Determination of macro, micro and trace elements in citrus fruits by inductively coupled plasma-optical emission spectrometry (ICP-OES), ICP-mass spectrometry and direct mercury analyzer

A Fluorescent Probe for Hg2+ Specific Recognition Based on Xanthene and its Application in Food Detection and Cell Imaging

The mercury-loving unit aminothiourea was introduced into the xanthene fluorophore to synthesized the probe molecule NXH. NXH has a specific response to Hg2+, and with the addition of (0 ~ 50 µM) Hg2+, the fluorescence intensity of the probe solution was quenched from 2352 a.u. to about 308 a.u. NXH exhibited excellent detection performance of high sensitivity (LOD = 96.3 nM), real-time response (105 s), wide pH range (2.1 ~ 9.3), and strong anti-interference ability for Hg2+. At the same time, NXH has wide range of applications for Hg2+ detection, which can fluorescence imaging of Hg2+ in Hela cells and tea samples, and can also be made into Hg2+ detection test paper.

Boron difluoride modified zinc metal-organic framework-based "off-on" fluorescence sensor for tetracycline and Al3+ detection

A novel fluorescence "off-on" probe was developed using a boron difluoride-modified zinc metal-organic framework (Zn-MOF3) for sensitive determination of tetracycline (TC) and Al3+. The Zn-MOF3 has excellent optical property and good applicability in aqueous phase. The fluorescence recorded at 436 nm was quenched at the excitation wavelength of 336 nm. Signal-off detection of tetracycline via fluorescence quenching of Zn-MOF3 is based on the inner filter effect. Fluorescence on-off-on detection of Al3+ occurs via the specific binding between tetracycline and Al3+. The limits of detection for TC and Al3+ were 28.4 nM and 106.7 nM, respectively. This probe exhibited high selectivity which was used for the determination of TC and Al3+ with satisfied recoveries (89.8 to 105.6% for TC, 90.0 to 110.4% for Al3+) and good precision (< 5%) in milk. The developed sensor represents the first "off-on" system for fluorescence detection of TC and Al3+ based on Zn-MOF3 with a better aspect of the innovation.

Novel poly (N-methacryloyl-L-alanine acid) grafted chitosan microspheres based solid-phase extraction coupled with ICP-MS for simultaneous detection of trace metal elements in food

Poly (N-methacryloyl-L-alanine acid) grafted tartaric acid-crosslinked chitosan microspheres (PNMA-TACS) were successfully synthesized and employed as a novel adsorbent for the separation and enrichment of metal ions in the food system. PNMA-TACS microspheres-based solid phase extraction (SPE) was coupled with ICP-MS for accurate quantification of trace V(V), Cr(III), As(III), Pb(II), Cd(II) and Cu(II). The obtained PNMA-TACS microspheres were characterized, and parameters influencing the method were optimized. Under optimal conditions, the calibration curves for Cu(II) and V(V) were linear within 0.01-30 μg L-1, the linear ranges of Cr(III), As(III), Pb(II) and Cd(II) were 0.01-15 μg L-1, and the detection limit of the developed approach was 1.1-3.7 ng L-1. The results were consistent with the consensus values of method validation implemented by two standards. Moreover, standard addition recovery experiments were performed in rice and milk powder, which achieved satisfactory recovery of 86.1-103.5%.

Nutritional value, elemental bioaccumulation and antioxidant activity of fruiting bodies and mycelial cultures of an unrecorded wild Lactarius hatsudake from Nanyue mountainous region in China

An unrecorded wild mushroom Lactarius hatsudake from Nanyue mountainous region in China was identified. Subsequently, comparative investigation on the nutritional value, elemental bioaccumulation, and antioxidant activity was performed in the fruiting body (FB) and mycelium (MY) samples of this species. It revealed that the contents of moisture (87.66 ± 0.16 g/100 g fw) and ash (6.97 ± 0.16 g/100 g dw) were significantly higher in FB, and the total carbohydrate, fat, and protein concentrations of FB were similar to those in MY. Among nutritionally important elements, FB possessed higher concentrations of potassium (37808.61 ± 1237.38 mg/kg dw), iron (470.69 ± 85.54 mg/kg dw), and zinc (136.13 ± 5.16 mg/kg dw), whereas MY was a better source of magnesium (1481.76 ± 18.03 mg/kg dw), calcium (2203.87 ± 69.61 mg/kg dw), and sodium (277.44 ± 22.93 mg/kg dw). According to the health risk estimation, FB might pose an aluminum-related health problem when a prolonged period of exposure, while MY was risk-free for consumers. The results of antioxidant capacity (1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays) in FB and MY were within the range of 104.19 ± 5.70 mg ascorbic acid equivalents (AAE)/g to 169.50 ± 4.94 mg AAE/g, and half maximal effective concentration EC50 values ranged from 0.23 ± 0.01 mg/mL to 0.62 ± 0.05 mg/mL. The aqueous extracts of MY demonstrated a strong ABTS radical scavenging capacity with the highest AAE value.

Elemental Analysis of Kimchi Cabbage Leaves, Roots, and Soil and Its Potential Impact on Human Health

In view of their rich mineral content and flavor, kimchi cabbage leaves and roots have high nutritional and medicinal values. In this study, we quantified major nutrient (Ca, Cu, Fe, K, Mg, Na, and Zn), trace (B, Be, Bi, Co, Ga, Li, Ni, Se, Sr, V, and Cr), and toxic (Pb, Cd, Tl, and In) elements in kimchi cabbage cultivation soil, leaves, and roots. The analysis method relied on inductively coupled plasma-optical emission spectrometry for major nutrient elements and inductively coupled plasma-mass spectrometry for trace and toxic elements and complied with the Association of Official Analytical Chemists (AOAC) guidelines. Kimchi cabbage leaves and roots featured high contents of K, B, and Be, while the contents of all toxic elements in all samples were below the WHO-stipulated threshold values and therefore did not pose any health risks. The distribution of elements was characterized by heat map analysis and linear discriminant analysis to reveal independent separation according to the content of each element. The analysis confirmed that there was a difference in content between the groups and that each group was independently distributed. This study may contribute to a better understanding of the complex relationships between plant physiology, cultivation condition, and human health.

Quality evaluation of citrus varieties based on phytochemical profiles and nutritional properties

Introduction

China is one of the major producers and exporters of various kinds of citrus fruits. As one of China's major citrus planting bases, Sichuan has a citrus planting area that exceeds 400,000 hectares. Meanwhile, citrus cultivation has become one of the important agricultural pillar industries in the region. Citrus fruits are reported to show various health-promoting effects, especially antioxidant activity. However, reports on the functional, nutritional and qualitative characteristics of different citrus varieties in Sichuan are still scarce.

Methods

The quality attributes (color parameters, shape, and size), juice properties (titratable acids and total soluble sugar), mineral elements, and health-promoting nutritional and functional components (protein, carbohydrates, fat, dietary fiber, ascorbic acid, phenolic acids, and flavonoids), as well as antioxidant properties of 10 typical citrus varieties cultivated in Sichuan, were systematically investigated and analyzed.

Results and Discussion

Significant differences among different citrus varieties were found. In particular, the total soluble sugar content of Mingrijian was higher than that of other citrus, suggesting its potential for fresh consumption and food processing. Moreover, a total of five flavonoids and nine phenolic acids were identified and quantified. Yuanhong, with higher contents of ascorbic acid and phenolic acids, was considered to be a valuable variety with excellent antioxidant capacity and can be used for value-added processing in the food industry. Principal component analysis and hierarchical cluster heatmap analysis suggested that there were significant differences among the 10 citrus varieties. Correlation analysis confirmed the significant contribution of ascorbic acid and phenolic acids to antioxidant capacity in citrus. The results can provide some references for the cultivation and selection of nutritious citrus fruits.

The Level of Heavy Metal in Fresh and Processed Fruits: A Study Meta-analysis, Systematic Review, and Health Risk Assessment

Intake of fruits is important for health. However, it can be a contamination source of potentially toxic elements (PTEs). The present study aimed to investigate the concentration of PTEs such as arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), and Iron (Fe) in various fresh and processed fruits. All the studies related to the concentration of PTEs in fresh and processed fruits by international databases including were included and non-carcinogenic risks assessment was evaluated based on the total hazard quotient (TTHQ). According to findings highest concentrations of As, Cd and Pb were observed in pineapple, mango, and cherry, while the lowest concentrations of these metals were found in berries, pineapple, and berries. Regarding trace elements, peach and cucumber represented the highest and lowest concentrations of Fe, respectively. Moreover, the highest and lowest concentrations of Cu were related to plum and banana, respectively. Considering the type of continents, the highest concentrations of As, Cd, Pb, Fe, Ni, and Cu among fresh and processed fruits belonged to Pan American Health Organization (EMRO), EMRO, African Region (AFRO), European Region (EURO), AFRO, and Western Pacific Region (SEARO). Eventually, the non-carcinogenic risk assessment of the heavy metal in fresh and processed fruits indicated that the risk pattern was different in various countries and the calculated TTHQ level in infants was below 1. Overall, the consumption of fresh and processed fruits is safe and does not pose a risk to the health of consumers.

Cognitive and biological effects of citrus phytochemicals in subjective cognitive decline: a 36-week, randomized, placebo-controlled trial

Background

Auraptene (AUR) and naringenin (NAR) are citrus-derived phytochemicals that influence several biological mechanisms associated with cognitive decline, including neuronal damage, oxidative stress and inflammation. Clinical evidence of the efficacy of a nutraceutical with the potential to enhance cognitive function in cohorts at risk of cognitive decline would be of great value from a preventive perspective. The primary aim of this study is to determine the cognitive effects of a 36-week treatment with citrus peel extract standardized in levels of AUR and NAR in older adults experiencing subjective cognitive decline (SCD). The secondary aim is to determine the effects of these phytochemicals on blood-based biomarkers indicative of neuronal damage, oxidative stress, and inflammation.

Methods

Eighty older persons with SCD will be recruited and randomly assigned to receive the active treatment (400 mg of citrus peel extract containing 0.1 mg of AUR and 3 mg of NAR) or the placebo at a 1:1 ratio for 36 weeks. The primary endpoint is a change in the Repeatable Battery for the Assessment of Neuropsychological Status score from baseline to weeks 18 and 36. Other cognitive outcomes will include changes in verbal and nonverbal memory, attention, executive and visuospatial functions. Blood samples will be collected from a consecutive subsample of 60 participants. The secondary endpoint is a change in interleukin-8 levels over the 36-week period. Other biological outcomes include changes in markers of neuronal damage, oxidative stress, and pro- and anti-inflammatory cytokines.

Conclusion

This study will evaluate whether an intervention with citrus peel extract standardized in levels of AUR and NAR has cognitive and biological effects in older adults with SCD, facilitating the establishment of nutrition intervention in people at risk of cognitive decline.

Trial registration

The trial is registered with the United States National Library of Medicine at the National Institutes of Health Registry of Clinical Trials under the code NCT04744922 on February 9^th, 2021 (https://www.clinicaltrials.gov/ct2/show/NCT04744922).

Effects of different pesticides treatments on the nutritional quality of kiwifruit

Pesticides are widely used in the process of kiwifruit growth to promote fruit expansion. This study was aimed to assess the effects of pesticides on the quality of kiwifruit by applying high and normal concentrations of forchlorfenuron (CPPU) and thidiazuron (TDZ) to "Xuxiang" (XX) green kiwifruit and "Jinyan" (JY) gold kiwifruit. Sixty kiwifruit trees were used to comprehensively evaluate the effects on the pulp and whole kiwifruit. In addition to the weight gain effect and basic physical-chemical properties (vitamin C, total protein, glucose and fructose, organic acids), the main nutritional qualities (in vitro and cellular antioxidant activity (CAA), and dietary minerals) were also evaluated. The vitamin C content of XX was not affected by pesticides, but the use of CPPU reduced vitamin C of JY pulp by 23% (p < 0.05). Pesticides did not reduce the antioxidant values of XX pulp in vitro but significantly reduced CAA values (32%-47%). In JY pulp, pesticides treatments had no significant effect on antioxidant values in vitro except that CPPU treatments significantly reduced the ferric reducing antioxidant power (FRAP) value by 21% (p < 0.05). Reasonable use of pesticides can effectively improve taste of kiwifruit, increasing kiwifruit weight and the content of certain nutrients. PRACTICAL APPLICATION: Based on observed changes in nutritional components, CPPU may be more suitable for XX while TDZ may be more suitable for JY. The significance of this study may affect kiwifruit farmers and ultimately help improve the sensory quality of kiwifruit.

Optimization and in-house validation of the TDA-AAS method for mercury control in water and wastewater treatment plant sludges

The thermal decomposition, amalgamation, and atomic absorption spectrometry (TDA-AAS) method was validated for mercury (Hg) determination in sludge samples. A linear range was obtained from 30 to 200 ng. The TDA-AAS method provides a limit of quantification (LOQ) well below the legal maximum admitted concentration of Hg in sludge samples, which makes it suitable to measure its concentrations at the imposed legal limits, and for monitoring studies of Hg trace levels in sludge samples. Repeatability and within-laboratory reproducibility of the method were good with relative standard deviations lower than 6%. Expanded uncertainty, estimated using a top-down approach with the data obtained from accuracy and precision studies, was 18% for a coverage factor k = 2. Mercury concentration in sludge samples from water treatment plants was below the LOQ (0.33 mg Hg per kg dw) and in wastewater treatment plants was well below the legal limit for their reuse in agriculture (16 mg Hg per kg dw).

Dietary Intakes of Zinc, Copper, Magnesium, Calcium, Phosphorus, and Sodium by the General Adult Population Aged 20-50 Years in Shiraz, Iran: A Total Diet Study Approach

In the present total diet study, the dietary intake of zinc (Zn), copper (Cu), magnesium (Mg), calcium (Ca), phosphorus (P), and sodium (Na) by healthy adults in Shiraz, Iran, was estimated from the foods as consumed. A total of 580 individual food items were collected, prepared, and pooled into 129 composite samples. The metal concentration was then evaluated using inductively coupled plasma–optical emission spectrometry. The mean intakes of Zn (12.92 mg/d), Cu (3.80 mg/d), and Mg (412.68 mg/d) exceeded the estimated average requirements (EARs), but they were well below the upper limits. A high prevalence of inadequate intake was observed for Ca (91.6%) and P (89.7%), which was mainly due to nutritionally imbalanced diets. Sodium intake for average and high consumers (97.5th percentile) was 123.6% and 237.8% of the tolerable upper intake level of 2300 mg/d, respectively, with 70% of the participants having intakes higher than this threshold value. Nutrition education, nutritional rehabilitation, Ca supplementation, food fortification, mandatory reduction of salt content in processed foods, and discretionary salt use (in home cooking or at the table) are among the possible strategies that can be adopted to combat the health problems.

Highly selective rapid colorimetric sensing of Pb2+ ion in water samples and paint based on metal induced aggregation of N-decanoyltromethamine capped gold nanoparticles

Lead is highly toxic. The detection of lead in the environmental bodies is difficult, because it is colourless and odourless. Herein, we report the synthesis of gold nanoparticles (AuNPs) using the interdigitized vesicles formed by N-decanoyltromethamine (NDTM). AuNPs stabilized by NDTM was pink in colour with spherical shape and the size is 29 ± 7 nm. The optical property of the NDTM-AuNPs was explored for the first time to detect toxic chemical, Pb²⁺. The addition of toxic metal ion Pb²⁺ to NDTM-AuNPs rapidly (< 1 min) alters the colour from pink to violet due to aggregation, which was confirmed by particle size analyser and TEM. The aggregation induced colour changes were realized via broad spectra in UV-Vis spectroscopy. NDTM-AuNPs showed a selective and sensitive spectrophotometric signal with Pb²⁺ when compared with other metal ions. The colorimetric change as a function of Pb²⁺ concentration gave a linear response in the range of 0-30 μM (R² = 0.9942). The detection limit was found at 10 μM by naked eye and 0.35 μM by spectrophotometry. The proposed method was successfully applied for the determination of Pb²⁺ ions in tap water and sewage water. Moreover, as a proof of concept, the NDTM-AuNPs sensor system was applied for the detection of lead in commercial paints. The results of the quantitative estimation of lead in paints by NDTM-AuNPs colorimetric sensor were as good as the standard method, atomic absorption spectroscopy.

Developing a highly selective method for preconcentration and determination of cobalt in water and nut samples using 1-(2-pyridylazo)-2-naphthol and UV-visible spectroscopy

BACKGROUND

Heavy metal contamination in water and agricultural products is a major concern that causes risks for human health. This article describes a highly selective approach to preconcentrate cobalt(II) (Co(II)) ions based on the standard UV-visible measurement of Co(II)-1-(2-pyridylazo)-2-naphthol complex at λ = 628 nm in water and nut samples. In this method, magnetic silica (mSiO₂ ) was utilized as a practical sorbent and 1-(2-pyridylazo)-2-naphthol was employed as a complexing agent in the elution step. The adsorbent was characterized via X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effects of the main variables (pH, adsorption time, sorbent amount, pH of eluent, ligand volume, and desorption time) were investigated and established.

RESULTS

The maximum recovery was achieved at pH 7 ± 0.3, adsorption time of 60 min, sorbent amount of 40 mg, eluent pH 8 ± 0.2, ligand volume of 2 mL (16.95 × 10^-4  mol L^-1 ) and desorption time of 30 min. The linearity of dynamic range (10-500 μg L^-1 ), limit of detection (0.32 μg L^-1 ), relative standard deviation (3.04%), and preconcentration factor (25) show the reliability of the method. The sorbent was reusable 12 times. Selectivity and the effect of interference ions were successfully examined. The adsorption process of Co(II) ions on mSiO₂ was investigated based on Langmuir and Freundlich isotherms. The Freundlich model was fitted with the system and the maximum capacity adsorption of mSiO₂ for Co(II) adsorption is 2.35 mg g^-1 . Then, the kinetics study revealed that the adsorption process of Co(II) ions on the mSiO₂ follows the pseudo-first-order model. The thermodynamics parameters ΔG, ΔS, and ΔH were calculated.

CONCLUSION

The method was fruitfully applied to preconcentrate Co(II) ions in water and nut samples. This method offers high selectivity and precision for determining Co(II) ions. © 2020 Society of Chemical Industry.

The speciation of inorganic arsenic in soil and vegetables irrigated with treated municipal wastewater

An efficient method using vortex-assisted microextraction based on a deep eutectic solvent followed by graphite furnace atomic absorption spectrometry was developed for the determination of arsenic species in soil and vegetables irrigated with treated wastewater.