Digestion Flasks Research Articles

A vessel-inside-vessel microwave-assisted digestion method based on SO3 generation in situ for the mineral determination of fatty samples

Vessel-inside-vessel microwave-assisted acid digestion was developed for the analysis of samples with high-unsaturated fat content. For the first time, thermal decomposition of (NH4)2S2O8 solutions was evidenced for SO3 generation in situ and gas-phase modification in pressurized digestion flasks. NMR analysis demonstrated the oxidative effect of SO3 on olefin double bonds despite incomplete mineralization of oil samples. In this context, (NH4)2S2O8 decomposition was used in association with HNO3 solutions for sample digestion and mineral determination in edible oils (safflower, coconut, flaxseed, and chia). For all oils, dissolved organic carbon (DOC) contents lower than 5% m m-1 were obtained under optimum conditions: 210 °C with an irradiation time of 40 min, 7.0 mol L-1 HNO3 and 2.0 mol L-1 (NH4)2S2O8 in 0.9 mol L-1 H2SO4. Thus, a DOC reduction of about 70% was reached compared to digestions using only HNO3 at the same conditions. Additionally, a time reduction of up to three-fold was achieved compared to typically demanding edible oil digestions. The proposed method allowed the determination of As, Cd, Cr, Mn, Ni, and Pb in edible vegetable oil samples by ICP-MS. Accuracy was evaluated against the reference method, and no significant difference was observed (p = 0.05), with wide linear ranges and good linearity (r ≥ 0.999) and LOD ranging from 0.48 (As) to 2.41 (Cd) μg L-1.

Assessing the Bioaccumulative Impact of Four Heavy Metals on the Endocrine System of Tilapia rendalli Fish Species in the Kafue River

The term, “heavy metals” (HMs) refers to a group of metals with atomic density greater than 4g/cm3. HM contamination is a major environmental problem worldwide today, especially in growing cities of developing countries mainly due to pollution. High levels of HMs can cause health problems in an organism, despite their various uses. Their biotoxic effects come into play once accumulation levels in organisms go beyond maximum permissible limits. Thus, this study aimed at assessing the bioaccumulative impact of cadmium (Cd), copper (Cu), nickel (Ni) and Lead (Pb) on the endocrine system of Tilapia rendalli fish in Kafue River. Water samples were collected in 2 x 500 mL polypropylene bottles, refrigerated at about 8 oC, then put at room temperature before filtering for analysis. Tissues (blood, gills, liver and muscle) were extracted per fish from 93 samples collected from upper, middle and lower sites of the river; KUP, ITT and SH respectively. Gills, livers and muscles were cleaned in distilled water, oven dried at 110 oC, weighed and transferred into digestion flasks. 10 mL of 55 % nitric acid and 5 mL of 70 % perchloric acid (ANALAR) were added into digestion flasks. Samples were digested at about 200 – 250 oC on a hot plate to a transparent solution after disappearance of initial brown fumes. White fumes indicated completion of digestion. Solutions were cooled and diluted to 20 mL using distilled water. The samples were assayed for Cd, Cu, Ni and Pb using Flame Atomic Absorption Spectrophotometric method (FAAS), Varian AAS 220 instrument. Blood samples were thawed at room temperature, centrifuged at 2016 x g (3000 rpm) for 10 minutes to collect supernatant serum. Serum was assayed for Estradiol (E2) and Testosterone (T) using the ELISA method and concentrations of unknowns determined from standard curves by interpolation using Graphpad prism 6.01. Hormone levels varied significantly among the fish samples. This difference was significantly related to variations in HM levels in fish tissues from the respective study sites. Highest mean levels of T (13.58±2.8 ng/mL) and E2 (774.33±66.98 pg/mL) were measured in SH while lowest mean levels of T (5.78±0.69 ng/mL) and E2 (63.75±45.39 pg/mL) were measured in ITT. The study further showed that low levels of Cd, Cu, and Ni in SH correlated significantly to high hormone levels recorded in fish at SH while high levels of Cu in livers and muscles, 496.73 ±184.96 mg/kg and 43.68±18.32 mg/kg respectively; recorded in ITT correlated negatively to low hormone levels in fish. Study also observed a positive correlation between hormone levels and Pb concentrations in tissues, indicating biphasic mechanisms of Pb and other metals on E2 and T levels in fish. Therefore, HM bioaccumulation affects expression levels of sex hormones in fish and this may be extrapolated to humans who are major consumers of fish along trophic levels. Since HM levels were high in internal organs than in muscle (flesh), high public awareness should be emphasized on the risk benefit of consuming fish with…

Comparison of closed-pressurized and open-refluxed vessel digestion systems for trace elements in the residual fuel oil reference material (SRM 1634c)

Samples of residual fuel oil reference material (SRM 1634c) were mineralized in closed digestion vessels from Milestone Laboratory Systems (MLS) or from PAAR (HPA) or in open-refluxed microwave digestion flasks from Prolabo. The three digestion systems were evaluated in terms of accuracy and precision, reagents and time saving, total organic carbon content, and method determination limits for the determination of trace elements (Be, Mg, Al, Ca, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Te, Ba, Hg, Tl, Pb, Bi, U) by inductively coupled plasma-mass spectrometry. The total organic carbon concentrations were 1160 (MLS), 240 (HPA), and < 10 (Prolabo) mg C kg-1. Concentrations of V, Ni, and As in the digests of the HPA and the MLS systems were in acceptable agreement with each other and with the certified values for these elements. The values for Co when using the HPA and the MLS systems were lower than the certified Co value (~80%). Higher values for Se are probably due to interference by 82Kr. The digests of the HPA were prone to contamination by Fe and Al from the digestion chamber. The Prolabo system generally resulted in a substantial reduction in the concentration of elements, probably due to volatilization losses. It was also prone to sulfur-based interference. For the majority of the elements the relative standard deviations (RSD, n = 5) were less than 5% for HPA and MLS but were higher than 10% for Prolabo.

Pretreatment of plant and soil samples a problem in boron analysis

Abstract Possible sources of errors in the determination of boron in plant samples were examined. This paper will first describe some general features and then the following steps in the pre‐treatment of plant samples: Drying Grinding Dry ashing, effects of temperature, time and additives Wet ashing, loss of boron when using different acids, boron contamination from glassware and other related aspects Extraction of plant samples During drying and grinding neither loss nor contamination of boron was observed. It was found that boron was slightly lost when muffling at temperatures higher than 550°C. The addition of Ca(OH)2 prevented the loss but gave rise to incomplete ashing in many cases. Nitrate salts added in order to enhance oxidation gave rise to boron loss. Wet ashing should be done preferably in a concentrated sulphuric acid or phosphoric acid medium at low temperatures. At higher temperatures the shape of the digestion flask is important ‐ long neck flasks are usually safe enough due to their conde...

Sulphuric—perchloric acid digestion of plant material for the determination of nitrogen, phosphorus, potassium, calcium and magnesium

Modifications of an earlier procedure to improve reliability in routine use are described. Contamination from glass beads and new digestion flasks may be significant. Other possible sources of error are discussed.

Total nitrogen determination for plant material containing nitrate

A nonfoaming method for semimicro Kieldahl determination of total nitrogen in plant samples containing appreciable amounts of nitrate was developed for use with a digestion block utilizing test tubes for digestion flasks. The sample (30 to 200 mg) is treated with 5 ml of a sulfuric acid:salicylie acid (30:1 v w ) mixture at room temperature for 1 hr. Catalyst [K 2SO 4:CuSeO 3·2H 2O:pumice 970:19:11 w/w/w)] is added and the mixture is digested at 360 to 380°C for 1 hr after the mixture clears. Ammonium in the digest is determined by a suitable method. This semimicro Kjeldahl procedure results in a 95% or better recovery of nitrate, either from KNO 3 or from KNO 3 added to plant material.

水蒸気蒸留法による魚介類中のアルキル水銀定量

The steam distillation method for the determination of alkyl mercury in fish and shells is described: The wet samples (5-50g) are put into 500ml distilling flasks and are steam distilled after adding 40ml of 6N hydrochloric acid and 40g of sodium chloride. The aqueous distillate is put into 10ml of 3N hydrochloric acid, final volume being about 180ml. The aqueous distillate is transferred into a 200ml volumetric flask and diluted with distilled water. A 50ml portion of aqueous distillate is transferred into a separating funnel and the alkyl mercury in the aqueous distillate is extracted with a 30ml, then a 20ml portion of benzene, after which it is reextracted with 10ml of 1% cysteine acetate solution. A 5ml portion of the cysteine acetate layer is removed into a digestion flask. Alkyl mercury in cysteine acetate solution is wet-digested by the method previously reported, and is determined by flameless atomic absorption The study has shown that the alkyl mercury, that is, the methyl, ethyl or butyl compound, is entirely distilled by steam distillation, but phenyl of inorganic mercury is not. By the steam distillation method herein described, alkyl mercury in fish and shells can be completely extracted without emulsification. The data have shown quantitative recovery of methyl mercury added to a variety of samples. The coefficient of variation for repeated determinations on a tuna meat sample has been 2.0%.

Determination of Aluminum in Food and Plant by Atomic Absorption Spectrometry

The determination of aluminum in food by the atomic absorption spectrometry was studied.The operating conditions were as follows: analytical line was 3092A for aluminum, electric current in the hollow cathode lamp was 15mA, and combustion gas flow rates were 6L/min for nitrous oxide and 5.5L/min for acetylene.The most suitable pH for the extraction of aluminum was studied, and it was found that the optimum pH was within 11 to 13. The relationship between the volume ratio (R) of the aqueos prepared solution containing aluminum ion to acetylacetone-butyl acetate and the extraction ratio was studied in order to obtain quantitative extraction. Aluminum was extracted quantitatively at R=3 to 6.In the case of analysis of aluminum in food, plant, and sake (Japanese wine) by atomic absorption spectrometry, it was necessary to destroy the organic substances. For this purpose, a wet digestion procedure was adopted. Approximately 5 to 10g of the food sample or 100ml of sake was taken into a digestion flask of 300ml capacity to which was added a mixture of nitric, and sulfuric acid (10+1). After digestion, the acidic digested solution was diluted to 100ml with distilled water, and the solution was used for preparated solution.The prepared solution was adjusted at pH 12, then extracted by acetylacetone-butyl acetate, and aluminum was determined by the atomic absorption method, the amounts of aluminum in food, plants, and sake were as follow: Miso (soybean paste), 2.4 to 32.9ppm; soybean, 22.0ppm; sake, 2.6ppm, and the coefficients of variation were about 14%.

Improved Method for the Determination of Ethylenebisdithiocarbamate Residues in Plants, Fruits, and Vegetables

Abstract A modified method for the determination of dithiocarbamate fungicide residues on crops is presented. A large representative subsample of the frozen crop is blended in ice-cold deaerated water and an aliquot of the homogenate is added to the analytical apparatus containing hot 5 0% sulfuric acid. Dithiocarbamates are decomposed to evolve CS2 which is removed by a continuous gentle air-sweep from the digestion flask. Variations in technique allow the analysis of dithiocarbamate fungicide residues in several ranges, 1-10, 10-200, and 200-1000 /ig maneb. Recoveries from a wide variety of crops averaged 70 to 103%. Certain crop types present low recoveries and/or high apparent control values, but modifications in the analytical procedure are successful in solving these problems.

Determination of Arsenic in Flue‐Cured Tobacco and in Soils

AbstractProcedures are described for the semimicro analysis for arsenic in flue‐cured tobacco and in soils. The plant material is digested with a mixture of nitric, sulfuric and perchloric acids and the soil with sulfuric and perchloric acids. Arsenic is distilled directly from the digestion flask, absorbed in an iodine solution and determined colorimetrically by the molybdenum‐blue method.The data show that good recovery of arsenic and reproducibility of results were obtained with the described procedures. The acid digestion method for plant material gave results which were comparable to those obtained by oxidation in an oxygen bomb. The evidence from soils indicates that the digestion and distillation procedure employed removed essentially all of the arsenic.

Notes on the Colorimetric Determination of Inorganic Orthophosphate

The effect of the amount of the amidol reagent on the rates of hydrolysis of some acid-labile phosphate compounds in the determination of inorganic orthophosphate according to the method of Allen and its modifications by Whelan and Bailey and by Nakamura is reported. It is shown in this paper that the most important factor in these methods is the temperature at which molybdenum blue color is developed. The rate constants of acid hydrolysis of adenosine triphosphate, glucose-1-phosphate, fructose-1,6-diphosphate phosphoryl (enol) pyruvate and inorganic pyrophosphate at various temperatures under the experimental conditions of Nakamura’s method in the presence and absence of molybdate are also presented. In the determination of total phosphorus, there was only a very slight, if any, condensation of orthophosphate to polyphosphates when the sample to be tested was incinerated in perchloric acid or in sulfuric acid. Both colorimetric method and radioactivity measurements were applied for the determination of orthophosphate remained as such in the digest. Also, the loss of phosphoric acid was not observed when care was taken so as not to allow the white vapor of the acid emerge from the digestion flask during incineration.

Notes on the Colorimetric Determination of Inorganic Orthophosphate

In the determination of total phosphorus, there was only a very slight, if any, condensation of orthophosphate to polyphosphates when the sample to be tested was incinerated in perchloric acid or in sulfuric acid. Both colorimetric method and radioactivity measurements were applied for the determination of orthophosphate remained as such in the digest. Also, the loss of phosphoric acid was not observed when care was taken so as not to allow the white vapor of the acid emerge from the digestion flask during incineration.

Note on an accurate wet combustion method for the determination of carbon in soils

In April 1938 I published a method for the determination of carbon in soils (Alper, 1938). This method consists of digesting the soil with a mixture of sulphuric acid and potassium bichromate, passing the products of combustion through a heated combustion tube and absorbing the carbon dioxide produced in barium hydroxide. Digestion and absorption take place in a closed system which allows neither the escape nor entrance of carbon dioxide. The absorption flask is evacuated and separated from the digestion flask by a glass tap. During the process of digestion, as the pressure in the system increases, this tap is manipulated, allowing the escape of gas into the absorption flask. A pressure gauge in the system indicates when the tap should be opened.The sensitivity of this mercury pressure gauge causes some difficulty in technique. It is necessary to watch the experiment throughout the digestion and to manipulate the tap constantly. In order to obviate this difficulty an improvement in the apparatus has been effected. The pressure gauge has been replaced by an elastic bladder (a child's balloon serves the purpose admirably) which is connected to the system by means of a glass ┬-piece. At the commencement of the experiment the pressure within the system is slightly less than atmospheric owing to the suction of CO2-free air through the apparatus. This causes the complete deflation of the balloon. As digestion continues the balloon becomes distended. The distension of the balloon must not be allowed to go too far as too great a pressure in the system will result in losses through leakage.

A Micro-Kjeldahl Method Including Nitrates

Previous articleNext article No AccessA Micro-Kjeldahl Method Including NitratesRufus H. MooreRufus H. Moore Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 100, Number 1Sep., 1938 Article DOIhttps://doi.org/10.1086/334778 Views: 1Total views on this site Citations: 7Citations are reported from Crossref Journal History This article was published in the Botanical Gazette (1876-1991), which is continued by International Journal of Plant Sciences (1992-present). PDF download Crossref reports the following articles citing this article:R.B. BRADSTREET The Kjeldahl Digestion, (Jan 1965): 9–88.https://doi.org/10.1016/B978-1-4832-3298-0.50005-9R.B. BRADSTREET Digestion Procedure, (Jan 1965): 89–145.https://doi.org/10.1016/B978-1-4832-3298-0.50006-0 General Bibliography, (Jan 1965): 169–234.https://doi.org/10.1016/B978-1-4832-3298-0.50008-4Oskar Eichler Chemie, (Jan 1950): 6–70.https://doi.org/10.1007/978-3-642-99826-3_2H. E. STREET EXPERIMENTAL METHODS AVAILABLE FOR THE STUDY OF THE NITROGEN METABOLISM OF PLANTS. A REVIEW OF SOME RECENT ADVANCES, New Phytologist 48, no.11 (Feb 1949): 84–96.https://doi.org/10.1111/j.1469-8137.1949.tb05111.xE. Rauterberg, H. Benischke Die Bestimmung des Gesamtstickstoffs in nitrathaltigen Ernteprodukten, Bodenkunde und Pflanzenernährung 31, no.1-21-2 (Jan 2007): 118–125.https://doi.org/10.1002/jpln.19430310107K. Mothes Zur Biosythese der Säureamide Asparagin und Glutamin, Planta 30, no.55 (Apr 1940): 726–756.https://doi.org/10.1007/BF01917181

A Simple and Entirely Adjustable Rack for Kjeldahl Digestion Flasks.

A Simple and Entirely Adjustable Rack for Kjeldahl Digestion Flasks.