Determination of Alkylphenols Originated from Alkylphenol Ethoxylates by Cleavage Treatment Combined with GC-MS

A chemical cleavage technique was developed for the determination of alkylphenol ethoxylates (APEOs) in environmental samples involving the conversion of APEOs to alkylphenols (APs). Aluminum triiodide (AlI₃) and trimethylsilyl iodide were selected as cleavage reagents and the former was found to be highly reactive and suitable. With AlI₃ as cleavage reagent, nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs) were equivalently converted to the corresponding origins—nonylphenol (NP) and octylphenol (OP), which were detected by gas chromatography—mass spectrometry (GC-MS). The cleavage process was completed under refluxing condition. Water and methanol influenced the cleavage reaction significantly and should be removed prior to the cleavage reaction. The analytical approach was applied for the estimation of APEOs contents in wastewater by normalizing to APs and presented satisfactory recovery and reproducibility. This cleavage technique provides a common and reliable means to assess the environmental significance of samples contaminated by APEOs based on the presence of APs.     

Determination of chlormequat and mepiquat in pear,tomato, and wheat flour using on-line solid-phase extraction (Prospekt) coupled with liquid chromatography-electrospray ionization tandem mass spectrometry

A new methodology based on pressurized liquid extraction (PLE) followed by LC-MS is presented for the simultaneous and unequivocal determination of alkylphenol ethoxylates (APEOs) and their degradation products, alkylphenols (APs) and alkylphenoxy carboxylates (APECs), in sediment samples. The protocol, applicable to a full range of APEO oligomers and degradation products, permits the sensitive and selective determination of APEOs (nEO = 1-15), APECs (nEO = 0-1) and APs at low ppb levels (LODs = 1-5 microg/kg) in sediment samples. Optimization of the operational parameters of PLE clearly demonstrates that significant thermal losses of APs occur during extraction at elevated temperatures. The loss of octylphenol (OP) at 100 degrees C was 61.2% and of nonylphenol (NP) 40.0%, whereas other compounds were completely recovered. Thus, to avoid losses due to the volatility of alkylphenols, a low extraction temperature should be applied. The conditions that gave the best results for all target compounds were as follows: extraction solvent mixture, methanol-acetone (1:1, v/v); temperature, 50 degrees C; pressure, 1500 p.s.i.; two static cycles. Using PLE and a subsequent clean-up with solid-phase extraction (SPE), the simultaneous extraction of APEOs, APs and APECs from sediment samples was achieved yielding recoveries >70% and producing low MS background noise. The developed methodology was applied on a routine basis to the analysis of alkylphenolic compounds in sediment samples. APEOs and their persistent degradation products were detected in significant concentrations in sediments from Portuguese rivers, especially at sites situated in the proximity of industrial plants (mainly the textile industry). The total concentration of alkylphenolic compounds (APEOs+APs+APECs) ranged from 155 to 2400 microg/kg. Of all the alkylphenolic compounds, NP comprised 40 to 50% with concentrations up to 1172 microg/kg.     

Simultaneous determination of alkylphenol ethoxylates and their biotransformation products by liquid chromatography/electrospray ionisation tandem mass spectrometry

Reversed-phase LC-MS/MS is used to determine major estrogenic alkylphenol ethoxylates (APEOs) and their biotransformation products. It allows the simultaneous analysis of eight APEOs, alkylphenoxy carboxylates (APECs) and alkylphenols (APs) in sewage treatment plant (STP) effluents in the same extract after solid-phase enrichment on polymeric Oasis HLB. As precursor ions, [APEO + NH4]+, [APEC - H]- and [AP - H]- were monitored. Instrumental limits of detection (LOD) were 2-600 pg, corresponding to sample concentrations of 0.04-12 ng l(-1), without correction for overall method recoveries. Matrix-induced signal suppression during electrospray ionisation (ESI) and extraction as well as overall method recoveries were assessed and the suitability of deuterated surrogates as internal standards was evaluated.     

Multi-Target Strategy to Uncover Unexpected Compounds in Rinse-Off and Leave-On Cosmetics

The wide range and complexity of cosmetic formulations currently available on the market poses a challenge from an analytical point of view. In addition, during cosmetics manufacture, impurities coming from raw materials or formed by reaction of different organic compounds present in the formulation may be present. Their identification is mandatory to assure product quality and consumer health. In this work, micro-matrix solid-phase dispersion (μMSPD) is proposed as a multi-target sample preparation strategy to analyze a wide number of unexpected families of compounds including polycyclic aromatic hydrocarbons (PAHs), pesticides, plasticizers, nitrosamines, alkylphenols (APs), and alkylphenol ethoxylates (APEOs). Analytical determination was performed by gas chromatography-mass spectrometry (GC-MS) for the determination of 51 target compounds in a single run, whereas liquid chromatography tandem mass spectrometry (LC-MS/MS) was employed for the analysis of six APs and APEOs. Both methodologies were successfully validated in terms of linearity, accuracy, and precision in leave-on and rinse-off cosmetics. Limits of detection (LODs) were calculated in the low ng g⁻¹, showing their suitability to determine trace levels of impurities and banned compounds with different chemical natures, providing useful tools to cosmetic control laboratories and companies.     

Matrix Effects on Water Analysis for Alkylphenols Using Solid Phase Extraction Gas Chromatography-Mass Spectrometry

Gas chromatography with mass spectrometry is frequently used for the quantification of many classes of substances, including alkylphenols. Alkylphenol polyethoxylates are nonionic surfactants used in a wide variety of industrial and consumer applications. Alkylphenol polyethoxylates can degrade to alkylphenols, which are endocrine disruptors. In analytical validation procedures, the most common parameters studied are the detection and quantification limits, linearity, and recovery; however, the matrix effects are sometimes neglected. Although some investigators have evaluated matrix effects, there is no consensus on how to evaluate them during method validation. In this study, the matrix effects of alkylphenol polyethoxylates (nonylphenol monoethoxylate, nonylphenol diethoxylate, octylphenol monoethoxylate, octylphenol diethoxylate) and alkylphenols (nonylphenol and octylphenol) were studied using solid phase extraction and gas chromatography-mass spectrometry analysis. For alkylphenol polyethoxylates, the matrix effects ranged from 16 to 4692%, whereas for alkylphenols (nonylphenol and octylphenol), the effects were insignificant. Therefore, constructing an analytical curve in the matrix for alkylphenol polyethoxylates is essential.     

Determination of alkylphenol ethoxylates in textiles by normal-phase liquid chromatography and reversed-phase liquid chromatography/electrospray mass spectrometry

Comprehensive analytical methods based on pressurized liquid extraction followed by normal-phase liquid chromatography (NPLC) with ultraviolet detection and reversed-phase liquid chromatography (RPLC)/electrospray mass spectrometry (MS) have been developed for determination of alkylphenol ethoxylates (APEOs) in textile samples. NPLC with an aminosilica column allowed for the chromatographic separation of APEOs according to the increasing number of ethylene units and revealed the exact distribution of individual oligomers. RPLC coupled with electrospray MS was highly sensitive and enabled the complete qualitative and quantitative determination of individual APEOs in textile samples. The 2 analytical methods based on different chromatographic separation mechanisms, i.e., NPLC and RPLC, may provide complementary information of APEOs in textile materials. The 2 detection methods were successfully applied to the investigation of various textile samples, and the data of our research suggested actual pollution in real textile products.     

固相萃取净化-正相高效液相色谱测定纺织品中残留的烷基酚和烷基酚聚氧乙烯醚

建立了测定纺织品中烷基酚(AP)和烷基酚聚氧乙烯醚(APnEO)(n2～16)的正相高效液相色谱法。以甲醇为提取溶剂,用索氏抽提法提取纺织品中的AP和APnEO,用正相高效液相色谱法测定,并对提取溶剂、提取方式和净化条件等前处理条件进行优化。该方法的检出限为1.0 mg/kg,回收率为90.4%～104.1%,相对标准偏差为0.64%～4.21%。采用该方法对多种基质纺织品进行检测,可满足残留检测要求。     

Optimization of a matrix solid-phase dispersion method with sequential clean-up for the determination of alkylphenol ethoxylates in biological tissues

A modified Matrix Solid-Phase Dispersion (MSPD) method with sequential clean-up has been developed to isolate and purify alkylphenol ethoxylates (APEs) and alkylphenols in biological tissues. Elution profile, sequential clean-up adsorbent and experimental set up were optimized. Octadecylsilica was used as the solid-phase for matrix dispersion. Methanol was found to be the optimal eluting solvent for APEs. Aluminium oxide was quite efficient for removing the coeluting interferences. Quantitative analysis was done by reversed-phase HPLC with fluorescence detection. The optimized procedure was applied to analyze both fish and mussel samples. Average recoveries for all spiked tissue samples were greater than 90%. Typical limits of detection amount to tens of ppbs on a wet weight basis.     

Analysis of ethoxylated nonionic surfactants and their metabolites by liquid chromatography/atmospheric pressure ionization mass spectrometry.

The widespread use and questionable environmental acceptability of nonionic surfactants make the alkylphenol ethoxylates (APEOs) and their neutral and acidic degradation products a focus of interest in environmental analytical chemistry. The characterization and especially quantification of polyethoxylate mixtures in environmental matrices is a challenge, because of the complexity of the mixtures. A review on trace analysis of APEOs using atmospheric pressure ionization mass spectrometry, including sample preparation and liquid chromatographic separation, is presented. In this Special Feature, the performances of two ionization methods, atmospheric pressure chemical ionization and electrospray ionization, is discussed in terms of selectivity and sensitivity toward oligomeric mixtures of APEOs. Capabilities and limitations associated with the liquid chromatographic/mass spectrometric detection of APEOs, their main degradation products and their halogenated metabolites, and also specific issues related to the sample preparation, formation of fragments, adducts and cluster ions, quantification of oligomeric mixtures and signal suppression effects in complex matrices, are discussed. Conclusions and future perspectives are outlined.     

Determination of alkylphenol ethoxylates in industrial and environmental samples

Degradation products of nonionic surfactants, which are used in large quantities in several industrial applications, have been shown to elicit estrogenic effects in the laboratory as well as in the environment. This has prompted the monitoring of such products, in particular the alkylphenols (AP) and alkylphenol ethoxylates (APE), in the environment. This study presents a relatively simple method for the determination of AP and APE in industrial and environmental samples by HPLC and GC-MS. It discusses some of the inherent analytical issues concomitant with the determination of the complicated mixtures these analytes are composed of. The method was applied to marine and estuarine sediments as well as wastewater and sewage sludge samples taken from industrial plants. In all marine and estuarine samples APE were found with a predominance of oligomers containing 1–3 ethoxylate units.     

New quality-control materials for the determination of alkylphenols and alkylphenol ethoxylates in sewage sludge

The determination of alkylphenols in sewage sludge is still hindered by the complexity of the matrix and of the analytes, some of which are a mixture of isomers. Most of the methods published in the literature have not been validated, due to the lack of reference materials for the determination of alkylphenols in sludge. Given this situation, the objectives of the present study were to develop a new quality-control material for determining octylphenol, nonylphenol and nonylphenol monoethoxylate in sludge. The material was prepared from an anaerobically digested sewage sludge, which was thermally dried, sieved, homogenized and bottled after checking for the bulk homogeneity of the processed material. Together with the sewage sludge, an extract was also prepared, in order to provide a quality-control material for allowing laboratories to test the measuring step. The homogeneity and 1-year stability of the two materials were evaluated. Statistical analysis proved that the materials were homogeneous and stable for at least 1?year stored at different temperatures. These materials are intended to assist in the quality control of the determination of alkylphenols and alkylphenol ethoxylates in sewage sludge.

二氧化硅/聚苯乙烯复合微球的制备及作为固相萃取填料的研究

以分散聚合法制备了二氧化硅/聚苯乙烯单分散复合微球,以红外光谱、透射电镜(TEM)、扫描电镜(SEM)等手段对其进行了表征。以合成的二氧化硅/聚苯乙烯作为固相萃取填料制作固相萃取小柱。通过固相萃取与液相色谱联用,测定了水中邻硝基酚、间硝基酚、对硝基酚和辛基酚、壬基酚,考察了固相萃取条件对固相萃取柱性能的影响,选择了最佳的色谱分离条件。结果表明,自制固相萃取小柱对水中硝基酚、烷基酚的萃取率高,与HPLC联用测定结果重现性好,邻硝基酚、间硝基酚、对硝基酚、辛基酚、壬基酚的最低检出限分别为0.90、0.72、0.62、0.38和0.41μg/L。     

Focused ultrasound solid-liquid extraction and selective pressurised liquid extraction to determine bisphenol A and alkylphenols in sewage sludge by gas chromatography-mass spectrometry

A new method for determining endocrine disrupter compounds (EDCs) in sewage sludge is described in this paper. EDCs studied were bisphenol A (BPA) and alkylphenols (APs). In order to obtain a fast and simple method, selective pressurised liquid extraction (SPLE) and focused ultrasound solid-liquid extraction (FUSLE) were tested. Best results for SPLE were obtained using Florisil as clean-up sorbent and dichloromethane as extraction solvent, while temperature was the only significant variable. Analyte extraction by SPLE was completed in only one extraction cycle of 1 min at 130 °C. FUSLE was carried out in one step of 20 s at 75% power (0.5 cycles) and with 8 mL of ethyl acetate. Although the optimised FUSLE process was faster, simpler and cheaper, SPLE provided higher recovery values (ranging from 81 to 105%) and therefore SPLE-based method was selected and validated. The SPLE and GC-MS method showed an LOD of 10.7 ng/g for BPA and LODs between 1.2 and 41.6 ng/g for APs. Relative standard deviation values lower than 6% were obtained for all analytes. As a result, an efficient, fast and simple method based on SPLE and GC-MS for the determination of BPA and APs in sewage sludge is proposed.     

Studies of dynamic surface tension of polyoxyethylene alkylphenols at the air–water interface

This paper presents the study of dynamic surface tension of polyoxyethylene alkylphenol surfactants (Igepals) at the air–solution interface. The experimental investigation of the surface tension dynamics are carried out using a pendant drop method for two of the representative alkylphenols (Igepal-630 and Igepal-720) nonionic surfactants. The general trend of the dynamic surface tension for the two surfactants appears to be similar. However, the absolute surface activities are different. Between the two poloxyethylene alkylphenol surfactants, it was found that Igepal-C0-630 has a higher surface activity and a lower critical micelle concentration (CMC) value. This agreed well with their reported hydrophile–lipophile balance (HLB). The equilibrium adsorption parameters for these surfactant systems have been estimation using two different methods and are in good agreement. The theoretical model developed for the surface tension dynamics based on the Statistical Rate Theory (SRT) in our earlier (J. Colloid Interface Sci., 286, 2005, 14–27) work satisfactorily predicted the experimental results for the present systems.     

Gas chromatography-mass spectrometry analysis of alkylphenols in produced water from offshore oil installations as pentafluorobenzoate derivatives

A simple, highly selective and sensitive method for the determination of 14 representative alkylphenols from phenol (C0) to nonylphenol (C9) in produced water is described. Solid-phase extraction (SPE) by anion-exchange sorbent is used to extract alkylphenols from produced water. The samples are then derivatised by pentafluorobenzoyl chloride and analysed on GC-MS (negative ion chemical ionisation, NCI). The derivatisation procedure has been validated by means of two-level factorial design (2(7-4)) experiments. Quantification is done with isotope dilution of five internal standards of different alkyl chain length. The detection limits were at low ng/l levels. A comparison with GC-MS analysis of non-derivatised alkylphenol samples revealed the advantage of derivatisation as described in the method.     

固相萃取柱上衍生气相色谱-质谱法测定水中烷基酚

以烷基酚(APs)主要降解产物辛基酚(4-t-OP)、壬基酚(4-n-NP)为研究对象,建立了固相萃取(SPE)柱上衍生化、气相色谱-质谱(GC-MS)法测定水中APs的分析方法。以C18柱为固相萃取柱、N,O-(三甲基硅)三氟乙酰胺(BSTFA)为硅烷化试剂,设计五因素四水平正交实验L16(45),对衍生化影响因素、衍生化溶剂、衍生化时间以及SPE主要影响因素pH值、盐度和洗脱剂进行优化;在优化条件下,方法的回收率(高于80%)和重现性(RSD低于10%)结果令人满意,4-t-OP和4-n-NP的仪器检出限分别为3.35ng/L和6.38ng/L。采用建立的方法,回收率略高于传统的SPE萃取衍生法,具有有机溶剂用量少,方法简单快速、灵敏度高的特点,适用于河水和海水中痕量烷基酚的快速测定。     

Stir bar sorptive extraction and trace analysis of alkylphenols in water samples by thermal desorption with in tube silylation and gas chromatography-mass spectrometry

A novel method called thermal desorption (TD) with in tube silylation followed by gas chromatography-mass spectrometry (GC-MS), which is used for the determination of trace amounts of alkylphenols (APs) in river water samples, is described. APs are extracted from river water samples and concentrated by the stir bar sorptive extraction (SBSE) technique. The stir bar coated with polydimethylsiloxane (PDMS) is added to 2.0 ml water sample and stirring is carried out for 60 min at room temperature (25 degrees C) in the vial. Then, the PDMS stir bar is subjected to TD with in tube silylation followed by GC-MS. The detection limit is of the sub pg ml(-1) (ppt) level. The method shows good linearity and the correlation coefficients are higher than 0.99 for all analytes. The average recoveries of APs are higher than 90% (R.S.D.: 3.6-14.8%, n=6). This simple and sensitive analytical method may be used in the determination of trace amounts of APs in river water samples.     

Development and validation of a method for the determination of trace alkylphenols and phthalates in the atmosphere

An analytical method has been developed for the simultaneous extraction and determination of trace tertiary octylphenol (t-OP), technical nonylphenol isomers (NP), nonylphenol monoethoxylate isomers (NP1EO) and seven phthalates in the atmosphere using gas chromatography-mass spectrometry (GC-MS). High volume samples were collected using a high-volume pump equipped with a PUF/XAD-2 column for air and glass fiber filter for particles. The detection limits of the method for alkylphenols (APs) and the phthalates ranged from 0.0006 to 0.034 ng m⁻³ in air. The recoveries of t-OP, NP, NP1EO and the phthalates for the entire procedure were satisfactory (>69%). The method was successfully applied to the determination of the analytes in the atmosphere samples collected over land and the ocean. The concentrations of t-OP, NP, NP1EO showed decline trends from land to the open sea, and the phthalates present over land and the North Sea were comparable. It is suggested that the atmosphere is a significant pathway for the transport of alkylphenols and the phthalates in the environment.     

Simultaneous profiling analysis of alkylphenols and amines by gas chromatography and gas chromatography–mass spectrometry

Two-phase O-ethoxycarbonylation was performed to alkylphenols in acidic solution with ethyl chloroformate present in dichloromethane phase fortified with triethylamine with subsequent N-ethoxycarbonylation of amines after adjusting to alkaline pH. The resulting ethoxycarbonyl derivatives were subjected to pentafluoropropionylation, clean-up and concentration for analysis by gas chromatography and gas chromatography–mass spectrometry. The present method was linear (r ≥ 0.9959) in the range of 0.5–10.0 μg ml^−l with good precision (≤9.5%) and accuracy (−8.9 to 9.5%) for 20 phenols and 27 amines examined, allowing simultaneous screening for a total of one alkylphenol and four amines from wine and beer.     

Alkylphenol retention indices

A novel type of retention indices for alkylphenols and related compounds are proposed. The alkylphenol retention indices (APRI) use para-substituted n-alkylphenols as reference series. APRI for para-n-alkylphenols are per definition equal to the number of carbon atoms in the alkyl substituent; the value for phenol is zero. Application of the APRI system with different types of derivatisation of the phenolic hydroxy group showed that the derivatisation has limited influence on these indices. Especially para-substituted alkylphenols gave APRI values that could be transferred with high accuracy from one type of derivative to another. By comparing results obtained with different gradients in temperature-programmed GC, it was also shown that APRI is less affected by chromatographic conditions than retention indices based on n-alkanes.