Analysis of aliphatic alcohol ethoxylates in terms of alkyl and ethylene oxide chain lengths by reversed-phase liquid chromatography with evaporative light scattering detection

Allergenic components, biocides, and analysis techniques of some essential oils used in food products

Nowadays, almost 300 essential oils (EOs) are commonly traded in the world market, with a prediction to be worth over $14 billion in 2024. EOs are natural preservatives for food products in order to reduce the activity of pathogenic microorganisms, therefore their use as an antioxidant or a preservative in foods has been encouraged. They are not only considered as antimicrobial or flavoring agents, but are also incorporated into food packaging materials. There are several types of EOs which have been approved as food additives by the Food and Drug Administration. Hence, it is important to use safe EO products to minimize possible adverse effect risks such as nausea, vomiting, necrosis, nephropathy, mucous membrane, and skin irritation. This review article gives information about some EOs that are used in the food industries and the types of some allergenic compounds and biocides which could make the EOs hazardous or may cause allergenic reactions in the human body. Besides, some analysis techniques of possible allergenic compounds or biocides in EOs were introduced and supported with the most relevant studies. The overall conclusion from the study is that pregnant women, patients taking drugs (e.g., diabetics) or the having a history of allergy are the most prone to be affected from EO allergenic components. As regards to biocides, organochlorine and organophosphorus types of pesticides that are carried over from the plant may be found mostly in EOs. The most common allergic reaction is skin sensitization and irritation if the EO components are oxidized during storage or transportation. Moreover, drug interactions are one of the other possible adverse effect. Hence, determination of biocides and possible allergenic component concentrations is an essential factor when they are used as a preservative or flavoring agent. The most prominent analysis techniques are gas and liquid chromatography because most of the allergens and biocides are mainly composed of volatile components. PRACTICAL APPLICATION: Determining of the essential oil's content will be crucial if oils are used for food preservation or flavoring because they may have some hazardous effects, such as nausea, vomiting, necrosis and nephropathy. Therefore, after applying them to the food products, consumers (especially pregnant women) should be informed about their concentration levels and their possible adverse effects are taken into account when they are consumed over toxic limit. For this reason, we reviewed in our study that some allergenic components, biocides and toxic limits of EOs to be used in food products. In addition to this, recent analytical techniques have been explained and discussed which methods are suitable for analysis.

Determination of Dodecanol and Short-Chained Ethoxylated Dodecanols by LC-MS/MS (with Electrospray Ionization) After Their Derivatization (with Phenyl Isocyanate)

Abstract

This report describes the application of LC-MS/MS for the separation of dodecanol (C₁₂OH) and homogenous fatty alcohols ethoxylated (AE) containing a dodecyl moiety and 1-9 ethoxy groups. These ethoxylates and free alcohol were derivatized for LC-MS/MS analysis with phenyl isocyanate (PIC). The derivatives of analytes with PIC were separated using a C18 column. Gradient elution with a mixture of ethyl acetate and acetonitrile (5 mM) was employed. The described determination method is characterized by low detection limits (range from 0.005 µg L^-1 for: C₁₂OH, C₁₂EO_2-7 to 1 µg L^-1 for C₁₂EO₁) and quantification limits (range from 0.01 µg L^-1 for: C₁₂EO_5-7 to 2 µg L^-1 for C₁₂EO₁). The developed and validated method was used in combination with liquid-liquid extraction (using ethyl acetate) in order to identify and quantitatively determine the C₁₂OH and C₁₂EO_1-9 present in environmental samples collected from Warta river water in Poznan.

Graphical abstract

Photodegradation of non-ionic surfactant with different ethoxy groups in aqueous effluents by the photo-Fenton process

The photo-Fenton process was applied to degrade non-ionic surfactants with different numbers of ethoxy groups, seven (E7), ten (E10) and twenty-three (E23). The effects of H2O2 concentration, Fe(II) concentration and number of ethoxy groups on the mineralization of surfactants were investigated. The response surface methodology (RSM) was applied to determine optimal concentrations of Fenton's reagents for each surfactant. The efficiency of the photo-Fenton process reached 95% for all surfactants studied at 45 min in optimal conditions determined in this work. The analysis of results showed that the efficiency depends upon the number of ethoxy groups in the surfactant. The increase in ethoxy groups favoured the mineralization of surfactants. The analysis of variance (ANOVA) was applied, and according to the F-test the models for the mineralization of surfactants were considered significant and predictable. The photo-Fenton process has proven to be feasible for the degradation of ethoxylated surfactants in aqueous solution.

Evaporative light scattering detector: toward a general molecular weight cutoff characterization of nanofiltration membranes

An evaporative light scattering detector (ELSD) coupled with HPLC was used for the first time to characterize membranes. Polydispersed PEG-200, 600, and 1000 were selected as probe molecules to study the dependence of membrane retention on molecular weight via a gradient eluted HPLC separation coupled to ELSD detection. The results show that HPLC/ELSD is a really general and powerful technique to study the nanofiltration (NF) process since it does not require any special properties for the solutes (chromospheres or fluorophores) and possesses the required sensitivity. Especially in solvent resistant NF (SRNF), where a wide range of organic solvents is used, the ELSD detector was not affected by the interaction between solvent and solutes, which is a critical issue compared to other more common detectors.

Separation of derivatized alcohol ethoxylates and propoxylates by low temperature packed column supercritical fluid chromatography using ultraviolet absorbance detection

Supercritical fluid chromatography (SFC) is capable of separating oligomers of alcohol ethoxylates (AEOs) and propoxylates (APOs) samples with pure carbon dioxide. The instrumental conditions, however, needed for separation necessitate both high temperature and high pressure. Derivatization of alcohol polyether samples with an UV absorbing agent has been achieved with a phenylated disilazane in hopes of employing a solvent-modified CO2 mobile phase in conjunction with both lower CO2 pressure and lower temperature for oligomer separation. A silylether containing a single phenyl group was formed via the derivatization of the hydroxyl termini of AEO and APO samples. The derivatized polyethers were detected at 215 nm with little or no interference from the mobile phase. Octadecylsilica (ODS) and a polar embedded alkyl bonded silica stationary phase were studied with the organic solvent-modified CO2 mobile phase. The combination of an ODS phase and the polar embedded phase, tandemly stacked, produced the best chromatographic separation of oligomeric species. Data from SFC-UV separations combined with peak assignments from SFC with electrospray ionization-mass spectrometric (ESI-MS) detection produced average molar oligomer values for each surfactant sample.

Simultaneous separation and quantitation of four antiepileptic drugs—a study with potential for use in patient drug level monitoring

The purpose of this study was to illustrate the applicability of high-performance liquid chromatography (HPLC) coupled with evaporative light scattering detector (ELSD) in simultaneously separating and quantitating four commonly used antiepileptic drugs (AEDs). A mixture of the four AEDs were separated using a C8 column using volatile mobile phases and were detected using ELSD. Optimal instrumental conditions were obtained by assessing the effect of various critical experimental parameters such as evaporator tube temperature, carrier gas flow rate, photomultiplier gain on separation efficiency, accuracy, reproducibility and sensitivity of measurement on all four AEDs. A novel, rapid, accurate, sensitive, reproducible and robust HPLC-ELSD method for simultaneous separation and quantitation of four commonly used AEDs was developed. The physical basis of the results obtained as a consequence of varying several critical experimental parameters has been explained. This study illustrates the potential for use of HPLC-ELSD in drug level monitoring of patients undergoing mono- or polytherapy for epilepsy.

Retention mechanism of fatty alcohol ethoxylates in reversed-phase liquid chromatography

Fatty alcohol ethoxylates (FAEs) are widely used nonionic surfactants that have distributions in both alkyl and poly(ethylene oxide) (PEO) chain length. Generally, two-dimensional liquid chromatography technique is required for the complete characterization of both distributions. By selecting a proper stationary and mobile phase condition, however, we can obtain fully resolved chromatograms of a FAE sample (Brij 30) with respect to both alkyl and PEO chain length by using a single reversed-phase C18 column and aqueous acetonitrile mobile phase. FAEs show a peculiar reversed-phase liquid chromatography (RPLC) retention behavior with an aqueous-organic mobile phase, the retention mechanism of which has not been fully elucidated. For a fixed alkyl chain length, FAEs with higher-molecular-mass PEO block elutes first and the van't Hoff plot of the retention factor shows a curvature. The unique retention behavior can be understood from the opposite thermodynamic characteristics associated with RPLC retention of PEO block and alkyl chain: the sorption process of PEO to the non-polar stationary phase shows deltaH(o) > 0 and deltaS(o) > 0 while the alkyl chain shows deltaH(o) < 0 and deltaS(o) < 0 in contrast. The relative magnitude of the two contributions can change the elution order of the FAE. Therefore the often found, inverted elution order of FAEs (the early elution of FAEs with longer PEO block) is due to the positive enthalpic interaction of PEO blocks, which is a characteristic of the hydrophobic interaction. And the curvature of the van't Hoff plots was analyzed assuming the temperature dependent thermodynamic variables.