过硫酸钾氧化4-氨基安替比林光度法测定地表水中挥发酚

在 pH 值为10.0±0.2的缓冲溶液中,以过硫酸钾溶液作氧化剂,用经乙醇和正己烷(1+4)混合溶液提纯的4-氨基安替比林(4-AAP)作显色剂,采用三氯甲烷分光光度法测定地表水中挥发酚。结果表明,经乙醇和正己烷(1+4)混合溶液提纯的4-AAP,损失较少,且纯度较高,有利于准确配制4-AAP溶液。此外,稳定、无色的过硫酸钾溶液代替稳定性差、有毒的铁氰化钾溶液作氧化剂,有利于降低空白值,且显色稳定,方法检出限为0.3μg/L,满足标准方法的要求。本方法用于测定地表水中的挥发酚,平均加标回收率为96.0%。     

微波萃取-高效液相色谱法测定橡胶制品中六溴环十二烷

经粉碎的橡胶样品用正己烷及丙酮(1+1)混合溶剂萃取,所得萃取液氮吹至近干后,加正己烷溶解残渣,将溶液经硅胶固相萃取柱净化,吸附于柱上的六溴环十二烷用正己烷-二氯甲烷(1+1)溶液淋洗,洗出液吹氮至近干,用乙腈溶解并用高效液相色谱法测定。选用Zorbax EclipseXDB-C18色谱柱作固定相,用水-乙腈(15+85)溶液作流动相,紫外检测器测定波长为210nm。方法的检出限(3S/N)为1.5mg.kg-1。方法用于橡胶制品中六溴环十二烷的测定,回收率和测定值的相对标准偏差(n=7)分别在83.1%～94.3%和3.6%～6.4%之间。     

碘作氧化剂分光光度法测定水中的挥发酚

研究了以碘作氧化剂、4-氨基安替比林(4-AAP)分光光度法测定水中的挥发酚,方法的检出限为1μg/L,线性范围为2~24 g/L,相关系数为0.9995。条件优化后,方法的精密度为3.5%,加标回收率为91.3%~118.0%,方法的精密度和准确度均符合要求。     

气相色谱法测定茶叶中拟除虫菊酯及硫丹类杀虫剂残留量

应用气相色谱法对茶叶中拟除虫菊酯及硫丹类杀虫剂残留量作快速测定.用正己烷-丙酮(1+1)混合溶剂提取样品中的杀虫剂,残渣用正己烷-乙酸乙酯(1+1)混合溶剂溶解.此溶液先后经凝胶渗透色谱和固相萃取法进行纯化,固相萃取系ENVI-Carb柱和氟罗里硅土固相萃取柱连续净化.以正己烷-乙酸乙酯(1+1)混合溶液将杀虫剂从柱上洗脱,所得洗脱液在40℃蒸干,用正己烷溶解残渣,将此溶液引入气相色谱仪测定,测定采用电化学检测器并用外标法定量.共测定了茶叶样品中7种拟除虫菊酯和3种硫丹类杀虫剂,所得响应信号值与杀虫剂浓度在0.01～0.10 mg·kg-1范围呈线性关系,方法的检出限(3S/N)为0.01 mg·kg-1,方法的回收率在87.4%～91.9%之间,测定值的相对标准偏差(n=10)小于7%.     

高效液相色谱法测定橡胶及其制品中16种多环芳烃

经粉碎的橡胶样品用正已烷及丙酮(1+1)的混合溶剂萃取,所得萃取液蒸至近干后加入正己烷2 mL溶解残渣,将溶液经硅胶固相萃取柱分离并净化,吸附于柱上的多环芳烃用由正己烷及二氯甲烷(3+2)组成的淋洗液解吸,洗出液蒸至近干加入一定量的内标溶液使之溶解并用高效液相色谱法测定.选用LC-PAH色谱柱作固定相,用乙腈和水以不同比例混合的溶液作为流动相进行梯度淋洗,紫外检测器的测定波长为210 nm,以苝-d12作为内标进行定量测定,在优化的试验条件下16种多环芳烃可有效分离并测定.研究结果表明:16种多环芳烃的检出限(3S/N)、平均回收率及测定值的相对标准偏差(n=7)依次在0.05～0.10 mg·L-1,65.1%～101.7%及1.8%～7.3%之间.     

气相色谱法测定烟气中拟除虫菊酯杀虫剂在卷烟滤嘴中的残留量

用符合ISO 30008标准要求的吸烟机按标准条件抽吸卷烟样品,抽吸完毕后,取下滤嘴,用乙酸乙酯-环己烷(1+1)混合溶剂超声提取30min。将提取液经无水硫酸钠干燥后旋转蒸至近干,残渣溶于正己烷2mL中,所得溶液经石墨炭黑小柱进行净化。小柱用丙酮-正己烷(2+8)混合溶剂淋洗2次,收集洗脱液,旋转蒸发浓缩后,将溶液用上述混合溶剂定容至1.5mL,供气相色谱分析,采用Agilent HP-5色谱柱进行分离和电子捕集检测。测定了4种拟除虫菊酯,相对标准偏差(n=5)均小于6%,于20个滤嘴样品中加入相当于20μg的4种拟除虫菊酯混合标准溶液,回收率均大于92%。     

高效液相色谱法测定人血浆中的维生素D_3及25-OH-D_3

采用高效液相色谱法测定血浆中维生素D_3和25-OH-D_3的含量。样品经乙醇-乙腈(60+40)混合溶液提取后,提取液用氮气吹干,残渣用正己烷溶解后,过Waters silica固相萃取柱净化,净化液用氮气吹干后,将残余物溶于pH 6.5的5mmol·L-1磷酸盐溶液-乙腈-甲醇(30+15+55)缓冲溶液中。待测物在Symmetry C18色谱柱上分离,以pH 6.5的乙腈-5mmol·L~(-1)磷酸盐(20+80)混合液为流动相A,以甲醇-乙腈-四氢呋喃(65+20+15)混合液为流动相B,进行梯度洗脱;采用光电二极管阵列检测器,检测波长为265nm。维生素D_3和25-OH-D_3的线性范围均为3.0~72μg·L~(-1),检出限均为2.0μg·L~(-1)。加标回收率在88.5%~94.1%之间,测定值的相对标准偏差(n=6)小于4%。     

气相色谱-质谱法测定塑料制品中多环芳烃

将正己烷-二氯甲烷(2+1)混合溶剂加入于塑料样品中,在水浴中于室温下超声萃取30 min,所得溶液在控温30℃的水浴中用旋转蒸发浓缩至2 mL,并将此溶液通过硅胶柱净化分离.先用正己烷淋洗硅胶柱以洗去非极性的正构烷烃,然后以正己烷-二氯甲烷(3+2)混合溶剂淋洗,所得洗脱液先经旋转蒸发浓缩至2 mL,再用氮气吹拂浓缩至恰为1.0 mL,此溶液供气相色谱-质谱分析之用,对相应的分析条件也作了详述.由于采用了先旋转蒸发后氮气吹拂的浓缩方法,不仅使蒸发时间缩短,而且减少了低沸点多环芳烃(PAH)的挥发损失.按所提出的方法测定了塑料中16种PAH,方法的检出限(3S/N)小于0.01 mg·kg-1.选用一种含PAH甚少的塑料样品作为基体,加入3个浓度水平含16种PAH的混合标准溶液按方法操作进行回收试验,测得回收率在87.2%～100.2%之间,测定值的相对标准偏差(n=7)在1.3%～5.8%之间.     

高效液相色谱法测定果汁和果蔬中柑橘红2号染料

应用高效液相色谱法测定果汁、果蔬中柑橘红2号染料的含量。样品用丙酮-正己烷(1+3)混合溶剂提取,提取液于45℃蒸发至干。用甲酸-乙腈(0.5+99.5)溶液(经正己烷饱和)溶解残渣,正己烷脱脂。以Agilent TC C18色谱柱为分离柱,以乙腈与甲酸(0.1+99.9)溶液按体积比92比8混合作为流动相,用二极管阵列检测器在波长508 nm处进行测定。柑橘红2号染料的质量浓度在0.25~10.0 mg·L-1范围内与其峰面积呈线性关系,测定下限(10S/N)为0.1 mg·kg-1。以果汁、鲜橙和胡萝卜样品为基体,加入3种不同浓度水平的柑橘红2号标准溶液做回收试验,测得回收率在96.3%~104.0%之间,相对标准偏差(n=6)在1.0%~3.6%之间。     

高效液相色谱法同时测定那格列奈中顺式异构体和L-异构体

称取样品25mg,用正己烷-无水乙醇-三氟乙酸(80+20+0.1)混合溶液溶解并定容至25mL,采用Chiralpak IG色谱柱(250mm×4.6mm,5μm)分离待测物,以正己烷-无水乙醇-三氟乙酸(80+20+0.1)混合溶液为流动相,流量为0.8 mL·min~(-1),采用二极管阵列检测器进行测定,检测波长为210nm。那格列奈的顺式异构体和L-异构体的质量浓度分别在0.024~4.392,0.050~4.040mg·L~(-1)内与其峰面积呈线性关系,检出限(3S/N)分别为0.008,0.015mg·L~(-1)。加标回收率分别在94.1%~99.3%,100%~104%之间,测定值的相对标准偏差(n=6)小于5.0%。     

A New Extraction Spectrophotometric Method for the Determination of Phenol in Water

The product of the reaction among phenol, sodium nitroprusside and hydroxylamine hydrochloride in an alkaline solution can be extracted by chloroform in the presence of cetylpyridinium bromide(CPB), on the basis of which a new extraction spectrophotometric method for the determination of phenol in water is developed. The optimum determination wavelength is 720 nm. The molar absorptivity is 1.05×105 mol-1·L·cm-1 and the detection limit is 4.0 μg/L. For 30.0 and 60.0 μg/L standard solutions, the relative standard deviations are 4.5% and 2.2%, respectively(n=6). F values of the statistical analysis show that there is no notable difference between the proposed method and 4-AAP method. The results of the standard addition method for the natural water samples are satisfactory.     

Study of the behaviour of various phenolic compounds in the 4-aminoantipyrine and ultraviolet-ratio spectrophotometric methods without and with distillation

It is customary in industrial analysis in the determination of phenols by the 4-aminoantipyrine (4-AAP) and ultraviolet-ratio spectrophotometric methods to report the total of phenolic compounds as phenol. A study was therefore made of the behaviour of 36 representative phenolic compounds in the 4-AAP and UV-ratio methods, with and without distillation, to ascertain the apparent recoveries relative to that for phenol. The Fisher phenol analyser was used for the UV-ratio method, which depends upon the bathochromic shift (from about 270 to about 290 nm) usually obtained when the solution of the phenol is made alkaline. The apparent recoveries by the 4-AAP method both with and without distillation varied from 0 to 100%. The apparent recoveries by the UV-ratio method without distillation varied from 0 to 148%, and those with distillation varied from 0 to 110%. Sixteen of the compounds tested without distillation gave less than 10% recovery by the 4-AAP method and eleven gave less than 10% recovery by the UV-ratio method. The results after distillation indicated that several of the compounds did not distil completely.     

Effect of acidity and alkalinity on the distillation of phenol: interferences of aromatic amines and formaldehyde with the 4-aminoantipyrine spectro-photometric method for phenol

As determined by the 4-aminoantipyrine (4-AAP) spectrophotometric method, the distillation of phenol is quantitative over the range from about pH 6 to very strongly acidic solutions. Recovery from alkaline solutions decreases with increasing alkalinity. Aromatic amines can interfere with the 4-AAP method by producing colors. The extent of the interference varies markedly with different aromatic amines and is much greater for the extraction method than the direct method. The interference can be considerably reduced by distillation from a strongly acidic solution (10 ml of concentrated sulfuric acid per 500 ml); for large amounts of aromatic amines, double distillation may be necessary. Formaldehyde can interfere by reacting with phenol and repressing the color development. This interference can be eliminated by treatment with ammonium sulfate and sodium hydroxide to form hexamethylenetetramine, followed by acidification and distillation.     

Reversed flow injection spectrophotometric determination of trace amount of ammonia in natural water by oxidation of ammonia to nitrite

A new sensitive flow injection method for determination of ammonia in natural water samples have been developed, based on the oxidation of ammonia to nitrite by hypochlorite in the presence of large amount of potassium bromide. The oxidant solution obtained by on-line mixing of hypochlorite and potassium bromide was injected into a water carrier stream, and then mixed with sample stream. Ammonia in the sample solution was oxidized to nitrite. Nitrite was then determined by spectrophotometry with sulfanilamide and N-1-naphthylethylenediamine. By reversed injection of the oxidant solution, the interference of nitrite and turbidity of the sample can be removed. The linear range of the method for ammonia is 0.2-12 muM. The proposed method is simple and sensitive. It had been applied to the determination of ammonia in lake water samples. Recoveries of 95-104% were obtained.     

Trace level determination of low-molecular-weight alcohols in aqueous samples based on alkyl nitrite formation and gas chromatography.

A simple and sensitive method for the determination of liquid methanol and ethanol at trace levels by an alkyl nitrite formation reaction has been established. Alcohol was allowed to react with nitrous acid, which was yielded from sulfuric acid and sodium nitrite in the solution, to form the corresponding alkyl nitrite in the hexane organic phase. Alkyl nitrites in hexane were analyzed by a gas chromatograph with an electron capture detector (GC-ECD). The detection limits, which were determined at a signal-to-noise ratio of 3, were 1.1 and 0.7 micrograms/L for methanol and ethanol, respectively, by 1 microL injection. The relative standard deviations for n = 8 were 4.0 and 3.3% for methanol and ethanol, respectively. The method was applied to determine the alcohol concentration in a rice paddy, pond water, tap water, and well water. Those aqueous samples were also spiked with standard alcohols; the average recoveries of spiked methanol and ethanol were 98 and 91% with relative standard deviations of 6.1 and 4.0%, respectively.     

4-乙烯基吡啶与丙烯酰胺共聚合的研究

以过硫酸钾为引发剂 ,采用溶液自由基共聚合方法 ,实现了丙烯酰胺 (AM)与 4 乙烯基吡啶 (4 VP)的共聚合 .通过详细研究共溶剂体系、单体总浓度、反应温度、反应时间及引发剂量对共聚合过程中转化率和分子量的影响 ,从而确定了适宜的共溶剂体系和最佳的工艺条件 .用紫外分光光度法测得了共聚物的组成 .用Kelen Tudos方法 ,求得 4 乙烯基吡啶 (4 VP)和丙烯酰胺 (AM)单体的竞聚率 ,r4 VP =0 6 4 4 ,rAM =0 371.最后通过FTIR和1 3C NMR表征共聚物的结构并验证了共聚物的组成 .     

连续流动分析法测定土壤中的挥发酚

建立了连续流动分析仪测定土壤中挥发酚含量的方法。称取5 g左右的土壤样品,以磷酸调节p H值为4,加入适量水并进行蒸馏,馏出液用连续流动分析仪测定挥发酚含量。在4.96~200μg/L范围内,挥发酚的质量浓度与相对峰高线性相关,线性方程为y=235.31x+51.6,相关系数r~2=0.999 8,挥发酚的检出限为1.24μg/L。取2种土壤样品分别进行6次平行测定,测定结果的相对标准偏差分别为1.52%,1.56%。对2种挥发酚标准样品进行测试,相对误差分别为1.90%,2.08%,加标回收率在87.8%~95.5%之间。该方法适合大批量样品的连续分析,且无需使用三氯甲烷,与传统方法相比更安全环保。     

Determination of delta 1-tetrahydrocannabinol in human fat biopsies from marihuana users by gas chromatography-mass spectrometry

A gas chromatographic-mass spectrometric (GC/MS) method for analysis of delta 1-tetrahydrocannabinol (delta 1-THC) in human fat samples is described. The fat sample, obtained from heavy marihuana users 1 week before and 4 weeks after smoking, is homogenized in hexane + 2-propanol, centrifuged, and the supernatant mixed with Lipidex 5000. The solvent is evaporated and the dried gel is packed in a glass column. delta 1-THC is eluted from the column with methanol + water + acetic acid, diluted with water and the eluent is passed through a bed of Octadecylsilane-bonded silica. After washing and drying, the retained delta 1-THC is eluted with hexane, derivatized with N-methyl-N-(t-butyl-dimethysilyl)trifluoroacetamide (MTBSTFA) and finally purified by HPLC on an Octadecyl Sl 100 column in methanol. The amount of delta 1-THC is determined by GC/MS, using selected ion monitoring, and a deuterated internal standard. The recovery of delta 1-THC is about 80%, and the concentration of delta 1-THC in the fat samples analysed ranged between 0.4 and 193 ng/g wet tissue.     

In-line flow injection extraction-preconcentration through a passive hydrophilic membrane. Determination of total phenols in oil by flow-injection analysis

 An in-line flow injection extraction-preconcentration procedure for the determination of total phenols in oil is described. The reaction between phenolic compounds and 4-aminoantipyrine in the presence of K₂S₂O₈ as oxidizing reagent was used. The phenols were extracted and preconcentrated from a xylene solution by using a more selective passive hydrophilic Spectrapor membrane which also removed interferences. The phenols deprotonated after diffusion to the basic acceptor stream and the preconcentrated phenolate was injected into a carrier stream containing 4-aminoantipyrine as colour reagent. The carrier stream then merged with the oxidant stream, followed by detection at 500 nm. The system was suitable for the determination of total phenols in oil at a sampling rate of 12 samples per hour with an RSD of better than 1.3%. The detection limit was 0.09 mg/l for phenol, 0.18 mg/l for o-cresol and 0.02 mg/l for m-cresol. The results of the proposed system compared favourably with a standard manual 4-AAP method and a standard GC procedure. Received: 30 July 1996/Accepted: 25 August 1996     

氧化锌修饰铅笔芯电极电致化学发光法测定苯酚的研究

采用滴涂法将氧化锌纳米颗粒滴涂在自制铅笔芯电极上制成氧化锌修饰铅笔芯电极,当以过硫酸根为共反应剂时,该修饰电极在氢氧化钠溶液中具有良好的电致化学发光(ECL)行为,对其发光机理进行了考察。基于苯酚对该修饰电极的ECL具有抑制作用,建立了一种测量苯酚的新方法,当苯酚浓度为2×10~(-8)~2×10~(-6)mol/L时,发光强度与苯酚浓度的对数呈线性关系,检出限为1×10~(-8)mol/L。该方法具有灵敏度高、方法简单、快速、稳定性好等优点,将其应用于工业废水中苯酚浓度的检测,回收率为96.5%~104.5%。