Microwave Digestion Technique Research Articles

Investigating Trace and Macro-element Composition of Herbal and Nutraceutical Dietary Supplements Marketed in Oman: Insights into Safety and Labeling.

With the global increase in the use of dietary supplements to provide nutrients in one's regular diet, these supplements' potential health risks and benefits have become a topic of significant interest. Interestingly, as dietary supplements, the Food and Drug Administration (FDA) in the United States (USA), Europe, and most countries do not require manufacturers and distributors to obtain approval or provide safety assessments before marketing those products. This research explores for the first time 16 heavy, trace and macro-elemental contents, namely, As, Ni, Cd, Pb, Cu, Co, Mn, Cr, Zn, V, Fe, Al, K, Na, Mg, and Ca, within 24 nutraceutical and herbal supplements marketed in Oman. The research is focusing on ensuring their compositions, concentrations, and freedom of toxic elements. ICP-OES was utilized, preceded by a microwave digestion technique to digest the samples in concentrated HNO3 and HCl (3:1, v/v). The method was validated within linear ranges of 0.03-5.00ppm and 1.0-200.0ppm for micro- and macro-elements, respectively, with %recoveries ranging from 90 to 104%. The limits of detection ranged from 0.01 to 0.09 and 0.14 to 0.30ppm, while the limits of quantification ranged from 0.03 to 0.28 and 0.46 to 0.91ppm for micro- and macro-elements, respectively. The detected levels were compared to online databases for risk assessment. Although As and Cd were not detected in all samples, Pb was found in nine samples, with some exceeding regulated limits of exposure. About 80% of the samples contained Al, of which two samples were susceptible to serious health risks of exceeding exposure limits in their compiled doses. The locally harvested Omani herbal supplements revealed significant amounts of Zn, Mg, Mn, and Cu. The results highlighted the potential risks associated with both dosage compliance and labeling discrepancies.

Influence of Cr-doping on structural, magnetic and dielectric properties of M-type hexaferrites synthesized using microwave digestion technique

M-type hexaferrite SrCrxFe12-xO19 compounds doped with Cr (x = 0, 1, 2, 3 and 4 at.%) were prepared by microwave digestion system. X-ray diffraction was used to study the structure and crystallization of the samples. The samples are found to have a hexagonal phase, SrFe12O19, as a main phase at 2θ ≈ 33.144° and 35.618° for x = 0 and 1 respectively, and 32.451° and 34.295° for x ≥ 2. The Rietveld refined parameters such as the lattice parameters (a = b, c), direct and indirect cell volume, crystallite size and microstrain were investigated. TEM and SEM results showed that the samples have hexagonal shape and grain size range from 126 nm to 379 nm. Magnetization, M, as a function of the applied magnetic field, H, was obtained from the hysteresis loop. The coercive field, H C , saturation, M s and remnant, M r , magnetization and squareness ration, M r /M s , were extracted from the hysteresis loop results. These results revealed that H C is inversely proportional with the grains size of the samples but directly proportional with Cr-doping values candidating these compounds to be used in computer hard disk memories applications. M values are inversely proportional with Cr-doping values. The variation of conductivity, σ, impedance, Z, dielectric constant, ε, dielectric loss factor, tan δ and dissipation factor as functions of both AC frequency, F(Hz) and Cr-doping, x, were investigated. The maximum value of the dissipation factor was at x = 2 which equals 8.05 × 109 m F−1 when F = 2 × 105 Hz. The impedance of the samples behaved as a capacitor reactance that makes our compounds candidate for many crucial dielectric applications.

Iron and Zinc Determination in Dietary Supplements by Flame Atomic Absorption Spectrophotometry

Recent studies have demonstrated that 30% of the world’s population suffers of anemia, half of the cases are related to iron deficiency, and the most common treatment is the use of iron supplementation. In this framework, the iron and zinc determination from different dietary supplements was performed by flame atomic absorption spectrophotometry. Concerning the dissolution of supplements, direct acid dissolution, wet digestion, and microwave digestion (MW) techniques were used for sample preparation. The iron and zinc recovery results demonstrated that the MW technique was the most appropriate for all of the supplements with the highest metal recovery yields. Moreover, the method validation parameters referred to a linear range for iron of 0.1-4 mg L-1 with a regression coefficient (R2) of 0.9998 ± 0.002, while for zinc it was 0.01-1 mg L-1 (R2 = 0.9997 ± 0.003). The limit of detection and quantification values were calculated as 0.03 and 0.09 mg L-1 for iron and 0.01 and 0.02 mg L-1 for zinc, respectively. The accuracy of the method was evaluated from the % recovery yield for iron and zinc, which, respectively, resulted in an oscillate of 99.2% to 102%, and 99.4% to 100.4% for the dietary investigated supplements. The precision of the method was determined by intra-day and inter-day precision with a relative standard deviation that was <2.0%.

Facile fabrication of nitrogen–ferric-doped carbon dots for highly sensitive and selective detection of dopamine and 4-nitrophenol

Nowadays, dopamine (DA) receives huge attention because it plays an importance role in chemical transmitter for peripheral and central nervous systems. 4-Nitrophenol (4-NP) is one of the common hazardous waste, because it can cause various serious diseases to humans and environment. Herein, a simple and highly efficient technique for the detection DA and 4-NP using nitrogen–ferric-doped carbon dots (N/Fe-CDs) was reported in this article. The N/Fe-CDs were prepared using microwave digestion technique with a high quantum yield of 49.52%. The N/Fe-CDs exhibited excellence selectivity toward the detection of DA and 4-NP. Based on the quenched fluorescence between N/Fe-CDs and DA and 4-NP to detect DA and 4-NP, the linear range of DA was 0.5 - 300 µM with a detection limit of 0.07 µM (S/N =3), while the linear range of 4-NP was 0.1 - 250 µM with a detection limit of 0.02μM. Additionally, the anticipated sensing technique has been successfully applied for real sample analysis such as human serum and urine samples for DA, lake water and tap water for 4-NP with satisfactory results. So, the proposed fluorescent probe is more precise detection for biological and environmental applications.

A Microwave Digestion Technique for the Analysis of Rare Earth Elements, Thorium and Uranium in Geochemical Certified Reference Materials and Soils by Inductively Coupled Plasma Mass Spectrometry.

Two different digestion methods—microwave digestion (Mw) and Savillex digestion (Sx)—were used to evaluate the best quality control for analysis of the rare earth elements, Th and U in the geochemical certified reference material JSd-2, supplied by the Geological Survey of Japan (GSJ). The analysis of trace elements was carried out using inductively coupled plasma mass spectrometry (ICP-MS). The digestion recovery was > 90% for almost all elements by both methods. Mw-4 (four repeats of the microwave digestion) was found to be more effective and faster than Sx. In order to evaluate the efficiency of Mw-4, three other GSJ certified reference materials, JLk-1, JB-1 and JB-3, as well as five different soil samples from Belarus, Japan, Serbia and Ukraine were also analyzed. The Mw-4 method was seen to be promising for complete digestion and recovery of most of the elements. The U/Th ratio showed some heterogeneity for Ukraine and Serbia soils affected by Chernobyl nuclear power plant accident and depleted uranium contamination, respectively. This method can be successfully applied to any type of soils for elemental analyses.

Determination of Residual Heavy Metals in an Incinerator Bottom Ash from Municipal Solid Waste Power Plant

Bottom ash is a part of by-product from the municipal solid waste power plants which is always a wider problem for the urban and rural communities due to its disposal plants may cause serious environmental pollution. This work was focused on the residual heavy metal in an incinerator bottom ash from the municipal waste power plant placed in Nongkham district, Bangkok. Four bottom ash samples were obtained in 2017. After drying and grounding, the bottom ash samples were prepared to clear solution with the microwave digestion technique using nitric, hydrochloric and hydrofluoric acid under the heating program. The total residual heavy metals in the incinerator bottom ashes, such as lead, copper, zinc, and cadmium were determined by using flame atomic absorption spectrophotometer (FAAS) with deuterium background correction. The total concentration of lead, copper, zinc and cadmium were found in the range of 280.40-354.22mg kg-1, 365.35-524.45 mg kg-1, 1,527.25-2,074.34 mg kg-1, and 0.48-1.02 mg kg-1, respectively. The recovery of all metals was found in the range of 89.4-101.2% and the relative standard deviation (RSD) was to be 2.15-3.55 % (n=7). The concentration of zinc, copper, and lead was found high levels, while cadmium was low concentration. Heavy metals in solid waste material occur in different chemical forms and phases. The sample preparation based on the microwave digestion was successfully developed for the waste samples with a good reliability.

The carbon isotopic composition of occluded carbon in phytoliths: A comparative study of phytolith extraction methods

Phytoliths are microscopic siliceous particles that precipitate within epidermal cells of plant leaves. Phytolith morphology and its carbon isotopic composition (δ13C) are often used to understand the past vegetation composition. To extract phytoliths from modern plants, two different wet-oxidation, dry ashing and microwave digestion techniques have been used. However, the impact of these techniques on the δ13C value of phytoliths of different plant species (trees, shrubs and grasses) is not well understood. The present study compares the recovered materials (RM) from these four extraction methods by scanning electron microscope (SEM) and carbon isotopic composition (δ13CRM). We find that the recovery yield is high in one of the wet-oxidation methods, showing significant organic residues (tissues) as evident from the SEM images. In other three methods, the SEM images show near-complete removal of bulk plant residues. However, the wide variation (up to 14‰) seen in the δ13CRM values (even within a species) suggests a difference in response of bulk tissues and phytoliths towards the extraction methods. The difference in organic constituents within the cell wall and lumen phytoliths also possibly contribute to the variation in δ13CRM values. The characteristic difference observed in 13C/12C ratio between the RM and bulk tissue (Δ13CRM-Bulk) suggests the predominance of lumen phytoliths in grasses and cell wall phytoliths in trees/shrubs species. Since the same extraction methods are also used to remove the organic residues adhering to the phytoliths in soils/paleosols, careful consideration is required before employing phytolith δ13C value for vegetation reconstruction in paleoecological and archeological studies.

ICH Q3D based elemental impurities study in liquid pharmaceutical dosage form with high daily intake – comparative analysis by ICP-OES and ICP-MS

Guideline for Elemental Impurities-Q3D of the International Conference on Harmonisation represents a new paradigm in the control of elemental impurities (EIs) in pharmaceuticals. It changes the approach toward control of EIs from the historical ‘heavy metals test’, to a scientific-based risk assessment and testing by modern analytical instrumentation such as inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS). Management of EIs related to all finished drug products must be implemented in strict compliance with the regulatory requirements of pharmaceutical industry due to their quality and safety concerns. Testing for presence of EIs from Class 1 and Class 2a in methadone hydrochloride 1 mg/ml oral solution with recommended daily intake of 150 mg methadone hydrochloride was initially performed on ICP-OES using in-house validated method according to the requirements of pharmacopoeias, in line with Q3D. During the procedure, it became apparent that ICP-OES has its own limitations, especially when it comes to testing arsenic and lead in low concentrations. ICP-MS in-house validated method was developed and employed for determination of trace concentrations of arsenic and lead, providing resourceful information that were compared and correlated to the data obtained by ICP-OES analysis. Sample preparation using microwave digestion technique was applied for the analyses by both techniques. Although the applied ICP-OES in-house method is suitable for determination of Hg, Cd, Co, V, and Ni, more sensitive technique such as ICP-MS is required for accurate determination of As and Pb concerning pharmaceuticals with high daily intakes.

Environmental Health: Evaluation of heavy metals pollution in Isfahan industrial zone from soils, well / eluent waters and waste water by microwave- electro-thermal atomic absorption spectrometry

In this study, soils, well waters, drinking waters, and waste water in the Isfahan industrial area were sampled in spring and summer 2018. In 8 points of industrial zone, important toxic heavy metals such as, lead (Pb), Cobalt (Co), Nickel (Ni), Chromium (Cr), and Cadmium (Cd) were sampled from surface soil (up to 2 m), well/drinking waters and waste water. After sample preparation with micro-wave digestion technique, the concentration of heavy metals was determined by electro-thermal atomic absorption spectrometry (ET-AAS). According to the well water analysis, the mean concentration of Cr, Ni, Co, Cd, and Pb in well water were 95 μg L-1, 146 μg L-1, 185 μg L-1, 12 μg L-1, and 11 μg L-1, respectively. In well water, the concentrations of Cd, Ni, Cr and Co were found much higher than Pb in comparison with the references of World Health Organization (WHO).

The application of microwave digestion in decomposing some refractory ore samples with solid fusion agent

It is known that most of the refractory ore are the basis of national economy and widely applied in various fields, however, the complexity of the chemical composition and the diversity of the crystallinity in the mineral phases make the sample pre-treatment of refractory ore still remains a challenge. In this work, the complete decomposition of the refractory ore sample can be achieved just by exposing the solid fusion agent and the refractory ore sample in the microwave irradiation environment for a few minutes, and induced by a drop of water. A digestion time of 15 min for 3.0 g solid fusion agent mixture of sodium peroxide/sodium carbonate (Na2O2/Na2CO3) in a corundum crucible via microwave heating is sufficient to decompose 0.1 g refractory ore sample. An excellent microwave digestion solid agent should meet the following conditions, a good decomposition ability, an outstanding ability of absorbing microwave energy and converting it into heat quickly, a higher melting point than the decomposing temperature of the ore sample. In the research, the induction effect of water plays an important role for the microwave digestion. The energy which is released by the reaction of water and the solid fusion agent (Na2O2) is the key to decompose refractory ore samples with solid fusion agent, which replenished the total energy required for the microwave digestion and made the microwave digestion completed successfully. This microwave digestion technique has good reproducibility and precision, RSD % for Mo, Fe, Ti, Cr and W in the refractory ore samples were all better than 6, except RSD % for Be of about 8 because of the influence of matrix-effect. Meanwhile, the analysis results of the elements in the refractory ore samples provided by the microwave digestion technique were all in good agreement with the analysis results provided by the traditional fusion method except for Cr in the mixture ore samples. In the study, the non-linear dependence of the electromagnetic and thermal properties of the solid fusion agent on temperature under microwave irradiation and the selective heating of microwave are fully applied in this simple microwave technique. Comparing to the traditional fusion decomposition method, this microwave digestion technique is a simple, economical, fast and energy-saving sample pre-treatment technique.

Metal Contents and Pb Isotopes in the Surface Seawater of the Gulf of Prigi, Indonesia: Detection of Anthropogenic and Natural Sources

In order to investigate the anthropogenic and natural sources of metals in the Gulf of Prigi, Indonesia, it was analyzed their metal contents and Pb isotopes of surface seawater together with sediment, grouper fish, mosh, seaweed, soil, and sharp grass for protecting the environmental pollution of the study area. Samples were leached using a microwave digestion technique. Metal (Ca, Fe, Mn, Cu and Pb) concentrations and 206Pb, 207Pb and 208Pb in the leached solutions were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). The level concentrations of Ca (491436 µg kg–1), Fe (12123 µg kg–1), Mn (37.2 µg kg–1), Cu (84.0 µg kg–1) and Pb (34.5 µg kg-1) in the surface seawater were low compared with those of background seawater levels issued by World Health Organization (WHO). The range of Pb isotope ratios (207Pb / 206Pb = 0.7966-0.9945 and 208Pb / 206Pb = 2.2600-2.8243) in surface seawater was higher in the plotted Pb growth curve suggesting unpolluted Pb reflected by natural sources such as mineral sources or lithogenic from marine sediment.

An experimental approach to the determination of the gross activity of uranium, plutonium, americium and strontium in human biological samples using solid-state scintillation

Rapid bioassay methods have been mainly proposed for the sequential measurements of actinides in human blood, bone marrow and urine. The method involves sample treatment using microwave digestion techniques followed by direct measurement of digested products using powder scintillator and alkaline solution as a replacement for traditional liquid scintillation cocktail. The selected group of radionuclides was chosen due to their occurrence in the nuclear fuel cycle, nuclear accident, high radiotoxicity, and the possibility of potential misuses, such as dirty bombs. The work aimed at verifying the connection of microwave digestion using alkaline solution with solid-state scintillation using a powder scintillator YAP:Ce together with an alkaline medium.

A new sample preparation method for crude or fuel oils by mineralization utilizing single reaction chamber microwave for broader multi-element analysis by ICP techniques

The objective of this study was to develop an effective and routine single sample preparation method to accurately and precisely analyze multiple elements (up to 57) in crude oils using both an inductively coupled plasma-optical emission spectrometer (ICP-OES) for high abundance elements and a triple quadrupole-inductively coupled plasma-mass spectrometer (QQQ-ICP-MS) (or ICP-MS) for low abundance trace and ultra-trace elements. A critical aspect of this study was to develop a single sample preparation method that could be effective in analyzing the largest number of quantifiable elements with instruments used in tandem to cover a wider and more practical combined dynamic range. Three sample preparation techniques were investigated and tested, including high pressure combustion with strong-acid digestion, high pressure and high temperature strong-acid digestion within Parr bombs, and high temperature and high pressure digestions in a Single Reaction Chamber (SRC) microwave. For the combustion method, no element showed recovery above 75%, thus this method was deemed unacceptable for accurate and precise analysis of crude oil. Average recoveries ranging from 94% to 106% for 19 analytes were achieved with high pressure and high temperature acid digestion within Parr bombs. A drawback of the method, however, was a rather small sample sizes (100mg) that could be achieved without venting, which places limitations on detection and quantitation limits of large numbers of low abundance analytes in natural crude oils. The best of the SRC microwave-assisted acid digestion tests, however, was also shown to be acceptable for 19 analytes using a certified organometallic standard, with average recoveries ranging from 93% to 113%. Because of rapid sample throughput and the larger sample sizes (1.2g sample size per digestion session) that can be accommodated with the single reaction chamber microwave digestion technique, better method detection and quantification limits and high precision on a range of low abundance elements could be achieved. We also then successfully tested the recovery of 53 elements with this SRC microwave method by adding a multi-element spike to Conostan base oil. This optimum SRC digestion method tested was then used to examine a NIST natural crude oil research material (NIST RM 8505) in an attempt to quantify up to 57 elements. The mean vanadium concentration (mass fraction) is reported as 390±0.4µg/g, the mean value of 5 replicate digestions by our method, which agrees well with the recommended value for the only element recommended for NIST 8505 of 390±10µg/g. The number of quantified analytes for the RM 8505 was further extended to a total of 52 elements with RSDs <5% for 38 elements, between 5% and 10% for 10 elements, and between 10% and 15.6% for 4 elements, all of which met our acceptability limits set at ≤20% RSD. Of the 57 elements analyzed in RM 8505, certain elements B, Nb, and W, although above method quantitation limits, were judged unacceptable because RSDs were ≥31.4%, whereas Ag and Tl were below method quantitation limits, and their RSDs were ≥44.2% and judged unacceptable. However, these elements have been quantified in other natural crude oils with higher abundances, which indicates that up to 57 elements can be potentially assessed in crude oils or refined oils with this method. The NIST RM 8505 crude oil reported here and others are being evaluated as potential natural crude oil standards to provide references values for more routine multi-element analysis.

Levels of essential and non-essential metals in edible mushrooms cultivated in Haramaya, Ethiopia

Fruiting bodies of two oyster mushroom (Pleurotus ostreatus and Pleurotus florida) species and their respective substrate samples cultivated and collected from the Mushroom Research, Production and Training Laboratory of the Haramaya University, Ethiopia, were analyzed for essential and non-essential metals, viz., Cu, Fe, Zn, Mn, Cd and Pb contents by flame atomic absorption spectrometry after digestion employing dry, wet and microwave digestion techniques. Concentrations of the analyzed metals were expressed on a dry weight basis (mg/kg). The mean metal concentration (mg/kg in dry weight) in the mushroom and respective substrate samples, respectively; for Pleurotus ostreatus were: Cu (51.19, 48.97), Fe (220.87, 299.51), Zn (89.68, 62.55) and Mn (47.55, 58.32). The mean metal concentration (mg/kg in dry weight) in mushroom and the respective substrate samples, respectively, for Pleurotus florida were: Cu (53.56, 51.87), Fe (243.92, 265.23), Zn (95.26, 64.25) and Mn (41.29, 62.55). However, Cd and Pb was not detected in both mushroom and substrate samples. The bio-accumulation factor of the heavy metals was calculated and a highest accumulation of Cu and Zn from substrate was observed for all the analyzed mushrooms samples. The observed results were also compared with the reported results. In this study, the highest concentrations of Cu, Fe, Zn and Mn were confirmed. These elements generally are essential for humans, and may not possibly cause health problems even if mushrooms are consumed regularly. Furthermore, the quantities of the metals found in the samples were within the limits recommended by international organizations like the WHO/FAO Expert Committee on Food Additives. On the other hand, the amounts of Cd and Pb were found to be very low. These elements are toxic to humans, especially at higher doses; however, the concentrations of these non-essential metals were below detectable limit.

Accurate Determination of Sulphur Content in Sediments by Double Focusing Inductively Coupled Plasma Mass Spectrometry Combined with Microwave Digestion and Studies on Related Matrix Effect

Abstract A robust method for measuring sulphur content in sediments was established using double focusing inductively coupled plasma mass spectrometry at medium resolution combined with microwave digestion technique. The capability of Standard curve method (SCM) and Standard addition method (SAM) using Rh as internal standard was compared in correction of the matrix effect. The results showed that the matrix effect was not suppressed by SCM, but was effectively eliminated by SAM with drawback of low sample throughout. Therefore, the Standard addition calibration method (SACM) was creatively proposed in this study, which could simply and easily correct the matrix effect as the matrix content of sample and standard solution was matched within ±50%. The detection limit and liner range of this method were proved to be 0.5 mg kg −1 and 3.0–1000 μg L −1 , respectively, with spiked recovery of 95.8%-99.2%. Four sediment standard reference materials GBW07306, GBW07309, GBW07313 and SRM1646a were measured repetitively with the obtained sulphur contents of (853 ± 14) μg g −1 (2σ, n = 12), (181 ± 7) μg g −1 (2σ, n = 9), (3131 ± 52) μg g −1 (2σ, n = 12) and (3543 ± 70) μg g −1 (2σ, n = 9), respectively. The relative error of the four reference materials was +8.8%, +13.3%, +1.0% and +0.7%, respectively, with precision (RSD) less than 2%. This method was applied to measure the sulphur content in the sediment cores collected in the Yangtze Estuary and Hangzhou Bay. This proposed method was demonstrated as an accurate and rapid way of determining sulphur content in great batch of sediment samples, and has a broad application range including soil samples.

Evaluation of trace metals in sediment, water, and fish (Mugil cephalus) of the central Black Sea coast of Turkey

ABSTRACTIn this study, concentrations of trace metals such as As, Cd, Cu, Cr, Fe, Pb, Ni, Sn, Se, and Zn were determined in sediments, water, and a kind of fish (Mugil cephalus) of the central Black Sea coasts by employing Inductively Coupled Plasma Mass Spectrometry and microwave digestion technique. Gill, muscle, liver, and other tissues were analyzed separately for each sample. The accuracy of the results were checked by using a certified reference material (DORM-4). In water samples, the metal determined at highest concentrations was Cu (1645.44 µg/L). In sediment samples, the metal determined at highest concentrations was Fe (12223.50 mg/kg). The levels of trace metals found in the different parts of the fish were: Zn in muscle tissue (30393.28 mg/kg), Sn in gill tissue (5140.08 mg/kg), and Cu in liver tissue (289.31 mg/kg). These results were also compared with various relevant guidelines and literature.

Selection of wet digestion methods for metal quantification in hazardous solid wastes

Quantifying metal concentration in a hazardous solid waste is critical in evaluating techniques for metal removal or recovery from the waste. Numerous protocols have been published on the digestion of hazardous waste, with diverse methods yielding dissimilar extraction efficiencies for different metals, due to differences in composition of the wastes and chemical forms of the metals. The lack of standard methods (or failure to state the method used) has resulted in inconsistencies in data reported by different laboratories, leading to variations in metal recoveries. Using fly ash as an example, this study compares 11 metal extraction methods including ASTM, USEPA, ultrasonic-assisted and microwave digestion methods as well as a modified Tessier’s sequential extraction procedure for the extraction of metals (Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn). The efficacy of acid digestion was metal dependent. ASTM method D 6357-11 was found to be an effective digestion method for most metals primarily due to the dissolution of metals bound in silicate matrices, while a microwave digestion technique (which hastened the digestion process significantly) was effective for Cd and Pb. This study highlights the importance in the selection of the most appropriate protocol for the digestion of hazardous solid waste.

The assessment of trace metals at gill, muscle and liver tissue in Mugil cephalus.

In this paper, concentrations of trace metals such as Cr, Mn, Fe, Ni, Cu, As, Se, Ag, Cd and Pb were determined in Mugil cephalus of the middle Black Sea coasts by employing inductively coupled plasma mass spectrometry (ICP-MS) and microwave digestion technique. Different parts of fish samples were analysed separately such as the gill, muscle and liver. The accuracy of the results has been checked by using a certified reference material (DORM-4). The highest trace metal values determined in different parts of fish were Cr in muscle tissue (0.416μg/g), Mn in gill tissue (52.246μg/g), Fe in muscle tissue (11.899μg/g), Ni in muscle tissue (108.057μg/g), Cu in liver tissue (261.911μg/g), As in liver tissue (4.162μg/g), Se in liver tissue (11.418μg/g), Ag in liver tissue (0.323μg/g), Cd in liver tissue (1.11μg/g) and Pb in gill tissue (3.047μg/g). These results were also compared with various relevant literature and guidelines.

Efficiency of Extraction of Trace metals from Blood samples using Wet Digestion and Microwave Digestion Techniques

The efficiency of extraction of trace metals using conventional wet acid digestion method (CDM) and microwave induced acid digestion method (MWD) was determined by recovery experiments. The high percentage recoveries obtained from microwave induced acid digestion method make it to be a more efficient method than the conventional wet acid method. The conventional wet acid digestion method is time consuming while the MWD method saves time, less than four minutes are required to complete the digestion of the biological samples in this study.

Microwave Digestion—Vacuum Filtration-Automated Scanning Electron Microscopy as a sensitive method for forensic diatom test

Diagnosis of drowning is one of the most difficult issues in forensic practice. A number of methods have been developed over the years to determine whether a person was drowned. Microwave Digestion-Vacuum Filtration-Automated Scanning Electron Microscopy (MD-VF-Auto SEM) method we developed is a new qualitative and quantitative method of diatom test for diagnosis of drowning. The new method is based on microwave digestion technique, vacuum filtration, and automated SEM, which would achieve a maximal recovery of diatoms and identify diatoms easily by SEM with high resolution. This study was designed to evaluate the sensitivity of this method, the recovery of diatom, and loss ratio of centrifugation, which were compared using the MD-VF-Auto SEM method and the conventional acid digestion method. Two groups of samples were designed in the study. Groups A (n = 20) and B (n = 20) were performed by MD-VF-Auto SEM method and the conventional acid digestion method, respectively. In addition, another eight water samples were centrifuged, and the diatoms in the supernatant and precipitate were counted and measured, respectively, in order to find out how many diatoms were lost after centrifugation. The difference between the two groups was statistically highly significant, and about 34% of diatoms were lost after centrifugation at 4,000rpm for 15min. The results showed that the MD-VF-Auto SEM method was more sensitive and specific.