高效液相色谱-串联质谱法同时测定肉类罐头中双酚-二缩水甘油醚

建立了同时测定肉类罐头中双酚A-二缩水甘油醚(BADGE)、双酚F-二缩水甘油醚(BFDGE)及其衍生物双酚A-(2,3-二羟丙基)甘油醚(BADGE•H2O)、双酚A-双(2,3-二羟丙基)醚(BADGE•2H2O)、双酚A-(3-氯-2-羟丙基)(2,3-二羟丙基)醚(BADGE•H2O•HCl)、双酚A-(3-氯-2-羟丙基)甘油醚(BADGE•HCl)、双酚A-双(3-氯-2-羟丙基)醚(BADGE•2HCl)、双酚F-双(2,3-二羟丙基)醚(BFDGE•2H2O)、双酚F-双(3-氯-2-羟丙基)醚(BFDGE•2HCl)9种环境激素的高效液相色谱-串联质谱分析方法。样品经叔丁基甲醚提取,HLB固相萃取小柱净化,C18色谱柱分离,用5 mmol/L醋酸铵溶液(含0.1%甲酸)与甲醇为流动相梯度洗脱,质谱多反应监测(MRM)模式检测,基质标准校正,外标法定量。结果表明,这9种化合物在10.0～2000.0 μg/L范围内线性关系良好;定量限(以信噪比≥10计)为10.0 μg/kg;在高、中、低3个加标水平下9种化合物的平均添加回收率为79.6%～100.9%,相对标准偏差为6.3%～12.1%。该方法具有较高的灵敏度和准确度,能满足法规要求的对肉类罐头中双酚A-二缩水甘油醚、双酚F-二缩水甘油醚及其衍生物残留量的快速检测及准确定量。     

Analysis of leachable and total trace metals in air particulate matters by capillary electrophoresis

A new analytical procedure was developed for simultaneous determination of ammonium, leachable and total metals in fine and coarse air particulate matters using a new capillary electrophoresis (CE) procedure, with a new buffer system containing 10 mM histidine, 2 mM 18-crown-6 and 8 mM lactic acids with pH adjusted to 4.0. A two complexes system, 18-crown-6 ether and lactic acid, was developed to solve the co-migration problem of NH(4)(+) and K(+) and to give satisfactory separation of transition metals. Satisfactory separation and quantitation of NH(4)(+), K(+), Ca(2+), Na(+) , Mg(2+) and Zn(2+) were obtained using the CE procedure developed for both leachable and total metals in coarse (10-3 mum) and fine (<3 mum) air particulate matters. Wide working ranges (ppb to ppm range) and sensitive detection limits (ppb) were obtained for the cations investigated. The reliability was established by parallel method comparison with the ICP-AES method. The analytical procedure developed is shown to provide a quick, sensitive, precise and economic method for simultaneous determination of ammonium, leachable and total metals in air particulate matters.     

Rapid determination of methyl tert-butyl ether using dynamic headspace/ion mobility spectrometry

Using an original, experimental set-up named dynamic headspace/IMS (DHS/IMS), ppb levels of methyl tert-butyl ether (MTBE), a gasoline additive and environmental pollutant, were determined in drinking and ground water. A portable IMS (Bruker, Raid-1 model) was connected to the outlet of a Drechsel bottle containing 100 ml of water-based sample. Automatically activated to sample air, the IMS built-in pump was used to produce a continuous and gentle air flow bubbling through the water-based sample. This allowed volatile MTBE to be isolated and transferred into the Drechsel headspace and then into the IMS. Analyses of reference solutions and real samples resulted in MTBE detection limits of 20 ppb, calibration curves in the 20-200 ppb range, and relative standard deviations of 4.7 and 8.4%, respectively, for inter- and intra-day reproducibility tests. Detection limits were further improved to 0.5 ppb by means of a Tenax trap cooled with liquid nitrogen, placed between the sample bottle and the IMS. Overall, DHS/IMS could well become a simple and cost-effective tool for rapid and on-line analysis of volatile organic compounds in water.     

Determination of low molecular weight alcohols including fusel oil in various samples by diethyl ether extraction and capillary gas chromatography

Low molecular weight alcohols including fusel oil were determined using diethyl ether extraction and capillary gas chromatography. Twelve kinds of alcohols were successfully resolved on the HP-FFAP (polyethylene glycol) capillary column. The diethyl ether extraction method was very useful for the analysis of alcohols in alcoholic beverages and biological samples with excellent cleanliness of the resulting chromatograms and high sensitivity compared to the direct injection method. Calibration graphs for all standard alcohols showed good linearity in the concentration range used, 0.001-2% (w/v) for all alcohols. Salting out effects were significant (p < 0.01) for the low molecular weight alcohols methanol, isopropanol, propanol, 2-butanol, n-butanol and ethanol, but not for the relatively high molecular weight alcohols amyl alcohol, isoamyl alcohol, and heptanol. The coefficients of variation of the relative molar responses were less than 5% for all of the alcohols. The limits of detection and quantitation were 1-5 and 10-60 microg/L for the diethyl ether extraction method, and 10-50 and 100-350 microg/L for the direct injection method, respectively. The retention times and relative retention times of standard alcohols were significantly shifted in the direct injection method when the injection volumes were changed, even with the same analysis conditions, but they were not influenced in the diethyl ether extraction method. The recoveries by the diethyl ether extraction method were greater than 95% for all samples and greater than 97% for biological samples.     

Using an on-line microdialysis/HPLC system for the simultaneous determination of melamine and cyanuric acid in non-dairy creamer

The recent revelation of melamine (MEL) contamination in foodstuffs in China has rocked the international public health community. Many food categories have been involved in this scandal, including non-dairy creamer (NDC). In this study, we investigated the use of hollow-fiber microdialysis (MD) sampling coupled on-line with high-performance liquid chromatography (HPLC) as an alternative to sample pretreatment for the direct determination of MEL and its analogue cyanuric acid (CYA) in NDC. After MD sampling, the dialysate was injected on-line into the chromatographic system for analysis of MEL and CYA with UV detection at 203 nm. We monitored the effects of various parameters affecting the MD efficiency, namely the characteristics of the MD probe membrane, the flow-rate and the nature of the polarity modifier in the perfusion stream, and the addition of salt in the sample solution. The optimal enrichment efficiency for collecting MEL and CYA from aqueous NDC samples occurred with MD sampling using a hollow polysulfone MD fiber and MeOH as the perfusate at a flow rate of 10 μL min⁻¹. The optimized chromatographic conditions involved using a reversed-phase phenyl column and a mobile phase of 5 mM phosphate buffer in 10% (v/v) MeOH, buffered at pH 6.5. Detection was linear in the concentration range from 0.02 to 5 ppm for MEL and from 2 to 100 ppm for CYA, with detection limits of 1 ppb for MEL and 30 ppb for CYA. The volume of perfusate required to extract MEL and CYA from the NDC solution was only 21 μL. The total MD sampling time was 2.1 min. This method allows the sensitive, eco-friendly, and rapid determination of MEL and CYA in NDC—a risk food for economically motivated adulteration.     

Selective and simultaneous determination of phosphate and silicate ions in leaching process waters for ceramics glaze raw materials of narutal origin by ion-exclusion chromatography coupled with UV-detection after postcolumn derivatization.

The selective and simultaneous ion-exclusion chromatography (IEC) with UV-detection on a weakly acidic cation-exchange resin column in the H+ -form (TSKgel Super IC-A/C) was developed and applied for the simultaneous determination of phosphate and silicate ions as the water quality parameters required for optimizing the water-leaching process for ceramics glaze raw materials of natural origin including feldspar, woods-ash, and straw-ash. Phosphate and silicate ions in these water-leaching process water samples were separated selectively from the coexisting anions such as sulfate, chloride, nitrate and carbonate ions, based on the ion-exclusion separation mechanism. They were detected selectively and simultaneously by a postcolumn derivatization with molybdenum-yellow using the UV-detector. Under the optimized separation and detection conditions (eluent, 0-1 mM sulfuric acid; reactant, 10 mM sodium molybdate-25 mM sulfuric acid; detector, UV at 370 nm; temperature, 45 degrees C), the linearity of calibration was in the range 0.1 - 10 ppm for both phosphate and silicate ions, and the detection limits at S/N = 3 were 2.58 ppb for silicate ions and 4.75 ppb for phosphate ions. The effectiveness of this method was demonstrated in practical applications to the water-leaching process for some ceramics glaze raw materials.     

A highly sensitive and selective dimethyl ether sensor based on cataluminescence

A sensor for detecting dimethyl ether was designed based on the cataluminescence phenomenon when dimethyl ether vapors were passing through the surface of the ceramic heater. The proposed sensor showed high sensitivity and selectivity to dimethyl ether at an optimal temperature of 279 °C. Quantitative analysis were performed at a wavelength of 425 nm, the flow rate of carrier air is around 300 mL/min. The linear range of the cataluminescence intensity versus concentration of dimethyl ether is 100-6.0 × 10³ ppm with a detection limit of 80 ppm. The sensor response time is 2.5 s. Under the optimized conditions, none or only very low levels of interference were observed while the foreign substances such as benzene, formaldehyde, ammonia, methanol, ethanol, acetaldehyde, acetic acid, acrolein, isopropyl ether, ethyl acetate, glycol ether and 2-methoxyethanol were passing through the sensor. Since the sensor does not need to prepare and fix up the granular catalyst, the simple technology reduces cost, improves stability and extends life span. The method can be applied to facilitate detection of dimethyl ether in the air. The possible mechanism of cataluminescence from the oxidation of dimethyl ether on the surface of ceramic heater was discussed based on the reaction products.     

Development and validation of analytical methodology using capillary electrophoresis for separation and determination of anions in rainwater

A new capillary electrophoresis (CE) procedure was developed for simultaneous determination of both organic and inorganic anions in rain water using a background electrolyte (BGE) containing 5 mM molybdate, 0.15 mM CTAH, 0.01% PVA and 5 mM Tris buffer to adjust pH at 7.9. Under optimised conditions, good repeatability (RSD for sulphate in migration time=0.36% and peak area=4.2%), low detection limit (2 ppb for chloride) and satisfactory working range (50 ppb-20 ppm for hydrodynamic injection, 10 ppb-3 ppm for electrokinetic injection for chloride) were obtained. The reliability of the CE procedure developed was established by satisfactory recovery tests and good agreement of results obtained by both the CE and ion chromatography (IC) methods. The procedure developed had been successfully applied for field monitoring of rainwater showing good repeatability and capability of detecting trace anions at ppb levels beyond the IC working range. Thus, the new CE procedure developed provides a quick, sensitive, economic and reliable method to meet the need for the simultaneous determination of both organic and inorganic anions in the acid rain monitoring programme.     

β-Naphthol as a Chromophore and Fluorophore Forming Reagent in the HPLC Determination of Alkyl Halides

Abstract

A suitable chromophore- and fluorophore- forming reagent for the detection of alkyl halide water contaminants is β-naphtol. The ether derivatives are separated from each other and excess β-naphthol reagent by reverse, phase HPLC and are detected by ultraviolet absorption or fluorescence. A method for the determination of alkyl halides is presented. The method is applicable to concentration levels in the ppm range for UV detection and in the ppb concentration range using fluorescence detection.     

Determination of pentachlorophenol in wood samples using liquid chromatography with UV absorbance, amperometric and electron-capture detection

The potential of reversed-phase liquid chromatography (RPLC) with UV and amperometric detection (AD), and of normal-phase liquid chromatography (NPLC) with UV and electron-capture detection (ECD) for the determination of pentachlorophenol (PCP) in wood samples has been studied. When PCP concentrations of at least 1-5 ppm have to be determined, RPLC-UV and RPLC-AD on C18-modified silica are useful techniques, provided a two- or three-step sample-preparation step is used. NPLC-UV on bare silica columns does not offer any advantage over RPLC-UV. NPLC-ECD on bare silica and with an acidified toluene-hexane mixture as eluent offers good selectivity and sensitivity, as well as satisfactory linearity and reproducibility for the determination of PCP in wood samples down to low ppb levels. Use of the two-step clean-up procedure is sufficient, and even a single-step procedure has been utilized. In the latter case, analysis times are longer because of the presence of late-eluting ECD-active interferences. The two-step clean-up procedure generally used involves a liquid-liquid extraction with dichloromethane, and solid-liquid sorption using a Sep Pak C18 cartridge. PCP recovery over the 0.2-10 ppm range is 75-100%. Several wood samples containing 1-50 ppm of PCP have successfully been analyzed, and the good potential of NPLC-ECD for trace-level determination of PCP has been demonstrated.     

Analysis of ergosterol for the detection of mold in soils by automated on-fiber derivatization headspace extraction-SPME-GC/MS

The estimate of ergosterol ([5,7,22-ergostatrien-3β-ol] has been used by many to relate its concentration to the amount of mold in soils. This new method using on-fiber derivatization-solid phase microextraction-GC/MS method for the analysis of ergosterol presents a quick and straightforward method where low detection limits (1.5 ppb) and good limit of quantitation range (3 ppb to 90 ppm) can be achieved with careful control of analytical parameters. After saponification of real soil samples, sampling without extensive workup can be performed and analysis by a standard addition method can be utilized to deduce the original sample concentration of ergosterol. Peak area extraction analysis by MS SIM on selected characteristic fragment ions gives results with RSD ≤ 2.2%.     

Determination of microtraces of Bi, Co, Cu, Fe, Mn, In, Ni, Pb, Sb and Zn in phosphoric acid and ammonium phosphate

Summary Methods for the determination of Bi, Co, Cu, Fe, Mn, In, Ni, Pb, Sb and Zn in phosphoric acid by ETA-AAS using the platform technique were developed. The detection limits are in the range of 1 to 30 ppb for conc. H₃PO₄. Relative standard deviations of 5–10% at 10 times the detection limits were achieved. The results obtained by five different atomic spectroscopic methods are in good agreement (direct Zeeman-ETA-AAS, D₂-ETA-AAS and FAAS; OES and FAAS after trace extraction).     

Sensitive analyses of agricultural chemicals by capillary electrochromatography

Capillary electrochromatography using a monolithic matrix was employed to develop a rapid and highly efficient separation methodology for the analyses of mixtures of agrochemical importance. Using this method, ppm‐ppb detection limits for urea, carbamate, and phenoxy acid herbicides were achieved without a preconcentration technique. The detection limits were further decreased to low‐ppb levels for the same class of compounds using an on‐column preconcentration technique.     

Determination of diethyl ether and methyl iodide in dimethylcadmium using headspace analysis

The possibility of direct gas-chromatographic analysis of dimethylcadmium was demonstrated. A procedure for determining impurities of diethyl ether and methyl iodide using headspace analysis was developed. The limits of detection for diethyl ether and methyl iodide were 3 x 10^-4 and 2 x 10^-3 mol %, respectively.     

Determination of methyl tert.-butyl ether and tert.-butyl alcohol in seawater samples using purge-and-trap enrichment coupled to gas chromatography with atomic emission and mass spectrometric detection

A rapid and simple analytical method has been established for the determination of methyl tert.-butyl ether (MTBE) and tert.-butyl alcohol (TBA), in seawater. The method involves purge-and-trap enrichment followed by gas chromatographic (GC) determination. Two different detection systems have been compared: atomic emission detection (AED) and MS (selected ion monitoring mode). Validation parameters and possible matrix effects have been evaluated. The linearity and analytical precision was good with both methods, but limits of detection reached by AED (10 microg l(-1)) were not low enough to evaluate current environmental concentrations. GC-MS detection presented much better sensitivity [limits of detection (LODs) of 0.04 microg l(-1) for MTBE and 0.09 microg l(-1) for TBA] and selectivity, providing a more reliable determination. The analysis of samples collected from various marinas in the south of Spain (Almería and Málaga) showed, in all cases, detectable concentrations of MTBE that ranged from below LOD to 1842 microg l(-1), depending on the sampling point and time. TBA was also detected in some cases, with concentration levels that ranged from 400 to 600 microg l(-1). These preliminary results should be followed by monitoring programs in coastal waters, in order to establish real levels of presence of MTBE in our coasts and its possible effect on the marine environment.     

Novel ion chromatography technique for the rapid identification and quantification of saturated and unsaturated low molecular weight organic acids formed during the Fenton oxidation of organic pollutants

The Fenton oxidation process is one of the most widely used technologies in the oxidation of organic pollutants. The identification and quantification of end products of these oxidation processes is of prime importance due to environmental concerns of pollution and toxicity. In this work, we have developed a highly sensitive, cheap, easy and rapid method of determining low molecular weight mono and dicarboxylic acids using ion exclusion chromatography with inverse chemical suppression and conductivity detection. Eleven organic acids were simultaneously separated in 22min with detection limits ranging from 10 to 500ppb and limits of quantification from 0.05 to 50ppm. The method was tested and proved to be accurate, reproducible, precise and highly sensitive. Linearity was in the range of R2: 0.977-0.999, with a percentage error of less than 2% for oxalic and maleic acids, and less than 1% for the rest of the organic acids studied.     

Analysis of estrogens in environmental waters using polymer monolith in-polyether ether ketone tube solid-phase microextraction combined with high-performance liquid chromatography

A simple, rapid and sensitive on-line method for simultaneous determination of four endocrine disruptors (17beta-estradiol, estriol, bisphenol A and 17alpha-ethinylestradiol) in environmental waters was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). A poly(acrylamide-vinylpyridine-N,N'-methylene bisacrylamide) monolith, synthesized inside a polyether ether ketone (PEEK) tube, was selected as the extraction medium. To achieve optimum extraction performance, several parameters were investigated, including extraction flow-rate, extraction time, and pH value, inorganic salt and organic solvent content of the sample matrix. By simply filtered with nylon membrane filter and adjusting the pH of samples to 6.0 with phosphoric acid, the sample solution then could be directly injected into the device for extraction. Low detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method were achieved in the range of 0.006-0.10 ng/mL and 0.02-0.35 ng/mL from spiked lake waters, respectively. The calibration curves of four endocrine disruptors showed good linearity ranging from quantification limits to 50 ng/mL with a linear coefficient R(2) value above 0.9913. Good method reproducibility was also found by intra- and inter-day precisions, yielding the RSDs less than 12 and 9.8%, respectively. Finally, the proposed method was successfully applied to the determination of these compounds in several environmental waters.     

Determination of Trace of Methyl tert-Butyl Ether in Water Using Liquid Drop Headspace Sampling and GC

The possibility of applying headspace microextraction into a single drop of solvent for the determination of methyl tert -butyl ether in aqueous solutions has been demonstrated. A drop of benzyl alcohol is used for extraction. The analyte is extracted by suspending a 1.8 μL extracting drop directly from the tip of a microsyringe fixed above an extraction vial with a septum such that the needle passes through the septum and the needle tip is positioned above the surface of the solution. After the extraction is finished, the drop is retracted back into the needle and injected directly into a GC column. Optimization of experimental variables (time, temperature, stirring rate and ionic strength of the solution) with respect to the extraction efficiency was investigated. The calibration range for methyl tert-butyl ether was 0.01–10 ppm and the detection limit 7 ppb. The relative standard deviation for 0.1 ppm methyl tert -butyl ether in water was 5.5%.     

Determination of flotation reagents used in tin-mining by capillary electrophoresis.

Alkyl xanthates (O-alkyl dithiocarbonates) and phosphonates are important organic collectors for the flotation of metals from crude ore. Leaching from waste dumps into river and ground water, these substances can cause environmental pollution. A capillary electrophoretic method for the routine determination of ethyl, isopropyl, hexyl xanthate, and styrene phosphonate has been developed. Separation within 12 min could be achieved in borate pH 8.8 performing UV detection at 254 and 300 nm simultaneously. To improve the limits of detection obtained with hydrodynamic injection (0.4-1.5 ppm), field amplified sample injection (FASI) and stacking were investigated. An increase in sensitivity up to 4-8 fold could be achieved by pressure assisted FASI. Applying a stacking method to enrich the analytes by filling the capillary with sample solution to one third of its length, the limits of detection could be decreased to 10-40 ppb. Water samples from a former tin ore mining area have been analyzed using the optimized stacking technique. Quantitation was performed by standard addition. Good precision and accuracy were obtained, making this robust capillary electrophoretic method well-suited for routine analysis.     

Confirmation method for the identification and determination of some organophosphorus and organochlorine pesticides in cocoa beans by gas chromatography-mass spectrometry

The main objective of this work is to develop a routine quality control method for pesticide residues in cocoa beans, using gas chromatography-mass spectrometry. The investigated pesticides, which are used to control pests in the growing of cacao, are: Acephate, Propoxur, HCH, Heptachlor, Fenitrothion, Pirimiphos-methyl, Aldrin, Dieldrin, pp'-DDE, op-DDE and DDT. Two extraction methods were tested. The first was based on strong attack by concentrated sulphuric acid and later extraction with n-hexane: the investigated residues were Acephate, HCH, Fenitrothion and DDT; recoveries were 68-95% and the detection limits 0.5-10 ppb. The second extraction method was based on the Universal Trace Residue Extractor (UNITREX), which consists of a distillation system for organophosphorus and organochlorine pesticides in fatty samples. The investigated residues were Heptachlor, Pirimiphos-methyl, Aldrin, Propoxur, Dieldrin, op-DDE and pp'-DDE; recoveries were 67-88% and the detection limits 1-10 ppb.