What Should be Noted When Using a Colorimeter?
A colorimeter is a laboratory instrument for measuring or specifying colors by comparison with synthetic pigments. Colorimeter is an essential analytical instrument in pharmaceutical analysis. In addition to understanding its purpose and working principle, we also need to pay attention to some problems during use.
In this article, we explain some issues that need to be paid attention to during the installation of the ATO automation colorimeter.
Linearity of instrument photometric:
It is well known that light absorption analysis must obey the linear relationship of the Lambert-Beer law. The photometric linearity of the colorimeter is related to the strength of the light source energy, the minimum detection limit of the received light signal, the highest receiving capacity, and the quality and performance of the monochromatic color.
The photometric accuracy:
Photometric error In daily use, it is often difficult to check the accuracy and reproducibility of photometrics. The reliability and accuracy of measurement data depend on:
- The source of the sample.
- Sample preparation process (including volume, solvent reagents, pH value, time, temperature, etc.)
- Sample tank quality (sample clamp position, tank quality, etc.)
- The performance of the instrument itself (optical system performance, amplifier stability and linearity, receiving machine linearity and noise levels, the mechanical system or computer control capabilities of the instrument, etc).
- Instrument operation (baseline zero calibration blank control, etc).
Quantitative analysis methods. It is necessary to choose a suitable calculation method, especially in the calculation method, there are derivatives, simultaneous equations, etc. The most commonly used cup-shaped calibration curve method has many influencing factors due to the poor linearity of the sample. For example, in the wavelength, the standard curve The method is only used when the variation range is large, and it is easy to produce large errors. If, for no standard or other reasons, a standard curve measured by someone else in other environments and in other instruments is used as a direct reference, the error is entirely conceivable.
There are two calculation methods in quantitative analysis: calculation method, reference material method and absorption coefficient method. The handheld colorimeter given by the intelligent instrument should be selected reasonably to avoid the substitution of systematic errors. The control method is to compare the control with the tested sample. The operation is simple, the requirements for the operation of the instrument are not high, and sometimes the requirements for blank control are very small. Under the same conditions, the error of the measurement results is small, the source of the reference material is standardized and highly recognized, and the sampling volume and dilution factor are required.