Fluid extracts liquid preparations

High performance liquid chromatography (HPLC) has been by far the most important method for separating chlorophylls. Open column chromatography and thin layer chromatography are still used for clean-up procedures to isolate and separate carotenoids and other lipids from chlorophylls and for preparative applications, but both are losing importance for analytical purposes due to their low resolution and have been replaced by more effective techniques like solid phase, supercritical fluid extraction and counter current chromatography. The whole analysis should be as brief as possible, since each additional step is a potential source of epimers and allomers. 

More elaborate sample preparation is often needed for complex sample matrices, e.g., lotions and creams. Many newer SP technologies such as solid-phase extraction (SPE), supercritical fluid extraction (SFE), pressurized fluid extraction, accelerated solvent extraction (ASE), and robotics are frequently utilized (see Ref. [2]). Dosage forms such as suppositories, lotions, or creams containing a preponderance of hydrophobic matrices might require more elaborate SP and sample cleanup, such as SPE or liquid-liquid extraction. 

For sample preparation, isolation and separation traditional methods like distillation (e.g. essential oil content of raw materials) or Soxhlet extraction are still in use. Beyond that, more recent methods are employed, for example supercritical fluid extraction with liquid carbon dioxide. 

A. It is confusing because the term is often used to refer to various preparations derived from Salvia. Technically, in pharmacy and medicine the dictionary definition of an extract is a solid preparation obtained by evaporating a solution of a drug. There is also such a thing as a fluid extract (or tincture), which is a concentrated liquid preparation containing a definite proportion of the active principles of a medicinal substance. The solvent usually used is ethyl alcohol or a mixture of ethyl alcohol and water. However various Salvia preparations are often referred to (loosely) as extracts. Q. What are the advantages of using extracts . 

Before the extraction procedure may commence, the sample must be prepared in such a way that it is in a condition for extraction of the analyte(s). For analyzing sulfonamide residues in liquid samples such as milk, a pretreatment dilution step with water prior to direct fluorometric detection may be required (207). Dilution of milk with aqueous buffer (208) or sodium chloride solution (209) prior to sample cleanup has also been reported. For the analysis of honey a simple dissolution of the sample in water (210, 211) or aqueous buffer (212) is generally required. Semisolid samples such as muscle, kidney, and liver, require, however, more intensive sample pretreatment. The analyte(s) must be exposed to extracting solvents to ensure maximum extraction. The most popular approach for tissue break-up is through use of a mincing and/or homogenizing apparatus. Lyophilization (freeze-drying) of swine kidney has been carried out prior to supercritical-fluid extraction of trimethoprim residues (213). 

Analytes can be separated from complex matrices by sample preparation techniques that include liquid extraction, supercritical fluid extraction, and solid-phase extraction. Dilute ionic analytes can be preconcentrated by adsorption onto an ion-exchange resin. Nonionic analytes can be concentrated by solid-phase extraction. Derivatization transforms the analyte into a more easily detected or separated form. 

Decontamination of soils using supercritical fluids is an attractive process compared to extraction with liquid solvents because no toxic residue is left in the remediated soil and, in contrast to thermal desorption, the soils are not burned. In particular, typical industrial wastes such as PAHs, PCBs, and fuels can be removed easily [7 to 21]. The main applications are in preparation for analytical purposes, where supercritical fluid extraction acts as a concentration step which is much faster and cheaper than solvent-extraction. The main parameters for successful extraction are the water content of the soil, the type of soil, and the contaminating substances, the available particle-size distribution, and the content of plant material, which can act as adsorbent material and therefore prolong the extraction time. For industrial regeneration, further the amount of soil to be treated has to taken into account, because there exists, so far, no possibility of continuous input and output of solid material for high pressure extraction plants, so that the process has to be run discontinuously. 

Online coupling of supercritical fluid extraction and high-performance liquid chromatography considerably decreases sample preparation time and analysis time [175]. Dunkers [128] showed that by using dilute dichloromethane as a static modifier, 20-30 minute supercritical fluid extractions gave results comparable to those obtained by conventional four-hour sampling methods in soil extractions. 

While it is wonderful to be able to inject neat samples directly, sample preparation can often improve selectivity and sensitivity. If the resolution is poor, the salt content of the sample too high, or the capillary fouls, consider a sample cleanup. This can include liquid-liquid extraction, solid-phase extraction, supercritical fluid extraction, protein precipitation, or dialysis, depending on the solutes and application [38]. The final sample diluent should be a solution that is CE-Mendly. That usually means low ionic strength compared to the BGE. 

The preparation of high-purity tocopherols and phytosterols involves steps such as molecular distillation, adduct formation, liquid-liquid extraction, supercritical fluid extraction, saponification, and chromatography (175). The extraction of tocopherols from soybean oil deodorizer distillate by urea inclusion and saponification of free fatty acids resulted in good recovery of tocopherols (208). To improve the separation of sterols and tocopherols, Shimada et al. (209) used a lipase to esterify sterols with free fatty acids. Then the steryl esters and tocopherols were separated better by molecular distillation. Chang et al. (210) used supercritical fluid CO2 extraction to recover tocopherols and sterols from soybean oil deodorizer distillate. A patent by Sumner et al. (211) advocated treatment of the distillate with methanol to converted free fatty acids and other fatty acid esters to methyl esters that can then be removed by a stripping operation. Then separation of sterols and tocopherols could be carried out by molecular distillation. 

Eye Washes. See Solutions, ophthalmic. Fluidextracts Fluidextracts are concentrated liquid preparations representing the therapeutically active principles of vegetable drugs. They are formulated in such a way that the activity of one gram of the drug is contained in one milliliter of the fluid-extract. They are generally prepared by some form of percolation, using alcohol in the menstruum. Fluid-extracts first became official in 1850 when five were entered in the United States Pharmacopeia by their... 

Flavoring agents may be classified as natural, artificial, or natural and artificial (N A) by combining the allnatural and synthetic fiavors. Pharmaceutical flavors are available as liquids (e.g., essential oils, fluid extracts, tinctures, and distillates), solids (e.g., spray-dried, crystalline vanillin, freeze-dried cinnamon powders, and dried lemon fluid extract), and pastes (e.g., soft extracts, resins, and so-called concretes, which are brittle on the outside and soft on the inside). Liquid flavors are by far the most widely used because they diffuse readily into the substrate. They are available both as oily (e.g., essential oils) or non-oily liquids. Their texture is generally dependent on the solvent within which they are prepared. Fluid extracts may contain a single ingredient or a variety of compounded ingredients. Tinctures are obtained by maceration or percolation of specific herbs and spices in alcohol. 

Novel sample preparation techniques include ultrasonic extractions that use high frequency acoustic waves to heat and break up samples (9), as well as microwave-assisted extractions (MAE) that use long wavelength radiation for faster and less energy intensive extractions of thermally sensitive analytes (JO-13). Other innovations treat samples with high pressure and high temperature solvents in the liquid or in the supercritical state. These adaptations reduce the overall solvent use and speed the extractions. These methods include accelerated solvent extraction (ASE) (14) and supercritical fluid extraction (SEE) (8). 

Sample preparation represents a formidable challenge in the chemical analysis of the real-world samples. Not only is the majority of total analysis time spent in sample preparation, but also it is the most error-prone, least glamorous, and the most labor-intensive task in the laboratory. The components to be separated from the matrix are usually taken up with an auxiliary substance such as a carrier gas, an organic solvent, or an adsorbent. These separation processes can be regarded as extraction procedures (i.e., liquid-liquid extraction, liquid-solid extraction, Soxhlet extraction, solid-phase extraction, supercritical fluid extraction, solid-phase microextraction, etc.). 

Chapter 8 provides practical guidance on the use of widely used extraction and isolation techniques from the sample preparation perspective. The first two sections, solid-phase extraction and liquid-liquid extraction deal with liquid samples. The sections on supercritical fluid extraction and accelerated solvent extraction focus mainly on solid samples while the centrifugation and filtration sections handle suspensions. A successful sample preparation protocol accounts for specificity and homogeneity as well as recovery and final physical state of the targeted material. The ultimate aim is to produce a sample that is compatible with the desired analytical technique to assure generation of maximum information. 

Membrane filtration is a widely used but narrowly understood technique for sample preparation in chemical analysis. This section has the goal of providing some basic information to aid in the use of filtration tools with drug impurities. Many of the common sample preparation approaches described elsewhere in this chapter, such as liquid extraction, supercritical fluid extraction, and accelerated solvent extraction are effective at removing the dissolved analytes of interest from the matrix while leaving behind many poorly soluble or insoluble matrix components. In contrast, filtration is designed to remove these suspended particles from the extract prior to subsequent analytical steps. Unfiltered samples can destroy the performance of a downstream analytical technique such as HPLC or optical spectroscopy.68,69... 

Carbon dioxide is pumped from the bottom of the liquid tank and compressed, heated, and then the samples are extracted (Fig. 9.3). The analytes are trapped in an organic solvent as the carbon dioxide is vented from the extractor. Supercritical fluid extraction (SFE) involves some experimentation with the proper pressure to achieve the extraction of the analyte of interest. Several vendors sell the automated supercritical fluid extractors. Both the accelerated solvent extractor and the supercritical fluid extraction are expensive methods, in the price range of 50,000 each. Several general reviews of SFE include Gere and Derrico (1994), Smith (1995), and a general sample preparation review by Majors (1995). 

Cascara sagrada is available in tablets, capsules, liquids (fluid extracts), and syrups. Fluid extracts are more reliable than the solid dosage forms. Aromatic cascara fluid extract is less bitter and less active than cascara sagrada fluid extract because of the use of magnesium oxide in its preparation (Curry, 1986). Cascara tea is available, but has an extremely bitter taste (Tyler, 1994). 

In the sample preparation of semi- and nonvolatile compounds, solvent extraction is typically used for extracting the analytes of interest from a sample matrix. For volatile analytes, head-space or thermal extraction are good alternatives to solvent-based techniques. Several novel extraction systems that utilize elevated temperatures of pressures in the extraction have been developed particularly for solvent-based extraction methods. These new methods typically are much faster and often more selective than older methods and consume smaller amounts of organic solvents and reagents. Commercially available systems with the ability to heat and pressurize liquids include pressurized liquid extraction (PLE), microwave-assisted extinction (MAE) and supercritical fluid extraction (SFE). Also sonication-assisted extraction (SAE) has given promising results. 

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