Determination of total mercury in nuts at ultratrace level

Rapid and Portable Detection of Hg and Cd in Grain Samples Based on Novel Catalytic Pyrolysis Composite Trap Coupled with Miniature Atomic Absorption Spectrometry

As toxic metals, Hg and Cd are a concern for food safety and human health; their rapid and portable analysis is still a challenge. A portable and rapid Hg-Cd analyzer constructed from a metal-ceramic heater (MCH)-based electrothermal vaporizer (ETV), an on-line catalytic pyrolysis furnace (CPF), a composite Pt/Ni trap, and a homemade miniature atomic absorption spectrometer (AAS) was proposed for grain analysis in this work. To enhance sensitivity, a new folded light path was designed for simultaneous Hg and Cd analysis using charge coupled device (CCD) in AAS. To eliminate the grain matrix interference, a catalytic pyrolysis furnace with aluminum oxide fillers was utilized to couple with a composite Pt/Ni trap. The method limits of detection (LODs) were 1.1 μg/kg and 0.3 μg/kg for Hg and Cd using a 20 mg grain sample, fulfilling the real sample analysis to monitor the grain contamination quickly; linearity R² > 0.995 was reached only using standard solution calibration, indicating the sample was free of grain matrix interference. The favorable analytical accuracy and precision were validated by analyzing real and certified reference material (CRM) grains with recoveries of 97-103% and 96-111% for Hg and Cd, respectively. The total analysis time was less than 5 min without sample digestion or use of any chemicals, and the instrumental size and power consumption were <14 kg and 270 W, respectively. Compared with other rapid methods, this newly designed Hg-Cd analyzer is proven to be simple, portable, and robust and is, thus, suitable to quickly monitor Hg and Cd contamination in the field to protect grain and food safety.

Paper-Based Analytical Devices for Colorimetric and Luminescent Detection of Mercury in Waters: An Overview

Lab-on-paper technologies, also known as paper-based analytical devices (PADs), have received increasing attention in the last years, and nowadays, their use has spread to virtually every application area, i.e., medical diagnostic, food safety, environmental monitoring, etc. Advantages inherent to on-field detection, which include avoiding sampling, sample preparation and conventional instrumentation in central labs, are undoubtedly driving many developments in this area. Heavy metals represent an important group of environmental pollutants that require strict controls due to the threat they pose to ecosystems and human health. In this overview, the development of PADs for Hg monitoring, which is considered the most toxic metal in the environment, is addressed. The main emphasis is placed on recognition elements (i.e., organic chromophores/fluorophores, plasmonic nanoparticles, inorganic quantum dots, carbon quantum dots, metal nanoclusters, etc.) employed to provide suitable selectivity and sensitivity. The performance of both microfluidic paper-based analytical devices and paper-based sensors using signal readout by colorimetry and luminescence will be discussed.

Assessment of the Safe Consumption of Nuts in Terms of the Content of Toxic Elements with Chemometric Analysis

Nuts are characterized by high nutritional value and are recommended as a part of a healthy diet. At the same time, toxic elements could also be found in them. In this research, we measured the content of As, Cd, Pb and Hg in a wide variety of edible nuts. To determine the As content, inductively coupled plasma mass spectrometry (ICP-MS) was applied. Cd and Pb were detected by the electrothermal atomic absorption spectrometry analytical technique (ETAAS) with Zeeman background correction, while atomic absorption spectrometry method (AAS) with the amalgamation technique in the case of Hg was used. The study material consisted of 120 samples without replications (10 for each subgroup) including the following nuts: Almonds, Brazil nuts, cashew nuts, hazelnuts, macadamia nuts, peanuts, pecan nuts, pine nuts, pistachios and walnuts. Indicators such as the target hazard quotient (THQ), cancer risk (CR) and hazard index (HI) were used to assess the health risk. The highest median As, Cd, Pb and Hg contents were observed for pistachios (192.42 µg/kg), pine nuts (238.40 µg/kg), peanuts (82.06 µg/kg) and pecans (82.06 µg/kg), respectively. The exceedance of the established limits was found in the case of Pb for nine samples: macadamia nuts (221.49 µg/kg; 2350.94 µg/kg; 2581.43 µg/kg), pine nuts (266.33 µg/kg), peanuts (1353.80 µg/kg) and pecans (2689.13 µg/kg, 2758.26 µg/kg, 2992.29 µg/kg and 3169.41 µg/kg). Extremely high (>2500 µg/kg) Pb content was found in 33% of studied pecans imported from the USA. The health risk indicators did not identify increased health risk. This research is significant considering the food safety issues and indicates the need to regularly control the content of toxic elements in food, as well as to establish the specific limits for heavy metals content in nuts. The chemometric analysis included cluster analysis and principal component analysis (PCA). Cluster analysis made it possible to distinguish four subgroups on the basis of the ability to accumulate toxic elements: pine nuts, pecans, pistachios and other analysed nuts. PCA indicated primarily factor 1, distinguishing mainly pecans, macadamia nuts and peanuts. Chemometric analysis can be a useful tool in estimating the ability of different nut species to accumulate contaminants.

[Progress of sample preparation and analytical methods of dried fruit foods]

坚果、果脯等干果类食品含有丰富的营养成分,深受国内外广大消费者的喜爱。但这些食品在果实生产、加工、储运时会使用农药或产生霉变等,造成干果中农药、重金属、霉菌毒素或添加剂等有害成分残留,甚至超过国家限量要求,带来严重的食品安全问题。因此,加强干果类食品的质量监督具有重要的经济和社会意义。但干果类食品基质复杂,有害物质种类多,结构和性质差异大,含量低,其分析检测需要快速高效的样品前处理技术和准确灵敏的分析检测方法。该文主要综述了近十年来干果类食品中有害物质的样品前处理及分析检测方法研究进展。其中样品前处理方法主要包括各种场辅助萃取法、相分离法和衍生化萃取方法等。场辅助萃取法主要是借助超声波和微波场等外场(协同)作用加快干果中有害物质的溶出速度,提高其萃取效率。相分离法,包括固相(微)萃取、分散固相萃取和液相(微)萃取法等,具有溶剂消耗少、分离富集效率高的优势,是干果样品分析中较常使用的前处理方法。该文还重点介绍了干果中各类有害成分分析检测技术,主要包括色谱、原子光谱、无机质谱、电化学分析等常规实验室方法,以及一些适用于现场分析的快速检测技术,并以此为基础,展望了干果类食品中有害物质分析检测技术的发展趋势。

Biogenic and Risk Elements in Walnuts (Juglans regia L.) from Chosen Localities of Slovakia

Walnuts (fruits Juglans regia, L.) belong among to the most spread, commercially grown tree nuts in the world. Nuts have grown higher attention in last years as valuable sources of essential elements; they are rich in non-essential fatty acids, proteins, fibre, plant sterols and minerals including potassium and magnesium and antioxidants. Determination of elements distribution in nuts is required not only for evaluation of total intake of essential elements in our food, but it is also useful for gaining data on contamination of foodstuffs by risk elements, but also for monitoring of heavy metal contamination in foodstuffs. Walnut samples were taken from three selected areas in Slovakia. The first location is in the vicinity of the cities Strážske, Humenné and Vranov nad Topľou, the second one is situated close to the city of Prievidza and the last one is close to the city of Vráble. The results of evaluation showed that the content of the elements monitored in location of Vráble did not exceed the limits set by the Regulation of Ministry of Health of Slovak Republic No 2/1994. In the half of samples taken from the location of Strážske, higher content of cadmium as the permitted limit has been found. The samples exceeded the amounts allowed by the Regulation No 2/1994 in contaminated area called "The dangerous triangle". Potential consumption of these walnuts could negatively affect human organism, but only if the kernels from the exact locality would be consumed in very high daily amounts (100-fold higher intake as daily intake according to the Statistical Office of SR).

Risk assessment and prediction for toxic heavy metals in chestnut and growth soil from China

BACKGROUND

Toxic heavy metals (THMs) cause severe environmental hazards and threaten human health through various consumption of food stuff. However, little is known of THMs in chestnuts. In this study, the risk assessment and prediction of THMs [lead (Pb), arsenic (As), chromium (Cr), cadmium (Cd) and mercury (Hg)] in chestnuts and growth soils from China were investigated.

RESULTS

The main detected THMs in chestnuts and growth soils were As and Cd. The total pollution levels of the five THMs (Nemerow pollution indexes, NPIs) were 0.062 and 1.06, respectively. The dietary risks for children were higher than those of adults, especially short-term non-carcinogenic risk. The main combined risks from the relationships between THMs were Pb-Cr (r = 0.85, P < 0.01) in chestnuts and Pb-As (r = 0.59, P < 0.01) in growth soils. The risk source was found to be the uptake effect of THMs from soil to chestnut, with the highest bioaccumulation factors (BCFs) of Cd (0.254). Several comprehensive risk models were established with the highest coefficient of determination (R² ) of 0.79. In addition, the main contribution rates of different soil parameters to comprehensive risk of THMs uptake were 49.8% (Cd), 23.4% (pH), 13.8% (Cr) and 13.0% (organic carbon).

CONCLUSION

The total pollution levels of THMs fell outside of the safety domain in growth soils. Furthermore, more attention needs to be paid to Cd pollution owing to its low environment background value and high accumulation ability. Three main soil parameters (Cr content, pH, organic carbon) played important roles in the formations and accumulations of THMs in chestnuts. © 2019 Society of Chemical Industry.

Highly selective and portable chemosensor for mercury determination in water samples using curcumin nanoparticles in a paper based analytical device

Curcumin nanoparticle (CURNs) are employed in a paper based analytical device (PADs) for monitoring Hg²⁺ concentration.

Recent Developments in the Speciation and Determination of Mercury Using Various Analytical Techniques

This paper reviews the speciation and determination of mercury by various analytical techniques such as atomic absorption spectrometry, voltammetry, inductively coupled plasma techniques, spectrophotometry, spectrofluorometry, high performance liquid chromatography, and gas chromatography. Approximately 126 research papers on the speciation and determination of mercury by various analytical techniques published in international journals since 2013 are reviewed.