Magnetic Dummy Template Silica Sol–Gel Molecularly Imprinted Polymer Nanospheres as Magnetic Solid-Phase Extraction Material for the Selective and Sensitive Determination of Bisphenol A in Plastic Bottled Beverages

In this study, a core–shell magnetic dummy molecularly imprinted polymer (MDMIP) was prepared with a novel and simple method. The imprinting layer was synthesized directly on the surface of Fe₃O₄ by only one step, which avoided further modification on the exterior of magnetic core. 4,4′-Dihydroxybiphenyl (DDBP) was used as dummy template instead of bisphenol A (BPA) to eliminate the effect of template leakage on quantitative analysis. When used as solid-phase extraction sorbent, a rapid, sensitive, and accurate method for the simultaneous extraction, concentration, and determination of trace BPA in plastic bottled beverage samples by MDMIP-SPE coupled with high-performance liquid chromatography (HPLC) was developed. Advantages of such method may be counted as the mild working temperature during the synthesis, simplicity of extraction procedure, avoidance of leakage of template, time-saving, and high binding capacity and affinity. Several parameters affecting the extraction efficiency of the analytes including the sorbent mass, the pH of sample solution, the HAc percentage in the elute, and the desorption time were investigated. Under optimized conditions, the calibration graph was linear over the range of 11.4–4560 ng mL^?1 with the limit of detection of 0.083 ng L^?1. In addition, the higher enrichment factors (400-fold) and good recoveries (88.6–99.5%) with relative standard deviation (RSD) values less than 9.5% were achieved. Moreover, the developed extraction protocol simplified the process of traditional solid-phase extraction (SPE) provided the possibility for separation and enrichment of BPA from complicated food matrices.     

Solid-Phase Extraction of Florfenicol from Meat Samples by a Newly Synthesized Surface Molecularly Imprinted Sol–Gel Polymer

A new molecularly imprinted polymer (MIP) as a solid-phase sorbent for selective extraction of florfenicol (FF) was prepared by combination of the surface molecular imprinting technique with the sol–gel process. The FF-imprinted silica sorbent was prepared using FF as template, 3-aminopropyltriethoxysilane as functional monomer and tetraethoxysilicate as cross-linker on the silica gel support. The non-imprinted silica (NIP) was synthesized in the same way without addition of FF. The MIP was evaluated as a sorbent in column extraction approach for extraction of FF from aqueous solutions followed by spectrofluorometric determination. The influence of certain variables including the sample pH, the sample volume, the sample flow rate, the type of eluent, and its flow rate on the extraction efficiency of FF was assessed. The prepared FF-MIP silica sorbent showed higher adsorption capacity (64.9 mg g^?1) and significant selectivity than the corresponding NIP (11.5 mg g^?1). The FF-MIP-based solid phase extraction method was successfully applied to the separation and determination of FF from fish and chiken meat samples under the optimized extraction conditions.     

Application of Ion-Imprinted Polymer Nanoparticles for Selective Trace Determination of Palladium Ions in Food and Environmental Samples with the Aid of Experimental Design Methodology

A solid phase extraction method using Pd²⁺ ion-imprinted polymer (Pd²⁺-IIP) nanoparticles combined with flame atomic absorption spectrophotometry (FAAS) was developed for the preconcentration and trace detection of palladium ions. The Pd²⁺-IIP nanoparticles were obtained by precipitation polymerization of 4-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator), Eriochrome Cyanine R (the lead-binding ligand), and palladium ions (the template ion) in acetonitrile solution. The parameters affecting adsorption and desorption steps were optimized by a Box–Behnken design through response surface methodology. Three variables (pH value, extraction time, and amount of the synthesized IIP) were selected as the main factors affecting sorption step, while four variables (type of eluent, volume of the eluent, concentration of the eluent, and elution time) were selected for desorption step in the optimization study. The optimized values by this optimization method were 30 mg, 15 min, 6.0, HCl, 4.0 mL, 1.8 mol L^-l HCl, and 14 min, for amount of polymer, retention time, pH of solution, type, volume, concentration of the eluent, and elution time, respectively. Under the optimized conditions, the detection limit for the proposed method was found to be 0.2 μg L^?1, while the relative standard deviation (RSD) for five replicate measurements was calculated to be <3 %. Finally, the introduced solid phase extraction technique was successfully applied for extraction and determination of Pd²⁺ ions in food and environmental samples.     

Molecularly Imprinted Nanosilica Solid-Phase Extraction for Bisphenol A in Fish Samples

This paper reports a method using molecularly imprinted nanosilica as the solid-phase extraction sorbent to extract bisphenol A (BPA) from fish samples. The selective extraction efficiency of BPA from its structure-analogous by molecularly imprinted solid-phase extraction (MISPE) was compared with commercial C18 SPE column. The reproducibility of MISPE and optimal flow rate of sample were studied. There was a linear correlation in the concentration range of 0.7–114.1 μg l^?1 of BPA (r?=?0.997). The limit of detection (LOD) based on three times ratio of signal to noise was 0.11 μg l^?1. Under optimal conditions, the proposed method was applied to the analysis of BPA in fish samples. The amount of BPA in bream was 4.00 μg kg^?1, and both concentrations of BPA in crucian and weever were below the LOD. The recoveries of BPA standard solution spiked with fish samples were in the range of 92.56–102.3 % with the relative standard deviation less than 10 %.     

A Novel Method for Bisphenol A Analysis in Dairy Products Using Graphene as an Adsorbent for Solid Phase Extraction Followed by Ion Chromatography

A novel and reliable ion chromatography (IC) method using graphene (G) as a solid phase extraction (SPE) adsorbent for the rapid analysis of bisphenol A (BPA) in dairy products was developed. The performances of graphene (G) and commercial C18 for BPA extraction from dairy samples were evaluated; results showed that G had higher adsorption efficiency. IC coupled with an electrochemical detector (ED) is eco-friendly, labor and time saving compared to liquid chromatography mass spectrometry (LC-MS) and gas chromatography mass spectrometry (GC-MS). The effects of the experimental parameters of the IC-ED system were assessed, and the parameters were optimized to provide maximum sensitivity. The linear range is 5–20,000 ng?mL^?1 with an R value of 0.999. The limit of the detection is 0.8 ng?mL^?1 for a 25-μL injection loop. The mean relative recoveries ranged between 83.3 % and 104.6 %, the corresponding inter-day precision was below 5.3 % for 20, 200, 2,000, and 15,000 ng?mL^?1. This method was successfully employed to analyze BPA in dairy samples.     

Electrochemical Determination of Bisphenol A at Multi-walled Carbon Nanotubes/Poly (Crystal Violet) Modified Glassy Carbon Electrode

Bisphenol A (BPA) can disrupt endocrine system. In this study, a novel and sensitive electrochemical senor based on multi-walled carbon nanotubes (MWCNTs) and poly crystal violet (PCV) modified glass carbon electrode (GCE) was developed for determination of BPA. The morphologies and properties of modified electrode were characterized by scanning electron microscopy and electrochemical impedance spectra. Compared with bare GCE and other modified electrodes, this MWCNTs/PCV/GCE exhibited an excellent electrocatalytic role for the oxidation of BPA by significantly enhancing the current response and decreasing the BPA oxidation overpotential. Under optimum conditions, the electrochemical sensor can be applied to the quantification of BPA by linear sweep voltammetry (LSV) with a linear range covering 5 × 10^?8–1 × 10^?4 mol L^?1 (with a correlation coefficient of 0.9969), and the limit detection was 1 × 10^?8 mol L^?1 (S/N = 3). The recovery was between 98.38 and 103.51% in real plastic samples. This strategy might enable more opportunities for the electrochemical determination of BPA in practical applications.     

A New Ultrasonic Thermostatic-Assisted Cloud Point Extraction/Spectrophotometric Method for the Preconcentration and Determination of Bisphenol A in Food,Milk, and Water Samples in Contact with Plastic Products

Bisphenol A (BPA) contamination in foods and beverages usually occurs as a result of migration from the packages that contain it. In this context, a simple, easy-to-use, and efficient method was developed for the spectrophotometric determination of BPA in food, milk, and water samples in contact with plastic products after preconcentration by ultrasonic-thermostatic-assisted cloud point extraction (UTA-CPE). The method is based on the charge transfer-sensitive complexation of BPA with 3-methylamino-7-dimethylaminophenothiazin-5-ium chloride (AzB) in the presence of cetyltrimethylammonium bromide (CTAB) at pH 8.5 and then extraction of the formed complex into the micellar phase of polyethylene glycol dodecyl ether (Brij 35). The effects of the analytical variables affecting complex formation and extraction efficiency were systematically studied and optimized. Under optimized conditions, a good linear relationship was obtained in the range of 1.2–160 μg L^?1 with a detection limit of 0.35 μg L^?1. After preconcentration of a sample of 20 mL, a sensitivity enhancement factor was found to be 180. The accuracy and reliability of the method were evaluated by recovery studies from the spiked quality control samples and intraday and interday precision studies. From the studies conducted, the extraction efficiency (E%) was in the range of 94–103% with a relative standard deviation lower than 5.2% (as RSD%, n = 5). The method was successfully applied to the preconcentration and determination of BPA from the selected sample matrices.

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Graphical Abstract Migration of bisphenol A into the foodstuffs

     

Sodium benzoate and potassium sorbate preservatives in food stuffs in Iran

A high-performance liquid chromatography method was applied for the determination of the levels of benzoate and sorbate in 400 food samples, including pickled cucumbers, canned tomato pastes, sour cherry jams, soft drinks, fruit juices and dairy products (UF-Feta cheeses, Lighvan cheeses, lactic cheeses, yogurts and doogh). The results showed that 270 (67.5%) of all samples contained benzoate ranging from 11.9 to 288.5 mg kg^?1 in lactic cheese and fruit juice, respectively. The levels of sorbate in 98 (24.5%) of the samples were 20.1 to 284.3 mg kg^?1 in doogh and fruit juice, respectively. Moreover, benzoate was detected in all dairy products ranging from 11.9 mg kg^?1 in lactic cheese to 91.2 mg kg^?1 in UF-Feta cheese. A low concentration of benzoate could originate naturally, due to specific biochemical mechanisms during cheese, yogurt and doogh maturation. In conclusion, a minimum level for benzoate in dairy products should be defined in the legislation.     

Development and Validation of a LC-FD Method for the Simultaneous Determination of Eight Bisphenols in Soft Drinks

Bisphenol A (BPA) is a chemical widely used as a monomer in the production of polymers of plastics. It acts as an endocrine-disrupting agent and thus its contaminations of food and beverage should be carefully monitored in order to assess consumers’ risk. In this study, we propose a liquid chromatography-fluorescence detection (LC-FD)-validated method for the simultaneous determination of BPA and seven analogues, i.e., bisphenol AF, bisphenol B, bisphenol E, bisphenol F, BPA diglycidyl ether, bisphenol F diglycidyl ether, and Bisphenol M in soft drinks. A one-step solid-phase extraction (SPE) was effective at reducing the interferences, obtaining good purification of the samples, and consequently good recoveries of all analytes. The separation was obtained on a C18 column by using acetonitrile/water 55:45 (v/v) under isocratic conditions. Method validation was performed according to the European Commission Decision 2002/657/EC criteria, providing good results regarding the analytical parameters of linearity, selectivity, sensitivity, precision, recovery, decision limit (CCα), detection capability (CCβ), limit of detection (LOD), limit of quantification (LOQ), stability, and robustness. The method allows the detection of BPA and BADGE at levels much lower than their legal limits in the food, which are 0.06 and 9.00 mg kg^?1, respectively.     

High Sensitive Method for Determination of the Toxic Bisphenol A in Food/Beverage Packaging and Thermal Paper Using Glassy Carbon Electrode Modified with Carbon Black Nanoparticles

A voltammetric method for fast and high sensitive determination of Bisphenol A (BPA) using glassy carbon electrode (GC) modified with carbon black nanoparticles (CB) was developed. Cyclic voltammetry study in the 0.1 M phosphates of pH = 7.0 gave single anodic peak at 578 mV. Adsorption-controlled oxidation of BPA was found to be irreversible with the participation of two electrons and two protons. The proposed CB/GC electrode significantly improved the oxidation peak current of BPA compared to the bare electrode. Under the optimum conditions, calibration curve was linear in the concentration of BPA from 0.01 to 3 × 10^?6 mol L^?1 with the detection limit of 3.4 × 10^?9 mol L^?1. Moreover, the proposed method was successfully validated by studying the recovery of BPA in commonly available samples: thermal paper (receipt, ticket) and food/beverages packaging. This paper introduces carbon black as a new, perspective material for electrode modification used in voltammetry.     

Hydroxymethylfurfural in fruit puree and juice: preconcentration and determination using microextraction method coupled with high-performance liquid chromatography and optimization by Box–Behnken design

In the present study, a sensitive and rapid method for separation and determination of hydroxymethylfurfural (HMF) in fruit puree and juices was proposed. Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC) was used for extraction and quantitative determination of HMF in fruit puree and juices. The effective parameters such as the type and volume of extraction and dispersive solvents, pH and salt amount (NaCl) were studied and optimized with the aid of response surface methodology based on Box–Behnken design to obtain the best condition for HMF extraction. At the optimized conditions, parameter values were 60 µL extracting solvent, 600 µL dispersive solvent, 2 g NaCl and pH 5. Repeatability of the method, described as the relative standard deviation, was 3.1% (n?=?6) and the recovery was 98.4%. The limit of detection and limit of quantitation were 1.47 and 5.28 µg L^?1, respectively. The merit figures of DLLME–HPLC–UV method showed that the proposed method can be noticed as a new, fast and good alternative method for investigation of HMF in various fruit puree and juice samples.     

Reusable 2-(Dimethylamino)ethyl Methacrylate Polymers On-line Solid-Phase Extraction Coupled to Liquid Chromatography Tandem Mass Spectrometry for Rapid Determination of Acidic Pesticides in Foods

A rapid and easy method was developed for the sensitive determination of six acidic pesticides (2,4,5-trichlorophenoxyacetic acid, acifluorfen, methyl-4-chlorophenoxyacetic acid, fluroxypyr, haloxyfop, and bispyribac-sodium) in pear, apple, cucumber, and rice samples. This method was a full automatic platform using a novel polymeric monolith-based on-line solid-phase extraction (SPE) coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS). A poly(2-(dimethylamino)ethyl methacrylate-co-ethylene dimethacrylate) monolith was fabricated as the sorbent, and the morphology, surface area, and extraction performance of the polymers were characterized. With the addition of 10.0 mL of acetonitrile and 1.0 to 5.0 g of anhydrous NaCl, the food samples were homogenized and centrifuged. The extracted samples were directly loaded and cleaned on the polymers using a 5 mmol L^?1 ammonium acetate solution and subsequently eluted into the analytical column for next separation with an acetonitrile-1.5% formic acid solution as eluting solvent. The detection limit (S/N?=?3) was 0.2 to 2.0 μg kg^?1 for the analytes, and the intra- and inter-day recoveries in pear, apple, cucumber, and rice samples ranged from 80 to 104%, and 83 to 115% with relative standard deviations of less than 13.5%. The developed on-line SPE LC-MS/MS protocol permits an automated and high-throughput determination in only 15 min. Moreover, the intra-batch (n?=?5) and inter-batch precisions (n?=?3) for the preparation of the polymers were lower than 11.6% and the sorbent was sufficiently stable for 500 extraction cycles without a significant loss in the extraction efficiency. The developed method was successfully applied to monitor six acidic pesticides in vegetable, fruit, and cereal samples.     

Analytical determination of bisphenol A (BPA) and bisphenol analogues in paper products by GC-MS/MS

ABSTRACT

Bisphenol A (BPA; 4-[2-(4-hydroxyphenyl)propan-2-yl]phenol), a suspected endocrine disruptor with a weak estrogenic activity, is used in a variety of consumer products, including food-contact materials made of paper and cardboard products. Due to restrictions on the use of BPA because of its potential health risks, BPA is gradually being replaced by other bisphenols because no limitations exist for these substances. This study presents a method for the simultaneous analysis of BPA, bisphenol AF (BPAF), bisphenol B (BPB), bisphenol E (BPE), bisphenol F (BPF) and bisphenol S (BPS) in paper and board products using gas chromatography-tandem mass spectrometry (GC-MS/MS). Paper samples were extracted by liquid extraction, as well as by Folch extraction, derivatised with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and the results compared. The developed method showed good linearity (R² > 0.9965) and precision, yielding relative standard deviations (RSDs) of less than 16.6% for reproducibility and 19.8% for repeatability. The limits of detection and limits of quantification for the different bisphenols ranged from 0.23 to 2.70 µg kg^–1 paper and from 0.78 to 9.10 µg kg^–1 paper, respectively. Analysis of different paper products (recycled, virgin fibre) showed that all the analysed bisphenols were present in the samples, except for BPAF and BPB. A calculation of the ‘worst-case’ scenario assuming a maximum potential migration of 100% of the analytes into food showed that the analysed products can be assumed to be safe regarding the migration of bisphenols.     

Highly Selective Determination of Chrysoidine in Foods Through a Surface Molecularly Imprinted Sol–Gel Polymer Solid-Phase Extraction Coupled with HPLC

A highly selective determination method for chrysoidine, an industrial azoic dye banned in foods, was developed through a novel molecularly imprinted polymer (MIP) online solid-phase extraction coupled with high-performance liquid chromatography. The MIP was firstly synthesized by a surface molecular imprinting technique in combination with a sol–gel process and characterized by FT-IR and adsorption experiments. The MIP exhibited high selectivity and high adsorption capacity for chrysoidine and offered a fast kinetics for the adsorption and desorption of chrysoidine. A number of parameters, including the pH of loading solution, the sample loading flow rates, and eluting time of analyte, were carefully optimized to improve the extraction efficiency. Under the optimal experimental conditions, for a 50-mL sample solution, the enrichment factor was 279 and the detection limit (S/N?=?3) was 6 ng L^?1. The linear plots with r ²?>?0.99 were achieved over a range of 0.04–40 μg L^?1, and the peak area precision (relative standard deviation) for nine parallel determinations was below 6.32 %. This method was employed for quantitative determination of chrysoidine in oil bean curd, yellow croaker, and paprika with satisfactory recoveries (89.3–97.6 %).     

Determination of free and total bisphenol A in human milk samples from Canadian women using a sensitive and selective GC-MS method

A sensitive and selective GC-MS method was developed and used to analyse human milk samples for both free and total bisphenol A (BPA). Total BPA was detected in 72 of the 278 human milk samples (25.9%) at concentrations from < 0.036 to 2.5 ng g^–1 with a geometric mean (GM) of 0.13 ng g^–1 and median of 0.11 ng g^–1, while free BPA was detected in fewer samples, 46 of the 278 samples (16.5%) at concentrations ranging from < 0.036 to 2.3 ng g^–1 with a GM of 0.11 ng g^–1 and median of 0.10 ng g^–1. Ratios of [free BPA]/[total BPA] for the positive samples ranged from 7.9% to 100% with a GM of 57.2% and median of 70.3%. Concentrations of free and total BPA in most samples were low with 0.39 and 0.65 ng g^–1 at the 95th percentile for free and total BPA, respectively, and they are also lower than those reported in other countries. Based on the low frequency of detection of free BPA in human milk samples, in general, dietary exposure to BPA for Canadian breast-fed infants is expected to be somewhat lower compared with exposure among formula-fed infants.     

Determination of folic acid by ion-pair RP-HPLC in vitamin-fortified fruit juices after solid-phase extraction

A sensitive and reliable method was developed for the determination of folic acid (FA) in vitamin-fortified fruit juices and fruit drinks. After solid-phase extraction clean-up with strong-anion-exchange material, FA was determined by ion-pair reversed phase high-performance liquid chromatography (RP-HPLC). Limits of detection (LOD) and quantitation (LOQ) were 0.04 and 0.06 mg/l, respectively. Average recoveries at two fortified levels (0.5 and 1.0 mg/l) were 97% in 0.1 M acetate buffer (pH 4.9) and ranged from 78 to 93% in spiked blackcurrant nectar, apple juice, and cherry nectar, with standard deviations less than 2.3%. The method was used to analyze nine commercial fruit juices and fruit drinks containing FA in the range of 0.30–1.40 mg/l. In two samples significantly less FA was found than specified.     

Determination of phthalate esters in non-alcoholic beverages by GC–MS and optimization of the extraction conditions

A quantificational method for 7 phthalate esters in non-alcoholic beverages was developed. Dimethyl phthalate, di-ethyl phthalate, di-propyl phthalate (DPP), di-butyl phthalate (DBP), benzyl butyl phthalate, di-(2-ethylhexyl) phthalate (DEHP), and di-octyl phthalate (DOP) were extracted from non-alcoholic beverages with the optimized solid-phase extraction method, and quantification was achieved by gas chromatography–mass spectrometry with isotope internal standard of d₄-di-(2-ethylhexyl) phthalate (DEHP-d₄). The inter-day method repeatability (RSD) was 8–13 %, whereas the intra-day method repeatability (RSD) was 9–15 %. The mean spiking recoveries were 84–105 %. A wide variety of phthalate concentrations was observed in 48 non-alcoholic beverages. DEHP was the most abundant phthalate compound followed by DBP, DPP, and DOP. DEHP was found in sport drinks (0.015–0.098 mg L^?1), tea (0.016–0.123 mg L^?1), coffee (0.028–0.159 mg L^?1), and fruit juices (0.022–0.126 mg L^?1).     

Development of CO<Subscript>2</Subscript>-Mediated Switchable Hydrophilicity Solvent-Based Microextraction Combined with HPLC-UV for the Determination of Bisphenols in Foods and Drinks

In traditional dispersive liquid-liquid microextraction procedures, both extraction and dispersive solvents are required, and thus, it increases the consumption of organic solvent. Herein, we reported a CO₂-mediated switchable hydrophilicity solvent-based microextraction (SHS-BME) for the determination of bisphenol compounds (BPCs) in complex milk and drink samples. N,N-Dimethylcyclohexylamine was used as a switchable hydrophilicity solvent; it can switch reversibly between one form that is miscible with water and another that forms a biphasic mixture with water, and thus allow extraction of the analytes in a homogeneous phase without dispersive solvent. Several important parameters were screened and optimized by single factor experiments and central composite design as follows: 782 μL of switchable solvent, 375 μL of NaOH solvent, and 1.1:1 switchable solvent/water (v/v). Under the optimized SHS-BME conditions, the limit of detections (LODs) for BPCs in milk, orange juice, and energy drink samples were in the range of 0.27–0.40 μg L^?1 for BPE, 0.17–0.30 μg L^?1 for BPA, and 0.50–0.67 μg L^?1 for BPB, respectively, and the extraction recoveries for BPCs were in the range of 79.5–103.4% in milk, of 84.5–97.5% in orange juice, and of 91.9–101.2% in energy drinks. The precision of the method, based on relative standard deviations (RSDs), ranged from 1.7 to 4.8% and from 2.1 to 5.7% for intra-day and inter-day comparisons, respectively. In total, this SHS-BME method possesses many advantages, such as high extraction recovery and high detection sensitivity (low LODs and RSDs), no requirement of dispersive solvent, simple operational procedure, reducing the pretreatment time and workload, and so on. Therefore, it has a great potential application value for detection of trace BPCs in routine food tests.     

Development of a Headspace-Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (HS-SPME-GC/MS) Method for the Determination of Benzene in Soft Drinks

A method based on headspace-solid phase microextraction and gas chromatography with mass spectrometry has been developed and validated for the determination of benzene in soft drinks. The extraction step was optimized using a rotatable central composite design including the following experimental variables: extraction temperature, extraction time, sample weight, and salt concentration. The optimized procedure, which was carried out at 30 °C during 30 min by using a 75 μm carboxen-polydimethylsiloxane fiber, showed good linearity within the concentration range 0–25 μg?kg^?1 (r ² ?>?0.999), mean recoveries from 97.5 to 103.1 %, and coefficients of variation from 1.5 to 13.4 % for repeatability and from 1.5 to 15.7 % for within-laboratory reproducibility. Limits of detection and quantification were calculated at 0.02 and 0.08 μg?kg^?1, respectively. The method was applied to determine the concentrations of benzene in 77 samples of beverages from the Brazilian market. Levels from <0.08 to 10.84 μg?kg^?1 were obtained, which are comparable to those verified in other countries. Most of the samples (72.2 %) contained benzene up to 1 μg?kg^?1.     

Determination of Bisphenol A and Alkylphenols in Soft Drinks by High-Performance Liquid Chromatography with Fluorescence Detection

A highly sensitive and selective method was developed for the purification and determination of bisphenol A and alkylphenols in soft drinks by using 2-(11H-benzo[a]carbazol-11-yl) ethyl chloroformate (BCEC-Cl) as pre-column labeling reagent followed by high-performance liquid chromatography (HPLC) with fluorescence detection. The HPLC sensitivity of bisphenol A and alkylphenols was greatly enhanced through the introduction of BCEC-Cl moiety with excellent fluorescence property into the target molecules. Meanwhile, the introduction of highly hydrophobic BCEC-Cl moiety into the analytes also greatly increased the hydrophobicity of the target compounds and distinguished them from hydrophilic matrices. Therefore, little interference was observed. Solid-phase extraction with C18 cartridges was applied to sample purification procedure with recoveries of higher than 82 %. When 20 mL of sample was used for analysis, the limits of quantifications of the analytes were between 0.06 and 0.1 μg?L^?1. The proposed method was successfully applied to the determination of the target compounds in soft drink samples with a much higher sensitivity than traditional HPLC methods.