Headspace gas chromatographic determination of 1,4-dioxane with adsorption preconcentration on silica modified with λ-carrageenan

Organosilica materials containing λ-carrageenan on their surface are synthesized. The conditions for the immobilization of the polysaccharide, such as phase contact time and pH and concentration of solutions, are optimized. It is shown that the chemisorption of the polysaccharide passes through ion exchange multipoint immobilization, which provides a high hydrolytic stability of the prepared organosilica. The rate of washing of λ-carrageenan to the solution does not exceed 0.5%. The physical and chemical characteristics of the new material are studied. In particular, it is shown that the material is completely stable up to 200°C and reversibly desorbs water at 120°C; it well adsorbs 1,4-dioxane from the gas phase and desorbs it under heating to 70°C. This ensures the use of the prepared carrageenan-containing material as an adsorbent for a solid-phase cartridge designed for the adsorption preconcentration of 1,4-dioxane in its headspace gas chromatographic determination in samples of nonionic surfactants. The developed procedure ensures the determination of 1,4-dioxane by gas chromatography with a flame ionization detector in the concentration range 0.012–3.750 mg/L with a limit of detection of 0.0014 mg/L. Preconcentration lowers the limit of detection in the determination of 1,4-dioxane by 50 times.     

Occurrence of 1,4-dioxane in cosmetic raw materials and finished cosmetic products.

Surveys of cosmetic raw materials and finished products for the presence of the carcinogen 1,4-dioxane have been conducted by the U.S. Food and Drug Administration since 1979. Analytical methods are described for the determination of 1,4-dioxane in ethoxylated cosmetic raw materials and cosmetic finished products. 1,4-Dioxane was isolated by azeotropic atmospheric distillation and determined by gas chromatography using n-butanol as an internal standard. A solid-phase extraction procedure based on a previously published method for the determination of 1,4-dioxane in cosmetic finished products was also used. 1,4-Dioxane was found in ethoxylated raw materials at levels up to 1410 ppm, and at levels up to 279 ppm in cosmetic finished products. Levels of 1,4-dioxane in excess of 85 ppm in children's shampoos indicate that continued monitoring of raw materials and finished products is warranted.     

Headspace gas chromatography analysis of toxic contaminants in ethoxylated alcohols and alkylamines

Summary Headspace-gas chromatography was used to determine the contents of toxic 1,4-dioxane, ethylene oxide and ethylene glycol in ethoxylated alcohols and alkylamines, and in commercial cosmetics and washing products. A Permaphase PEG capillary column was used for the determination of 1,4-dioxane and ethylene oxide and a DB-17 column for ethylene glycol determination. Dimethylformamide was used as the solvent in the determination of 1,4-dioxane and ethylene oxide, and undecanol in the case of ethylene glycol. The detection limits for ethylene oxide, 1,4-dioxane and ethylene glycol are 1,2 and 10 μg·g⁻¹, respectively.     

Impurity analysis of 1,4-dioxane in nonionic surfactants and cosmetics using headspace solid-phase microextraction coupled with gas chromatography and gas chromatography-mass spectrometry

1,4-Dioxane impurity in nonionic surfactants and cosmetics were analyzed using solid-phase microextraction (SPME) coupled with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Experimental results show that there is no significant difference using SPME-GC and SPME-GC-MS for analysis of 1,4-dioxane in three types of nonionic surfactants at the 95% confidence level. The relative standard deviation (R.S.D.) values of each analytical method were smaller than 3%. The amount of 1,4-dioxane was found to vary from 11.6 +/- 0.3 ppm to 73.5 +/- 0.5 ppm in 30% of nonionic surfactants from manufacturers in Taiwan. These methods were linear over the studied range of 3-150 ppm with correlation coefficients higher than 0.995. The recoveries of 1,4-dioxane for these nonionic surfactants following SPME were all higher than 96 +/- 1% (n = 3). The detection limits of 1,4-dioxane for these nonionic surfactants following SPME were from 0.06 ppm to 0.51 ppm. The experimentally determined level of 1,4-dioxane in cosmetics from manufacturers in Taiwan varied from 4.2 +/- 0.1 ppm to 41.1 +/- 0.6 ppm in 22% of daily used cosmetics following SPME coupled with GC and GC-MS. Conventional solvent extraction takes around 1 h for extraction and reconcentration but SPME takes only around 10 min. SPME provides better analyses of 1,4-dioxane in nonionic surfactants and cosmetics than conventional solvent extraction and head space pretreatments in term of simplicity, speed, precision, detection limit, and solvent consumption.     

An internal surface reversed phase column for the effective removal of humic acid interferences in the trace analysis of mecoprop in soils with coupled-column RPLC-UV

In the development of a screening method for the determination of residues of mecoprop in soils involving coupled-column RPLC-UV (228 nm) the cleanup performance of a 5 μm GFF-II internal surface reversed phase (ISRP, Pinkerton) analytical column (50 × 4.6 mm I.D.) as a first column was investigated. In comparison to an analytical C18 column the ISRP column substantially improved the separation between acidic analyte and co-extracted humic substances. Under the selected coupled-column conditions soil extracts obtained after hydrolysis with an aqueous alkaline solution, acidifying and centrifugation could be analyzed directly allowing the determination of mecoprop in soils to a level of about 0.02 mg/kg. A rapid concentration step on a 100 mg C18 solid phase extraction (SPE) cartridge was adopted into the procedure providing a limit of detection (S/N = 3) of 0.01 mg/kg of mecoprop in soil. The method was validated by analyzing freshly spiked soil samples and samples with aged residues. In case of freshly spiked samples the overall recovery was 87% (n = 18, spiked level 0.02–8.0 mg/kg) with a repeatability of 6.8% and a reproducibility of 8.3%. No significant decrease of the recovery was observed for samples with aged residues (n = 15, spiked level 0.1 and 8.0 mg/kg) during a storage of 29 days in the refrigerator at about 4?°C; a storage of 67 days provided a mean recovery of 76% (n = 14, spiked level 8.0 mg/kg).     

Schnelle Methode zur gas-chromatographischen Bestimmung von 5-Brom-5-nitro-1,3-dioxan in Shampoos und Badepr?paraten

Zusammenfassung Zur Bestimmung von 5-Brom-5-nitro-1,3-dioxan in tensidhaltigen nicht-emulsionsartigen Cosmetica wie Shampoos, Schaum- und Duschbädern wurde — unter Berücksichtigung eines zu erwartenden Konzentrationsbereichs von 0,001–0,1% sowie der allgemein bekannten Problematik der Abtrennung von Wirkstoffen aus Tensidmatrices 3- eine schnelle und einfach durchzuführende, für die Routine geeignete Analysenmethode entwickelt. Die qualitative und quantitative Bestimmung erfolgt gas-chromatographisch mittels Electron-Capture Detector (ECD) nach säulen-chromatographischer Isolierung. Aufgrund der hohen Elektronenaffinität des Moleküls und der daraus resultierenden Selektivität des ECD's wird 5-Brom-5-nitro-1,3-dioxan äußerst empfindlich registriert, so daß die Nachweisgrenze 2 pg absolut beträgt. Die durchschnittlichen Wiederfindungsraten wurden im angegebenen Konzentrationsbereich zu 96% ermittelt. Die Standardabweichung beträgt ±0,14 mg/100 g bei einem mittleren Gehalt von 2 mg/100 g. Der Zeitaufwand für parallel durchgeführte Doppelanalysen beträgt etwa 60 min. An einer Auswahl von Handelsproben wurde die Methode geprüft. Danach enthielten von 18 untersuchten Proben acht 5-Brom-5-nitro-1,3-dioxan zwischen 0,002 und 0,04%.

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Rapid method for the gas-chromatographic determination of 5-Bromo-5-nitro-1,3-dioxane in shampoos and bath preparations

Summary A simple and rapid method suitable for routine analysis was developed to determine 5-bromo-5-nitro-1,3-dioxane in non-emulsified cosmetics containing surfactants. Its concentration in shampoos, foam baths and shower bath preparations was expected between 0.001 and 0.1%. The qualitative and quantitative determination was made by gas chromatography with an electron-capture detector (ECD) after column-chromatographic separation. The sensitive recording of 5-bromo-5-nitro-1,3-dioxane is due to the intensive electron affinity of the molecule and the selectivity of the ECD. The detection limit is 2 pg. The average recovery rate in the given concentration range was ascertained to be 96%. The standard deviation is ±0.14mg/100g for an average content of 2mg/100g. The expenditure of time for a duplicate determination is about 60 min. A selection of 18 commercial products was examined. Eight samples contained 0.002–0.04% of 5-bromo-5-nitro-1,3-dioxane.

     

Transition Metals and Organic Ligands Influence Biodegradation of 1,4-Dioxane

1,4-Dioxane, a contaminant increasingly detected in water supplies, is a public health concern because it is classified as a possible human carcinogen. 1,4-Dioxane can be biodegraded by aerobic bacteria via monooxygenase-catalyzed reactions. While these metalloenzymes require trace metals as cofactors in their catalytic sites, these metals may be toxic at elevated concentrations. In this study, the effects of transition metals on 1,4-dioxane biodegradation by Pseudonocardia dioxanivorans CB1190, a monooxygenase-expressing bacterium, were investigated. Dose-dependent inhibition of 1,4-dioxane biodegradation by Cd(II), Cu(II), and Ni(II) was observed, whereas Zn(II) had no measurable effect on biodegradation rates. 1,4-Dioxane biodegradation in cultures exposed to 2 mg/L Cu(II) was restored in the presence of 0.005, 0.05, and 0.5 mM alginin, 0.05, and 0.5 mM cysteine, and 0.005 mM tannin. These results indicated that specific ligands bind with transition metals and alleviate bacterial toxicity. In parallel experiments, tannin and cysteine inhibited 1,4-dioxane biodegradation, but alginin, BSA, and SRNOM did not affect the biodegradation rates. Thus, monooxygenase-catalyzed biodegradation rates are subject to interactions among transition metals and natural organic ligands in the environment. Mechanistic insights and quantitative data obtained in this study will be useful for designing bioremediation strategies at sites simultaneously contaminated with metals and organic pollutants.     

An internal surface reversed phase column for the effective removal of humic acid interferences in the trace analysis of mecoprop in soils with coupled-column RPLC-UV

In the development of a screening method for the determination of residues of mecoprop in soils involving coupled-column RPLC-UV (228 nm) the cleanup performance of a 5 μm GFF-II internal surface reversed phase (ISRP, Pinkerton) analytical column (50 × 4.6 mm I.D.) as a first column was investigated. In comparison to an analytical C18 column the ISRP column substantially improved the separation between acidic analyte and co-extracted humic substances. Under the selected coupled-column conditions soil extracts obtained after hydrolysis with an aqueous alkaline solution, acidifying and centrifugation could be analyzed directly allowing the determination of mecoprop in soils to a level of about 0.02 mg/kg. A rapid concentration step on a 100 mg C18 solid phase extraction (SPE) cartridge was adopted into the procedure providing a limit of detection (S/N = 3) of 0.01 mg/kg of mecoprop in soil. The method was validated by analyzing freshly spiked soil samples and samples with aged residues. In case of freshly spiked samples the overall recovery was 87% (n = 18, spiked level 0.02–8.0 mg/kg) with a repeatability of 6.8% and a reproducibility of 8.3%. No significant decrease of the recovery was observed for samples with aged residues (n = 15, spiked level 0.1 and 8.0 mg/kg) during a storage of 29 days in the refrigerator at about 4 °C; a storage of 67 days provided a mean recovery of 76% (n = 14, spiked level 8.0 mg/kg). Received: 4 May 1998 / Revised: 11 July 1998 / Accepted: 18 July 1998     

High-performance liquid chromatography-diode array detection of trichloroethene and aromatic and aliphatic anionic surfactants used for surfactant-enhanced aquifer remediation

A method utilizing direct aqueous injection with high-performance liquid chromatography and diode array detection (HPLC-DAD) is presented for the quantitation determination of trichloroethene (TCE) in the presence of anionic surfactants that are used to enhance the recovery of dense non-aqueous phase liquids from contaminated groundwater aquifers. The anionic surfactants investigated in this study including alkyl diphenyloxide disulfonate (Dowfax 8390) and dihexylsulfosuccinate (Aerosol MA 80-1) are used to enhance the solubility, and hence recovery, of TCE. In this type of environmental engineering application, the levels of surfactants and TCE encountered are very high (part per million to part per thousand). The anionic surfactants and TCE are quantitatively determined by direct aqueous injection onto a reversed-phase HPLC column with diode array detection. The quantitation limits of the method obtained using 100 microl injections are 0.1 mg/l for alkyl diphenyloxide disulfonates, 20 mg/l for dihexylsulfosuccinate, and 0.05 mg/l for TCE. This approach is advantageous over using gas chromatography for TCE and HPLC for the surfactants because the use of a single analytical instrument reduces sample preparation and analysis times, which increases sample throughput.     

Analysis of Oxygenated Solvents in Groundwater by Dynamic Thermal Stripping-GC-MSD

Abstract

Analysis of three oxygenated solvents (acetone, THF and 1,4-dioxane) in groundwater was conducted by dynamic thermal stripping followed by thermal desorption into a GC-MSD with monitoring of selected ions. This method has a significantly better practical quantitation limit than the current EPA method (13 vs. 150 μg/L for 1,4-dioxane). Using this method a plume of groundwater contaminated with 1,4-dioxane emanating from a former solvent disposal site was mapped. More than 10 years after disposal, concentrations of 1,4-dioxane greater than 3 mg/L were measured at points more than 300 m from the site.     

顶空气相色谱法测定土壤中苯胺

采用顶空气相色谱法测定土壤中的苯胺,对盐类及其用量、顶空温度等条件进行了优化。当加入2.5 g NaOH,80 ℃进行顶空时,苯胺在0.05~2.50 mg/kg范围内线性良好,方法检出限0.007 mg/kg,样品加标平行测定的RSD低于6%,回收率高于80%。方法操作简单,检出限低,适用于土壤中苯胺的测定。     

并联式双三元高效液相色谱系统快速检测土壤中6种蒽醌类化合物

建立了用于住宅建设污染土壤中1,8-二硝基蒽醌、1,5-二硝基蒽醌、1-氨基蒽醌、蒽醌、萘、1,4,5,8-四氯蒽醌等6种蒽醌类化合物含量的高效液相色谱分析方法。利用Ultimate双三元液相色谱仪的特点,设计了一套并联式双系统,采用2根相同的色谱柱(Dikma Diamonsil C18)交叉分析,节省了41.46%的分析时间。以50 mL N,N-二甲基甲酰胺-1,4-二氧六环-甲醇(5:20:25, v/v/v)为萃取剂,采用超声波辅助方法提取样品中的6种目标物。6种目标物的平均加标回收率为82.7%～101%,相对标准偏差为1.8%～3.2%,检出限(以信噪比为3计)为0.007～0.054 mg/kg,可满足北京地方标准DB11/T 811-2011的限量要求。该方法简便、准确,并能节省检测时间,有良好的重现性,可用于土壤中蒽醌类化合物的检测。     

Residue determination of glyphosate, glufosinate and aminomethylphosphonic acid in water and soil samples by liquid chromatography coupled to electrospray tandem mass spectrometry

This paper describes a method for the sensitive and selective determination of glyphosate, glufosinate and aminomethylphosphonic acid (AMPA) residues in water and soil samples. The method involves a derivatization step with 9-fluorenylmethylchloroformate (FMOC) in borate buffer and detection based on liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS). In the case of water samples a volume of 10 mL was derivatized and then 4.3 mL of the derivatized mixture was directly injected in an on-line solid phase extraction (SPE)-LC-MS/MS system using an OASIS HLB cartridge column and a Discovery chromatographic column. Soil samples were firstly extracted with potassium hydroxide. After that, the aqueous extract was 10-fold diluted with water and 2 mL were derivatized. Then, 50 microL of the derivatized 10-fold diluted extract were injected into the LC-MS/MS system without pre-concentration into the SPE cartridge. The method has been validated in both ground and surface water by recovery studies with samples spiked at 50 and 500 ng/L, and also in soil samples, spiked at 0.05 and 0.5 mg/kg. In water samples, the mean recovery values ranged from 89 to 106% for glyphosate (RSD <9%), from 97 to 116% for AMPA (RSD < 10%), and from 72 to 88% in the case of glufosinate (RSD < 12%). Regarding soil samples, the mean recovery values ranged from 90 to 92% for glyphosate (RSD <7%), from 88 to 89% for AMPA (RSD <5%) and from 83 to 86% for glufosinate (RSD <6%). Limits of quantification for all the three compounds were 50 ng/L and 0.05 mg/kg in water and soil, respectively, with limits of detection as low as 5 ng/L, in water, and 5 microg/kg, in soil. The use of labelled glyphosate as internal standard allowed improving the recovery and precision for glyphosate and AMPA, while it was not efficient for glufosinate, that was quantified by external standards calibration. The method developed has been applied to the determination of these compounds in real water and soil samples from different areas. All the detections were confirmed by acquiring two transitions for each compound.     

Experimental determination and modeling of structure II hydrates in mixtures of methane+water+1,4-dioxane

Hydrate phase equilibrium conditions were measured with a Cailletet apparatus in the pressure range 2<14 MPa. The investigated 1,4-dioxane concentrations were 1, 2, 5, 7, 10, 20 and 30 mol% relative to water. The results show that adding 1,4-dioxane up to concentrations of 6 mol%, about the stoichiometric ratio of large sII cages to water (1/17), reduced the equilibrium pressure of hydrate formation. Adding 1,4-dioxane beyond 6 mol% caused a slow increase of the equilibrium pressures. The hydrate phase equilibria data were modeled as equilibrium between a liquid phase of water and 1,4-dioxane, with a small amount of methane, and a sII hydrate of 1,4-dioxane and methane. The chemical potential of the hydrate phase was described using the van der Waals and Platteeuw theory. Activity coefficients of the liquid phase were calculated by a van Laar relation, based on literature 1,4-dioxane+water VLE data. The predicted equilibrium pressures calculated were within 5% of the data up to a concentration of 20 mol% 1,4-dioxane relative to water.     

液相色谱法测定番茄制品中链霉素和双氢链霉素的残留量

建立了测定番茄制品中链霉素和双氢链霉素残留量的净化方案.样品中的残留物用磷酸盐缓冲液(pH4)提取,经分散固相萃取法初步净化后,再经串联双柱固相萃取净化,用RPC18(Symmetry Shield)色谱柱在梯度洗脱下分离待测物,外标法定量.链霉素的线性范围为0.05～0.8 mg/L,相关系数r＞0.999 8.方法的回收率为71％～95％,定量限(S/N=10)为0.1 mg/kg,测定结果的相对标准偏差为2.6％～10.5％.该方法操作简便,净化效果好,灵敏、准确,检测成本低,适用于检测和分析番茄制品中链霉素和双氢链霉素的残留量.     

茶叶中氟虫腈残留量的测定

建立了快速测定茶叶中氟虫腈残留量的气相色谱方法.茶叶中的氟虫腈经丙酮与正己烷混合液提取,经中性氧化铝-石墨化碳混合柱净化,丙酮与正己烷混合液定容,用外标法定量,以气相色谱法（GC-μECD）测定.试验结果表明：样品中加入0.00080-0.00800 mg/kg浓度水平的氟虫腈,回收率在74.9%-116.8%,检测限为0.00080 mg/kg,相对标准偏差在0.94%-11.10%范围内,能满足我国茶叶对日出口检测的要求.     

Determination of 1,4-dioxane in cosmetic products by high-performance liquid chromatography

A rapid high-performance liquid chromatographic procedure has been developed for the assay of 1,4-dioxane in cosmetic products. After solid-phase extraction, using Bond Elut CN and Bond Elut C18 cartridges, samples were analysed directly on a LiChrospher CH-8 reversed-phase column with spectrophotometric detection at 200 nm and acetonitrile - water as eluent. Recovery of 1,4-dioxane from different cosmetic matrices was between 81.5 and 90.1% in the 30-90 microgram g(-1) range. The minimum quantifiable amount was 6.5 microgram g(-1). The method is simple, reproducible and specific and is suitable for routine analyses of commercial cosmetics.     

Gas chromatographic-mass spectrometric determination of hydrophilic compounds in environmental water by solid-phase extraction with activated carbon fiber felt

Simple gas chromatographic-mass spectrometric determination of hydrophilic organic compounds in environmental water was developed. A cartridge containing activated carbon fiber felt was made by way of trial and was evaluated for solid-phase extraction of the compounds in water. The hydrophilic compounds investigated were acrylamide, N,N-dimethylacetamide, N,N-dimethylformamide, 1,4-dioxane, furfural, furfuryl alcohol, N-nitrosodiethylamine and N-nitrosodimethylamine. Overall recoveries were good (80-100%) from groundwater and river water. The relative standard deviations ranged from 4.5 to 16% for the target compounds. The minimum detectable concentrations were 0.02 to 0.03 microg/l. This method was successfully applied to several river water samples.     

橙汁中苯甲酸含量测定的国际比对APMP.QM-P23

建立了橙汁中苯甲酸含量的高效液相色谱-紫外检测（HPLC-UV）和液相色谱-同位素稀释质谱法（LC-IDMS）两种准确测定方法,应用于亚太计量规划组织（Asia Pacific Metrology Programme,APMP）开展的橙汁中苯甲酸含量测定的国际比对（APMP.QM-P23）,取得了满意的结果,对我国在相关领域的国际计量等效互认提供了有力的支持。本研究着重考察了色谱分离条件和样品预处理条件对测定结果的影响,对两种方法测定比对样品结果的不确定度进行了详细分析研究。HPLC-UV方法的检出限（信噪比大于3）为0.75 mg/kg,在100 mg/kg添加水平下,橙汁中苯甲酸的平均回收率为99.4%;LC-IDMS方法的检出限为0.05 mg/kg,在相同浓度添加水平下,苯甲酸的平均回收率为99.6%。采用两种方法同时对样品进行测定,比对报出结果苯甲酸含量为（102.0±2.1）mg/kg（包含因子k=2）。两种方法均简单、准确、可靠,且具有较好的重现性,LC-IDMS方法由于灵敏度高更适合于橙汁中微量苯甲酸的测定。     

坚果及其制品中匹克司残留量气相色谱测定法

确立了坚果及其制品中匹克司残留量的气相色谱测定方法试样采用甲醇提取，经ＰＴ－硅镁柱净化，ＧＣ－ＥＣＤ测定，方法简便，快速灵敏，检出限０．０２＊１０＾－３ｇ／ｋｇ，添加回收率８７．４％－９３．２％，相对标准偏差４．４％－６．８８％．。