱法测定电池级碳酸锂中痕量阴离子

建立了一种测定电池级碳酸锂中痕量阴离子的方法。用超纯水超声辅助溶解碳酸锂,采用在线基体去除法去除碳酸锂基体,基体去除过程中,样品首先流入到ADRS600(4 mm)抑制器(抑制电流150 mA,抑制器再生液外接水流速2 mL/min)中,在抑制器内通过离子交换膜作用,碳酸锂中的锂离子与氢离子置换,碳酸锂变成碳酸;然后经过CRD 200(4 mm),碳酸以二氧化碳的形式排出离子色谱系统,从而达到去除碳酸锂基体的目的;最后待分析阴离子被自动富集在IonPac UTAC-LP2浓缩柱(35 mm×3 mm)上,通过阀切换技术将阴离子自动转移到色谱分析系统中。在色谱分析系统中,以IonPac AG18(50 mm×2 mm)为保护柱,IonPac AS18(250 mm×2 mm)为分析柱,柱温箱为30℃, KOH溶液为淋洗液进行梯度洗脱,泵流速0.30 mL/min,抑制器为ADRS600(2 mm),抑制电流25 mA,进样体积为250μL,检测器为电导检测器。结果显示：F^-、Cl^-、NO₂^-、Br     

固相萃取/高效液相色谱法同时测定水中4种直链烷基苯磺酸钠

建立了水中4种直链烷基苯磺酸钠的固相萃取/高效液相色谱的测定方法.样品经高速冷冻离心,用MAX复合阴离子交换小柱净化富集后直接进样.在以乙腈-100 mmol/L乙酸铵(体积比73:27)为流动相,流速1 mL/min,柱温30 ℃,检测波长225 nm,进样体积10 μL的条件下,4种直链烷基苯磺酸钠得到很好的分离....     

高效液相色谱法测定血浆中左亚叶酸钙的含量

建立了测定血浆中左亚叶酸钙含量的RPHPLC方法。采用DiamonsilC18色谱柱(150mm×4.6mm,5μm),乙腈50mmol/L磷酸氢二钾/磷酸二氢钾缓冲溶液(10∶90,V/V,用磷酸调pH至4.0)为流动相,用前经0.45μm的过滤膜,超声脱气,流速为1.0mL/min,紫外检测波长为290nm,柱温为35℃,进样量20μL。该方法最低检出限为0.2ng;线性范围为0.05～10mg/L,方法平均回收率在97.0%以上;日内及日间精密度的相对标准偏差分别小于4%和6%。该方法简单,快速,灵敏度高,重复性好。     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。