DNPH衍生化采样-溶剂解析-高效液相色谱法同时测定木制品中25种醛酮化合物

建立了DNPH衍生化采样-溶剂解析-高效液相色谱测定木制品中醛酮化合物的方法。采样时需在2,4-二硝基苯肼吸附管前串联一只SEP-PAK脱臭氧小柱;采样体积应≤10 L,流量≤400 m L/min。该法对25种醛(酮)化合物对应的衍生物分离效果良好,在0.005~3 mg/L范围内线性良好,相关系数R2≥0.999 6,回收率为85.3%~113.5%,精密度为2.67%~4.56%。采样量为10 L时,25种醛(酮)化合物的检出限和定量限分别≤0.16和0.50μg/m3。     

衍生化-液液萃取-气相色谱法测定水中苦味酸的技术关键

测定水中苦味酸的国标方法——衍生化-液液萃取-气相色谱法采用的提取溶剂苯毒性较大,杂质较多,苦味酸在衍生过程中有部分损失。在国标方法的基础上,改用环己烷为提取溶剂,以溶剂液封加盖的方式,降低了衍生化产物损耗。选用中口径毛细管色谱柱,优化了色谱条件,有效地将衍生化产物与杂质分离。方法在0.500μg/L～40.0μg/L范围内线性良好,检出限为0.083μg/L,标准溶液平行测定6次的RSD≤5.3%,实际样品加标回收率为93.9%～104%。     

OPA柱前衍生-反向高效液相色谱法测定水中游离氨基酸

采用邻苯二甲醛柱前衍生5种氨基酸,用反向高效液相色谱法测定衍生化产物,通过优化衍生化条件和色谱条件,使该方法在0.25μmol/L~25μmol/L范围内线性良好。方法检出限为0.08μmol/L~0.12μmol/L,标准溶液测定6次的RSD为0.1%~1.2%,空白加标样的回收率为80.3%~115%。用该方法测定实际水样,5种氨基酸测定值均低于0.514μmol/L,加标回收率在75.5%~120%之间。     

水中丙烯酰胺气相色谱测定方法研究

研究建立了大口径毛细管柱气相色谱法测定水中丙烯酰胺的方法。优化了水中丙烯酰胺的衍生化条件,用乙酸乙酯和正己烷混合溶剂萃取衍生产物,萃取后直接进行色谱分离分析,水中丙烯酰胺的最低检测浓度为0.05μg/L,回收率在94.5%～113%之间;进行6次平行精密度试验,相对标准偏差低于11.5%。研究建立的气相色谱法简便、快速、准确、重现性好,定量、定性准确可靠,适合水中丙烯酰胺的分析测定。     

高效液相色谱-柱前衍生法测定水中有机磷除草剂

建立了水样中痕量草甘膦、草铵膦和氨甲基磷酸的FMOC柱前衍生-高效液相色谱-荧光检测分析方法。草甘膦,草铵膦和氨甲基磷酸的平均加标回收率分别为94.2%、90.8%、98.6%;相对标准偏差分别为4.8%、0.68%、2.8%;方法的定性下限和定量下限分别为0.05、0.04、0.009μg/L和0.16、0.12、0.03μg/L。水样放置两天后,水样中的草甘膦、草铵膦分别降解了17.8%和19.5%,而水样经过衍生后在5天内是稳定的。     

气相色谱-电子捕获法直接测定水体中的五氯酚钠

建立了不经衍生直接测定水体中五氯酚钠残留量的气相色谱-电子捕获(GC-ECD)方法。用乙酸乙酯提取目标化合物,浓缩后上机测定。五氯酚钠标准溶液的线性范围在0.35～400μg/L之间,相关系数为0.9992;池塘水中五氯酚钠的添加浓度为1.0、5.0、10.0μg/L时,其加标回收率为95.8%～98.7%,相对标准偏差≤3.6%;检出限(信噪比为3时)为0.35μg/L,定量限(信噪比为10时)为1.0μg/L。     

醛类化合物检测方法中腙类物质的衍生条件

通过对醛类化合物的DNPH衍生化酸度、摩尔比、时间条件的研究和衍生化结果的验证获得了过量DNPH条件下制备15种醛的腙标准溶液制备方法。实验结果表明,其共同衍生化条件为1.0~2.0 mol/L盐酸溶液中DNPH/醛类摩尔比不小于2∶1条件下,醛类物质与DNPH可充分衍生化。     

催化快速法测定CODcr定量下限

该法规定的检出范围是 6 0 mg/L～ 1 0 0 0 mg/L ,废水浓度高于 1 0 0 0 mg/L须定量稀释后测定 ,而低于 6 0 mg/L时 ,即使能准确测定也不能报准确结果 ,只能按 6 0 mg/L的一半报出。分光光度计在低吸光度时分值较宽 ,易分辨且催化快速法在COD浓度较低时曲线有很好线性关系 ,使得降低定量下限成为可能。实验表明 ,催化快速法测定CODcr的定量下限为 1 0 mg/L。这样 ,地表水、低浓度 CODcr的废水均可用快速法测定 ,扩大了该法应用范围 ,减轻了测定低浓度 CODcr使用经典回流法、密封消解法劳动强度 ,节省成本和时间。催化快速法测定COD…     

气相色谱法测定固定污染源废气中氯甲基甲醚和二氯甲基醚的研究

氯甲基甲醚(CMME)和二氯甲基醚(BCME)属于确认人类致癌物，因此，建立精准、绿色的CMME和BCME检测分析方法十分必要。基于2,4,6-三氯苯酚+乙醇钠+乙醇衍生化体系，利用气相色谱法(电子捕获检测器)测定了固定污染源废气中的CMME和BCME,并且系统地优化了采样条件、衍生化条件，确定了衍生化产物的结构及衍生比率。结果表明：工作曲线相关系数均大于0.990;当采样量为10 L时，检出限均为0.003 mg/m³;当实际样品加标量分别为0.010、0.100、1.00 mg/m³时，测定结果的相对标准偏差分别为15%～16%、8.9%～13%、10%～11%,加标回收率分别为89.2%～90.8%、75.3%～78.6%、76.5%～77.2%。     

五氟苯甲酰氯衍生-气相色谱-质谱法测定地表水中一甲基肼

建立了五氟苯甲酰氯衍生-气相色谱-质谱法测定地表水中一甲基肼的方法。取200ml水样,调节后的pH为10,加入20ml衍生剂,在室温下剧烈振荡衍生1h,40ml二氯甲烷萃取10min,浓缩至1.0ml后用气相色谱-质谱联用分析。方法在5～500μg/L浓度范围内线性良好,相关系数大于0.996,方法检出限为2.67μg/L;加标水样的相对标准偏差为9.54%和8.38%;加标水样回收率为79.08%～102.96%。     

Evaluation of the methyl ester O-methyl acetate derivative of muramic acid for the determination of peptidoglycan in environmental samples by ion-trap GC-MS-MS

Muramic acid (MA) is a unique amino sugar that is a constituent of the peptidoglycan (PG) present in prokaryotic cell walls. MA can serve as a marker for quantifying bacterial load, e.g. in indoor environments, by using gas chromatography-tandem mass spectrometry (GC-MS-MS). We demonstrated recently that the methyl ester O-methyl acetate (MMA) derivative can be used to detect MA in house dust by ion-trap GC-MS-MS. However, since the MMA derivative is not formed from free MA quantification was not optimal. Here we report 1) significant improvements in sample preparation of the MMA derivative and 2) an evaluation of the performance of derivative, using for comparison the alditol acetate derivative, the gold standard in quantitative trace analysis of MA in complex matrices. The MMA derivative was analysed using an MS instrument with internal ionization and the alditol acetate derivative was analysed using an instrument with external ionization. 13C-labelled cyanobacteria, containing MA in their PG, were used as the internal standard. A linear relationship was found between the two methods in studies on 27 parallel samples of airborne dust from school classes collected on filters. Although the analytical sensitivity of the MMA derivatives was somewhat slightly lower than of the alditol acetate derivative, this may be due to differences in yield of derivative, sample clean-up efficiency, or different performance of the GC columns or MS instruments. However preparation of the MMA derivative is quick and compatible with preparation of methyl esters of 3-hydroxy fatty acids (used as markers of Gram negative endotoxin) allowing the levels of both markers to be determined in the same dust sample. In conclusion, the MMA procedure can be used to determine MA in environmental samples with good reproducibility provided the concentration of the 13C-labelled MA internal standard in the cyanobacteria is first determined with an alternative method.     

水中多种酚类化合物衍生化方法研究

对水中14种酚类化合物的衍生化过程进行研究，选取不同衍生化试剂、衍生温度和衍生时间、最大衍生量等多个对衍生效率有决定性影响的参数进行优化。通过上述条件的优化选择，实现了对苯酚、氯代酚、甲基酚和硝基酚等14种不同类型酚类化合物最优的衍生化，衍生效率达到75．5％～119％。     

Monitoring and measurement of microalgae using the first derivative of absorbance and comparison with chlorophyll extraction method

Monitoring of microalgae in water supplies and industrial applications are becoming increasingly important, yet there are few options available that are simple and accurate, and can provide real-time information. The present work illustrates a new method to determine the concentration of microalgae in water and wastewater using spectrophotometry and the first derivative of absorbance. Chlorella vulgaris was used as an indicator microalga, spiked in water samples representing a range of water qualities (distilled water, surface water, and wastewater), and correlations among C. vulgaris concentrations, absorbance, and the first derivative of absorbance measurements were investigated. In addition, detection limits were established and sensitivity analyses were carried out to determine the lowest C. vulgaris concentrations that can be confidently measured in different water matrices. Finally, the study compared the performance and detection limits of the spectrophotometry-based methods with the well-accepted chlorophyll extraction method. A strong linear relationship (R²?>?0.97) was found between C. vulgaris concentration and absorbance at 695 nm. Using the first derivative of absorbance improved C. vulgaris detection limits by reducing the effects of the background noise and interferences from other substances. The detection limits established using the first derivative method were 0.47, 0.56, and 1.96 mg TVS/L in distilled water, surface water, and wastewater, respectively. In comparison, the detection limits of the chlorophyll extraction method were found to be 19.6, 38.6, and 48.3 mg TVS/L in the same water matrices. These results indicate that first derivative of absorbance can be successfully used for monitoring of microalgae in surface waters and environmental samples as well as in bioreactors used for microalgae cultivation in industrial applications.     

Comparison of different semi-empirical algorithms to estimate chlorophyll-a concentration in inland lake water

Based on in situ water sampling and field spectral measurement from June to September 2004 in Lake Chagan, a comparison of several existing semi-empirical algorithms to determine chlorophyll-a (Chl-a) content was made by applying them to the field spectra and in situ chlorophyll measurements. Results indicated that the first derivative of reflectance was well correlated with Chl-a. The highest correlation between the first derivative and Chl-a was at 680 nm. The two-band model, NIR/red ratio of R_710/670, was also an effective predictor of Chl-a concentration. Since the two-band ratios model is a special case of the three-band model developed recently, three-band model in Lake Chagan showed a higher resolution. The new algorithm named reverse continuum removal relies on the reflectance peak at 700 nm whose shape and position depend strongly upon chlorophyll concentration: The depth and area of the peak above a baseline showed a linear relationship to Chl-a concentration. All of the algorithms mentioned proved to be of value and can be used to predict Chl-a concentration. Best results were obtained by using the algorithms of the first derivative, which yielded R ² around 0.74 and RMSE around 6.39 μg/l. The two-band and three-band algorithms were further applied to MERIS when filed spectral were resampled with regard to their center wavelengths. Both algorithms showed an adequate precision, and the differences on the outcome were small with R ² = 0.70 and 0.71.     

Simultaneous determination of parathion and p-nitrophenol in vegetable tissues by derivative spectrophotometry

A first derivative spectrophotometric method has been developedfor the determination of parathion and p-nitrophenol in vegetabletissues. Ethanol was used as solvent for extracting the compoundsfrom the tissues and subsequently the samples were evaluated against a vegetable tissue blank, directly by derivative spectrophotometry. The simultaneous determination of these compounds can be carried out using the zero-crossing approach for parathion at 253.0 nm and for p-nitrophenol at 273.1 nm. In the samples each analyte was determined in the presence of one another in the ranges between 4.9 to 3883.5 g g^-1 forparathion and 4.9 to 3285.3 g g^-1 for p-nitrophenol.The detection limits (3) were found to be 1.5 and 1.4 g g^-1 for parathion and p-nitrophenol, respectively. The relative standard deviations were in all instances less than1.8%. The proposed method was applied to the determination ofthe analytes in spiked leafs of corn. The results show a goodrecovery and they are in agreement with those obtained bypolarography.     

大气乙醛碳同位素分析方法的研究

利用气相色谱/燃烧/同位素比值质谱(GC/C/IRMS)分析技术,采用NaHSO3与半胱胺衍生化方法,测定了气态乙醛在衍生化反应过程中的碳同位素效应,探讨了采用该方法测定大气乙醛碳同位素组成的可行性。试验测定了乙醛、衍生剂半胱胺及相应衍生物的碳同位素比值,结果表明,乙醛衍生物的δ13C测量值与理论值的偏差范围为0.11‰～0.35‰,在仪器精密度范围内(<0.50‰),即在衍生化过程中基本不会发生碳同位素分馏。采用该方法初步测定了大气中乙醛的碳同位素组成,实测数据显示,广州地化所和肇庆鼎湖山大气乙醛δ13C平均值分别为(-34.21±0.27)‰和(-31.23±0.16)‰,相同采样点的大气乙醛碳同位素组成基本不变,可见该方法可作为研究大气乙醛不同排放源的一种有效方法。     

Simultaneous Determination of O- and P- Nitrophenol by First Derivative Spectrophotometry

A simple method by first derivative spectrophotometry is proposed for the simultaneous determination of o-nitrophenol and p-nitrophenol. The analytes were separated from samples by liquid-liquid extraction (pH = 7.4) as tetrabutylammonium ion pairs into the 1,2-dichloroethane organic phase and subsequently the extracts were evaluated directly by derivative spectrophotometry. Simultaneous determination of both analytes could be carried out using the zero-crossing and the graphical methods for o-nitrophenol and p-nitrophenol, respectively. The determination ranges were found to be between 0.115 to 3.00 ppm and 0.130 to 3.00 ppm for o-nitrophenol and p-nitrophenol, respectively. The relative standard deviations were in all instances less than 2.0%. The proposed method was applied to the determination of these compounds in fruit juices.     

Diffusive sampling of methyl isocyanate using 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ) as derivatizing agent

A diffusive sampling method for the determination of methyl isocyanate (MIC) in air is introduced. MIC is collected using a glass fiber filter impregnated with 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ). The urea derivative formed is desorbed from the filter with acetonitrile and analyzed by means of high-performance liquid chromatography (HPLC) using fluorescence detection (FLD) with lambdaex = 471 nm and lambdaex = 540 nm. Additionally, a method was developed using tandem mass spectrometric (MS-MS) detection, which was performed as selected reaction monitoring (SRM) on the transition [MIC-NBDPZ + H]+ (m/z 307) to [NBDPZ + H]+ (m/z 250). The diffusive sampler was tested with MIC concentrations between 1 and 35 microg m(-3). The sampling periods varied from 15 min to 8 h, and the relative humidity (RH) was set from 20% up to 80%. The sampling rate for all 15 min experiments was determined to be 15.0 mL min(-1) (using HPLC-FLD) with a relative standard deviation of 9.9% for 56 experiments. At 80% RH, only 15 min sampling gave acceptable results. Further experiments revealed that humidity did not affect the MIC derivative but the reagent on the filter prior to and during sampling. The sampling rate for all experiments (including long term sampling) performed at 20% RH was found to be 15.0 mL min(-1) with a relative standard deviation of 6.3% (N = 42). The limit of quantification was 3 microg m(-3) (LC-MS-MS: 1.3 microg m(-3)) for 15 min sampling periods and 0.2 microg m(-3) (LC-MS-MS: 0.15 microg m(-3)) for 8 h sampling runs applying fluorescence detection.     

衍生化气相色谱法测定环境水样中的多菌灵

通过对反应温度、时间等衍生化条件的优化研究,建立了环境水样中残留多菌灵的衍生化气相色谱氮磷检测方法。方法的最低检出浓度为0.10μg/L,样品加标回收率为83.2%～90.9%,相对标准偏差为4.6%。利用该方法能较好地满足GB 21523-2008《杂环类农药工业水污染物排放标准》中该杂环类农药的痕量测定要求。