用“半密闭系统注入法”测定CO_2浓度

将改装的ＣＤ—１型大气采样器串接在密闭气路中，采样器的出口端串接干燥管和钠石灰管，其后接三通并与红外线气体分析仪的工作室和参比室的进气口相连，气体的出口经另一三通与采样器的进气口相连，形成自动循环的密闭系统。待测气体从入口端注入工作室．根据记录仪的峰高计算ＣＯ２浓度。为保持系统内的气压不因注入待测气体而升高，在工作室的出口端插入一支注射针头，从而成为半密闭系统。此法便于应用在田间取样气法测定植物的光合速率，更适用于测定组培瓶、保鲜袋、种子或果蔬储藏库内的ＣＯ２浓度。半密闭系统注入法测定ＣＯ２浓度时，所用待测样气量少（每份样品ｌ～４０ｍＬ），测定快速（每份样品３～５ｍｉｎ），测定的ＣＯ２浓度范围较宽，系统稳定可靠。

Measurment of CO_2 Concentraton by Means of Injection Method with Semiclosed System

A closed circulatory system consists of an improved CD- 1 air collector and a infrared gas analyzer. The exit of air collector strings the drying tube,and tee joint connecting with the entries of work chamber and contrast chamber of the infrared gas analyzer. The exit of the chambers connects with the entry of air collector through anather tee joint. When the gas sample is injected into the work chamber at the entry,the CO_2 concentration can be evluated according to the crest value of recoder. To avoid higher pressure caused by gas sample injected into the system,a syringe needle is injected into the tube at the exit of work camber and the system becomes semiclosed. This system is suitable for measuring photosynthesis whose gas is got from field plant,and is more suitable for measuring CO_2 concentration (in culture flask,fresh-preservation bag and storehouse of fruits and vegetables. With this system the measurment of CO_2) needs smoller gas sample,has higher speed,is suitable for wieder range,of CO_2 concentration and is more stable and relieble.