Abnormal temperature control is one of the core factors causing efficiency decline. If the water bath temperature is set too low, the evaporation rate of solvent molecules will slow down, which will lead to an extension of concentration time. For example, when concentrating ethanol solution, if the water bath temperature is below 70 ℃ (ethanol boiling point 78 ℃), the evaporation efficiency may decrease by more than 30%. In addition, faults in the heating module or temperature sensor drift can also cause significant deviations between the actual temperature and the set value. It is necessary to calibrate a thermometer to detect the temperature uniformity of the heating module at multiple points to ensure that the displayed temperature deviates from the actual temperature by ≤± 1 ℃.

Improper airflow regulation directly affects the evaporation rate. When the nitrogen flow rate is insufficient, the gas-liquid equilibrium on the solvent surface is difficult to effectively break, resulting in a decrease in volatilization rate. For example, when concentrating 100mL of water sample, if the nitrogen flow rate is reduced from 200mL/min to 100mL/min, the concentration time may be extended by 50%. In addition, air needle blockage or air path leakage can also cause unstable airflow. It is necessary to use soapy water to detect whether there is a leak at the pipeline connection, and use a fine needle to clear or replace the blocked air needle.

Equipment status and maintenance are equally critical. After long-term use, the gas needle may become clogged due to solvent crystallization or impurity deposition, and should be regularly rinsed with acetone or ethanol. At the same time, aging of the sealing ring can cause air leakage. It is necessary to check all sealing rings and O-rings for cracks and replace them with fluororubber seals if necessary. In addition, the turbidity or accumulation of scale in the water bath can affect the heat transfer efficiency. It is necessary to replace distilled or deionized water every week and remove the scale and algae on the inner wall of the water bath.

Operational standards and environmental control cannot be ignored. Excessive sample volume or improper needle height (recommended 5mm from the liquid surface) may cause splashing or volatilization abnormalities, and the needle position needs to be adjusted according to the sample volume. Excessive temperature (>35 ℃) or humidity (>80%) in the laboratory environment can accelerate heat loss and affect concentration efficiency. It is necessary to place the equipment in a well ventilated environment with appropriate temperature and humidity (20-25 ℃, 40-60% RH).