Microwave-induced combustion for further determination of potentially toxic elements in honey by ICP-MS.

Microwave-induced combustion (MIC) was proposed in this study for honey decomposition aiming for As, Cd, Hg, and Pb determination by inductively coupled plasma mass spectrometry (ICP-MS). Sample mass (up to 1.0 g), absorbing solution (0.5 to 14.4 mol L-1 HNO3, and H2O), heating program, and combustion aids were evaluated. The Eurachem guidelines were used for method validation. The proposed method enabled combustion of a high sample mass (0.8 g of honey, with 0.4 g of microcrystalline cellulose and 100 µL of 6 mol L-1 NH4NO3) using 6 mL of an absorbing solution consisting of 1 mol L-1 HNO3, which resulted in low residual carbon in solution (< 25 mg L-1). Honey samples from different geographical origins were analyzed. Results showed no significant difference in comparison to other two microwave decomposition methods, based on microwave-assisted wet digestion with single reaction chamber (MAWD-SRC) and microwave-assisted wet digestion (MAWD). Standard addition experiments resulted in recoveries higher than 98%. The limits of detection ranged from 1.10 (As) to 4.60 ng g-1 (Pb). In addition to using only diluted reagents and resulting in digests virtually free of interferences, the proposed method was faster (< 30 min) than most of those presented in the literature.

Challenges and trends for halogen determination by inductively coupled plasma mass spectrometry: A review.

RATIONALE: In this review, works published in the past 25 years for fluorine, chlorine, bromine, and iodine determination in several matrices by inductively coupled plasma mass spectrometry (ICP-MS) were covered. Usually, the determination of halogens has been performed by ICP-MS using a previous sample preparation step or, more recently, by direct analysis of solid or liquid samples. METHODS: Methods based on combustion, extraction, pyrohydrolysis, sample dilution in organic or aqueous medium, and wet digestion, among others, are discussed. Moreover, the recent applications of methods based on laser ablation (LA) and electrothermal vaporization (ETV) coupled to ICP-MS are discussed. RESULTS: The main challenge for methods using sample preparation has been to obtain a final solution compatible with ICP-MS, as well as to overcome problems related to analyte losses and contamination. Interferences due to the presence of dissolved organic compounds in solution, enhancement or suppression of ionization of analytes, and related matrix effects have been of concern when using ICP-MS. For the determination of halogens by ICP-MS using LA and ETV systems, some limitations related to the difficulty of calibration are pointed out, impairing the widespread use of this approach. CONCLUSIONS: A critical view is presented for further halogen determination by ICP-MS, mainly for matrices considered difficult to digest using conventional protocols.

An ultrasound-assisted sample preparation method of carbonatite rock for determination of rare earth elements by inductively coupled plasma mass spectrometry.

RATIONALE: A method for the determination of rare earth elements in carbonatite rocks by inductively coupled plasma mass spectrometry (ICP-MS) was developed. METHODS: An alkaline rock, carbonatite, was submitted to ultrasound-assisted extraction (USAE) using an ultrasound bath, a cup horn system or an ultrasound probe. The main USAE parameters were evaluated, such as extraction time (1 to 30 min), extraction temperature (20 to 100°C) and ultrasound amplitude (10 to 100%). For ICP-MS, a desolvation system (APEX-Q) was used to reduce interference in lanthanide determination. To evaluate if the effect of ultrasound improved extraction, experiments were carried out using magnetic stirring (500 rpm) for comparison. RESULTS: The temperature and ultrasound amplitude optimized for the method were 70°C and 40%, respectively, using dilute nitric acid (3% v/v). Quantitative analyte recoveries were obtained using an ultrasound bath (25 kHz/100 W) which allowed for the simultaneous extraction of twelve replicates. CONCLUSIONS: All the results obtained with the use of ultrasound systems were better than those obtained with mechanical stirring. The extracts were suitable for ICP-MS analysis and the results were in agreement with those obtained by the reference method (using wet acid digestion). Based on the results, the use of USAE can be considered an alternative method for sample preparation of carbonatite rocks, under milder conditions, for further ICP-MS analysis.

Maxwell-Wagner Effect Applied to Microwave-Induced Self-Ignition: A Novel Approach for Carbon-Based Materials.

A new method for analytical applications based on the Maxwell-Wagner effect is proposed. Considering the interaction of carbonaceous materials with an electromagnetic field in the microwave frequency range, a very fast heating is observed due to interfacial polarization that results in localized microplasma formation. Such effect was evaluated in this work using a monomode microwave system, and temperature was recorded using an infrared camera. For analytical applications, a closed reactor under oxygen pressure was evaluated. The combination of high temperature and oxidant atmosphere resulted in a very effective self-ignition reaction of sample, allowing its use as sample preparation procedure for further elemental analysis. After optimization, a high sample mass (up to 600 mg of coal and graphite) was efficiently digested using only 4 mol L-1 HNO3 as absorbing solution. Several elements (Ba, Ca, Fe, K, Li, Mg, Na, and Zn) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Accuracy was evaluated by using a certified reference material (NIST 1632b). Blanks were negligible, and only a diluted solution was required for analytes absorption preventing residue generation and making the proposed method in agreement with green chemistry recommendations. The feasibility of the proposed method for hard-to-digest materials, the minimization of reagent consumption, and the possibility of multi elemental analysis with lower blanks and better limits of detection can be considered as the main advantages of this method.

Arctic and Subarctic Natural Soils Emit Chloroform and Brominated Analogues by Alkaline Hydrolysis of Trihaloacetyl Compounds.

There has been increasing recognition of the occurrence of natural, halogenated organic compounds in marine and terrestrial environments. Chloroform is an example of a halogenated organic compound with natural formation as its primary source. Chloroform emission from soil has been reported from diverse Arctic, temperate, and (sub)tropical ecosystems. The terrestrial environment is a significant source to the atmosphere, but little is known about the formation pathway of chloroform in soil. Here, we present evidence that chloroform is formed through the hydrolysis of trichloroacetyl compounds in natural, organic-rich soils. In situ emissions of chloroform from soil in nine Arctic and subarctic ecosystems were linked to soil trichloroacetyl turnover. The residence time from formation of the trichloroacetyl compounds in soil to the release of chloroform to the atmosphere varied between 1 and 116 active months in unfrozen topsoil, depending on soil pH. Nonspecific halogenation that leads to trihaloacetyl formation does not discriminate between chloride and bromide, and brominated analogues were formed alongside chloroform. Soil may therefore be a previously unrecognized, natural source of brominated haloforms. The formation pathway of haloforms through trihaloacetyl compounds can most likely be extended to other ecosystems with organic topsoils.

Triphenyltin hydroxide induces changes in the oxidative stress parameters of fish.

Among all organotin compounds , triphenyltin hydroxide (TPhTH) is widely used as fungicide and moluscicide in Brazil. However, the effects of TPhTH on the biochemical parameters of non-target organisms, such as fish, are little known. The aim of the present study is to assess the possible toxic effects of different concentrations of waterborne TPhTH on silver catfish belonging to species Rhamdia quelen. The fish were exposed to two different concentrations of TPhTH (1.08 and 1.70 µg/L as Sn) for 15 days and then compared to the control group (triplicate, n = 3). The antioxidant profile (catalase (CAT) and the glutathione S-transferase (GST)) and the oxidative stress parameters (TBARS-thiobarbituric acid-reactive substances and protein carbonyl (PC)) were set after the exposure to TPhTH. The TBARS level and the PC content increased in several organs of the Rhamdia quelen (brain, liver, muscle and gills) under the two concentrations of TPhTH in comparison to the control group. The CAT activity in the liver and gills has enhanced in all tested TPhTH concentrations. The GST activity increased in the brain, liver and muscle tissues under all the TPhTH concentrations. The significant changes in the biomarkers indicated that the investigated pesticide could have harmful effect on fish, in the field. However, these biomarkers were measured after the fish received doses lower than the recommended for use in agriculture.

Determination of elemental impurities in pharmaceutical products and related matrices by ICP-based methods: a review.

Interest in the determination of elemental impurities in pharmaceuticals has increased in recent years because of changes in regulatory requirements and the need for changing or updating the current limit tests recommended in pharmacopeias. Inductively coupled plasma (ICP) optical emission spectrometry and ICP mass spectrometry are suitable alternatives to perform multielemental analysis for this purpose. The main advantages and limitations of these techniques are described, covering the applications reported in the literature in the last 10 years mainly for active pharmaceutical ingredients, raw materials, and pharmaceutical dosage forms. Strategies used for sample preparation, including dissolution in aqueous or organic solvents, extraction, wet digestion and combustion methods are described, as well as direct solid analysis and ICP-based systems applied for speciation analysis. Interferences observed during the analysis of pharmaceutical products using ICP-based methods are discussed. Methods currently recommended by pharmacopeias for elemental impurities are also covered, showing that the use of ICP-based methods could be considered as a trend in the determination of these impurities in pharmaceuticals. However, the development of a general method that is accurate for all elemental impurities and the establishment of an official method are still challenges. In this regard, the main drawbacks and suitable alternatives are discussed.

Green method by diffuse reflectance infrared spectroscopy and spectral region selection for the quantification of sulphamethoxazole and trimethoprim in pharmaceutical formulations.

An alternative method for the quantification of sulphametoxazole (SMZ) and trimethoprim (TMP) using diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and partial least square regression (PLS) was developed. Interval Partial Least Square (iPLS) and Synergy Partial Least Square (siPLS) were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. Fifteen commercial tablet formulations and forty-nine synthetic samples were used. The ranges of concentration considered were 400 to 900 mg g-1SMZ and 80 to 240 mg g-1 TMP. Spectral data were recorded between 600 and 4000 cm-1 with a 4 cm-1 resolution by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The proposed procedure was compared to high performance liquid chromatography (HPLC). The results obtained from the root mean square error of prediction (RMSEP), during the validation of the models for samples of sulphamethoxazole (SMZ) and trimethoprim (TMP) using siPLS, demonstrate that this approach is a valid technique for use in quantitative analysis of pharmaceutical formulations. The selected interval algorithm allowed building regression models with minor errors when compared to the full spectrum PLS model. A RMSEP of 13.03 mg g-1for SMZ and 4.88 mg g-1 for TMP was obtained after the selection the best spectral regions by siPLS.

Feasibility of ultra-trace determination of bromine and iodine in honey by ICP-MS using high sample mass in microwave-induced combustion.

This work demonstrates the feasibility of ultra-trace determination of halogens in biological samples by inductively coupled plasma mass spectrometry (ICP-MS) after decomposition by microwave-induced combustion (MIC). The conventional MIC method was improved to allow the combustion of samples with mass higher than that used in previous works in order to achieve better limits of detection (LODs). The applicability of the proposed method for ultra-trace determination of bromine and iodine in organic samples was demonstrated here using honey. It was possible to decompose up to 1000 mg of honey using microcrystalline cellulose as a combustion aid and polyethylene film for sample wrapping. After combustion, analytes were absorbed using 50 mmol L(-1) NH4OH and recoveries for Br and I were between 99 and 104 %, and relative standard deviations were lower than 5 %. Microwave-assisted alkaline dissolution (MA-AD) was also evaluated for honey sample preparation using NH4OH or tetramethylammonium hydroxide solutions. However, the LODs for the MA-AD method were unsuitable because the high carbon content in digests required a dilution step prior to the analysis by ICP-MS. The LODs obtained by MIC were improved from 1143 to 34 ng g(-1) for Br and from 571 to 6.0 ng g(-1) for I, when compared to the MA-AD method. Furthermore, it was possible to decompose up to eight samples simultaneously in 30 min (including the cooling step) with very low reagent consumption and consequently lower generation of effluents, making MIC method well suited for routine ultra-trace determination of Br and I in honey. Graphical Abstract A high mass of honey was efficiently digested by MIC for subsequent Br and I determination by ICP-MS.

Anesthetic activity and bio-guided fractionation of the essential oil of Aloysia gratissima (Gillies & Hook.) Tronc. in silver catfish Rhamdia quelen.

This work aimed to determine the efficacy of the essential oil of A. gratissima as anesthetic for silver catfish, and to perform the bio-guided fractionation of essential oil aiming to isolate compounds responsible for the noted effects. Fish were submitted to anesthesia bath with essential oil, its fractions and isolated compounds to determine time of anesthetic induction and recovery. Eugenol (50 mg L(-1)) was used as positive control. Essential oil of A. gratissima was effective as an anesthetic at concentrations of 300 to 900 mg L(-1). Fish presented involuntary muscle contractions during induction and recovery. The bio-guided fractionation of essential oil furnished E-(-)-pinocamphone, (-)-caryophyllene oxide, (-)-guaiol and (+)-spathulenol. E-(-)-pinocamphone caused the same side effects observed for essential oil. (-)-Caryophyllene oxide, (-)-guaiol and (+)-spathulenol showed only sedative effects at proportional concentrations to those of the constituents in essential oil. (+)-Spathulenol (51.2 mg L(-1)) promoted deep anesthesia without side effects. A higher concentration of (+)-spathulenol, and lower or absent amounts ofE-(-)-pinocamphone could contribute to increase the activity and safety of the essential oil of A. gratissima. (+)-Spathulenol showed potent sedative and anesthetic activities in silver catfish, and could be considered as a viable compound for the development of a new anesthetic.

Lactating and nonlactating rats differ to renal toxicity induced by mercuric chloride: the preventive effect of zinc chloride.

This study evaluated the effects of HgCl2 on renal parameters in nonlactating and lactating rats and their pups, as well as the preventive role of ZnCl2 . Rats received 27 mg kg(-1) ZnCl2 for five consecutive days and 5 mg kg(-1) HgCl2 for five subsequent days (s.c.). A decrease in δ-aminolevulinic acid dehydratase (δ-ALA-D) activity in the blood and an increase in urine protein content in renal weight as well as in blood and urine Hg levels were observed in lactating and nonlactating rats from Sal-Hg and Zn-Hg groups. ZnCl2 prevented partially the δ-ALA-D inhibition and the proteinuria in nonlactating rats. Renal Hg levels were increased in all HgCl2 groups, and the ZnCl2 exposure potentiated this effect in lactating rats. Nonlactating rats exposed to HgCl2 exhibited an increase in plasma urea and creatinine levels, δ-ALA-D activity inhibition and histopathological alterations (necrosis, atrophic tubules and collagen deposition) in the kidneys. ZnCl2 exposure prevented the biochemical alterations. Hg-exposed pups showed lower body and renal weight and an increase in the renal Hg levels. In conclusion, mercury-induced nephrotoxicity differs considerably between lactating and nonlactating rats. Moreover, prior exposure with ZnCl2 may provide protection to individuals who get exposed to mercury occupationally or accidentally.

Thermosonication as an effective substitution for fusion in Brazilian cheese spread (Requeijão Cremoso) manufacturing: The effect of ultrasonic power on technological properties.

In this initial study, the impact of thermosonication as an alternative to the traditional fusion in Brazilian cheese spread (Requeijão Cremoso) manufacture was investigated. The effect of ultrasound (US) power was evaluated considering various aspects such as gross composition, microstructure, texture, rheology, color, fatty acid composition, and volatile compounds. A 13 mm US probe operating at 20 kHz was used. The experiment involved different US power levels (200, 400, and 600 W) at 85 °C for 1 min, and results were compared to the conventional process in the same conditions (85 °C for 1 min, control treatment). The texture became softer as ultrasound power increased from 200 to 600 W, which was attributed to structural changes within the protein and lipid matrix. The color of the cheese spread also underwent noticeable changes for all US treatments, and treatment at 600 W resulted in increased lightness but reduced color intensity. Moreover, the fatty acid composition of the cheese spread showed variations with different US power, with samples treated at 600 W showing lower concentrations of saturated and unsaturated fatty acids, as well as lower atherogenicity and thrombogenicity indexes, indicating a potentially healthier product. Volatile compounds were also influenced by US, with less compounds being identified at higher powers, especially at 600 W. This could indicate possible degradation, which should be evaluated in further studies regarding US treatment effects on consumer perception. Hence, this initial work demonstrated that thermosonication might be interesting in the manufacture of Brazilian cheese spread, since it can be used to manipulate the texture, color and aroma of the product in order to improve its quality parameters.

Determination of trace elements in fluoropolymers after microwave-induced combustion.

An effective approach to the digestion of fluoropolymers for the determination of Ag, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, and Ni impurities has been developed using microwave-induced combustion (MIC) in closed quartz vessels pressurized with oxygen. Samples that were examined included the following: polytetrafluorethylene (PTFE); polytetrafluoroethylene with an additional modifier, perfluoropropylvinylether (PTFE-TFM); and fluorinated ethylene propylene (FEP). A quartz device was used as a sample holder, and the influence of the absorber solution was evaluated. Determination of trace elements was performed by inductively coupled plasma-optical emission and mass spectrometry. Neutron activation analysis (NAA) was used for validation purposes. Results were also compared to those obtained using microwave-assisted acid extraction in high-pressure closed systems. Dilute nitric acid (5 mol L(-1)), which was selected as the absorbing medium, was used to reflux the sample for 5 min after the combustion. Using these conditions, agreement for all analytes was better than 98% when compared to values determined by NAA. The residual carbon content in the digests was lower than 1%, illustrating the high efficiency of the method. Up to 8 samples could be digested within 30 min using MIC, providing a suitable throughput, taking into account the inertness of such samples.

Analytical methods for the determination of halogens in bioanalytical sciences: a review.

Fluorine, chlorine, bromine, and iodine have been studied in biological samples and other related matrices owing to the need to understand the biochemical effects in living organisms. In this review, the works published in last 20 years are covered, and the main topics related to sample preparation methods and analytical techniques commonly used for fluorine, chlorine, bromine, and iodine determination in biological samples, food, drugs, and plants used as food or with medical applications are discussed. The commonest sample preparation methods, as extraction and decomposition using combustion and pyrohydrolysis, are reviewed, as well as spectrometric and electroanalytical techniques, spectrophotometry, total reflection X-ray fluorescence, neutron activation analysis, and separation systems using chromatography and electrophoresis. On this aspect, the main analytical challenges and drawbacks are highlighted. A discussion related to the availability of certified reference materials for evaluation of accuracy is also included, as well as a discussion of the official methods used as references for the determination of halogens in the samples covered in this review.

Toxicity of triphenyltin hydroxide to fish.

Triphenyltin (TPhT) is used worldwide in pesticide formulas for agriculture. Toxic effects of this compound to aquatic life have been reported; however, the biochemical response of fish exposed to different concentrations of TPhT hydroxide (TPhTH) was investigated for the first time in this study. The lethal concentration (LC50) of TPhTH to silver catfish, Rhamdia quelen, was calculated from an acute-exposure experiment (96 h). In addition, acethylcholinesterase (AChE) activity in brain and muscle-as well as glucose, glycogen, lactate, total protein, ammonia, and free amino acids in liver and muscle-were evaluated in a chronic-exposure experiment (15-day exposure). Speciation analysis of tin (Sn) was performed in fish tissues at the end of both experiments using gas chromatography coupled to a pulsed-flame photometric detector (GC-PFPD). Concentrations of TPhT, diphenyltin, and monophenyltin (reported as Sn) were lower than limits of quantification (10σ criteria). Waterborne TPhTH concentration used through the experiment was also evaluated by GC-PFPD, and no degradation of this species was observed. The LC50 value for silver catfish juveniles was 9.73 µg L(-1) (as Sn). Decreased brain and muscle AChE activities were observed in fish exposed to TPhTH in relation to unexposed fish (control). Liver glycogen and lactate levels were significantly higher in fish kept at the highest waterborne TPhTH concentration compared with the control. Liver and muscle glucose levels of fish exposed to all TPhTH concentrations were significantly lower than those of control fish. Silver catfish exposed to all TPhTH concentrations showed lower total protein values and higher total free amino acids levels in liver and muscle compared with controls. Total ammonia levels in liver and muscle were significantly higher for the highest TPhTH concentration compared with controls. In conclusion, TPhTH caused metabolic alterations in silver catfish juveniles, and the analyzed parameters can also be used as bioindicators for TPhTH contamination.

Sublethal zinc and copper exposure affect acetylcholinesterase activity and accumulation in different tissues of Leporinus obtusidens.

In this study, we investigated zinc and copper effects on acetylcholinesterase (AChE, EC. 3.1.1.7) activity and metal accumulation in tissues of native fish Leporinus obtusidens (piava). Fish were exposed to 10 and 20 % of the LC(50) that corresponded at 2.28 and 4.57 mg/L (zinc) and 0.018 and 0.038 mg/L (copper) for 30 and 45 days. The AChE activity was evaluated in brain and white muscle of fish and metals accumulation was measured in kidney, liver, muscle and brain. Exposure to zinc and copper significantly increased AChE activity in both tissues and times tested, except for brain AChE activity at 2.28 mg/L of Zn (II) after 45 days where a reduction of 52.5 % was observed. Fish exposed to zinc showed accumulation of this metal in liver and kidney in both concentrations and times tested. A different result was obtained for copper: significant copper accumulation was obtained only in brain at both concentrations tested after 45 days of exposure. These results suggest that piavas exposed to zinc and copper showed changes in AChE activity and also demonstrate accumulation in some tissues. These results demonstrate that L. obtusidens could be a good bioindicator to evaluate water containing metals. The metal accumulation absence in muscle tissue is an indicative of low potential contamination by metals in this fish species.

Ultrasonication for honey processing and preservation: A brief overview.

Honey is a food product consumed all over the world. Besides its nutritional properties, honey presents antibacterial, antioxidant, and wound-healing properties. To ensure that the final product meets qualitative and microbiological standards, honey treatment is of great importance. Conventional honey treatment is based on the heating of honey samples for decrystallization and bacteria and yeast inactivation. However, conventional heating can cause negative effects on honey quality, such as the formation of toxic compounds, reduction of enzyme activity, and loss of antioxidant and antimicrobial properties. The application of ultrasonic waves has demonstrated interesting effects on honey processing. Ultrasound (US) treatment can lead to the fragmentation of glucose crystals in crystalized honey and has little effect on its properties. In addition to inactivating microorganisms, US-assisted honey processing also preserves phenolic compounds content and antimicrobial properties. However, there is still limited information about honey sonication. The aim of the present review is to comprehensively show the possibilities of US application in honey processing and its effects on honey properties.

Ultrasonics and sonochemistry: Editors' perspective.

Ultrasonic waves can induce physical and chemical changes in liquid media via acoustic cavitation. Various applications have benefitted from utilizing these effects, including but not limited to the synthesis of functional materials, emulsification, cleaning, and processing. Several books and review articles in the public domain cover both fundamental and applied aspects of ultrasonics and sonochemistry. The Editors of the Ultrasonics Sonochemistry journal possess diverse expertise in this field, from theoretical and experimental aspects of acoustic cavitation to materials synthesis, environmental remediation, and sonoprocessing. This article provides Editors' perspectives on various aspects of ultrasonics and sonochemistry that may benefit students and early career researchers.

A simple, low cost and fast sample preparation method for fluorine determination by ISE in leguminous seeds and oilseeds.

This work presents the first report of the application of microwave-induced combustion in disposable vessels (MIC-DV) as a simple and fast sample preparation step for fluoride determination by ion-selective electrode (ISE) in leguminous seeds and oilseeds samples. Several experimental conditions of MIC-DV were evaluated, such as sample mass, absorbing solution, volume of combustion igniter, purging time with oxygen, and the use of successive combustion cycles. The accuracy of MIC-DV/ISE method was evaluated by comparing the results obtained by microwave-induced combustion and determination by ion chromatography, with agreements ranged from 94 to 106%. The method allowed to achieve relatively low limits of quantification (8.3 to 16 µg g-1) comparing to AOAC method (40 µg g-1), besides the use of small amounts of reagents, less handling of digests, making the method greener and with portable features comparing to other methods.

Determination of Cl and S in crude oil by ICP-OES after sample digestion by microwave-induced combustion in disposable vessels.

A simple, fast and promising sample preparation method based on microwave-induced combustion in disposable vessels (MIC-DV) was developed for Cl and S determination in crude oil by inductively coupled plasma optical emission spectrometry (ICP-OES). The MIC-DV consists of a new approach of conventional microwave-induced combustion (MIC). For the combustion, crude oil was pipetted on a disk of filter paper and placed on a quartz holder, followed by the addition of igniter solution (40 µL of 10 mol L-1 NH4NO3). The quartz holder was inserted into a commercial 50 mL disposable polypropylene vessel containing the absorbing solution, which was then inserted in an aluminium rotor. The combustion occurs under atmospheric pressure in a domestic microwave oven not compromising the operator's safety. The following parameters of combustion were evaluated: type, concentration and volume of absorbing solution, sample mass and the possibility of performing consecutive combustion cycles. Using MIC-DV, up to 10 mg of crude oil were efficiently digested, using 2.5 mL of ultrapure H2O as absorbing solution. Moreover, up to 5 consecutive combustion cycles were possible without analyte losses, reaching a total sample mass of 50 mg. The MIC-DV method was validated according to Eurachem Guide recommendations. Results obtained for Cl and S by MIC-DV were in agreement with those obtained using conventional MIC, as well as those obtained for S in a certified reference material of crude oil (NIST 2721). Analyte spike recovery experiments were performed and recoveries at three concentration levels ranged from 99 to 101% for Cl and from 95 to 97% for S, indicating a good accuracy. The limit of quantification achieved by ICP-OES after MIC-DV were 73 and 50 µg g-1 for Cl and S respectively, applying 5 consecutive combustion cycles.