Cold extraction method

The cold extraction method [15] involves moistening defined amounts of pigment powder (between 2 and 20 g) with small amounts of water, alcohol, or a suitable wetting agent. 200 ml of freshly distilled or completely deionized water are then added and the sample allowed to remain in this solvent for 1 h at ambient temperature. After thorough shaking, the liquid is removed by filtration. 

DIN 53 197 Bestimmung des Gehaltes an wasserloslichen Anteilen. ISO 787-8-1983 General methods of test for pigments and extenders, Part 8 Determination of matter soluble in water - cold extraction method. 

Treated papers should maintain at a pH in the range 7 and 8.5. The pH should not be higher than 8.5 to prevent alkaline hydrolysis of cellulose. The acidity or alkalinity may be determined as the amount of water-soluble acidity or as the hydrogen ion concentration (pH) of the paper extract. The pH is more indicative of the stability of paper than is the total acidity. The pH can be determined by either a hot or cold extraction method. In the cold extraction method,... 

The initial acidity or alkalinity of paper is measured conventionally by the pH of the water extract or by the total titratable acidity or alkalinity of the water extract (TAPPI T428 and ASTM D548). The extract for measurement of pH may be prepared as the cold water extract (TAPPI T509) or as the hot water extract (TAPPI T435 and ASTM D778). In the absence of hydrolyzable salts, it may be expected that hot and cold extraction methods will give approximately the same results. If hydrolyzable acid salts (particularly alum) are present, the hot extraction method yields a lower pH because of hydrolysis promoted at the higher temperature to yield free acids. 

The Lipid Determination of Fish by the "Cold Extraction Method" [48]... 

This cold extraction method is successfully performed in our and other laboratories for more than 20 years. Because hexane is neurotoxic, isohexane or heptane can be used as a hydrophobic solvent. A modified method can also be used as a semi-micro method for the lipid determination in fish, mussels, oysters, Daphnia, and other aquatic organisms or tissues. 

ISO 787 specifies two methods of determination of matter soluble in water. The Part 3 gives the hot extraction method. The material is boiled in water for 5 min, cooled to room temperature. Altered, extract is evaporated, and soluble matter determined gravimetrically. In Part 8, the cold extraction method is specified. Extraction is done at room temperature for 1 h. The next steps are the same as in hot extraction method. 

The cold extraction method using a centrifuge extractor (centrifugal filter paper method) is perhaps the most common method worldwide for the determination of the soluble binder content. 

Avocado (Persea americana Mill) is an important tropical fruit and a good source of lipophilic phytochemicals such as monounsaturated fatty acids, carotenoids, vitamin E and sterols [46]. It has several cultivars that present great variation on time of fruit production and oil content in the pulp. Studies have indicated that the avocado oil is similar to olive oil and can be used in cosmetics and also for human consumption [47, 48]. New Zealand, Mexico, Chile United States and South America are among the main avocado oil producers. Avocado oil has the advantage that can be obtained from the fruit by means of a cold extraction methods, which is an easy and low technology that allow maintain in the oil significant amounts of the bioactive phytochemicals present in the fruit [47]. 

Garlic oil macerate oil DAS, allyl methyl dimethyl, mono-to hexasulfides, allyl 1 -propenyl and methyl 1 -propenyl di-, tri-, and tetrasulfides Cold extraction method (maceration) and steam distillation Manufactured as capsule in diluted form for therapeutic use... 

The higher phenolic antioxidant contents of eoeonut oil prepared at high temperatures can be easily explained by considering the polarities of phenolic substances and coconut oil. Coconut oil can be considered as a non-polar substance and oil dissolves in nonpolar solvents such as hexane. On the other hand phenolic substances are polar substances and, therefore, the solubility of polar phenolic substances in nonpolar coconut oil is low. More phenolic substances are incorporated into coconut oil when oil is extracted by wet extraction with prolonged boiling of coconut milk emulsion. High temperatures improve the solubility of phenolic substances in coconut oil. In the cold extraction methods, the phenohc substances are not properly ineorporated into eoeonut oil due to the mild temperature conditions. 

Essentia.1 Oils. Essential oils (qv) are extracted from the flower, leaf, bark, fmit peel, or root of a plant to produce flavors such as mint, lemon, orange, clove, cinnamon, and ginger. These volatile oils are removed from plants either via steam distillation, or using the cold press method, which avoids heat degradation. Additional processing is sometimes employed to remove the unwanted elements from the oils, such as the terpenes in citms oils which are vulnerable to oxidation (49,50). 

Feldman and co-workers117) described a procedure for determining as little as 10 ppb of chromium in serum. The normal level is 30 ppb. At least 2 ml of serum are digested or dry ashed and treated with not permanganate to oxidize chromium to chromium(VI). The chromium(VI) is extracted from 3M HC1 into 5 ml MIBK in the cold. This method has been used to measure chromium levels in studies relating this element to diabetes. Thousands of analyses have been performed. Devoto (198) dry ashed 10 ml of blood and extracted the chromium with 5 ml of 10 % tributyl phosphate in MIBK. Recently, Feldman 119) has determined... 

Water-Soluble Sulfates, Chlorides, and Nitrates. The procedures are applicable to pigments and extenders. The choice of hot or cold extraction depends on the properties of the pigment and should be agreed. The anions are determined by the usual analytical methods. For standards, see Table 1 ( Sulfates , Chlorides , and Nitrates ). Apparatus Nessler tubes or spectrophotometer, equipment for pH measurement. 

Some flawless analytical methods do exist but more are needed. Quantitative extraction of all the phenolic compounds from skins and seeds is not possible however we have developed a standard, reproducible procedure. Using a solvent with physicochemical properties similar to wine, one performs three cold extractions followed by two warm ones. This gives an estimate of the total phenols and an idea of their solubilities—an important technological factor. Our work, done in 1969-1972 involved the two principal red varieties of Bordeaux (Merlot and Cabemet-Sauvignon) from two vineyards. One ( ) is a Grand Cru of the Medoc region characterized by fast maturation, and the other (SC) matures more slowly (46, 47). 

FFE is an extraction method using heptane which measures the churning out of fat during emulsion stabilization9. High protein and low fat content reduce destabilization, whereas the presence of emulsifiers, cold treatment at 5°C and mechanical treatment (whipping, possibly combined with freezing) increases destabilization. 

Citrus oil dominates this class of essential oil. It is obtained by the cold press method with the exception of lime oil, which is also prepared by steam distillation of essential oil separated during the production of juice.106,107 Aside from bergamot, these oils are primarily monoterpene hydrocarbon mixtures of which (if)-limonene (3) is usually the dominant compound. Since odor contribution of this monoterpene compound is low, it is often removed by distillation or repeated solvent extraction. The resulting oil rich in odor-active compounds is called terpeneless oil and is used extensively. In the case of bergamot and lemon oils, psoralen derivates like bergaptene (64) causing photosensitivity are problematic, and those for fragrance use are rectified to remove it (Table 8). 

Many other household products can be analysed in similar ways to those described above for chemicals. Household bleach is essentially an inorganic chemical. There has been concern expressed about mercury levels in hypochlorite bleach because of the way it is manufactured. The cold vapour reduction/aeration method referred to above is a good way of determining low mercury levels with minimal matrix problems [82]. In the past organo-mercurial compounds have been used (e.g. as bactericides) in some household products these may be selectively determined by extraction with an organic solvent (e.g. carbon tetrachloride or benzene), and then application of the cold-vapour method following the addition of cysteine acetate, or by coupled gas chromatography/atomic absorption [83],... 

Method. Apply 25 li1 of the reference solution to the first column of each of three plates. Divide the basic extract from the solvent extraction method, or the remainder of the column extract, equally between the three plates. Develop one plate in a tank containing 100 ml of methanol strong ammonia solution (100 1.5) (System TA, p. 167). Develop the other two plates in a tank containing ethyl acetate methanol strong ammonia solution (85 10 5) (System TE, p. 168). After development, remove Ihe plates from the tanks and dry under a stream of cold air until they no longer smell of ammonia. Avoid using a hot-airblower as methadone may volatilise. 

In this way the useful petroleum fractions are recovered from the surface or near surface exposures of tar sand by the two currently operating hot water process extraction plants in Alberta. The production of synthetic crude oil by Alberta tar sand processors has risen from 28 million barrels (ca. 4 million tonnes) in 1978, to 77.3 million barrels (ca. 10.5 million tonnes) in 2003, which now supplies about 13% of Canada s current crude oil requirements [48]. Other processes for bitumen recovery from minable sands, such as preliminary partial sand removal with the help of cold water, followed by direct coking of the whole of the bitumen/solid residue, and solvent extraction methods have both been tested but are apparently not attractive for commercial development [49]. 

Part 13 of ISO 787 determines water-soluble sulfates, chlorides and nitrates. The sample extract can be prepared by either cold or hot extraction method described in Section 4.28. The sulfates in the extract are determined by precipitation with barium chloride, the chlorides are determined by titration with silver nitrate, and the nitrates are determined by a colorimetric method using Nessler reagent." Part 19 gives an alternative method of determination of nitrates by a salicylic acid method. 

Supercritical fluid extraction is also a suitable technique for enhancing the quality of essential oils obtained by conventional extraction methods, by means of fractionation and deterpenation. Thus, the separation of citrus oils into different clssses of substances by supercritical CO2 has been widely investigated. Temelli et al. reported a method for the extraction of terpene hydrocarbons from cold-pressed Valencia orange oil with supercritical CO2, using both static and dynamic flow approaches (65). Another article has reported the SFE of terpenes from cold-pressed orange oil in a temperature range from 40°C to 70°C and pressures from 83 to 124 bar (66). The determination and elimination of psoralens from lemon peel oil by SFE has also been conducted (67). The procedure included the increase of CO2 density in successive steps. 

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