Determination of fatty alcohol ethoxylates by derivatisation with maleic anhydride followed by liquid chromatography with UV–vis 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.

Species discrimination of Radix Bupleuri through the simultaneous determination of ten saikosaponins by high performance liquid chromatography with evaporative light scattering detection and electrospray ionization mass spectrometry

A simple, rapid and robust high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD) method was established for the species discrimination and quality evaluation of Radix Bupleuri through the simultaneous determination of ten saikosaponins, namely saikosaponin-a, -b(1), -b(2), -b(3), -b(4), -c, -d, -g, -h, and -i. These compounds were chromatographed on an Ascentis(®) Express C18 column with a gradient elution of acetonitrile and water containing 0.1% acetic acid at a flow rate of 1.0 mL/min. Saikosaponins were monitored by ELSD, which was operated at a 50°C drift tube temperature and 3.0 bar nebulizer gas (N(2)) pressure. The developed method was validated with respect to linearity, intra- and inter-day accuracy and precision, limit of quantification (LOQ), recovery, robustness and stability, thereby showing good precision and accuracy, with intra- and inter-assay coefficients of variation less than 15% at all concentrations. Furthermore, a high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) method was developed to certify the existence of ten saikosaponins, as well as to confirm the reliability of ELSD. The extraction conditions of saikosaponins from Radix Bupleuri were also optimized by investigating the effect of extraction methods (sonication, reflux and maceration) and various solvents on the extraction efficiencies for saikosaponins. Sonication with 70% methanol for 40 min was found to be simple and effective for extraction of major saikosaponins. This analytical method was applied to determine saikosaponin profiles in 20 real samples consisting of four Bupleurum species, namely B. falcatum, B. chinense, B. sibiricum and the poisonous B. longiradiatum. It was found that three major saikosaponin-a, -c and -d were the major constituents in B. falcatum, B. chinense, and B. longiradiatum, while one major saikosaponin (saikosaponin-c) was not identified from B. sibiricum. In addition, no saikosaponin-b(3) was detected in B. longiradiatum samples, indicating that the toxic B. longiradiatum may be tentatively distinguished from officially listed Bupleurum species (B. falcatum and B. chinense) based on their saikosaponin profiles. Overall the simultaneous determination of ten saikosaponins in Radix Bupleuri was shown to be a promising tool to adopt for the discrimination and quality control of closely related Bupleurum species.

Chromium(VI) oxide oxidation of non-ethoxylated and ethoxylated alcohols for determination by electrospray ionization mass spectrometry

A new derivatization procedure to increase the sensitivity of electrospray ionization mass spectrometry (ESI-MS) to non-ethoxylated and ethoxylated alcohols was investigated. The analytes were oxidized with chromium(VI) oxide and the resulting carboxylic and ethoxy-carboxylic acids were isolated by extraction with ethyl acetate; the extracts were alkalinized and infused into the ESI-MS system working in the negative-ion mode. The yields of the combined oxidation-extraction were ca. 100% for non-ethoxylated fatty alcohols dissolved in acetone and they decreased moderately in samples containing increasing amounts of water (e.g., a 75% yield was obtained with 50% water). Ethoxylated alcohols with more than two ethylene oxide units resulted in yields of ca. 60%. Low limits of detection (LODs) were obtained when the procedure was applied to the analysis of body-care products and cosmetics containing fatty alcohols, e.g., in a varicose-vein cream, the LODs were 25 microg cetyl alcohol and 7.5 microg stearyl alcohol (detected as palmitic acid and stearic acid, respectively) per gram of sample. High molecular mass alcohols were also detected in seawater after pre-concentration by solid-phase extraction. Thus, the proposed method is particularly valuable for use in industrial samples having complex matrices and in environmental samples and it is competitive with other methods for the analysis of trace amounts of fatty alcohols.

Derivatization of fatty alcohol ethoxylate non-ionic surfactants using 2-sulfobenzoic anhydride for characterization by liquid chromatography/mass spectrometry

A derivatization procedure has been developed for the improved characterization of fatty alcohol ethoxylate non-ionic surfactants by liquid chromatography/mass spectrometry. The end hydroxyl group of each surfactant species was converted into an oxycarbonylbenzene-2-sulfonic acid group with 2-sulfobenzoic anhydride under mild conditions. The produced sulfonic acid group allows all species, including fatty alcohols and those with less than three ethoxylates, to be uniformly ionized by electrospray ionization (ESI) mass spectrometry. Both acid and base can be used as a mobile phase additive for liquid chromatography without affecting M(n) and average ethoxylate values, although ion intensities are suppressed during the ESI process. The method was used to analyze seven commercial fatty alcohol ethoxylate non-ionic surfactants, and the determined M(n) and EO values were comparable with the results obtained by NMR. The relative ratio of different fatty alcohol based ethoxylates in a sample can also be determined using the summed mass spectral data.