Comparison between GC-MS-SIM and GC-ECD for the determination of residues of organochlorine and organophosphorus pesticides in Brazilian citrus essential oils

High-Throughput Aptamer Microarrays for Fluorescent Detection of Multiple Organophosphorus Pesticides in Food

A novel high-throughput aptamer microarray fluorescent method based on thioflavin T (ThT) was established for the sensitive detection of phoxim, parathion, fensulfothion, and isocarbophos. In this work, the aptamers in binding buffer tended to have the antiparallel G-quadruplex structure, which can bind ThT and release its potential fluorescence signal. However, when the organophosphorus pesticides (OPs) were present, partial aptamers preferred to bind them, forcing the displacement of ThT from the G-quadruplex and resulting in the significant decrease in fluorescence signal. Under optimal experimental conditions (12T spacer, 300 nM aptamer, and 80 μM ThT), the OP aptamer microarray has low limits of detection of 25.4 ng/mL for phoxim, 12.0 ng/mL for parathion, 7.7 ng/mL for fensulfothion, and 9.9 ng/mL for isocarbophos. The accuracy and reliability of the method is further verified by testing the recovery rate of OPs spiked in two different complicated sample matrices (pears and radishes). It is worth mentioning that not only the developed aptamer microarray technology has low sensitivity and a broad spectrum, but it also allows for high-throughput and rapid analysis of a variety OPs, which overcomes some of the shortcomings of other OP detection methods.

An aptamer and flower-shaped AuPtRh nanoenzyme-based colorimetric biosensor for the detection of profenofos

A GO grafted SSM was prepared to load the freely mobile capture probe and novel flower-shaped AuPtRh nanospheres were synthesized to be a signal probe, which were constructed to form a colorimetric biosensor for the detection of profenofos.

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.

Nanoplasmonic sensor array for the detection and discrimination of pesticide residues in citrus fruits

Great attention has been directed towards developing rapid and straightforward methods for the identification of various pesticides that are usually used simultaneously in citrus fruits. The extensive use of diverse classes of pesticides in citrus fruits and their high toxicity may cause serious diseases in the human body. In the current study, a non-enzymatic sensor array has been developed for the identification and discrimination of five different pesticides belonging to diverse classes, including organophosphate, carbamate, and bipyridylium. For this aim, two gold nanoparticles (AuNPs) with different capping agents, citrate and borohydride, were used as sensing elements. The aggregation-induced spectra alterations of AuNPs were utilized to identify the pesticides in a wide range of concentrations (20-5000 ng mL-1). We have employed data visualization methods (i.e., heat maps, bar plots, and color difference maps), a supervised pattern recognition method (i.e., linear discrimination analysis), and partial least squares regression to qualitatively and quantitatively determine the pesticides. Finally, the practical applicability of the developed sensor array was evaluated for the identification of target pesticides in lime peel. The outcomes revealed that the probe could accurately verify the absence or presence of the pesticides in lime fruit.

Status, sources and contamination levels of organochlorine pesticide residues in urban and agricultural areas: a preliminary review in central-southern Italian soils

Organochlorine pesticides (OCPs) are synthetic chemicals commonly used in agricultural activities to kill pests and are persistent organic pollutants (POPs). They can be detected in different environmental media, but soil is considered an important reservoir due to its retention capacity. Many different types of OCPs exist, which can have different origins and pathways in the environment. It is therefore important to study their distribution and behaviour in the environment, starting to build a picture of the potential human health risk in different contexts. This study aimed at investigating the regional distribution, possible sources and contamination levels of 24 OCP compounds in urban and rural soils from central and southern Italy. One hundred and forty-eight topsoil samples (0-20 cm top layer) from 78 urban and 70 rural areas in 11 administrative regions were collected and analysed by gas chromatography-electron capture detector (GC-ECD). Total OCP residues in soils ranged from nd (no detected) to 1043 ng/g with a mean of 29.91 ng/g and from nd to 1914 ng/g with a mean of 60.16 ng/g in urban and rural area, respectively. Endosulfan was the prevailing OCP in urban areas, followed by DDTs, Drins, Methoxychlor, HCHs, Chlordane-related compounds and HCB. In rural areas, the order of concentrations was Drins > DDTs > Methoxychlor > Endosulfans > HCHs > Chlordanes > HCB. Diagnostic ratios and robust multivariate analyses revealed that DDT in soils could be related to historical application, whilst (illegal) use of technical DDT or dicofol may still occur in some urban areas. HCH residues could be related to both historical use and recent application, whilst there was evidence that modest (yet significant) application of commercial technical HCH may still be happening in urban areas. Drins and Chlordane compounds appeared to be mostly related to historical application, whilst Endosulfan presented a complex mix of results, indicating mainly historical origin in rural areas as well as potential recent applications on urban areas. Contamination levels were quantified by Soil Quality Index (SoQI), identifying high levels in rural areas of Campania and Apulia, possibly due to the intensive nature of some agricultural practices in those regions (e.g., vineyards and olive plantations). The results from this study (which is in progress in the remaining regions of Italy) will provide an invaluable baseline for OCP distribution in Italy and a powerful argument for follow-up studies in contaminated areas. It is also hoped that similar studies will eventually constitute enough evidence to push towards an institutional response for more adequate regulation as well as a full ratification of the Stockholm Convention.

Matrix Effects and Interferences of Different Citrus Fruit Coextractives in Pesticide Residue Analysis Using Ultrahigh-Performance Liquid Chromatography-High-Resolution Mass Spectrometry

The matrix effects of ethyl acetate extracts from seven different citrus fruits on the determination of 80 pesticide residues using liquid chromatography coupled to high-resolution time-of-flight mass spectrometry (UHPLC-(ESI)-HR-TOF) at 4 GHz resolution mode were studied. Only 20% of the evaluated pesticides showed noticeable matrix effects (ME) due to coelution with natural products between t_R = 3 and 11 min. Principal component analysis (PCA) of the detected coextractives grouped the mandarins and the orange varieties, but separated lemon, oranges, and mandarins from each other. Matrix effects were different among species but similar between varieties, forcing the determination of pesticide residues through matrix-matched calibration curves with the same fruit. Twenty-three natural products (synephrine, naringin, poncirin, glycosides of hesperitin, limonin, nomilin, and a few fatty acids, among others) were identified in the analyzed extracts. Twelve of the identified compounds coeluted with 28 of the pesticides under study, causing different matrix effects.