Application of Digital Technology in Color Test of Compound Lonicera Granules

Jianping ZHANG, Han GAO, Li CUI, Xuemei ZHOU

Inner Mongolia Autonomous Region Institute for Drug Control, Inner Mongolia Autonomous Region Key Laboratory of Standard Research of Chinese and Mongolian Medicine, Hohhot 010020, China

Abstract [Objectives]The research aimed to study application of digital technique in color test of Compound Lonicera Granules.[Methods]A method of color identification of Compound Lonicera Granules based on digital technology was proposed, and the "four-point collection method of color data" was summarized through experiments.[Results]The method was used to test color of 168 batches of Compound Lonicera Granules, and it was found that the method had the advantages of fast speed, high accuracy and good repeatability.[Conclusions]The method was used to test color of 168 batches of Compound Lonicera Granules, and it was found that the method had the advantages of fast speed, high accuracy and good repeatability.

Key words Digital technique, Compound Lonicera Granules, Character color, Four-point acquisition method

1 Introduction

In theChinesePharmacopoeiaof 2020, the character items are defined as recording the appearance, texture, section, odor, taste, solubility and physical constants of drugs, which could reflect quality characteristics of drugs to certain degree[1].Among them, appearance is a sensory description of the color and appearance of a drug.For drug inspectors, character is the first item to start inspection, and appearance is the most intuitive judgment of drugs[2].Whether its color meets the standard requirements often depends on the experience and feeling of inspectors, which leads to the obvious influence of human subjective factors in the process of color judgment[3].To avoid influence of human factors and solve poor repeatability of color judgment, digital technique could be used to break through the problem of uncontrollable color test.

Basic idea of the method is using color software to digitize colors, and international RGB color mode is used to express the specific situation of each color.Among them, R, G and B represent the color of red, green and blue channels, and this standard includes almost all colors that human vision can perceive, and is one of the most widely used color systems.

2 Instrument, software and sample source

Instrument: Canon Power Shot SX720 HS telephoto digital camera.Software: Colors MiniLab(color recognition software)v1.0 Chinese version.The software can freely obtain any color on the screen and convert it into hex or dodecal, with good color recognition accuracy.Sample source: national evaluation sampling.

3 Method and method verification

3.1 Method descriptionUnder natural light, the sample was laid on the table, and the thickness was between 0.5 and 1.0 cm.It took vertical photos with a digital camera to obtain sample photos, and the photos were imported to computer.Software Colors MiniLab was used for color recognition, and RGB data of its color were recorded.The data of R, G and B were respectively averaged, and color digitized data of the sample was obtained.

3.2 Four-point acquisition methodWhen using software Colors MiniLab for color recognition, the problem that how many points should be collected for calculation was studied and explored.20 points were collected from the same batch of samples, and the position was selected by evenly distributed collection method.After data comparison and research, it was found that the number of points collected did not need to be too much.By comparing many collection models: ring acquisition, square diagonal acquisition, trapezoid acquisition, and triangle acquisition, it was thought that the equilateral triangle acquisition method can meet the acquisition requirements, and the data repeatability and representativeness can also be met.Data collection point by the method was composed of four points, namely the three vertices and the center point of an equilateral triangle.The center point of the equilateral triangle was also located in the center of the picture, and its model distribution was shown in Fig.1.The advantage of this acquisition method was that the location of acquisition points was relatively fixed, and each direction was taken into account, with good repeatability and stability.

Fig.1 Distribution of four points of equilateral triangle acquisition model

3.3 Method validation

3.3.1Accuracy verification.Since the previous color test was judged by people based on experience, the accuracy verification of this method was carried out by comparing human judgment and digital method.First, the experienced chief pharmacist of the research team determined the color of the three batches of samples to be tested, and then other researchers digitized the color of the three batches of samples to compare the results of the two.The results showed that there was no significant difference between the two methods, and the accuracy of the method was good.

3.3.2Precision verification.Six times of color digitization experiments were carried out on the same batch of samples, and the results of six times of data were counted(Table 1).The results showed that the precision of the method was good.

Table 1 Precision validation of method

4 Results and analyses

Color digitization of 168 batches of samples was conducted, and the results were shown in Table 2.

Table 2 Color digitization results of 168 batches of samples

Color was mainly related to stability of original medicinal materials, stability of extraction process, and stability of total mixing process.Color results of 168 batches of samples in Table 2 were imported into software SPSS 19.0 for visual analysis, and results were shown in Fig.2.Seen from Fig.2, the main groups were relatively concentrated, but some were scattered.Color change was mainly induced by blue B and green G, and the relationship with red R was not obvious.It could be seen that the color of most batches is concentrated, namely "light yellow" described in the standard, but the color of some batches of some manufacturers is obviously out of group, such as yellowish brown(RGB was 123, 96, 56).

Fig.2 3D scatter diagram of color data visualization of 168 batches of samples

5 Discussion

Specified characters of Compound Lonicera Granules were as below: light yellow particles, tasting sweet and slightly bitter.The sample color of each production enterprise varied greatly, and the appearance color was related to the production process.Considering differences in production processes, and combining actual production situation, it should revise "light yellow" of original standard into "light yellow to yellowish brown", which more correspond with the description of actual sample.

The digital expression of color by digital technology is a new attempt to test the color of drugs.After the method is stable and mature, it is expected to develop a portable color recognition and judgment instrument, which is conducive to avoiding color misjudgment caused by lack of experience or feeling deviation, and can further enrich and standardize drug inspection and detection technology.