Determination of formaldehyde in spirits by high-performance liquid chromatography with diode-array detection after derivatization

A high-performance liquid chromatography (HPLC) method with diode-array detection (DAD) to identify and quantify formaldehyde (FA) in spirits is described. Formaldehyde was quantified with DAD after derivatization with ethyl 3-oxobutanoate and ammonia to yield the diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate. The response of the detection system was linear within the range of 0.25-2.00 μg/ml with a correlation coefficient of 0.9998. The average formaldehyde concentration in the samples ranged between 0.27 and 3.01 mg/l. The coefficient of variation was lower than 4.84% and recoveries ranged from 93.4 to 100.4%. Purity of formaldehyde derivative peak was confirmed by spectral data.     

Measurement uncertainty arising from trueness of the analysis of two endocrine disruptors and their metabolites in environmental samples. Part II. Solid-phase extraction from environmental natural waters

In this work, a preconcentration method for the simultaneous determination of the endocrine disrupting chemicals (EDCs), diuron (1-(3,4-dichlorophenyl)-3,3-dimethylurea), and linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea), as well as their metabolites DCPU (1-(3,4-dichlorophenyl) urea), DCPMU (1-(3,4-dichlorophenyl)-3-methylurea) and 3,4-DCA (3,4-dichloroaniline), present in natural waters was optimized and validated. Water was subjected to solid-phase extraction (SPE) and the influence of several experimental variables affecting the extraction efficiency of the target analytes was studied, including the sorbent material, elution solvents, pH and breakthrough volume, as well as some solution parameters that is, ionic strength and organic matter content. A high-performance liquid chromatography system coupled to UV-diode array detector (DAD) was used for the target analytes quantification at the optimum conditions described in Part I. The fully nested experimental design, adapted to the new experimental parameters, was used to study the measurement uncertainty arising from trueness by estimating proportional bias (in terms of recovery). The overall recoveries of the target analytes were in the range of 71.6-90.2%, except 3,4-DCA for which a low overall recovery of 51.4% was obtained. The analytical procedure was shown to be linear over the studied range of concentration (25-400 ng/l), exhibiting satisfactory repeatability and reaching limits of detection in the 1.3-11.2 ng/l range for all, quite different in nature, water types. The SPE method was further applied for the determination of the selected EDCs and their metabolites in water samples taken from selected study stations in the region of Epirus (N.W. Greece) corresponding to the sediment samples locations (Part I).     

Simultaneous analysis of nine active components in Gegen Qinlian preparations by high-performance liquid chromatography with diode array detection

HPLC with diode array detection (HPLC/DAD) was employed to determine the quantities of puerarin, daidzin, daidzein, berberine, palmatine, coptisine, baicalin, baicalein, and glycyrrhizin in Gegen Qinlian preparations of three different pharmaceutical forms including decoction, dispensing granule and pill. The calibration curves for the nine bioactive components were linear in the given concentration ranges. The precision of the method was in the range of 0.2 - 5.0% (RSD), and the recoveries of this method were between 96.5 and 104.1%. The proposed method was applicable to analyze Gegen Qinlian preparations.     

阳极微分脉冲伏安法测定3,4-二氢-2-羟基喹噁啉

3,4-二氢-2-羟基喹(?)啉(简称二氢喹(?)啉)是合成新型有机磷农药及一些喹(?)啉磺胺类药物的中间体.本文根据二氢喹(?)啉可被氧化成2-羟基喹(?)啉的性质,进行了阳极微分脉冲伏安法研究.结果表明,以玻碳电极为工作电极,在甲醇和Britton-Robinson混合液中,二氢喹(?)啉有良好的微分脉冲伏安峰.用此法测定了2-羟基喹(?)啉中二氢喹(?)啉的含量.经循环伏安法验证,电极反应为不可逆反应.     

Effective chemoselective deprotection of 3,4-dimethoxybenzyl (DMB) ethers in the presence of benzyl and p-methoxybenzyl (PMB) ethers by phenyliodine(III) bis(trifluoroacetate) (PIFA)

In this Letter, a selective deprotection of the alcohol protecting 3,4-dimethoxybenzyl (^3,4DMB) group is described. The hypervalent iodine(III) reagent phenyliodine bis(trifluoroacetate) (PIFA) is found to be an efficient reagent for the chemoselective deprotection of ^3,4DMB ethers in the presence of benzyl, p-methoxybenzyl, methoxymethyl, tert-butyldimethylsilyl, and tert-butyldiphenylsilyl ethers under mild conditions. This is the first example of the selective deprotection of the ^3,4DMB group from a hydroxy group with PIFA.     

微孔膜气体扩散分离流动注射光度法测定废水中氰化物

研究了利用吡啶-巴比妥酸显色体系反应的中间产物,采用微孔膜气体扩散分离流动注射分析技术测定工业废水中氰化物,该法具有简便、快速并能消除某些干扰的特点。进样频率为65个样/h,检出限为0.02μg/ml,取氰化物2.5μg/ml时测量的相对标准偏差为0.3％(n=20),测定实际样品结果令人满意。     

Comparison of UV and charged aerosol detection approach in pharmaceutical analysis of statins

CAD (charged aerosol detector) has recently become a new alternative detection system in HPLC. This detection approach was applied in a new HPLC method for the determination of three of the major statins used in clinical treatment—simvastatin, lovastatin and atorvastatin.The method was optimized and the influence of individual parameters on CAD response and sensitivity was carefully studied. Chromatography was performed on a Zorbax Eclipse XDB C18 (4.6 mm × 75 mm, 3.5 μm), using acetonitrile and formic acid 0.1% as mobile phase. The detection was performed using both CAD (20 pA range) and DAD (diode array detector—238 nm) simultaneously connected in series. In terms of linearity, precision and accuracy, the method was validated using tablets containing atorvastatin and simvastatin.The CAD is designated to be a non-linear detector in a wide dynamic range, however, in this application and in the tested concentration range its response was found to be perfectly linear. The limits of quantitation (0.1 μg/ml) were found to be two times lower than those of UV detection.     

高效液相色谱法测定打印油墨和色带中双酚A

提出了高效液相色谱法-二极管阵列检测器测定打印油墨和色带中双酚A含量的方法。采用正己烷-乙醚(30+70)溶液为提取溶剂,以XB-C18色谱柱为分离柱,以乙腈与甲酸(0.1+99.9)溶液按体积比40比60混合为流动相,流量1.0mL.min-1,检测波长为227nm。双酚A的质量浓度在0.34～10.96mg.L-1范围内与其峰面积呈线性关系,检出限(3S/N)为3.4μg.L-1。在3个浓度水平下做加标回收试验,回收率在89.8%～93.7%之间,相对标准偏差(n=7)在1.2%～2.5%之间。     

Rapid analysis of the nitrification inhibitor 3,4-dimethylpyrazole phosphate in soil using LC-MS/MS

Nitrate from the biological nitrification of ammonium fertilisers causes environmental damage via groundwater contamination and nitrous oxide emission. To limit nitrate formation, nitrification inhibitors (NIs) are used in conjunction with ammonium-based fertilisers in agricultural land management. The NI 3,4-dimethyl-1H-pyrazole phosphate (DMPP), with an active constituent 3,4-dimethyl-1H-pyrazole (3,4-DMP), is commercially available and its effectiveness and behaviour in soils have been studied. However, only one method for the analysis of 3,4-DMP in soil has been reported and relies on extensive sample preparation to remove matrix interferences prior to HPLC analysis. A new method was developed to allow monitoring of 3,4-DMP residues in soil after appliaction, which utilises the greater selectivity and sensitivity of LC-MS/MS. A 3,4-DMP limit of quantitation of 0.5 ng/g was achieved, which is 10 times more sensitive than the published method, and was achieved using 10,000 times less 3,4-DMP injected on-column, with an injection volume 100 times smaller. Four internal standards were evaluated to improve the accuracy of the extraction method. The isotope-substituted structural isomer 3,5-dimethyl pyrazole-¹⁵N₂ provided the best and most consistent recoveries over the 300-fold concentration range tested. The new method was employed to investigate the persistence and mobility of 3,4-DMP in an agricultural soil. 3,4-DMP had a half-life of 5 days in the top 0.5 cm of soil at normal and double recommended application rates, while half-lives in the 2.5 cm soil profile were 28 and 21 days, respectively. 3,4-DMP mobility in the clay loam soil tested was low, with only 15–25% of applied 3,4-DMP detected below the top 0.5 cm, suggesting the loss of 3,4-DMP was either due to volatilisation or degradation, rather than leaching into the soil profile.     

Quantitative analysis of nicotinic acid, nicotinamide and 3-cyanopyridine in industrial effluent by high performance liquid chromatography

A rapid and reliable high performance liquid chromatographic (HPLC) method for the simultaneous determination of heterocyclic compounds, namely nicotinic acid, nicotinamide, and 3-cyanopyridine, in industrial effluent is described. A Φ4.6 mm × 150 mm, 5 μm C-18 reversed phase stationery phase, and a methanol-acetonitrile-water tertiary mobile phase (20:20:60 v/v) were used for separation. The detection wavelength of a diode array (DAD) was set at 216 nm with a bandwidth of 16 nm. Phenol was used as an internal standard. The regression equations revealed a linear relationship between the concentration of the analytes injected and the peak area detected by DAD. The limits of detection (S/N = 3) ranged from 0.70 to 1.18 mg L⁻¹, the recoveries ranged from 87% to 102% and the precision expressed as % RSD intra-day and inter-day varied from 0.9 to 3.9 and 1.2 to 5.6, respectively. This method is rapid, sensitive and suitable for the monitoring of nicotinic acid, nicotinamide, and 3-cyanopyridine in effluent of related pharmaceutical manufacturing plants.     

GC/MS Identification of Organic Pollutants in the Caroni River,Trinidad

Abstract

Water samples from the Caroni River, Trinidad and other rivers which flow into the Caroni River were qualitatively analyzed for trace organic contaminants by procedures based on XAD extraction followed by GC/MS analysis. Pesticides, polyaromatic hydrocarbons, aliphatic hydrocarbons, phenols and phthalate esters were the main groups of compounds found. Many of the contaminants present in these water samples are known industrial pollutants, and several have been found in waste waters examined by other workers, which suggests that the factories of an industrial complex located upstream of the Caroni/Arena Water Treatment Plant may be the major source of the pollutants. Some compounds identified in the water samples have not been previously reported.     

Improvement of Adenosylcobalamin Production by Metabolic Control Strategy in Propionibacterium freudenreichii

An efficient metabolic control approach was developed to improve the industrial anaerobic fermentation of adenosylcobalamin (ado-cbl) by Propionibacterium freudenreichii. The effects of 5,6-dimethylbenzimidazole (DMB) on cell growth and ado-cbl biosynthesis were investigated. Subsequently, the results obtained from the batch culture showed that an important intermediate of ado-cbl separated from the cell extract was identified as adenosylcobinamide (ado-cbi) by high-performance liquid chromatography coupled to an ultraviolet diode array detector and ESI mass spectrometry analysis. Ado-cbi can be converted to ado-cbl when linked to DMB, which is an essential compound for ado-cbi bioconversion. This key ado-cbi is useful not only in determining ado-cbl concentration in the fermentation process but also in serving as an effective compound to guide DMB incorporation for the harvest of the maximum ado-cbl concentration. Accordingly, with scaling up to 100?L fermentation, the experimental results showed that the discrepancy was less than 1?% using the developed prediction technique. Overall, the findings show that the method is efficient in evaluating the fermentation of ado-cbl by propionibacteria.     

Measurement uncertainty arising from trueness of the analysis of two endocrine disruptors and their metabolites in environmental samples. Part I: ultrasonic extraction from diverse sediment matrices

The validation of preconcentration strategies for the simultaneous determination of two endocrine disrupting compounds (EDCs) and their metabolites present in the aquatic environment including natural waters and freshwater sediments as well as the estimation of uncertainty arising from trueness using fully nested experimental designs are presented in a series of two papers. In this work, we present Part I of our ongoing study, the validation of an analytical method based on ultrasonic extraction of the target analytes from various freshwater sediments and the estimation of the method measurement uncertainty. The selected endocrine disruptors included two widely used herbicides, diuron (1-(3,4-dichlorophenyl)-3,3-dimethylurea) and linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) and their common degradation products namely, 3,4-dichloroaniline (3,4-DCA), 1-(3,4-dichlorophenyl) urea (DCPU) and 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU). A high-performance liquid chromatography system coupled to UV-diode array detector (HPLC/UV-DAD) was used for the target analytes quantification. A fully nested experimental design was applied to study the measurement uncertainty arising from trueness by estimating proportional bias (in terms of recovery). The overall recoveries, that is, those determined by the nested experiments were in the range of 59.5-85.1%, except 3,4-DCA for which a low overall recovery of 29.0% was observed. The analytical method was shown to be linear over the studied range of concentrations (5-100 microg/kg), exhibiting satisfactory repeatability and reaching limits of detection usually in the 0.6-4.6 microg/kg range on dry sediment basis. The method used permitted the determination of the target EDCs and their metabolites in sediment samples collected from selected study stations in the region of Epirus (N.W. Greece) at the concentration levels demanded by current legislation.     

The application of digital image recognition to the analysis of two-dimensional fingerprints

High-performance liquid chromatography (HPLC) fingerprint has been commonly used in the quality control and assessment of herbal medicines, and two-dimensional (2D) fingerprint obtained by means of HPLC-diode array detector (HPLC/DAD) can provide higher reliability. In this paper, an approach to the analysis of the 2D HPLC/DAD fingerprints, which was based on digital image recognition techniques, was developed for the first time. First, wavelet transform was employed to eliminate noise signal in the 2D fingerprint, and then the 2D fingerprint was converted into grayscale image. Second, several features of the image were calculated, and hierarchical clustering. This approach was applied to the qualitative analysis of the different samples of coptis chinensis, and the clustering result of samples was all highly consistent with the real situation. Based on the densities in grayscale image, three components in standard samples were quantitative analyzed, and the obtained correlation coefficients between concentration and grayscale density were more than 0.999. Our study indicated that the analysis of the 2D HPLC/DAD fingerprint was successful based on the idea and techniques of digital image recognition techniques, and this proposed approach provided a new pathway for the analysis of two-dimensional spectrums.     

Metals in precipitation and lake waters in the North-West of Russia

Standard monitoring data on the concentration of metals in precipitation and lake water in 2000s have been analyzed. All monthly average concentrations of Pb in Cd in precipitation were lower than the corresponding maximum allowable concentrations (MACs), whereas the concentrations of Cu, Zn, and Fe in lake surface waters were similar to or exceeded MACs for fishery reservoirs. The peak concentration of Pb in precipitation in June indicated increased dust content of air in late spring and early summer due to soil exposure and plowing. Increased concentration of Zn in the Kubenskoe Lake surface water in spring is likely to result from the peak discharge of anthropogenic pollutants on melting of snow and ice.     

Determination of trace amounts of 3,4-dichloroaniline by high-performance liquid chromatography with amperometric detection and its application to pesticide residue analysis

Summary High-performance liquid chromatography with amperometric detection was used for the determination of trace amounts of 3,4-dichloroaniline. The latter was separated with Nucleosil C₁₈ as stationary phase and methanolwater (70:30 V/V) containing 0.05 mol/l ammonium acetate as eluent. The voltage of the working electrode (glassy carbon) was set at +960 mV vs. Ag/AgCl. The linear dynamic range between limiting current and concentration was about 1×10² (0.2–20 ng) and the minimum detectable amount was 0.2 ng. This method was applied to the determination of trace amounts of linuron and free 3,4-dichloroaniline in potatoes. The minimum quantitative level was 0.01 ppm. The method requires less clean-up steps than the GC and HPLC methods (using UV detection).     

Photoinitiated,inverse emulsion polymerization of acrylamide: Some mechanistic and kinetic aspects

The kinetics of photoinitiated, inverse emulsion polymerization of acrylamide with 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA) as a photoinitiator was investigated under three different cases. First, in a quartz reactor transparent to full UV light, the polymerization rate (R_p) increased and then decreased with the change of initiator order from 0.27 to a negative value when the DMPA concentration was increased, and it was particularly unusual that monomer orders at different DMPA concentrations were lower than the first. Second, for polymerization without DMPA in a quartz reactor, the dependence of R_p on monomer concentration was similar to that of R_p on initiator concentration in the aforementioned case. Third, when polymerization was carried out in a Pyrex reactor where the far UV light was filtered, a peak rate was also observed, and initiator orders varied from 0.24 to a negative value; however, under this case monomer orders at different initiator concentrations were greater than the first. These results indicated that the effect of absorbance often observed in bulk or solution photopolymerization also existed in this system, and the self‐initiation of monomer had some influence on polymerization, and the role of primary radical termination could not be neglected, as evidenced by kinetic analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 846–852, 2004     

Determination of the Insecticide Imidacloprid in Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.) and Onion (<Emphasis Type="Italic">Allium cepa</Emphasis>) by High-Performance Liquid Chromatography with Diode-Array Detection

A high-performance liquid chromatography (HPLC) method has been proposed for the determination of imidacloprid residues in fortified potato (Solanum tuberosum L.) and onion (Allium cepa) and in treated potato and onion samples. Sample preparation consisted of dichloromethane extraction of imidacloprid from the plant material, followed by purification of the obtained onion extract on an LC-Florisil disposable cartridge. The obtained potato extracts were further analyzed without purification. The HPLC-diode-array-detection (DAD) method has been developed on reversed phase for separation of imidacloprid with isocratic elution with a mixture of 0.01 M phosphate buffer (pH 3.15) and acetonitrile (75 : 25, v/v). Spectral data obtained with DAD allow the identification of imidacloprid residue. Detector response showed a linear dynamic range from 0.0125 to 0.500 μg/mL. Imidacloprid was recovered from fortified samples in a range of 94–99%. The within-day RSD of repeatability of the retention time of imidacloprid standard solution was less than 0.1% and of the obtained peak area less than 5%. For potato and onion samples, the limits of detection were 0.0075 and 0.0060 mg/kg and the limits of determination were 0.015 and 0.012 mg/kg, respectively. __________ From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 12, 2005, pp. 1273–1278. Original English Text Copyright ? 2005 by Mandic, Lazic, Okresz, Gaal. The text was submitted by the authors in English.     

Comparison of two different isolation methods of benzimidazoles and their metabolites in the bovine liver by solid-phase extraction and liquid chromatography–diode array detection

A new analytical method that uses high performance liquid chromatography–diode array detector (HPLC–DAD) was developed for the analysis of 14 benzimidazoles residues, including metabolites, in bovine liver. Samples were extracted using two different extraction procedures: with phosphate buffer after enzymatic hydrolysis (method A) or using organic solvent, i.e. acetonitrile (method B). Then, samples were purified on a strong cation exchange (SCX) cartridge and analyzed in HPLC/DAD. The recovery percentages, obtained spiking the matrix (liver) at concentrations of 500 and 100 μg kg^?1 with a standard mixture of benzimidazoles, were in the range 6–101% and 80–102% for methods A and B, respectively. The repeatability of the methods was assessed in all cases by the % of correlation value (CV) that was lower than 19%. The limits of quantification (LOQs) in the matrix for methods A and B were in the range 40–60 and 20–50 μg kg^?1, respectively. The best of the two methods, method B, was used for the analysis of 10 bovine liver samples.     

橡胶及橡胶制品中4种酚类防霉剂的高效液相色谱法测定

建立了橡胶及其制品中硝基苯酚(PNP)、2,3,5,6-四氯苯酚(TeCP)、五氯苯酚(PCP)、邻苯基苯酚(OPP)4种酚类防腐剂的高效液相色谱测定方法。样品冷冻粉碎后,经甲醇超声提取,在Venusil-XBP C18色谱柱(250 mm×4.6 mm,5μm)上以10 mmol/L醋酸铵和甲醇为流动相梯度洗脱,采用二极管阵列检测器,PCP、TeCP、OPP的检测波长为220 nm,PNP的检测波长为320 nm。4种酚类防霉剂的质量浓度在0.5~250mg/L范围内与峰面积呈良好的线性关系,相关系数大于0.999 4。丁苯橡胶、硅橡胶基体的加标回收实验结果表明:TeCP、PCP、OPP、PNP在不同基质中的平均加标回收率分别为82%~95%、68%~90%、85%~98%、87%~98%,相对标准偏差小于5%。