Citrus solvent

Karlberg A-T, Magnusson K, Nilsson U (1992) Air oxidation of d-limonene (the citrus solvent) creates potent allergens. Contact Dermatitis 26 332-340... 

Karlberg A-T, Boman A, Melin B (1991) Animal experiments on the allergenity of D-limonene - the citrus solvent. Ann Occup Hyg 35 419-425... 

Simple Green, citrus solvent, or bike-specific solvent... 

Polyterpenes. Polyterpenes is one of the first classes of non-polar tack-ifiers to be developed. Terpene monomers are a by-product in the extraction of rosin from wood stumps or tree sap, and from the extraction of oils from citrus fruits. The latter is the dominant source. As such, polyterpene prices generally mirror those of citrus fruits, which fluctuate substantially from one growing season to the next. Terpenes like rosin are cyclic, see Fig. 6, which is partly responsible for their excellent solvent properties. 

It has been found that the compound 8-geranoxy psoralen is present in citrus oils, particu-lariy lemon and lime oils. This compound can be isolated from the oil by a process which involves primarily absorption on an adsorbent material followed by elution with a suitable solvent. 

Teng, W.Y., Chen, C.C., and Chung, R.S., HPLC comparison of supercritical fluid extraction and solvent extraction of coumarins from the peel of Citrus maxima fmit, Phytochem. Anal, 16, 459, 2005. 

Residues are extracted with acetone. The extract is rotary evaporated to remove acetone, the concentrated residue is diluted with 5% aqueous sodium chloride, and residues are partitioned into dichloromethane. The extract is then concentrated and purified on a silica gel column. Residues of pyriproxyfen are quantitated by gas chromatography with nitrogen-phosphorus detection (GC/NPD). For citrus, a hexane-acetonitrile solvent partition step is required for oil removal prior to the dichloromethane partition step. 

The first fully comprehensive coupling of NP and RP, where the previously described difficulties related to solvents immiscibility were overcome, was developed by Dugo et al. and applied to the analyses of oxygen heterocyclic components of lemon essential oils [22], Based on the configuration described in this work, other applications were developed for the analysis of carotenoids in citrus samples [48], citrus fruit extracts [29], pharmaceutical products [29], and triglycerides in fats and... 

Normal phases (unmodified silica gel) are rarely employed, except for the occasional separation of weakly polar flavonoid aglycones, polymethoxylated flavones, flavanones, or isoflavones. The polymethoxylated flavones present in citrus fruits can, for example, be separated on silica gel columns. The big drawback is that solvent gradients cannot normally be run with normal phases. 

Citrus fruits—here a mixture of oranges, lemons, and limes—contain acidic juices. A characteristic of aqueous acidic solutions is the presence of hydronium ions—one can be seen among the water molecules. There is a continuing dynamic equilibrium between the acid molecules and the solvent molecules in the solution. 

Most cases of isocratic HPLC reported were carried out on reversed-phase chromatography on silica-based ODS (C,8 bonded phase) columns (1) for citrus juices. For mobile phases utilizing C,8 columns, isocratic solvents of 80-82% aqueous acetic acid with acetonitrile were commonly used. A ternary mobile-phase system of water-acetonitrile-glacial acetic acid... 

For flavones in citrus peel oils, separations were accomplished with isocratic mobile phases of 38% and 40% acetonitrile in H20 (1). The extracts of peel and cold-pressed peel oils were diluted in ethanol and analyzed by reversed-phase on various C18 columns with good results. For the dilute citrus oils, gradient elution was preferred, to prevent the accumulation of terpenes on the column. With normal-phase chromatography, the elution order is reversed terpenes elute with the solvent front and are not a problem. 

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