Organic sample preparation

APPENDIX VIII SOME COMMON INORGANIC AND ORGANIC SAMPLE PREPARATION METHODS USED IN ARCHAEOLOGY... 

Nowicki et al. [51] point out that in the development of a Soxhlet sample preparation technique for sediment samples, the empty paper Soxhlet thimbles contained organic contaminants which adversely affected results. Glass thimbles were tried and found to be satisfactory. The authors detail the identification of organics solvent-extracted from paper and glass Soxhlet thimbles, and discuss the stability for multiple use of the two materials for trace organic sample preparation. 

The manipulation of equilibrium conditions is at the heart of most organic sample preparations. 

Atomization The most important difference between a spectrophotometer for atomic absorption and one for molecular absorption is the need to convert the analyte into a free atom. The process of converting an analyte in solid, liquid, or solution form to a free gaseous atom is called atomization. In most cases the sample containing the analyte undergoes some form of sample preparation that leaves the analyte in an organic or aqueous solution. For this reason, only the introduction of solution samples is considered in this text. Two general methods of atomization are used flame atomization and electrothermal atomization. A few elements are atomized using other methods. 

Sample preparation for the modified Fischer assay technique, a standard method to determine the Hquid yields from pyrolysis of oil shale, is necessary to achieve reproducible results. A 100-g sample of >230 fim (65 mesh) of oil shale is heated in a Fischer assay retort through a prescribed temperature range, eg, ca 25.5—500°C, for 50 min and then soaked for 20 min. The organic Hquid which is collected is the Fischer assay yield (7). The Fischer assay is not an absolute method, but a quaHtative assessment of the oil that may be produced from a given sample of oil shale (8). Retorting yields of greater than 100% of Fischer assay are possible. 

Spectrometric Analysis. Remarkable developments ia mass spectrometry (ms) and nuclear magnetic resonance methods (nmr), eg, secondary ion mass spectrometry (sims), plasma desorption (pd), thermospray (tsp), two or three dimensional nmr, high resolution nmr of soHds, give useful stmcture analysis information (131). Because nmr analysis of or N-labeled amino acids enables determiaation of amino acids without isolation from organic samples, and without destroyiag the sample, amino acid metaboHsm can be dynamically analy2ed (132). Proteia metaboHsm and biosynthesis of many important metaboUtes have been studied by this method. Preparative methods for labeled compounds have been reviewed (133). 

Approved techniques for manual and mechanical sampling are often documented for various commodities handled in commerce by industiy groups. Examples are the International Standards Organization (ISO), British Standards Association (BSA), Japan Institute of Standards (JIS), American Society for Testing Materi s (ASTM), and the Fertihzer Institute. Sampling standards developed for use in specified industry applications frequently include instructions for labora-toiy work in sample preparation and analysis—steps (2) and (3) above. 

Investigated is the influence of the purity degree and concentration of sulfuric acid used for samples dissolution, on the analysis precision. Chosen are optimum conditions of sample preparation for the analysis excluding loss of Ce(IV) due to its interaction with organic impurities-reducers present in sulfuric acid. The photometric technique for Ce(IV) 0.002 - 0.1 % determination in alkaline and rare-earth borates is worked out. The technique based on o-tolidine oxidation by Ce(IV). The relative standard deviation is 0.02-0.1. 

Theoretical and applied aspects of microwave heating, as well as the advantages of its application are discussed for the individual analytical processes and also for the sample preparation procedures. Special attention is paid to the various preconcentration techniques, in part, sorption and extraction. Improvement of microwave-assisted solution preconcentration is shown on the example of separation of noble metals from matrix components by complexing sorbents. Advantages of microwave-assisted extraction and principles of choice of appropriate solvent are considered for the extraction of organic contaminants from solutions and solid samples by alcohols and room-temperature ionic liquids (RTILs). 

The performance of microwave-assisted decomposition of most difficult samples of organic and inorganic natures in combination with the microwave-assisted solution preconcentration is illustrated by sample preparation of carbon-containing matrices followed by atomic spectroscopy determination of noble metals. Microwave-assisted extraction of most dangerous contaminants, in particular, pesticides and polycyclic aromatic hydrocarbons, from soils have been developed and successfully used in combination with polarization fluoroimmunoassay (FPIA) and fluorescence detection. 

DEVELOPING SAMPLE PREPARATION AND DETERMINATION OF TOTAL IODINE IN COMPLEX ORGANIC MATRIX... 

The methods I- 4 of sample preparation are classics. As a mle they give a high value of blank and some of them take a lot of time. Microwave sample preparation is perspective, more convenient and much more faster procedure than classical mineralization. There are some problems with the combination Cendall-Kolthoff s kinetic method and microwave sample preparation which discussed. The experimental data of different complex organic matrix are demonstrated (food products on fat, peptides, hydrocarbone matrix, urine etc). 

One of trends of development of thin-layer chromatography implies that replacement of aqueous-organic eluents by micellar surfactants solution. This is reduces the toxicity, flammability, environmental contamination and cost of the mobile phases, reduce sample prepar ation in some cases. 

Recent developments in Raman equipment has led to a considerable increase in sensitivity. This has enabled the monitoring of reactions of organic monolayers on glassy carbon [4.292] and diamond surfaces and analysis of the structure of Lang-muir-Blodgett monolayers without any enhancement effects. Although this unenhanced surface-Raman spectroscopy is expected to be applicable to a variety of technically or scientifically important surfaces and interfaces, it nevertheless requires careful optimization of the apparatus, data treatment, and sample preparation. 

Colorless phosphate ester surfactants were also prepared by treating P4O,0 with an organic OH-containing compound in the presence of a phosphinic acid color inhibitor, e.g., bis(hydroxymethyl)phosphinic acid color inhibitor. Thus, 558 parts dodecanol containing 2.4 parts of phosphinic acid color inhibitor was treated with 142 parts P4O10 at 100-135°C. The phosphate ester surfactant had a VCS color value of 1, whereas a sample prepared without the color inhibitor had a VCS color value of 5. Twenty-eight similar surfactants were prepared using various alcohols and alcohol-alkylene oxide condensates [22]. 

Before the actual sample preparation procedure is described some general observations should first be made. However excellent the sample preparation and however sophisticated the equipment, the accuracy of the analysis will only be as good as the quality of the sample that is taken. If the sample is that of a reaction mixture from an organic synthesis laboratory, it is likely to be taken from a single bottle or container, by a professional chemist, and is likely to be truly representative of the bulk of the material. 

The analysis of a pharmaceutical tablet (6) requires sample preparation that is little more complex as most tablets contain excipients (a solid diluent) that may be starch, chalk, silica gel, cellulose or some other physiologically inert material. This sample preparation procedure depends on the insolubility of the excipient in methanol. As the components of interest are both acidic and neutral, the separation was achieved by exploiting both the ionic interactions between the organic acids and the adsorbed ion exchanger and the dispersive interactions with the remaining exposed reverse phase. 

Sample preparation Dried greater celandine was pulverized and briefly boiled in 0.05 mol sulfuric acid. After cooling to room temperature the mixture was placed in a separating funnel and adjusted to pH 10 with ammonia solution and extracted once with chloroform. The organic phase was dried with sodium sulfate and evaporated to dryness under reduced pressure. The residue was taken up in methanol and used as the sample solution for TLC. 

The primary method for detecting methyl parathion and metabolites in biological tissues is gas chromatography (GC) coupled with electron capture (BCD), flame photometric (FPD), or flame ionization detection (FID). Sample preparation for methyl parathion analysis routinely involves extraction with an organic solvent (e g., acetone or benzene), centrifugation, concentration, and re suspension in a suitable solvent prior to GC analysis. For low concentrations of methyl parathion, further cleanup procedures, such as column chromatography on silica gel or Florisil are required. 

Second, the properties of micro/nano friction and wear/ scratch of several representative films are introduced. These films include from organic molecular films, solid films, to multilayers. The experiments were designed reasonably to understand the behaviors of micro/nano friction and wear of the films. The sample preparation methods were also de-... 

External quality assessment schemes involve the distribution by the organizer, to participating laboratories, of aliquots from the same sample. Participants analyze the received specimen and send the results back to the organizer who prepares a report to summarize all data. 

Sample preparation by contract research organization. In Japan, GLP for field residue study work has not yet been established and sample preparation for residue studies by private companies is not authorized. Contract research organizations are limited to prefectural research institutes and MAFF-recognized local research institutes, mainly neutral organizations, such as the Japan Plant Protection Association (JPPA). 

Because of their polymeric forms, alkylenebis(dithiocarbamates) are insoluble in water and most organic solvents. Additionally, they form strong complexes with different metal ions No extraction and chromatographic procedure has been reported for the parent compound of this chemical class. These compounds decompose readily under acidic conditions, for example by contact with the fruit or plant juice generated during sample preparation. 

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