Determination of trace level cadmium in SRM 3280 Multivitamin/Multielement Tablets via isotope dilution inductively coupled plasma mass spectrometry

Comparative study between the top six heavy metals involved in the EU RASFF notifications over the last 23 years

From the Rapid Alert System for Food and Feed (RASFF) database, a total of 4728 notifications regarding the six most frequently notified heavy metals (i.e., arsenic, cadmium, lead, mercury, chromium, and nickel) were tracked from January 1, 2000, to December 31, 2022, and analyzed based on year, notification classification, notifying countries, countries of origin, product types, product categories, risk decision, and action taken. Human risk assessment owing to consumption of mercury- and cadmium-contaminated seafood was estimated as well. Results revealed that the highest numbers of notifications were on mercury (36.6%), cadmium (25.1%), and lead (14.1%). Interestingly, the number of total notifications was at its peak between 2011 and 2014; from 2015 onward, it started to decrease considerably. Alert, border rejection, and information notifications represented 29.6%, 21.9%, and 48.5% of the total notifications, respectively. Chromium and nickel resulted in 33.8% and 23.3% of border rejection notifications, respectively. About 52.0% of the alert notifications were on mercury. Serious notifications represented 34.9% of the total notifications. Mercury and cadmium notifications accounted for 54.9% and 25.8% of serious notifications, respectively. Italy was the most notifying country, recording the highest number of notifications on cadmium (29.0%), mercury (52.6%), chromium (81.0%), and nickel (78.7%). China was the most notified origin country with regards to arsenic (18.7%), cadmium (12.8%), lead (27.6%), chromium (71.2%), and nickel (66.9%) notifications. Notifications on food, food contact materials (FCM), and feed represented 71.9%, 23.4%, and 4.7%, respectively, of the total notifications. About 91.5% of mercury notifications were on fish and fish products; 24.3% of arsenic notifications related to fruits and vegetables; and 20.1% of cadmium notifications corresponded to cephalopods and products thereof. Notified products were largely withdrawn from the markets according to arsenic (20.3%), lead (17.9%), and mercury (18.0%) notifications and re-dispatched because of cadmium (20.5%), chromium (42.1%), and nickel (49.5%) notifications. The target hazard quotient (THQ) values for mercury in swordfish, sharks, and tuna and cadmium in squid were all also below the threshold value of 1, implying that there is no significant risk for consumers. Overall, media coverage of RASFF alerts and actions may raise awareness of heavy metal contamination among the general public and industry professionals. The primary dietary advice of our study is to stay away from species with high mercury contents. Also, identifying the most dangerous heavy metals (HMs) and the most polluting products can help researchers prioritize their efforts in finding sustainable solutions for them.

The Importance of Reference Materials and Method Validation for Advancing Research on the Health Effects of Dietary Supplements and Other Natural Products

Insufficient assessment of the identity and chemical composition of complex natural products, including botanicals, herbal remedies, and dietary supplements, hinders reproducible research and limits understanding mechanism(s) of action and health outcomes, which in turn impede improvements in clinical practice and advances in public health. This review describes available analytical resources and good methodological practices that support natural product characterization and strengthen the knowledge gained for designing and interpreting safety and efficacy investigations. The practice of validating analytical methods demonstrates that measurements of constituents of interest are reproducible and appropriate for the sample (e.g., plant material, phytochemical extract, and biological specimen). In particular, the utilization of matrix-based reference materials enables researchers to assess the accuracy, precision, and sensitivity of analytical measurements of natural product constituents, including dietary ingredients and their metabolites. Select case studies are presented where the careful application of these resources and practices has enhanced experimental rigor and benefited research on dietary supplement health effects.

Multi-walled carbon nanotube-based nanobiosensor for the detection of cadmium in water

Industrial and agricultural processes have led to the prevalence of cadmium in the ecosystem. A successive build-up of cadmium in food and drinking water can result in inadvertent consumption of hazardous concentrations. Such environmental contamination of cadmium can pose a substantial threat to human and animal life. In humans, it is known to cause hypertension, cardiovascular diseases, DNA lesions, inhibition of DNA repair protein or disturb the functioning of lung, liver, prostate and kidney. The development of a reliable method for Cd (II) ions detection would reduce the exposure and complement existing conventional methods. In this study, a DNA based electrochemical method is employed for the detection of Cd (II) ions using ethyl green (EG) and multi-walled carbon nanotube (MWCNT). Glassy carbon electrode (GCE)/MWCNT forms the working electrode for differential pulse voltammetry (DPV) analysis for the detection of Cd (II) ions. The dsDNA is immobilized onto the working electrode. The indicator dye EG, preferably binds to ssDNA and its reduction peak current is noticeably less in the presence of dsDNA. The Cd (II) ions after interacting with dsDNA, unwinds the dsDNA to ssDNA, upon which the EG molecules bind to ssDNAs, giving a higher reduction peak current. The difference in the reduction peak currents in the presence and absence of Cd (II) ions is proportional to its concentration. The linear detection range achieved in this method is 2 nM-10.0 nM with a sensitivity of around 5 nA nM^-1 and the limit of detection is 2 nM, which is less than the permissible limit of WHO for human exposure. This study considerably broadens the possible application of multi-walled carbon nanotube modified electrodes as biosensors and holds prospects for the detection of other heavy metals in environmental samples.

Determination of cadmium in sediments by diluted HCI extraction and isotope dilution ICP-MS

Isotope dilution ICP-MS is proposed to measure the mass fraction of Cd extracted by diluted HCl in marine sediments, using a fast and simple extraction procedure based on ultrasonic probe agitation. The ¹¹¹Cd isotope was added before the extraction to achieve isotope equilibration with native Cd solubilized from the sample. The parameters affecting trueness and precision of isotope ratio measurements were evaluated carefully and subsequently corrected in order to minimize errors; they were: detector dead time, spectral interferences, mass discrimination factor and optimum sample/spike ratio. The mass fraction of Cd extracted was compared with the sum of the certified contents of the three steps of the sequential extraction procedure of the Standards, Measurements and Testing Programme (SM&T) analysing the BCR 701 sediment to validate the method. The certified and measured values agreed, giving a measured / certified mass fraction ratio of 1.05. Further, the extraction procedure itself was studied by adding the enriched isotope after the extraction step, which allowed verifying that analyte losses occurred during this process. Two additional reference sediments with certified total cadmium contents were also analysed. The method provided very good precision (0.9%, RSD) and a low detection limit, 1.8 ng g^-1. The procedural uncertainty budget was estimated following the EURACHEM Guide by means of the 'GUM Workbench' software, obtaining a relative expanded uncertainty of 1.5%. The procedure was applied to determine the bioaccessible mass fraction of Cd in sediments from two environmentally and economically important areas of Galicia (rias of Arousa and Vigo, NW of Spain).

Sequential coprecipitation and matrix removal for determination of cadmium impurities from multivitamin supplements by inductively coupled plasma mass spectrometry and method validation by isotope dilution analysis of SRM 3280 multivitamin/multielement tablets

In this paper, we examined three different sequential coprecipitation schemes based on Mg(OH)₂ and CaF₂ precipitation using triethylamine (TEA) and hydrofluoric acid (HF), respectively, for determination of cadmium (Cd) impurities from multivitamin/mineral (MVM) supplements by isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS). The schemes involved three-step coprecipitation with either TEA alone or in combination with HF and are designated as Scheme 1 (TEA-TEA-TEA), Scheme 2 (TEA-HF-TEA) and Scheme 3 (HF-TEA-TEA) according to the addition sequence of each reagent. Experiments were carried out with MVM solutions spiked with 60 μg L^-1 Cd from a multielement standard solution. All schemes provided quantitative separation of Cd from MVM matrix. Scheme 1 was the least effective in removal of interfering concomitant elements, molybdenum (Mo) and tin (Sn). Scheme 2 performed better for Sn, but failed in eliminating Mo. Scheme 3 was the most effective in eliminating both Mo and Sn. Mo levels in test MVM solutions reduced from 4.3 μg mL^-1 to as low as 0.014 μg mL^-1 while that for Sn decreased from 0.5 μg mL^-1 to 0.018 μg mL^-1 allowing interference-free determination of Cd to be achieved. Salt-matrix due to Mg, Ca, P and K along with the essential elements (Mn, Fe, Cu and Zn) levels was also reduced significantly. Reagent blanks from HF and TEA were insignificant (0.008 μg L^-1) allowing a limit of detection of 0.004 μg L^-1 or 0.26 ng g^-1 Cd to be achieved (3σ, n = 6). The performance of the coprecipitation method (Scheme 3) was validated by determination of Cd in multivitamin/multielement tablets certified reference material (SRM 3280) by ID-ICP-MS. Experimental results (ng g^-1) and recoveries were 78.8 ± 4.7 (98.5%), 77.9 ± 5.2 (97.4%) and 76.5 ± 4.8 (95.6%) for ¹¹⁰Cd, ¹¹¹Cd and ¹¹⁴Cd isotopes, respectively. Several commercial MVM supplements were analyzed using the method. Mean Cd concentration ranged from 21.4 ng g^-1 to 93.3 ng g^-1. These values are much lower than those reported to date for various MVM supplements by ICP-MS determinations without chemical separation.

Heavy Metals in Notifications of Rapid Alert System for Food and Feed

Heavy metals represent the fourth most often notified hazard category in the Rapid Alert System for Food and Feed (RASFF) from 1980-2016. The goal of the study was to examine the similarities in notifications of particular heavy metals within the RASFF year, product category, notifying country, country of origin, notification basis, notification type, distribution status, risk decision, and action taken, taking into account the particular product type, such as food, food contact material, and feed. The data originated from the RASFF database. Cluster analysis on pivot tables was applied using joining and two-way joining methods. Most notifications concerned food, in which the highest number were related to mercury, cadmium, chromium, lead, arsenic, and nickel. Notifications were mainly related to fish and food contact materials, in addition to fruits and vegetables, seafood, and dietetic food. The number of notifications decreased in 2015 and 2016. The majority of products were notified by Italy, Spain, Germany, and France. The notified products originated mainly from China and Spain. The notification was usually based on official controls on the market, as well as border controls. The notification types were mainly information, alert, and border rejections. Products were not frequently distributed due to distribution restriction to the notifying country or the possibility of distribution to the market. A risk decision was not usually made. The taken actions included re-dispatch of products, withdrawal from the market, or destruction. The data on heavy metals from the RASFF database can help European and national authorities in shaping public health.

Maize tassel-modified carbon paste electrode for voltammetric determination of Cu(II)

The preparation and application of a practical electrochemical sensor for environmental monitoring and assessment of heavy metal ions in samples is a subject of considerable interest. In this paper, a carbon paste electrode modified with maize tassel for the determination of Cu(II) has been proposed. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study morphology and identify the functional groups on the modified electrode, respectively. First, Cu(II) was adsorbed on the carbon paste electrode surface at open circuit and voltammetric techniques were used to investigate the electrochemical performances of the sensor. The electrochemical sensor showed an excellent electrocatalytic activity towards Cu(II) at pH 5.0 and by increasing the amount of maize tassel biomass, a maximum response at 1:2.5 (maize tassel:carbon paste; w/w) was obtained. The electrocatalytic redox current of Cu(II) showed a linear response in the range (1.23 μM to 0.4 mM) with the correlation coefficient of 0.9980. The limit of detection and current-concentration sensitivity were calculated to be 0.13 (±0.01) μM and 0.012 (±0.001) μA/μM, respectively. The sensor gave good recovery of Cu(II) in the range from 96.0 to 98.0 % when applied to water samples.