»Lemon Oil is the volatile oil obtained by expression,without the aid of heat,from the fresh peel of the fruit of Citrus x limon(L.)Osbeck (Fam.Rutaceae),with or without the previous separation of the pulp and the peel.The total aldehyde content,calculated as citral (C10H16O),is not less than 2.2percent and not more than 3.8percent for California-type Lemon Oil,and not less than 3.0percent and not more than 5.5percent for Italian-type Lemon Oil.
NOTEDo not use Lemon Oil that has a terebinthine odor.
Packaging and storage Preserve in well-filled,tight containers,and avoid exposure to excessive heat.
Labeling The label states the Latin binomial and,following the official name,the part of the plant source from which the article was derived.Label it to also indicate whether it is California-type or Italian-type Lemon Oil.The label indicates that Oil is not to be used if it has a terebinthine odor.
Specific gravity á841ñ: between 0.849and 0.855.
Angular rotation á781Añ: between +57and +65.6.
Refractive index á831ñ: between 1.473and 1.476at 20.
Ultraviolet absorbance Transfer about 250mg of Oil,accurately weighed,to a 100-mLvolumetric flask,add alcohol to volume,and mix.Record the UVabsorption spectrum of this solution from 260to 400nm in a 1-cm cell,using alcohol as the blank.Determine the absorbance at the wavelength of maximum absorbance at about 315nm using the line drawn tangent to the curves appearing as minima in the spectrum in wavelength regions above and below the maximum wavelength as the baseline.The absorbance,calculated on the basis of a 250-mg specimen,is not less than 0.20for California-type Lemon Oil,or not less than 0.49for Italian-type Lemon Oil.
Heavy metals,Method IIá231ñ: 0.004%.
Foreign oils Place 50mLof Oil in a four-bulb Ladenburg flask having the following dimensions:the lower or main bulb is about 6cm in diameter,and the smaller condensing bulbs are about 3.5,3.0,and 2.5cm in diameter;the distance from the bottom of the flask to the side-arm is about 20cm.Distill Oil at a rate of 1drop per second until the distillate measures 5mL:the angular rotation of the first 5mLis not more than 6less than that of the original Oil.The refractive index at 20of this same portion is between 0.001and 0.003lower than that of the original Oil.
Assay Dissolve 4.5g of hydroxylamine hydrochloride in 13mLof water,add 85mLof tertiary butyl alcohol,mix,and adjust with 0.5Npotassium hydroxide to a pHof 3.4.Pipet 50mLof this solution into a conical flask containing about 5mLof Oil,accurately weighed.Insert the stopper in the flask,and allow to stand at room temperature for 30minutes,with occasional shaking.Titrate the liberated hydrochloric acid with 0.5Nalcoholic potassium hydroxide VSto a pHof 3.4.Each mLof 0.5Nalcoholic potassium hydroxide consumed in the titration is equivalent to 76.12mg,of total aldehydes,calculated as citral (C10H16O).
Auxiliary Information Staff Liaison:Claudia C.Okeke,Ph.D.,Associate Director
Expert Committee:(CRX)Compounding Pharmacy
USP28NF23Page 3025Pharmacopeial Forum:Volume No.27(4)Page 2798