Citrus oil sample

Rinse 10-(il syringe 2 to 3 times with citrus oil sample. 

The citrus oil samples were analyzed neat. Other samples were prepared by dissolving in an appropriate solvent such as methylene chloride, methanol or acetone (HPLC grade). 

Citrus Oil Sample. A synthetic test mixture of 10 volatile citrus oil components was prepared. The highest molecular weight... 

A 10-g representative sample (5-g sample for citrus oil or cotton substrates) was extracted by adding 150 mL of acetonitrile-water (4 1, v/v) to the sample in an 8-oz bottle and homogenized with a Polytron at high speed for 2 min. The extract was filtered through a Whatman No. 1 filter-paper into a 500-mL side-arm flask. The extraction bottle was rinsed with 50 mL of acetonitrile-water (4 1, v/v) for citms and cottonseed oil (for molasses use lOmL of water followed by 40 mL of acetonitrile for rinsing). The extract was transferred to a 500-mL separatory funnel and partitioned twice, each time with 50 mL of hexane for 1 min. The hexane fractions... 

The average recoveries and standard deviations for the many citrus, pome fruit, tree nut, fruiting vegetables, and cotton substrate sample types were acceptable when fortified at concentration levels ranging from 0.01 to 4 mg kg. The LOQ of the method was 0.01 mgkg , except for citrus oil (0.02mgkg Q, and the LOD was 1.25 ng injected. 

Hexane-acetonitrile partition. Partition the sample between hexane and acetonitrile as described for fruit and vegetables to remove citrus oils. Evaporate the... 

Interfaciai Tension Procedure. IFT measurements were made by the Wilhelmy plate method. The apparatus was the same as that described previously (2). A standard protocol was followed for all IFT determinations. The desired interface was formed at a specified temperature by partially filling a thermostatted sample holder with the desired aqueous phase. This phase, distilled water (mono triple) or a supernatant aqueous phase isolated from a complex coacervate system, completely covered the Wilhelmy plate (roughened platinum). The desired citrus oil was carefully layered onto the aqueous phase. It had been preheated (or cooled) to the same temperature as the aqueous phase. Once the citrus oil/aqueous phase interface was formed, the Wilhelmy plate was drawn completely through the interface and into the oil phase where it was zeroed. 

Figures 1-4 illustrate the IFT behavior of four citrus oils against water as a function of time at different temperatures. All but one of the lemon oil 2 and orange oil 2 runs were made with triple distilled water. All lemon oil 1 and orange oil 1 runs were made with mono distilled water. Surface tension of the two water samples differed by 0.2 dynes/cm (mean of 6 runs). This difference is not believed to make a major contribution to the IFT aging behavior observed.

Basic Protocols 3 through 9 are primarily useful as quality control measures. They are rapid, usually within 30 min, given reagent preparation. The results are used to monitor the quality of a process. These results support established values for high quality citrus oil. Basic Protocols 1 and 2 are more involved and are better suited for research purposes. The equipment is more sensitive and also more expensive. Furthermore, the strength of the GC analysis can be enhanced by the addition of a mass spectrometer to identify either contaminates or unknown compounds present in a sample. 

The quality of citrus oils is based on the purity of the sample as determined by a gas chromatogram (GC) profile. A small sample is injected onto a column, which separates the individual components. Separation is based on the physical interaction between the column and the sample as indicated by retention times. Figure Gl.5.1 illustrates the GC setup. 

Optical rotation measures the degree that light is rotated (see Table Gl.5.7 in Anticipated Results). In citrus oils, d-limonene is the major enantiomer in the sample. Since other optically active compounds are often present in racemic mixtures, there is no net rotation and thus they are ignored. If a compound is a racemic mixture, the polarimeter will not give a reading. Readings can be verified with known standards. 

Aldehyde content is considered an important flavor note included in the standard of identities for citrus oils. The flavor strength of an oil is based on the aldehyde content, where higher is better. The two major aldehydes are acetaldehyde and octanal. The quantification of aldehydes is based on the reaction of citral in the sample with a hydroxylamine solution, followed by titration with KOH in the presence of ethyl orange indicator. It is modified from AOAC Method 955.32 (AOAC, 1990c Redd et al., 1986). This method was originally developed for lemon oils however, it is applicable to other citrus oils. 

Ultraviolet Absorbance Determine as directed under Ultraviolet Absorbance of Citrus Oils, Appendix VI, using about 50 mg of sample, accurately weighed. The absorbance maximum occurs at 315 3 nm. 

Classification of the citrus oils was possible by using Soft Independent Modeling of Class Analogy (SIMCA). This type of algorithm is designed to compare new samples against previously-analyzed sets. Another ability if SIMCA is the determination if a sample does not belong to any predefined class. 

Using the mass spectrometry based chemsensor the entire headspace volatiles of each of the 8 flavor samples were sampled and a characteristic fingerprint mass spectrum was obtained. For example. Figures 1 and 2 represent the TIC and MS obtained for formulations 1 and 8 respectively. Inspection of these two figures indicates that each flavor sample has a characteristic mass spectrum. Similar results were observed with the mass spectrum from the rest of the flavors formulations. Even though the mass spectral fingerprints of the citrus oils were similar there were sublte differences in some ion ratios. 

In order to explore tlie influence of citrus variety on PMF content, we analyzed 33 different tangerine peel oil samples most of which were collected during variety-specific processing. The results are shown in Table II. Most 6f the samples originated from tangerine varieties grown in Florida. The Mexican tangerine oil samples represented conunercial oil samples from Mexico. Tliey... 

In this paper, work is presented showing capillary SFC analyses of a soybean oil, a hops extract, a celery seed oleoresin, and an essential citrus oil. In addition, results showing the determination of pesticide residues in a parsley sample by capillary SFC are presented. 

Some natural complex matrices do not need sample preparation prior to GC analysis, for example, essential oils. The latter generally contain only volatile components, since their preparation is performed by SD. Citrus oils, extracted by cold-pressing machines, are an exception, containing... 

The oxygen heterocyclic compounds present in the nonvolatile residue of citrus essential oils have also been extensively investigated by means of HPLC-atmospheric pressure ionization-mass spectrometry (HPLC-API-MS) [99]. The mass spectra obtained at different voltages of the sample cone have been used to build a library. Citrus essential oils have been analyzed with this system, using an optimized NP-HPLC method, and the mass spectra were compared with those of the laboratory-constructed library. This approach allowed the rapid identi cation and characterization of oxygen heterocyclic compounds of citrus oils, the detection of some minor components for the rst time in some oils, and also the detection of authenticity and possible adulteration. 

One of the best examples of the application of comprehensive NPLC x RPLC in essential oil analysis is represented by the analysis of oxygen heterocyclic components in cold-pressed lemon oil, by using a normal phase with a microbore silica column in the D and a monolithic C18 column in the with a 10-port switching valve as interface [133]. In Figure 7.12, an NPLC x RPLC separation of the oxygen heterocyclic fraction of a lemon oil sample is presented. Oxygen heterocyclic components (coumarins, psoralens, and PMFs) represent the main part of the nonvolatile fraction of cold-pressed citrus oils. Their structures and substituents have an important role in the characterization of these oils. Positive peak identi cation of these compounds was obtained both by the relative... 

Some natural complex matrices do not need sample preparation prior to GC analysis, for example, essential oils. The latter generally contain only volatile components, since their preparation is performed by SD. Citrus oils, extracted by cold-pressing machines, are an exception, containing more than 200 volatile and nonvolatile components. The volatile fraction represents 90-99% of the entire oil, and is represented by mono- and sesquiterpene hydrocarbons and their oxygenated derivatives, along with aliphatic aldehydes, alcohols, and esters the nonvolatile fraction, constituting 1-10% of the oil, is represented mainly by hydrocarbons, fatty acids, sterols, carotenoids, waxes, and oxygen heterocyclic compounds (coumarins, psoralens, and polymethoxylated flavones—PMFs) [92]. 

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