Development Of On-line Metering System For Pipette Based On Photometric Method

A pipette is a sort of measuring instrument to remove liquid from a container into another container.Primarily,it is employed extensively in fields like biology and chemistry.Traditional pipettes are devised on static measurements.They demand a stringent laboratory environment and are incapable of online detection.However,realization of online detection is of great market value to a pipette.In this subject,a spectrophotometer was applied to measure absorbance based on photometry.Then,a linear relationship was established between the absorbance of solution and the volumes of solutes,so as to precisely verify the measurement of a pipette.1.A photometry-based verification system was designed on the basis of LambertBeer’s law.Solutions required for the system were involved in lectotype and configuration.2.With investigations on the detection principles of various sorts of spectrophotometers,in-depth exploration and model selection were conducted on the operating principles and working parameters of each optical component.Moreover,the relative positions of light sources,a CCD sensor and each optical component were determined.The overall structure of a spectrophotometer was devised,based on which the spectrophotometer was assembled.3.According to the specifications in the Regulations of Pipettes Verification JJG646-2006,a device was designed to verify the airtightness of the pipette.This device was used to test airtightness prior to volume verifications performed by the pipette.4.For the system,a PC control software was devised,and its modules and overall functions were completed.Then,measurements,experiments and analyses were performed on different pipettes and checkpoints.To the test results error analysis and uncertainty evaluation were carried out next.Indicated by the experiment results all the checkpoints between 0.5μL and 100μL met the regulations of pipette verification.