Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry

Quantitative analysis of human hairs and nails

Hair and nails are human biomarkers capable of providing a continuous assessment of the concentrations of elements inside the human body to indicate the nutritional status, metabolic changes, and the pathogenesis of various human diseases. Laser-induced breakdown spectroscopy (LIBS) and X-ray fluorescence (XRF) spectrometry are robust and multi-element analytical techniques able to analyze biological samples of various kinds for disease diagnosis. The primary objective of this review article is to focus on the major developments and advances in LIBS and XRF for the elemental analysis of hair and nails over the last 10-year period. The developments in the qualitative and quantitative analyses of human hair and nail samples are discussed in detail, with special emphasis on the key aspects of elemental imaging and distribution of essential and non-essential elements within the hair and nail tissue samples. Microchemical imaging applications by LIBS and XRF (including micro-XRF and scanning electron microscopy, SEM) are also presented for healthy as well as diseased tissue hair and nail samples in the context of disease diagnosis. In addition, main challenges, prospects, and complementarities of LIBS and XRF toward analyzing human hair and nails for disease diagnosis are also thoroughly discussed here.

Electrochemical detection of selected heavy metals in water: a case study of African experiences

The safety of water resources throughout the globe has been compromised by various human activities and climate change over the last decades. Consequently, the world is currently confronted with a severe shortage of water supply and a water safety crisis, amidst a growing population. With poor environmental regulations, indiscriminate budding of urban slums, poverty, and a lack of basic knowledge of hygiene and sanitation, the African water supply has been critically threatened by different organic and inorganic contaminants, which results in several health issues. Inorganic pollutants such as heavy metals are particularly of interest because they are mostly stable and non-biodegradable. Therefore, they are not easily removed from water. In different parts of the continent, the concentration of heavy metals in drinking water far exceeds the permissible level recommended by the World Health Organization (WHO). Worse still, this problem is expected to increase with growing population, industrialization, urbanization, and, of course, corruption of government and local officials. Most of the African population is ignorant of the standards of safe water. In addition, the populace lack access to affordable and reliable technologies and tools that could be used in the quantification of these pollutants. This problem is not only applicable to domestic, but also to commercial, communal, and industrial water sources. Hence, a global campaign has been launched to ensure constant assessment of the presence of these metals in the environment and to promote awareness of dangers associated with unsafe exposure to them. Various conventional spectroscopic heavy metal detection techniques have been used with great success across the world. However, such techniques suffer from some obvious setbacks, such as the cost of procurement and professionalism required to operate them, which have limited their applications. This paper, therefore, reviews the condition of African water sources, health implications of exposure to heavy metals, and the approaches explored by various indigenous electrochemists, to provide a fast, affordable, sensitive, selective, and stable electrochemical sensors for the quantification of the most significant heavy metals in our water bodies.

Application of Laser-Induced Breakdown Spectroscopy and Chemometrics for the Quality Evaluation of Foods with Medicinal Properties: A Review

Laser-induced Breakdown Spectroscopy (LIBS) is becoming an increasingly popular analytical technique for characterizing and identifying various products; its multi-element analysis, fast response, remote sensing, and sample preparation is minimal or nonexistent, and low running costs can significantly accelerate the analysis of foods with medicinal properties (FMPs). A comprehensive overview of recent advances in LIBS is presented, along with its future trends, viewpoints, and challenges. Besides reviewing its applications in both FMPs, it is intended to provide a concise description of the use of LIBS and chemometrics for the detection of FMPs, rather than a detailed description of the fundamentals of the technique, which others have already discussed. Finally, LIBS, like conventional approaches, has some limitations. However, it is a promising technique that may be employed as a routine analysis technique for FMPs when utilized effectively.

Electrochemical Characterization and Detection of Lead in Water Using SPCE Modified with BiONPs/PANI

The need for constant assessment of river water qualities for both aquatic and other biological survival has emerged a top priority, due to increasing exposure to industrial pollutants. A disposable screen print carbon electrode was modified with a conductive polymer (PANI) and Zn and/or Cu oxides NPs, obtained through bioreduction in citrus peel extracts (lemon and orange), for ultra-sensitive detection of PB2+, in the Crocodile River water sample. The synthesized materials were characterized with Fourier-transform infra-red spectroscopy (FTIR), ultra-violet visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM). The SPC-modified electrodes designated as SPCE/LPE/BiONPs/PANI and SPCE/OPE/BiONPs/PANI were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and eventually deployed in the electrochemical detection of PB2+ in water using square wave voltammetry (SWV) technique. The electrochemical responses of the modified electrodes for both CV and EIS in 0.1 M HCl demonstrated enhanced performance relative to the bare SPCE. A detection and quantification limit of 0.494 ppb and 1.647 were obtained at SPCE/LPE/BiONPs/PANI, respectively, while a detection and quantification limit of 2.79 ppb and 8.91 ppb, respectively, were derived from SPCE/OPE/BiONPs/PANI. The relative standard deviations (RSD) for SPC electrode at a 6.04 µM PB2+ analyte concentration was 4.76% and 0.98% at SPCE/LPE/BiONPs/PANI and SPCE/LPE/BiONPs/PANI, respectively. The effect of copper, zinc, iron, cobalt, nickel, and magnesium on the stripping peaks of PB2+ at SPCE/OPE/BiONPs/PANI, showed no significant change except for cobalt, with about 17.67% peak current drop. The sensors were assessed for possible determination of PB2+ in spiked river water samples. The average percentage recovery and RSD calculated were 94.25% and 3.74% (n = 3) at SPCE/LPE/BiONPs/PANI and, 96.70% and 3.71% (n = 3) at SPCE/OPE/BiONPs/PANI, respectively. Therefore, the fabricated sensor material could be used for environmental assessment of this highly toxic heavy metal in the aquatic system.

Detection of nutritional and toxic elements in Pakistani pepper powders using laser induced breakdown spectroscopy

In the current study, we applied laser induced breakdown spectroscopy (LIBS) to determine the elemental distribution of nutritional and trace heavy metals in pepper powders available in Pakistan using the standard calibration curve of laser induced breakdown spectroscopic (CC-LIBS) technique. The samples were found to contain elements such as K, Ca, Mg, Na, Fe, Zn, Al, Pb, Cu, and Cr. In addition, we also identified the atmospheric H-alpha line of hydrogen in the spectra, which was used to estimate the electron number density. To achieve a highly sensitive LIBS system to determine the trace amounts of nutritional and toxic metals in the pepper powders and to achieve the best limit of detection, the LIBS system was optimized by studying the dependency of the LIBS signal intensity on laser irradiance, variation in spacing between the focusing lens and target, as well as on the gate width. To justify the results of the LIBS study, we also determined the concentration of similar (duplicate) peppers by digesting the samples in appropriate solvents using a standard method such as inductively coupled plasma-optical emission spectrometry (ICP-OES). The minimum detection limit was obtained for trace heavy metals from the calibration curves. The results of LIBS displayed noteworthy conformity with those acquired from the ICP-OES analysis. The results of both the techniques clearly revealed that K was the most abundant element in all the peppers, followed by Ca, Mg, Na, Fe, Al, Pb, Zn, Cu, and Cr. The relative accuracy of our LIBS system for different species as compared with the ICP technique was in the range of 0.08-0.3 at 2.5% error confidence. Conclusively, the present work demonstrated the suitability of the LIBS technique due to its rapid, non-destructive, and eco-friendly approach for food security.

Qualitative and quantitative analysis of human nails to find correlation between nutrients and vitamin D deficiency using LIBS and ICP-AES

In this work, we analysed human fingernails of people who suffer from vitamin D deficiency using the laser-induced breakdown spectroscopy(LIBS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES)techniques. The measurements have been conducted on 71 nail samples collected randomly from volunteers of different genders and ages ranged between 20 and 50 years. The main aim of this study is to find the correlation between vitamin D deficiency and the intensity of some dominated lines in the LIBS spectra. A LIBS spectrum consists of dominant lines of fifteen elements including calcium, magnesium, sodium, potassium, titanium, iron, chloride, sulphur, copper, chromium, zinc, nitrogen, phosphor, and oxygen. By recording the spectrum in specific ranges and focusing on calcium, magnesium, sodium, and potassium, we found a correlation between the intensity of the potassium (K) lines at (766.5 and 769.9 nm)and vitamin D level in both age groups (20 and 25 years old), with weak correlation for the calcium (Ca), magnesium (Mg), and sodium (Na) lines. To verify the validity of the LIBS results, we analysed the nail samples with ICP, a standard analytical technique. The elements detected with our LIBS technique are in a good agreement with those identified by ICP-AES. From the health and physiological perspectives, the LIBS system, which is used for spectral analysis in this work, is appropriate for diagnostic purposes such as to find the correlation between vitamin D deficiency and potassium content, especially for hypertensive patients who simultaneously take potassium-based medication and vitamin D supplement.

Mineral content analysis of root canal dentin using laser-induced breakdown spectroscopy

OBJECTIVES

This study aimed to introduce the use of laser-induced breakdown spectroscopy (LIBS) for evaluation of the mineral content of root canal dentin, and to assess whether a correlation exists between LIBS and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) methods by comparing the effects of irrigation solutions on the mineral content change of root canal dentin.

MATERIALS AND METHODS

Forty teeth with a single root canal were decoronated and longitudinally sectioned to expose the canals. The root halves were divided into 4 groups (n = 10) according to the solution applied: group NaOCl, 5.25% sodium hypochlorite (NaOCl) for 1 hour; group EDTA, 17% ethylenediaminetetraacetic acid (EDTA) for 2 minutes; group NaOCl+EDTA, 5.25% NaOCl for 1 hour and 17% EDTA for 2 minutes; a control group. Each root half belonging to the same root was evaluated for mineral content with either LIBS or SEM/EDS methods. The data were analyzed statistically.

RESULTS

In groups NaOCl and NaOCl+EDTA, the calcium (Ca)/phosphorus (P) ratio decreased while the sodium (Na) level increased compared with the other groups (p < 0.05). The magnesium (Mg) level changes were not significant among the groups. A significant positive correlation was found between the results of LIBS and SEM/EDS analyses (r = 0.84, p < 0.001).

CONCLUSIONS

Treatment with NaOCl for 1 hour altered the mineral content of dentin, while EDTA application for 2 minutes had no effect on the elemental composition. The LIBS method proved to be reliable while providing data for the elemental composition of root canal dentin.