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Analytica Chimica Acta (v.667, #1-2)

Editorial Board (pp. iii).

Application of a superoxide (O₂⁻) thermal source (SOTS-1) for the determination and calibration of O₂⁻ fluxes in seawater by M.I. Heller; P.L. Croot (pp. 1-13).

Superoxide (O₂⁻) is an important short lived transient reactive oxygen species (ROS) in seawater. The main source of O₂⁻ in the ocean is believed to be through photochemical reactions though biological processes may also be important. Sink terms for O₂⁻ include redox reactions with bioactive trace metals, including Cu and Fe, and to a lesser extent dissolved organic matter (DOM). Information on the source fluxes, sinks and concentration of superoxide in the open ocean are crucial to improving our understanding of the biogeochemical cycling of redox active species. As O₂⁻ is a highly reactive transient species present at low concentrations it is not a trivial task to make accurate and precise measurements in seawater. In this study we developed the appropriate numerical analysis tools and investigated a number of superoxide sources and methods for the purposes of calibrating O₂⁻ concentrations and/or fluxes specifically in seawater. We found the superoxide thermal source bis(4-carboxybenzyl)hyponitrite (SOTS)-1 easy to employ as a reliable source of O₂⁻ which could be successfully applied in seawater. The thermal decomposition of SOTS-1 in seawater was evaluated over a range of seawater temperatures using both a flux based detection scheme developed using two spectrophotometric methods: (i) 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and (ii) ferricytochrome c (FC), or a concentration based detection scheme using a chemiluminescence flow injection method based on the Cypridina luciferin analog 2-methyl-6-(p-methoxyphenyl)3-7-dihydroimidazol[1,2-α]pyrazin-3-one (MCLA) as reagent. Our results suggest SOTS-1 is the best available O₂⁻ source for determining concentrations and fluxes, all detection systems tested have their pros and cons and the choice of which to use depends more on the duration and type of experiment that is required.

Keywords: Superoxide; Seawater; Hydrogen peroxide; Chemiluminescence; Spectrophotometry

Variables selection methods in near-infrared spectroscopy by Zou Xiaobo; Zhao Jiewen; Malcolm J.W. Povey; Mel Holmes; Mao Hanpin (pp. 14-32).

Near-infrared (NIR) spectroscopy has increasingly been adopted as an analytical tool in various fields, such as the petrochemical, pharmaceutical, environmental, clinical, agricultural, food and biomedical sectors during the past 15 years. A NIR spectrum of a sample is typically measured by modern scanning instruments at hundreds of equally spaced wavelengths. The large number of spectral variables in most data sets encountered in NIR spectral chemometrics often renders the prediction of a dependent variable unreliable. Recently, considerable effort has been directed towards developing and evaluating different procedures that objectively identify variables which contribute useful information and/or eliminate variables containing mostly noise. This review focuses on the variable selection methods in NIR spectroscopy. Selection methods include some classical approaches, such as manual approach (knowledge based selection), “Univariate” and “Sequential” selection methods; sophisticated methods such as successive projections algorithm (SPA) and uninformative variable elimination (UVE), elaborate search-based strategies such as simulated annealing (SA), artificial neural networks (ANN) and genetic algorithms (GAs) and interval base algorithms such as interval partial least squares ( iPLS), windows PLS and iterative PLS. Wavelength selection with B-spline, Kalman filtering, Fisher's weights and Bayesian are also mentioned. Finally, the websites of some variable selection software and toolboxes for non-commercial use are given.

Keywords: Near-infrared spectroscopy; Chemometrics; Wavelength; Variable selection

Review of preparative and analytical procedures for the study of proteins in grape juice and wine by D. Le Bourse; S. Jégou; A. Conreux; S. Villaume; P. Jeandet (pp. 33-42).

Proteins have a great influence on wine quality as they exhibit a various range of properties. In fact, they are involved among others in white wine turbidity, organoleptic characteristics and foam formation in sparkling wines. These compounds could also be of major interest for varietal differentiation, regarding wine authentication and traceability issues.To provide a better understanding of the role played by these biomolecules in wine processing and explore their potential applications, there is a manifest need for the quantification and characterization of each individual one in terms of sequence, structure and intrinsic and functional properties.We thus present an overview of preparative and analytical methods for the study of proteins in grape juices and wines, from routine techniques to dedicated methodologies. They include sample preparation with chromatographic methods for the purification and identification of proteins, quantification protocols and characterization procedures such as electrophoretic techniques, immunological methods, sequencing, mass spectrometry, physico-chemical and structural analyses, and so on. We expose advantages and limits of each technique and focus on the different but complementary information they can provide.Despite the past years advances in the field proteins identification, the elucidation of the full protein profile for grape juices and wines remains strenuous. Their interactions with other wine compounds make the challenge even harder. We therefore emphasize the requirement of the techniques to be refined and suggest the developments to be expected.

Keywords: Abbreviations; PR; pathogenesis-related; SDS-PAGE; sodium dodecyl sulfate polyacrylamide gel electrophoresis; RP-HPLC; reversed phase high performance liquid chromatography; ELISA; enzyme-linked immunosorbent assay; FPLC; Fast Protein Liquid Chromatography; HPSEC; high performance size exclusion chromatography; HIC; hydrophobic interaction chromatography; ConA; concanavalin A; EPE; electroendosmotic preparative electrophoresis; CE; capillary electrophoresis; CGE; capillary gel electrophoresis; MS; mass spectrometry; FFE; free-flow electrophoresis; IEF; isoelectric focusing; ESI-FTICR-MS; electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry; 2D-E; two-dimensional electrophoresis; MS/MS; tandem mass spectrometry; MALDI-TOF; matrix-assisted laser desorption/ionization time-of-flight; 2D-IF-LDS; two-dimensional isoelectric focusing-lithium dodecyl sulfate; PAS; periodic acid-Schiff; PTA; plate trapped antigen; PVDF; polyvinylidene fluoride; NMR; nuclear magnetic resonance; TOCSY; total correlation spectroscopy; HMQC; heteronuclear multiple quantum coherence; EST; expressed sequence tag; iTRAQ; isobaric tag for relative and absolute quantitationProtein; Grape juice; Wine; Chromatography; Electrophoresis; Mass spectrometry

Determination of mercury in rice by cold vapor atomic fluorescence spectrometry after microwave-assisted digestion by Maria José da Silva; Ana Paula S. Paim; Maria Fernanda Pimentel; M. Luisa Cervera; Miguel de la Guardia (pp. 43-48).

A cold vapor atomic fluorescence spectrometry method (CV-AFS) has been developed for the determination of Hg in rice samples at a few ngg⁻¹ concentration level. The method is based on the previous digestion of samples in a microwave oven with HNO₃ and H₂O₂ followed by dilution with water containing KBr/KBrO₃ and hydroxylamine and reduction with SnCl₂ in HCl using external calibration. The matrix interferences and the effect of nitrogen oxide vapors have been evaluated and the method validated using a certified reference material. The limit of detection of the method was 0.9ngg⁻¹ with a recovery percentage of 95±4% at an added concentration of 5ngg⁻¹. The concentration level of Hg found in 24 natural rice samples from different origin ranged between 1.3 and 7.8ngg⁻¹.

Keywords: Cold vapor; Atomic fluorescence spectrometry; Mercury; Microwave digestion; Rice

Spectrophotometric determination of carminic acid in human plasma and fruit juices by second order calibration of the absorbance spectra–pH data matrices coupled with standard addition method by Fayezeh Samari; Bahram Hemmateenejad; Mojtaba Shamsipur (pp. 49-56).

A simple analytical method based on the second-order calibration of the pH gradient spectrophotometric data was developed for assay of carminic acid (CA) in human plasma and orange juice over the concentration range of 1.5–14.0μM. The multi-way data analysis method was coupled with standard addition to encounter the significant effects of plasma and juices matrices on the acid–base behavior and UV–vis. absorbance spectra of CA. Thus, the standard addition three-way calibration data of plasma or fruit juices samples were analyzed by parallel factor analysis (PARAFAC) and the concentration related scores were used to derive a standard addition plot such as one obtained in univariate standard addition method. The number of PARAFAC components was obtained utilizing different criteria such as core consistency and residual errors through pf-test implementation. The applicability of the proposed method was evaluated by analysis of human plasma and fruit juices spiked with different levels of standard CA solutions. The results confirmed the success of the proposed method in the analysis of pH gradient spectrophotometric data for determination of CA. The recoveries were between 86.7 and 106.7.

Keywords: Carminic acid; pH gradient; Parallel factor analysis; Standard addition; Plasma; Fruit juices

Fabrication of DNA functionalized carbon nanotubes/Cu²⁺ complex by one-step electrodeposition and its sensitive determination of nitrite by Shanli Yang; Binyuan Xia; Xiandong Zeng; Shenglian Luo; Wanzhi Wei; Xiaoying Liu (pp. 57-62).

In this paper, DNA functionalized single-wall carbon nanotubes/Cu²⁺ (DNA–CNTs/Cu²⁺) complex was one-step electrodeposited onto the glassy carbon electrode (GCE), which fabricated a DNA–CNTs/Cu²⁺/GCE sensor to detect nitrite. Cyclic voltammogram of DNA–CNTs/Cu²⁺/GCE showed a pair of well-defined redox peaks for Cu²⁺/Cu⁺. Compared with DNA–CNTs/GCE and DNA–Cu²⁺/GCE, the prepared DNA–CNTs/Cu²⁺/GCE exhibited more excellent electrochemical properties. Thus, the prepared DNA–CNTs/Cu²⁺/GCE was proposed as nitrite sensor. The effects of Cu²⁺, CNTs and DNA concentration in the mixture together with electrodeposition time and determination conditions such as applied potential, pH value on the current response of DNA–CNTs/Cu²⁺/GCE toward nitrite were optimized to obtain the maximal sensitivity. In addition, electrochemical experiments revealed that the modified electrode showed high electrocatalytic activity to the reduction of nitrite ion (NO₂⁻). The linear range for the detection of NO₂⁻ was 3×10⁻⁸ to 2.6×10⁻³M, and the response was very fast (less than 3s). A low detection limit of 3×10⁻⁸M (S/N=3) for NO₂⁻ was achieved.

Keywords: DNA functionalized single-wall carbon nanotubes/Cu; ²⁺; complex; One-step electrodeposition; Determination of nitrite ions; Sensitivity

Computational investigation and synthesis of a sol–gel imprinted material for sensing application of some biologically active molecules by Nada F. Atta; Maher M. Hamed; Ali M. Abdel-Mageed (pp. 63-70).

A hybrid sol–gel material was molecularly imprinted with a group of neurotransmitters. Imprinted material is a sol–gel thin film that is spin coated on the surface of a glassy carbon electrode. Imprinted films were characterized electrochemically using cyclic voltammetry (CV) and the encapsulated molecules were extracted from the films and complementary molecular cavities are formed that enable their rebind. The films were tested in their corresponding template solutions for rebinding using square wave voltammetry (SWV). Computational approach for exploring the primary intermolecular forces between templates and hydrolyzed form of the precursor monomer, tetraethylorthosilicate (TEOS), were carried out using Hartree–Fock method (HF). Interaction energy values were computed for each adduct formed between a monomer and a template. Analysis of the optimized conformations of various adducts could explain the mode of interaction between the templates and the monomer units. We found that interaction via the amino group is the common mode among the studied compounds and the results are in good agreement with the electrochemical measurements.

Keywords: Molecular imprinting; Surface template; Neurotransmitters; Computational design; Molecular modeling

Partitioning and accumulation rates of polycyclic aromatic hydrocarbons into polydimethylsiloxane thin films and black worms from aqueous samples by Zhipei Qin; Sandra Mok; Gangfeng Ouyang; D. George Dixon; Janusz Pawliszyn (pp. 71-76).

Partition equilibriums and extraction rates of polycyclic aromatic hydrocarbons (PAHs) were examined for live biomonitoring with oligochaetes (black worms, Lumbriculus variegatus) and for high surface area chemical passive samplers constructed from polydimethylsiloxane thin film. The goals were to better understand the principles of bioconcentration by aquatic organisms and to aid in the design of a convenient and simple chemical monitoring tool to replace the use of live animals. The worms and films were exposed simultaneously to the contaminated water stream. In the initial extraction stage, similar extracted amount per surface area indicated that thin-film samplers could mimic the behavior of worms for passive sampling. Equilibrium was reached faster by the thin films than by the worms. A good linear relationship between the bioconcentration factors and the film–water partition coefficients of PAHs was found, which demonstrated the feasibility of thin-film sampler for determining the bioavailability of PAHs in water. Compared to the lengthy and inconvenient process of liquid–liquid extraction in worm treatment, thin-film technique simplifies the sample pretreatment procedure by integrating sampling and sample preparation.

Keywords: Thin film; Worm; Passive sampling; Polycyclic aromatic hydrocarbons

Polypyrrole solid phase microextraction: A new approach to rapid sample preparation for the monitoring of antibiotic drugs by Malgorzata Szultka; Ricarda Kegler; Patricia Fuchs; Pawel Olszowy; Wolfram Miekisch; Jochen K. Schubert; Boguslaw Buszewski; Ralf G. Mundkowski (pp. 77-82).

Simple or even rapid bioanalytical methods are rare, since they generally involve complicated, time-consuming sample preparation from the biological matrices like LLE or SPE. SPME provides a promising approach to overcome these limitations. The full potential of this innovative technique for medical diagnostics, pharmacotherapy or biochemistry has not been tapped yet.In-house manufactured SPME probes with polypyrrole (PPy) coating were evaluated using three antibiotics of high clinical relevance – linezolid, daptomycin, and moxifloxacin – from PBS, plasma, and whole blood. The PPy coating was characterised by scanning electron microscopy. Influences of pH, inorganic salt, and blood anticoagulants were studied for optimum performance. Extraction yields were determined from stagnant media as well as re-circulating human blood using the heart-and-lung machine model system.The PPy-SPME fibres showed high extraction yields, particularly regarding linezolid. The reproducibility of the method was optimised to achieve RSDs of 9% or 17% and 7% for SPME from stagnant or re-circulating blood using fresh and re-used fibres, respectively.The PPy-SPME approach was demonstrated to meet the requirements of therapeutic monitoring of the drugs tested, even from re-circulating blood at physiological flow rates. SPME represents a rapid and simple dual-step procedure with potency to significantly reduce the effort and expenditure of complicated sample preparations in biomedical analysis.

Keywords: Antibiotics; Blood; Heart-and-lung machine; Plasma; Polypyrrole; Solid phase microextraction

A novel solidified floating organic drop microextraction method for preconcentration and determination of copper ions by flow injection flame atomic absorption spectrometry by Çiğdem Arpa Şahin; İlknur Tokgöz (pp. 83-87).

A rapid, simple and cost effective solidified floating organic drop microextraction (SFODME) and flow injection flame atomic absorption spectrometric determination (FI-FAAS) method for copper was developed. In this method, a free microdrop of 1-undecanol containing 1,5-diphenyl carbazide (DPC) as the complexing agent was transferred to the surface of an aqueous sample including Cu(II) ions, while being agitated by a stirring bar in the bulk of the solution. Under the proper stirring conditions, the suspended microdrop can remain at the top-center position of the aqueous sample. After the completion of the extraction, the sample vial was cooled by placing it in a refrigerator for 10min. The solidified microdrop was then transferred into a conical vial, where it melted immediately and diluted to 300μL with ethanol. Finally, copper ions in 200μL of diluted solution were determined by FI-FAAS. Several factors affecting the microextraction efficiency, such as type of extraction solvent, pH, complexing agent concentration, extraction time, stirring rate, sample volume and temperature were investigated and optimized. Under optimized conditions for 100mL of solution, the preconcentration factor was 333 and the enrichment factor was 324. The limit of detection (3s) was 0.4ngmL⁻¹, the limit of quantification (10s) was 1.1ngmL⁻¹ and the relative standard deviation (RSD) for 10 replicate measurements of 10ngmL⁻¹ copper was 0.9%. The proposed method was successfully applied to the determination of copper in different water samples.

Keywords: Copper determination; Solidified floating organic drop microextraction; Preconcentration; Flow injection; Flame atomic absorption spectrometry

In situ analysis of proteins at high temperatures mediated by capillary-flow hydrothermal UV–vis spectrophotometer with a water-soluble chromogenic reagent by Kunio Kawamura; Hiroki Nagayoshi; Toshio Yao (pp. 88-95).

In situ monitoring of quantities, interactions, and conformations of proteins is essential for the study of biochemistry under hydrothermal environments and the analysis of hyperthermophilic organisms in natural hydrothermal systems on Earth. We have investigated the potential of a capillary-flow hydrothermal UV–vis spectrophotometer (CHUS) for performing in situ measurements of proteins and determining their behavior at extremely high temperatures, in combination with a chromogenic reagents probe, which interacts with the proteins. The spectral shift obtained using a combination of water-soluble porphyrin (TPPS) and bovine serum albumin (BSA) was the best among the spectral shifts obtained using different combinations of chromogenic reagents and proteins. The association behavior of TPPS with BSA was investigated in detail using CHUS at temperatures up to 175°C and the association constant ( K_ass) of TPPS with BSA was successfully determined at temperatures up to 100°C. The ln K_ass values were inversely proportional to the T⁻¹ values in the temperature range 50–100°C. These analyses showed for the first time that the decrease of association of TPPS with BSA is due to the conformational change, fragmentation, and/or denaturing of BSA rather than the decrease of the hydrophobic association between TPPS and BSA. This study conclusively demonstrates the usability of the CHUS system with a chromogenic reagent as an in situ detection and measurement system for thermostable proteins at extremely high temperatures.

Keywords: In situ analysis of proteins; Hydrothermal reactions; UV–vis spectrophotometry; Stability of biomolecules; Stability of organic molecules; Interactions between organic molecules under hydrothermal conditions

Simultaneous determination of bovine α-lactalbumin and β-lactoglobulin in infant formulae by ultra-high-performance liquid chromatography–mass spectrometry by Yiping Ren; Zheng Han; Xiaojun Chu; Jingshun Zhang; Zengxuan Cai; Yongjiang Wu (pp. 96-102).

A reliable ultra-high-performance liquid chromatography–mass spectrometry method for simultaneous determination of bovine α-lactalbumin (α-La) and β-lactoglobulin (β-Lg) was developed. Compared to the previous methods, the developed approach with mass spectrometer operated in selected area monitoring mode offered increased speed and enhanced lower detection limit. A linear gradient mobile phase, consisting of (A) water containing 0.1% trifluoroacetic acid (TFA) and (B) acetonitrile containing 0.1% TFA, and an Acquity UPLC BEH300 C18 column (150mm×2.1mm, 1.7μm) were employed to obtain the best resolution of the target analytes. The accurate quantitation was achieved by employing human α-lactalbumin as the internal standard. The established method was extensively validated by determining the linearity ( R²≥0.9991), sensitivity (limit of quantitation, 0.15–0.19μgmL⁻¹), recovery (94.0–98.7%), precision (relative standard deviation≤11.1%) and repeatability (relative standard deviation≤5.7%). It was shown to be a suitable method for simultaneous determination of the major whey proteins in biological samples. Current validated method was successfully applied to the nutrient investigation of infant formulae.

Keywords: Ultra-high-performance liquid chromatography–mass spectrometry; α-Lactalbumin; β-Lactoglobulin; Infant formulae

Measurement of temperature-dependent diffusion coefficients using a confocal Raman microscope with microfluidic chips considering laser-induced heating effect by Ying Lin; Xinhai Yu; Zhenyu Wang; Shan-Tung Tu; Zhengdong Wang (pp. 103-112).

Conventional methods for measuring diffusion coefficients ( D) are complex and time consuming. This study presents a method for the continuous measurement of temperature-dependent diffusion coefficients using a confocal Raman microscope with microfluidic chips. Concentration information was collected by a Raman microscope to extract D values. An isothermal diffusion process at various temperatures was ensured by coupling the silicon-based microfluidic chip with an isothermal plate. In the simple silicon/glass chip, the heating effect induced by a Raman laser was observed to contribute to abnormally high D values. To eliminate the heating effect, a 200nm-thick aluminum (Al) reflection film was used to coat the channel bottom. The Al film substantially reduced absorption of laser power, thus ensuring precise D values in excellent agreement with literature data. Other potential methods to eliminate the heating effect were also evaluated by computational fluid dynamics (CFD) simulations and were found impractical for implementation. Consequently, this method for the continuous measurement of temperature-dependent diffusion coefficients is proven to be accurate, efficient, and reliable.

Keywords: Temperature-dependent diffusion coefficient; Raman microscope; Microfluidic chip; Laser-induced heating

Highly sensitive immunoassay based on E. coli with autodisplayed Z-domain by Joachim Jose; Min Park; Jae-Chul Pyun (pp. 113-118).

The Z-domain of protein A has been known to bind specifically to the F_c region of antibodies (IgGs). In this work, the Z-domain of protein A was expressed on the outer membrane of Escherichia coli by using “Autodisplay” technology as a fusion protein of autotransport domain. The E. coli with autodisplayed Z-domain was applied to the sandwich-type immunoassay as a solid-support of detection-antibodies against a target analyte. For the feasibility demonstration of the E. coli based immunoassay, C-reactive protein (CRP) assay was carried out by using E. coli with autodisplayed Z-domain. The limit of detection (LOD) and binding capacity of the E. coli based immunoassay were estimated to be far more sensitive than the conventional ELISA. Such a far higher sensitivity of E. coli based immunoassay than conventional ELISA was explained by the orientation control of immobilized antibodies and the mobility of E. coli in assay matrix. From the test results of 45 rheumatoid arthritis (RA) patients’ serum and 15 healthy samples, a cut-off value was established to have optimal sensitivity and selectivity values for RA. The CRP test result of each individual sample was compared with ELISA which is the reference method for RA diagnosis. From this work, the E. coli with Z-domain was proved to be feasible for the medical diagnosis based on sandwich-type immunoassay.

Keywords: Autodisplay; Z-domain; C-reactive protein; Rheumatoid arthritis; Diagnosis

Monitoring of diisopropyl fluorophosphate hydrolysis by fluoride-selective polymeric films using absorbance spectroscopy by Madhumati Ramanathan; Lin Wang; James R. Wild; Mark E. Meyeroff; Aleksandr L. Simonian (pp. 119-122).

In this study, a novel system for the detection and quantification of organofluorophosphonates (OFP) has been developed by using an optical sensing polymeric membrane to detect the fluoride ions produced upon OFP hydrolysis. Diisopropyl fluorophosphate (DFP), a structural analogue of type G chemical warfare agents such as Sarin (GB) and Soman (GD), is used as the surrogate target analyte. An optical sensing fluoride ion selective polymeric film was formulated from plasticized PVC containing aluminum(III) octaethyl porphyrin and ETH 7075 chromoionophore (Al[OEP]-ETH 7075). Selected formulations were used to detect the fluoride ions produced by the catalytic hydrolysis of DFP by the enzyme organophosphate hydrolase (OPH, EC 3.1.8.1). The changes in absorbance that corresponded to the deprotonated state of chromoionophore within the film results from simultaneous coextraction of fluoride and protons as DFP hydrolysis takes place in the solution phase in contact with the film. The developed sensing system demonstrates excellent sensitivity for concentrations as low as 0.1μM DFP.

Keywords: Diisopropyl fluorophosphate; Organophosphate hydrolase; Fluoride; Absorbance; Coextraction; Biosensor

Liquid chromatography method to determine polyamines in thermosetting polymers by M.S. Dopico-García; J.M. López-Vilariño; G. Fernández-Martínez; M.V. González-Rodríguez (pp. 123-129).

A simple, robust and sensitive analytical method to determine three polyamines commonly used as hardeners in epoxy resin systems and in the manufacture of polyurethane is reported. The studied polyamines are: one tetramine, TETA (triethylenetetramine), and two diamines, IPDA (Isophorone diamine) and TCD-diamine (4,7-methano-1H-indene-5,?-dimethanamine, octahydro-). The latter has an incompletely defined structure, and, as far as we know, has not been previously determined by other methods. All three polyamines contain primary amines; TETA also contains secondary amines.The analytical method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, used for the first time for these compounds, followed by high performance liquid chromatography (HPLC) analysis with a fluorescence (FL) detector ( λ excitation 248nm, λ emision 395nm). The HPLC-DAD-LTQ Orbitrap MS was used in order to provide structural information about the obtained derivatized compounds. The hybrid linear ion trap LTQ Orbitrap mass spectrometer has been introduced in recent years and provides a high mass accuracy. The structures of the derivatized analytes were identified from the protonated molecular ions [M+H]⁺ and corresponded to the fully labelled analytes.The following analytical parameters were determined for the method using the HPLC-FL: linearity, precision (2.5–10%), instrumental precision intraday (0.8–1.5%) and interday (2.9–6.3%), and detection limits (0.02–0.14mgL⁻¹). The stability of stock solutions and derivatized compounds was also investigated. The method was applied to determine the amine free content in epoxy resin dust collected in workplaces.

Keywords: Epoxy resins; Derivatization; Fluorescence detection; High performance liquid chromatography; Polyamines; Mass spectrometry detection

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Analytica Chimica Acta (v.667, #1-2)

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Analytica Chimica Acta (v.667, #1-2)