Oxygen concentration in penicillin vials is currently detected by destructive measurement of off-line samples

which has many limitations including long lead time

low precision

and high missing detection rate. Using tunable diode laser absorption spectroscopy (TDLAS)

a theoretical correlation model between oxygen concentration

temperature

and second harmonic signal strength was constructed

and an on-line detection method to determine vial's oxygen concentration was proposed by temperature parameter. The experimental design and procedure were described in detail

angle of incidence and main parameters of the system were optimized. Under condition of 1 atm (101.325 kPa) air pressure and 296 K temperature

a conventional oxygen concentration inversion model was established on vials of different oxygen concentrations. At the same time

the second harmonic signal amplitude of 21% oxygen concentration sample was used as reference for quantitative prediction by temperature parameters. Experimental results show that temperature parameter for detecting vial's oxygen concentration can effectively overcome direct influence of large temperature variation on concentration inversion. The root mean square error of prediction (RMSEP) was reduced by 80.33%

compared to prediction method of relative direct concentration inversion.