Example 1
Isopropyl myristate (IPM) was recovered from biphasic culture by centrifugation at 4000 g for 5 minutes. 20 μl of IPM was diluted 20× in hexane before quantification. 2 μl of diluted sample was injected on a Waters Acquity UPC2 system (Milford, USA) coupled to a Waters Acquity UPC2 PDA eLambda detector. Separation of the compounds was achieved on a Waters Acquity UPC2 HSS C18 SB column (1.8 μm, 3.0 mm×100 mm), kept at 40° C. Mobile phases A and B were CO2 and acetonitrile, respectively. A flow of 2.0 ml/min was used. The gradient profile was as follow: 0.2 min constant at 1% B, a linear gradient from 1% B to 10% B in 1.8 min, a wash for 1 min at 10% B and back to the initial condition. The Automatic Back-Pressure Regulator (ABPR) pressure was kept at 2000 psi on the Water Acquity CO2 convergence manager.
Monoterpenes, including citronellal, geranial, citronellol and geraniol, were analyzed by recording their UV 210 nm absorbance. Detected monoterpene compounds were quantified using a linear calibration curve with authentic standards (ranging from 0.625 mg/l to 320 mg/l; Sigma-Aldrich, Buchs, Switzerland) using Waters TargetLynx software.