Recognizing and overcoming analytical error in the use of ICP-MS for the determination of cadmium in breakfast cereal and dietary supplements

An ultrasensitive Cd2+ detection biosensor based on DNAzyme and CRISPR/Cas12a coupled with hybridization chain reaction

The detection of cadmium is essential because it poses a significant threat to human health and the environment. Recent advancements in biosensors that detect nonnucleic-acid targets using CRISPR/Cas12a in combination with aptamers or DNAzymes show promising performance. Herein, we integrated DNAzyme, hybridization chain reaction (HCR) and CRISPR/Cas12a into a single biosensor for the first time and realized the ultrasensitive detection of Cd2+. A single phosphorothioate ribonucleobase (rA)-containing oligonucleotide (PS substrate) and a Cd2+-specific DNAzyme (Cdzyme) are used for Cd2+ recognition, releasing short single-stranded DNA. Then, the HCR is triggered by the cleavage products for signal transduction and amplification. Next, the trans-cleavage activity of Cas12a is activated due to the presence of crRNA complementary strands and PAM sites in the HCR products. As a result, FQ-reporters are cleaved, and the fluorescence values can be easily read using a fluorometer, allowing Cd2+ quantification by measuring the fluorescent signal. The Cd2+ detection biosensor is ultrasensitive with a detection limit of 1.25 pM. Moreover, the biosensor shows great stability under different pH and various anion conditions. The proposed sensor was utilized for environmental water sample detection, demonstrating the dependability of the detection system. Considering the high sensitivity and reliable performance of the assay, it could be further used in environmental monitoring. In addition, the design strategy reported in this study could extend the application of CRISPR/Cas12a in heavy metal detection.

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.

Pseudo isotope dilution (PID) as an approach for correcting barium-related spectral interferences on the measurement of europium by inductively coupled plasma mass spectrometry (ICP-MS)

Pseudo isotope dilution (PID) was suggested as a simple and practical approach for the correction of barium-related spectral interferences on the measurement of europium by inductively coupled plasma mass spectrometry (ICP-MS). The interferents, i.e. oxides and hydroxides of barium, were regarded as pseudo europium isotopes. An equation for calculating the concentration of europium was deduced and the net contribution of europium isotopes can be obtained by measuring the signal intensity ratios of ¹⁵¹I/¹⁵³I in a sample, a europium standard, and a barium standard, respectively. The validity of the approach was confirmed by the determination of europium in standard solutions with different concentrations of barium. Determination of europium in river water and seawater certified reference materials was carried out, whose results were in coincidence with reference values.

Optimised ICP-MS quantification method for using animal faeces as a measure of protected area ecosystem health

Pollution is a key threat to biodiversity and ecosystem health within protected areas. Using a non-invasive, multi-matrix approach, sediment, vegetation and faecal material from lion (Panthera leo) and giraffe (Giraffa camelopardalis) were collected and assessed for the simultaneous quantification of 20 trace elements using an optimised method for Inductively Coupled Plasma--Mass Spectrometry (ICP-MS). Method Linearity was confirmed over an analytical range of 0.1-50 mg/kg for aluminium (Al) and iron (Fe); 0.4-400 µg/kg for vanadium (V), cobalt (Co), molybdenum (Mo), and cadmium (Cd); 0.5-5 µg/kg for mercury (Hg); and 1-1 000 µg/kg for elements arsenic (As), boron (B), barium (Ba), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), selenium (Se), tin (Sn), strontium (Sr) and zinc (Zn). Coefficient of determination (R²) was above 0.99 for all elements. Accuracy (% recovery) and precision (% RSD) of replicate measurements for certified reference material controls fell within 20% of expected value at lower concentrations and 15% at higher concentrations for all elements except Al. Results for instrument and method limit of detections (LOD), method limit of quantification (LOQ) and expanded uncertainty were satisfactory. Preliminary data indicate As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn were present in all matrices evaluated. This raises concerns regarding the combined action of multiple elements at concentrations that can adversely affect ecosystem and wildlife integrity.•Sample quantity is reduced due to the power and sensitivity of ICP-MS.•The optimised method is capable of detecting differences in trace element concentrations over large orders of magnitude in animal faeces containing different amounts of organic content.•The method can be applied to the quantification of essential and potentially toxic elements in faeces across a wide range of terrestrial species.

Fractionation of cadmium in tobacco and cigarette smoke condensate using XANES and sequential leaching with ICP-MS/MS

Fractionation data for cadmium in tobacco products, as obtained by sequential leaching of cadmium species with ICP-MS/MS analysis, and separately by X-ray absorption near edge structure (XANES) are presented here for the first time. The total amount of cadmium found in 3R4F cigarette cut tobacco was 1526 ± 42 μg kg-1, of which 5% was found in the smoke under ISO smoking conditions. XANES analysis showed that Cd in tobacco, cigarette smoke and ash was present in the + 2 oxidation state. Examination of the gas-particle partitioning of smoke cadmium suggests that Cd in mainstream smoke is best viewed as semi-volatile, existing in both particulate and gas phases. Sequential extraction of trapped tobacco smoke was carried out to get a deeper insight into the chemistry of cigarette smoke cadmium compounds. Consecutive extractions with ultrapure water, dilute (1%) nitric acid and 10% nitric acid led to extraction of a total amount of Cd which agreed with that obtained after microwave digestion of the whole sample, suggesting that cadmium was quantitatively leachable into aqueous/acidic solutions. Most Cd (~ 90% of the total Cd in the smoke condensate) was extracted into dilute nitric acid (likely as CdO, Cd(OH)2 and CdCO3) with a minor percentage (3%) extracted into water (likely as CdCl2) and in 10% nitric acid (likely as CdS). Extraction of trapped mainstream smoke with pentane, followed by ICP-MS/MS analysis, to examine the possible presence of organocadmium in 3R4F tobacco smoke, did not show the presence of organocadmium compounds above the method LOQ (2 μg kg-1), possibly due to their reactivity under the experimental conditions. The high selectivity with sufficient sensitivity achieved by ICP-MS/MS was invaluable to quantify Cd (at low μg kg-1levels) simultaneously with sulphur and chlorine in the tobacco smoke fractions of complex matrix. The cadmium chemistry in the smoke, identified in this study, is consistent with both relatively high lung absorption and DNA binding; both potentially important factors for disease progression in smokers. Graphical Abstract This paper provides quantitative fractionation data for cadmium in tobacco and smoke by using sequential leaching with ICPMS and XANES.

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).

Development of a kelp powder (Thallus laminariae) Standard Reference Material

A Standard Reference Material (SRM) of seaweed, SRM 3232 Kelp Powder (Thallus laminariae) has been developed to support food and dietary supplement measurements in compliance with the Food Safety Modernization Act (FSMA) and the Dietary Supplement Health and Education Act of 1994 (DSHEA). The material was characterized for nutritional minerals, arsenic species, isomers of vitamin K1, proximates, and toxic elements. Kelp is a rich source of vitamins and minerals, and it is an excellent source of dietary iodine. Kelp also contains a large amount of arsenic, which is toxic as inorganic species but much less so as organic species. To capture the dietary profile of kelp, certified values were issued for As, Ca, Cd, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Mo, Na, Pb, and Zn. Reference values for proximates were assigned. For the first time, a certified value for iodine, reference values for isomers of vitamin K1, and reference values for arsenic species including arsenosugars were assigned in a seaweed. SRM 3232 fills a gap in Certified Reference Materials (CRMs) needed for quality assurance and method validation in the compositional measurements of kelp and similar seaweeds used as food and as dietary supplements. Graphical Absract Arsenic species and isomers of vitamin K1 were determined in the development of SRM 3232 Kelp Powder (Thallus laminariae).

Synthesis and Characterization of Porous MnCo2O4 for Electrochemical Determination of Cadmium ions in Water Samples

To utilize the maximum activity of nanomaterials, it was specifically synthesized by appropriate physicochemical properties. In that aspect, we have described the synthesis of porous MnCo2O4 by simple chemical route and applied for the selective detection of cadmium (Cd (II)). The as-prepared porous MnCo2O4 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) adsorption isotherm, X-ray diffraction pattern analysis (XRD), Fourier transform infra-red spectroscopy (FT-IR), energy dispersive X-ray (EDX) and electrochemical techniques. The porous MnCo2O4 exhibited an excellent electrochemical behaviour and good analytical response towards the determination of Cd (II). Those analytical factors such as pH, deposition potential and deposition time are optimized by using differential pulse anodic stripping voltammetry (DPASV). A wide linear concentration range from 2.3 to 120 µg L-1, limit of detection (LOD) of 0.72 µg L-1 and the limit of quantification (LOQ) of 0.91 µg L-1 were achieved for determination of Cd (II). The selectivity of the developed sensor was explored in the presence of co-interfering ions. Also our sensor exhibits a good stability, reproducibility and repeatability. In addition, the practicability of proposed sensor was evaluated for the detection of Cd (II) in real water samples.

Selection and characterization of DNA aptamers for the development of light-up biosensor to detect Cd(II)

In order to develop a facile, cost-effective and quick-testing light-up biosensor with excellent specificity for cadmium ions (Cd(II)) detection, a modified selection method based on target-induced release of strands was used to isolate aptamers of Cd (II) with high specificity. Circular Dichroism (CD) data confirmed that one of the selected aptamers underwent a distinct conformational change on addition of Cd (II). A biosensor for Cd(II) was developed based on the Cd(II)-induced release of fluorescence-labeled aptamer from complex with a quencher-labeled short complementary sequence. The sensing platform displayed a Cd(II) concentration-dependent increase of fluorescence intensity in the low micromolar range and had an excellent selectivity in the presence of various interfering metal ions. Such biosensor could potentially be used for the detection of Cd(II) in environmental samples.

Deep sea water prevents balloon angioplasty-induced hyperplasia through MMP-2: an in vitro and in vivo study

Major facts about the development of restenosis include vascular smooth muscle cells (VSMCs) proliferation and migration. A previous study showed that in vitro treatment with magnesium chloride has the potential to affect the proliferation and migration of VSMCs. Magnesium is the major element in deep sea water (DSW) and is a biologically active mineral. It is unclear whether DSW intake can prevent abnormal proliferation and migration of VSMCs as well as balloon angioplasty-induced neointimal hyperplasia. Thus, we attempted to evaluate the anti-restenotic effects of DSW and its possible molecular mechanisms. Several concentrations of DSW, based on the dietary recommendations (RDA) for magnesium, were applied to a model of balloon angioplasty in SD rats. The results showed that DSW intake markedly increased magnesium content within the vascular wall and reduced the development of neointimal hyperplasia. The immunohistochemical analysis also showed that the expression of proteins associated with cell proliferation and migration were decreased in the balloon angioplasty groups with DSW supplement. Furthermore, in vitro treatment with DSW has a dose-dependent inhibitory effect on serum-stimulated proliferation and migration of VSMCs, whose effects might be mediated by modulation of mitogen-activated protein kinase (MAPK) signaling and of the activity of matrix metalloproteinase-2 (MMP-2). Our study suggested that DSW intake can help prevent neointimal hyperplasia (or restenosis), whose effects may be partially regulated by magnesium and other minerals.

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

Cadmium was quantified at 80.15±0.86 ng/g (mean±95% expanded uncertainty) in NIST SRM 3280 Multivitamin/Multielement Tablets, using isotope dilution mass spectrometry. The method described utilized various precipitation and solid-phase extraction separation methodologies to isolate Cd from Sn and Mo, present respectively, at 11.1±0.9 mg/kg and 70.7±4.5 mg/kg in the tablet matrix. This allowed for measurement of (111)Cd/(113)Cd and (111)Cd/(114)Cd isotope ratios using both quadrupole collision cell technology inductively coupled plasma mass spectrometry (Q-CCT-ICP-MS) and sector field (SF)-ICP-MS equipped with a desolvating nebulizer system to mitigate the MoO(+) and MoOH(+) molecular ion interferences that typically affect the envelope of Cd isotopes.