这个气体ppb浓度是怎么计算出来的?用红外分光计测得某乙酸戊酯溶液（n-amylacetate,nAA;CAS;628-63-7;MW130.18;99%purity)挥发速度为68ng/min,加载到速度为4升每分钟（4lpm）的气流中,那么该气流中的nAA

Question

这个气体ppb浓度是怎么计算出来的?
用红外分光计测得某乙酸戊酯溶液（n-amyl acetate,nAA;CAS;628-63-7;MW 130.18;99% purity)挥发速度为68ng/min,加载到速度为4升每分钟（4 lpm）的气流中,那么该气流中的nAA浓度为3.13ppb.
这个气流浓度是怎么算出来的?
文献原文：
In order to characterize lab-made PTs,we used an IR spectrometer (MIRAN SapphIRe Ambient Air Analyzer,model 205B; Thermo Environmental Instruments Inc.; Franklin,MA) in a closed loop system of known volume.The rate of increase in concentration allowed the release rate to be calculated.For example,one PT had a release rate of 68 ng/min,which would result in a concentration of 3.13 ppb when this PTwas placed in a stream of 4 litres per minute (lpm).

Answer 1

68*0.99/130.18*22.4/4