Liquid/air partition coefficients of four terpenes.

Abstract

The liquid/air partition coefficients of four common terpenes, a-pinene, ,B-pinene, 3-carene, and limonene, have been determined in vitro using head space technique. The liquids used were water, human blood, and olive oil. a-Pinene, P-pinene, and 3-carene were practically insoluble in water The aim of the present study was to determine the in vitro blood/air, oil/air, and water/air partition coefficients of four common terpenes: a-pinene, ,Bpinene, 3-carene, and limonene. Materials and methods CHEMICALSThe chemicals used were sodium chloride (analytical grade, Merck), olive oil (purum, Kebo Lab AB), apinene (98%, Aldrich), a-pinene (98%, Aldrich), 3-carene (95%, Aldrich), and limonene (99%, Fluka Chemie AG). All chemicals were used without further purification. SAMPLE PREPARATIONBlood was collected from the brachial vein of ten healthy volunteers (five men and five women) in heparinised 10 ml Vacutainer tubes (Beckton Dickinson, Paramus, NJ) and were pooled immediately before the experiment. Aliquots of 0 5 ml olive oil, 2 ml water (containing 0 3 M sodium chloride), or 2 ml pooled fresh human blood were added to a head space vial (22-4 ml, SD = 0 2). A reference vial was filled with glass beads to a volume corresponding to the sample volume (0-5 and 2 ml, respectively) and treated exactly the same way as the sample; this was done to reduce the difference in pressure which could affect the partition coefficient.To obtain the desired concentrations (0-84-354 uM in oil and 0-21-89 jM in blood and water) 3, 30, or 250 pl of each terpene was added to a thermostated (37°C) air chamber of 4-445 1 volume. After 20 minutes equilibration (37C) a sample of0 1, 0-25, or 0-5 ml was taken out with a gas tight syringe and added into a head space vial. Before the standards were made, the head space vials were thermostated (37C) and capped with Teflon lined rubber stoppers. An air volume (corresponding to the sampling volume later added to each vial) was taken from each vial with a gas tight syringe. Blanks ofblood, olive oil, and water were made without added terpenes. Double samples were made, in each liquid, for all the concentrations. GAS CHROMATOGRAPHIC ANALYSISThe terpenes in the gas phase of the headspace vials were determined by gas chromatography (Perkin Elmer 8700) using a head space autosampler (Perkin Elmer HS-101) and a flame ionisation detection. A polar, wide bore capillary glass column (Supelcowax 10, Supelco inc 30 m, 0 75 mm inner diameter,

Uptake, distribution and elimination of alpha-pinene in man after exposure by inhalation.

“…The average relative uptake of a-pinene, of the two higher concentrations, was 59 % (table 1), lower than that for styrene (68 %) but higher than that for toluene (49 %) in similar experiments (14,15). The partition coefficients between the blood and air for toluene and a-pinene are of the same magnitude, while the corresponding coefficient for styrene is higher (4,16). Metabolic rate and fat solubility may be other reasons for the differences in the relative uptake between the three solvents.…”

“…The high solubility of terpenes in blood and adipose tissue should imply a high respiratory uptake and accumulation in adipose tissues (4). The respiratory and percutaneous uptake of terpenes has been observed in man (5,6), but no quantitative study was found regarding absorption.…”

“…Less than 0.001 % of the dose was excreted in the urine during the first 30 min after the exposure (table 1), and after this period the concentrations in the urine were below the detection limit. A low urinary elimination of unchanged solvent is to be expected from the low in vitro partition coefficient of 0.008 between water and blood (4). The average concentration of a-pinene indicated linear kinetics for the urine, as well as for the blood, but the individual variations were high ( figure 5).…”

Empirical Relations Predicting Human and Rat Tissue:Air Partition Coefficients of Volatile Organic Compounds

“…Equation (1) was also applied to data on the partitioning of four terpenes (Falk et al, 1990) and four gases (Steward et al, 1973) in human blood. Both chemical classes are not included in the data of Table 1.…”

Conifer-Derived Monoterpenes and Forest Walking

“…e proportions of MTs vary with season, species and locality. According to the documented physicochemical properties of MTs, 2) they are sparingly soluble in water but are soluble in blood and lipophilic tissues. α-and β-Pinene dominate emissions from conifer trees and research investigations have raised concerns regarding the physiological e ect of α-pinene on humans.…”