Titrimetric and gravimetric determination of the specific pore volume of microparticulate silica gels

1988 ◽  
Vol 53 (2) ◽  
pp. 269-277 ◽  
Author(s):  
Zdeněk Šimek ◽  
Radim Vespalec ◽  
Jiří Neča
Keyword(s):  
Pore Volume ◽  
Barometric Pressure ◽  
Point Of View ◽  
The Other ◽  
Silica Gels ◽  
Specific Pore Volume ◽  
Gravimetric Determination ◽  
Relative Standard ◽  
Gravimetric Procedure

The titrimetric and gravimetric methods of determination of the specific pore volume were studied unmodified and modified chromatographic silica gels of mean particle size above 5 μm. The apparatus and titrimetric procedure suggested elsewhere were adapted so that the relative standard deviation of measurement did not exceed 2%. Water, n-octane, and methanol were used as titrants, and methanol was found to suit best from the point of view of accuracy and rapidity of analysis and versatility of use. This solvent is also suitable for the gravimetric measurements, which can be carried out without thermostatting and at barometric pressure. The titrimetric procedure is less time consuming than the gravimetric procedure which, on the other hand, is less tedious and less instrumentation-demanding.

Gravimetric Determination of Carbon Dioxide in Wines

1975 ◽  
Vol 58 (1) ◽  
pp. 136-139
Author(s):  
Graham A Castillo
Keyword(s):  
Carbon Dioxide ◽  
Vacuum Pump ◽  
Vacuum System ◽  
Reaction Flask ◽  
Magnesium Perchlorate ◽  
Titrimetric Method ◽  
Gravimetric Determination ◽  
Before And After ◽  
Gravimetric Procedure

Abstract A gravimetric determination of CO2 in wines was both accurate and relatively fast when compared with the titrimetric method. When 21 samples of lightly carbonated wine were analyzed by both methods the average results agreed within 0.2 mg (range of agreement from 0.1 to 5.0 mg CO2/100 ml wine). In the gravimetric procedure, the CO2 contained in the wines is converted into the carbonate by adding 50% NaOH to the previously chilled sample. An aliquot is introduced into a closed vacuum system. The CO2 is evolved by adding HCl and shaking and warming the reaction flask. The generated gases are pulled through the system by a vacuum pump. Along the path, the gases are dried and purified, and finally the CO2 is absorbed by Indicarb reagent between layers of anhydrous magnesium perchlorate. The absorption bulb is weighed before and after absorption of CO2.

Microchemical Method for Oxygen

1963 ◽  
Vol 46 (4) ◽  
pp. 559-564
Author(s):  
Al Steyermakk
Keyword(s):  
Organic Compounds ◽  
The Other ◽  
Gravimetric Procedure

Abstract A specific gravimetric procedure was submitted to the collaborators for this year’s study on the determination of oxygen in organic compounds. Three compounds were analyzed: one contained no oxygen, one contained only carbon, hydrogen, and oxygen, and the other was a sulfa compound. The results obtained were good, and the method is recommended as official, first action.

scholarly journals Determination of Cholecalciferol (Vitamin D3) in Selected Foods by Liquid Chromatography: NMKL Collaborative Study

2003 ◽  
Vol 86 (2) ◽  
pp. 400-406 ◽  
Author(s):  
Anders Staffas ◽  
Arne Nyman ◽  
K Ask ◽  
E Hermansson ◽  
J S Jacobsen ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Fish Oil ◽  
Vitamin D3 ◽  
Collaborative Study ◽  
The Other ◽  
Vitamin D2 ◽  
Cooking Oil ◽  
Relative Standard

Abstract Results are presented from an NMKL (Nordic Committee on Food Analysis) collaborative study of a method for the determination of cholecalciferol (vitamin D3) in foods. The method is based on the addition of an internal standard (vitamin D2), followed by saponification and extraction with n-heptane. The fraction that contains vitamin D2/D3 is separated by preparative normal-phase liquid chromatography (LC), and the analytes are determined by reversed-phase LC with UV detection at 265 nm. The method was tested by 8 participating laboratories. In this study 6 different matrixes were analyzed for cholecalciferol content: milk, liquid infant formula (gruel), cooking oil, margarine, infant formula, and fish oil. The contents varied from 0.4 to 12 μg/100 g. Three matrixes (milk, gruel, and margarine) were fortified with vitamin D3. In the other matrixes, vitamin D3 was added at 3 different levels at the Swedish National Food Administration. The milk was analyzed as a blind duplicate, whereas the other matrixes were analyzed as split-level pairs. The recoveries from the samples with vitamin D3 added varied from 93 to 102%. The repeatability relative standard deviation (RSDr) values for accepted results varied between 2.2% (fish oil) and 7.4% (cooking oil), whereas the reproducibility relative standard deviation (RSDR) values varied between 6.8% (margarine) and 24% (cooking oil).

scholarly journals URGENSI PENETAPAN KRITERIA FAKIR MISKIN BAGI PENYALURAN ZAKAT DI INDONESIA

2018 ◽  
Vol 4 (1) ◽  
pp. 167
Author(s):  
Kuntarno Noor Aflah
Keyword(s):  
Comparative Research ◽  
Basic Needs ◽  
Point Of View ◽  
The Other ◽  
Local Conditions ◽  
Other Hand ◽  
The Difference ◽  
The Government ◽  
Literacy Research

Poverty has many definitions, parameters, and standards. From the viewpoint of Islam, many theologians define and measure poverty by various terms and sizes. The difference among theologians’ opinion is caused by poverty terms contained in the Qur’an and Hadits. “Fakir” and “poor” have many meanings. It allows a wide interpretation of the verse and word from theologians. It is also seen from the regulation point in Indonesia, there are many definitions, standards and parameters of poverty. The difference of point of view on determination of poverty criteria and regulations according to Islam in Indonesia shows that the ways of ijtihad by theologians and the government elements is very open. The absence of standard stipulation held, encouraging the writer to conduct a comparative research in this paper; through literacy research. Syafi’i sect does not specify a quantitative standard for poverty. Poverty is only categorized on requirement. As long as people are not able to cover 50% of their basic needs, they are called as fakir. If people are only able to cover close to 70% of their basic needs then they are categorized as poor. Meanwhile, according to Hanafi sect, the qualitative standards turned to the Syafi’i sect. Poor conditions are more severe than the fakir. Besides,the quantitative standard of poverty is one nisab of zakat or the equivalent of 85 grams of gold. On the other hand, BPS and BKKBN formulate the concept and standard of poverty by economic concepts. Poverty is conceptualized as the inability of someone to meet basic consumption needs of the formulation adapted to local conditions respectively.

scholarly journals Determination of β-Carotene in Commercial Foods: Interlaboratory Study

1997 ◽  
Vol 80 (5) ◽  
pp. 1057-1064 ◽  
Author(s):  
Willy Schuep ◽  
Joseph Schierle
Keyword(s):  
Sample Preparation ◽  
Collaborative Study ◽  
The Other ◽  
High Quality ◽  
Carotene Content ◽  
Relative Standard ◽  
Simple Extraction ◽  
Β Carotene ◽  
Significant Underestimation

Abstract Two sample preparation procedures for determination of total β-carotene and (all-)-β-carotene were tested in a collaborative study involving 14 laboratories and using 4 commercial products containing supplemented or natural β-carotene. One assay used classical sample preparation, consisting of saponification, extraction, washing, and drying ofthe extract and redissolution of residue for liquid chromatography (LC). The other assay used simple extraction without saponification. LC conditions were left for the analysts to decide as long as aclear separation of lycopene and ϑ-carotene from Bcarotene was achieved. Mean contents of test samples ranged from 0.3 to 18 mg/100 g for total β-carotene and from 0.2 to 16 mg/100 g for (all-)-β-carotene. Repeatability relative standard deviations (RSDr)for total B-carotene ranged from 2.9 to 5.6% and relative reproducibility standard deviation (RSDR) ranged from 6.5 to 15%. Corresponding values for(all-)-β-carotene were 3.3-5.1 % for RSDr and 8.4- 14% for RSDR. Excluding the (Z)-isomers from uantitation of β-carotene can result in significant underestimation of the effective β-carotene content especially if the LC systems used is high quality.

scholarly journals On the annual variations of some of the principal fixed stars

1833 ◽  
Vol 2 ◽  
pp. 251-252
Keyword(s):  
Point Of View ◽  
The Other ◽  
Astronomical Observations ◽  
Annual Variations ◽  
The Subject

This communication consists of a table stating the annual variations of 23 of the principal fixed stars, as deduced from Dr. Brinkley’s observations, and those of the Astronomer Royal. On. these Mr. Pond remarks, that out of 16 stars observed at Dublin, 13 either indicate a southern deviation, or at least are not inconsistent with it, and that of these 13, about half indicate a greater deviation than that assigned by Mr. Pond himself. The other half a less, while the three remaining stars deviate northwards. Mr. Pond further remarks, that the examination of this table is calculated rather to increase than to diminish scepticism on the subject of the determination of such very small quantities by astronomical observations. He concludes by disclaiming all intention of placing he subject in a controversial point of view, and by expressing a hope that the difficulty will in a very few years be satisfactorily cleared up.

Two Kinds of Soft Facts

2018 ◽  
Vol 95 (1) ◽  
pp. 34-53 ◽  
Author(s):  
Ciro De Florio ◽  
Aldo Frigerio
Keyword(s):  
Point Of View ◽  
The Other ◽  
Future Contingents ◽  
The Past ◽  
Other Hand ◽  
Divine Knowledge ◽  
Soft Fact ◽  
The One ◽  
Definition Of

The concept of soft facts is crucial for the Ockhamistic analysis of the divine knowledge of future contingents; moreover, this notion is important in itself because it concerns the structure of the facts that depend—in some sense—on other future facts. However, the debate on soft facts is often flawed by the unaware use of two different notions of soft facts. The facts of the first kind are supervenient on temporal facts: By bringing about a temporal fact, the agent can bring about these facts. However, on the one hand, the determination of the existence of these facts does not affect the past; on the other hand, assimilating divine knowledge into this kind of facts does not help the Ockhamist. The authors will argue that, to vindicate Ockhamism, another definition of “soft fact” is necessary, which turns out to be much more demanding from a metaphysical point of view.

Localization of micropores in polymer films

1978 ◽  
Vol 36 (1) ◽  
pp. 490-491
Author(s):  
W.F. Geymayer ◽  
F. Grasenick
Keyword(s):  
Polymer Films ◽  
Pore Volume ◽  
Porous Polymer ◽  
The Other ◽  
Monomer Mixture ◽  
Interesting Problem ◽  
Sensitive Material ◽  
High Importance ◽  
Osmotic Properties

For studying corrosion problems, for the understanding of osmotic processes or generally for the investigation of reactions inside porous polymer films the knowledge of the frequency and the size of the pores as well as the registration of the course of penetrating pores is of high importance for the determination of the active pore-volume.In most of these processes at least one of the reactants is a fluid being in contact with the diaphragm through which it reacts with the medium on the other side. The fluid often begins to swell the polymer layer, a process that may even be necessary to develop the osmotic properties of the membrane.Thus it was an interesting problem, to find a way of detecting the pores in a possibly swollen organic diaphragm without altering it. Drying the specimens completely disturbs the original conditions, chemical dehydration with subsequent soaking the pores with a suitable monomer-mixture causes strong changes of the sensitive material by uncontrolled shrinkag.

Semiautomated Method for the Determination of Reserpine in Tablets

1970 ◽  
Vol 53 (4) ◽  
pp. 815-818
Author(s):  
Donald P Page
Keyword(s):  
Hydrochloric Acid ◽  
Colorimetric Assay ◽  
Chloroform Solution ◽  
Methanol Solution ◽  
The Other ◽  
Relative Standard ◽  
Chromatographic Procedure ◽  
Chloroform Methanol ◽  
Semiautomated Method

Abstract A chloroform solution of reserpine tablets is automatically sampled, washed successively with aqueous solutions of citric acid and sodium bicarbonate, and diluted with methanol. The chloroform-methanol solution is split into 3 streams: one flows sequentially through 2 UV spectrophotometers, recording the absorbances at 268 and 295 nm; the other 2 streams are used for the colorimetric assay (addition of hydrochloric acid and sodium nitrite) and blank (hydrochloric acid only). Day-to-day relative standard deviations were 0.40–0.95%. Comparisons with Barkan’s chromatographic procedure and the USP XVII method are presented.

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