Physical and chemical inspection technology paper a: "Try to talk about the physical and chemical inspection quality control assessment of the relevant technology"
Abstract With the rapid development of the country's science and technology in recent years, the various scientific research work is also expanding. Physical and chemical inspection is an important part of our country to carry out scientific research and testing, especially in the supervision and management of health. Physical and chemical research due to its high demand for precision and the requirements of the detection process must improve the accuracy of the test, quality control is a very effective way to improve the accuracy of the test, for different tests, quality control control technology is not the same.
Keywords Physical and chemical inspection; quality control; technical analysis; physical; chemical
Physical and chemical inspection is to carry out physical and chemical testing and inspection with the help of some measuring tools, and thus also known as? Apparatus test? This measuring tool or apparatus are very precise, for example, the general use of measuring tools are micrometers, micrometer, gauge, microscope and so on. With China's reform of the health industry and the strengthening of health supervision and management, the health sector in the detection of higher requirements, and physical and chemical testing is an important means of health testing, which provides more accurate monitoring and law enforcement testing data, supervision and management of labor hygiene has an important role in the work.
1 Physical and chemical inspection quality control assessment of the relevant technology
According to the many researchers over the years to explore the discovery and summary, physical and chemical inspection quality control assessment can be divided into the following aspects.
1.1 Analysis of metal content deposited on the filter membrane This technology is the use of chemical methods, by adding the relevant chemical agents to make it precipitate and then filtered, filtered metal type, content and so on analysis. The stability of the metal samples deposited on the filter membrane is relatively high, under normal circumstances will not occur with the changes in the natural environment and loss, in the process of analysis of the metal content deposited on the filter membrane need to pay attention to preventing dust contamination, the extraction of the assessment of the samples should pay attention to the disinfection of the tools, drying treatment, so as to avoid the occurrence of contamination, resulting in inaccurate results of the assessment of the data. After the examination is completed, the sample should be put into a clean dryer.
1.2 Analysis of metal content in solid salts As the name suggests, this physical and chemical inspection and assessment technology is through the metal content and type of assessment of solid salts, the same as the metal samples deposited on the filter membrane, the metal samples of solid salts also have good stability. In the extraction of the sample should pay attention to the amount of samples should not be too much, in the extraction of the sample before the sample must be drying treatment, drying time of at least one hour or more, after the completion of the assessment of the samples should be placed in a clean dryer.
1.3 Activated carbon tube adsorption of organic toxic content analysis of this technology assessment principle is the role of chemical affinity, because the adsorption of activated carbon tubes have the opportunity to have a strong adsorption capacity, if the use of physical methods it is not easy to separate them, with chemical affinity will be separated and the sample assessment and analysis. Attention should be paid to dustproof and moisture-proof in the daily sample preservation. Thus, the activated carbon tube adsorption of organic toxic samples are not suitable for preservation in the refrigerator.
1.4 Analysis of toxic content in aqueous solution There are many toxic samples to be detected in aqueous solution, such as: hydrogen chloride content in aqueous solution, chromium trioxide content in aqueous solution, etc. The stability of toxic samples to be detected in aqueous solution is relatively poor, and in the normal state of nature will be with the changes in the environment and change, for example, when the ambient temperature rises, it increases the natural evaporation of sample water. For example, when the ambient temperature rises, it will increase the natural evaporation of sample water, and when the sample is preserved, if the cap of the aqueous solution bottle is not tightly closed, it will also lead to water evaporation. Therefore, the assessment of the preservation of aqueous samples is very important, in the preservation of the time to pay attention to the temperature will not change in the environment, the refrigerator or freezer is a good way, but also pay attention to the sample bottle is sealed.
2 sample assessment process should pay attention to the problem
2.1 Sample assessment process in strict accordance with the norms and standards for the physical and chemical inspection of the quality assessment, the state has introduced a relevant process norms and standards. Therefore, in the actual operation should be in strict accordance with the norms and standards, in order to prevent errors or test inaccurate. In the assessment should be analyzed before the operation of the plan written in detail, in accordance with the relevant indicators and standards for the configuration of reagents, at the same time to take a small number of test samples to test the first analysis, mainly to detect the concentration, to determine the analysis of the assessment of samples used in the sampling volume. In the actual assessment process, the first good standard curve, including the blank point *** five points, each point to do six copies, calculate the coefficient of variation is less than two percent, set out the regression equation, calculate the regression coefficient. In order to improve the accuracy of the assessment, should take the assessment of three samples according to the standard curve of the same method of operation, and then calculate the average of the three measurements as the final results, pay attention to the calculation of its relative standard value, the standard value should be less than five percent, otherwise, it is shown that the error is too large, the data can not be used as a result of the determination. Note that the writing process of various formats and units, etc. should be strictly in accordance with the standard format.
2.2 Notes on the use of instruments and reagents in the assessment process First of all, the pipette used in the experiment, the requirements must be used to obtain metrological certification of the unit production of standard measuring instruments, or after the assessment of the personnel themselves, because the pipette indicator parameters will also affect the accuracy of the test. Throughout the process of analyzing the assessment samples, special attention should be paid to the dosage of the aspirated standard reagent and the assessment sample solution. Next is the attention to the distilled water used in the experiment, the quality of distilled water in the process of sample analysis will y affect the blank value of the chemical analysis of lead, and ultimately affect the analysis results. And the purity of analytical reagents will also have a great impact on the analytical results. Therefore, in the actual assessment, in order to ensure the accuracy of the results of the assessment samples, heavy distilled water and analytical purity of reagents above should be used, and the assessment of gas chromatography with GR-grade chromatographic purity of reagents.
3 Conclusion
Physical and chemical inspection quality control assessment is not a complex project, but because of the importance of the test results require that the test results must be more accurate, so in the assessment process must ensure that the operation is carried out in strict accordance with the standard specifications to protect the samples from contamination, the test results report must be in accordance with the relevant requirements of the format, comprehensive and accurate. Through all aspects of the standardized operation to strengthen the quality control of physical and chemical testing.
References
[1] Huang Jiadian, Li Cheng, Du Hong, Zhang Yin, Fang Chen. Construction of a new mode of practice teaching for the specialty of sanitary inspection and quarantine technology [A]. Zhejiang Provincial Medical Association. 2012 Proceedings of Zhejiang Provincial Medical Education Academic Annual Conference [C]. Zhejiang Provincial Medical Association, 2012.4.
[2] on the holding of the National Materials Physical and Chemical Testing and Product Quality Control Academic Symposium and the "Physical and Chemical Inspection" 40 years of celebrations of the call for papers notice (No. 1) [J]. Physical and Chemical Testing (Physical Subsection), 2012, 02: 92.
[3] Zhang Yunxia, Cai Wangwei, Zhou Daifeng. Deepening the reform of biochemistry experimental teaching in medical school oriented to quality education[J]. Hainan Medical Science, 2011, 15: 135-137.
[4] Zhang Xiuli, Liao Xingguang, Zhang Meng, Gao Baochen. 2010 Evaluation and analysis of the results of the quality control assessment of food hygiene microbiological testing in Henan Province [J]. Chinese Journal of Hygiene and Inspection, 2011, 07: 856-857.
Physical and chemical inspection technology thesis II: "Tea Physical and Chemical Inspection Sample Preparation Technology"
Abstract: This paper is a preliminary analysis of the study of tea physical and chemical inspection samples of the preparation technology, and from the selection and processing of fresh leaves, pre-treatment and milled gross tea, homogeneous mixing and dispensing of milled samples, test sample The uniform stability of the test samples, detection characteristics of the value of the tea physical and chemical test sample preparation technology was analyzed, and finally put forward the standardized samples for the value of the value of the standardized samples, the value can be based on the detection of data provided by the laboratory to shift to the development of the proposal, I hope to be able for the development of our country's tea quality inspection and dedication to the development of their own strength.
Keywords: tea, physical and chemical inspection, sample preparation
One of the world's three major beverages is tea, compared with other beverages tea is more affordable and economical, so the drinking range of tea is also gradually expanding, with a growing number of consumer groups, and has become the 21st century world of healthy beverages, the first choice of objects. However, along with the rapid development and expansion of the commodity economy, the increasingly fierce market competition environment, the emergence of a variety of shoddy products, tea can not be excluded. In order to be able to meet the requirements of the commodity market, various forms of fake tea to crack down, effectively rectify the very chaotic tea market, the urgent need for physical and chemical inspection of tea.
First, the tea physical and chemical inspection of standardized samples overview
The content of the tea test contains a test of the quality of tea, physical and chemical standards, as well as health standards and so on. Among them, the physical and chemical inspection program focuses on the output of water immersion, moisture, tea polyphenols, caffeine and other indicators of the test; health inspection is the presence of tea in the six-six-six components of the implementation of a variety of residual pesticide testing, as well as heavy metals and microbiological and other items of the scientific test.
The standardized sample is specifically one or a variety of uniformly adequate and characteristic value has been determined material material, the main purpose is to calibrate the equipment and instruments, evaluation methods and materials with the assigned value. At present, the tea standard samples of inorganic elements with assigned values that exist in tea are researched and produced by the National Academy of Ecological and Environmental Sciences and other relevant units and sold by the standard material organization in China. There is no place to buy other standardized samples that can reflect the value of various indicators of physical and chemical properties of tea. In order to effectively improve the work of the national testing tea institutions, strengthen the reliability of testing institutions to determine the data, it is necessary to design for the physical and chemical indicators of tea produced by the replication of standardized samples, which has become the fact that each testing unit of the laboratory testing tea project objective understanding of the factual basis of the technical level.
Second, tea physical and chemical testing standardized sample preparation techniques
(a) selection and processing of fresh leaves
Factors affecting the value of the physical and chemical indicators of tea mainly include the type of tea tree, the time of the tea production, the freshness of the raw materials and processing links. In order to fundamentally control the overall quality of raw materials, it is necessary to select the same type of tea, the same tea plantation, according to the same picking requirements for the implementation of the picking of fresh leaves. And under the same steps of processing to produce the same grade of gross tea samples. There are two aspects to focus on: on the one hand, there is the effective control of the level of gross tea content. The important factor to ensure the quality of tea is the moisture contained in the tea leaves, and for the gross tea samples to be standardized tea samples, their moisture content should be below 6.5%. On the other hand, the tenderness of raw materials is reasonably controlled. Processing tea leaves with good tenderness not only consumes higher costs, but also appears more fluffy and is very unfavorable to the preparation of uniform samples. To make tea standardized samples, it is better to choose the fresh leaves of one bud or three or four leaves as raw materials, and use the second grade or below as raw materials for gross tea. Some tea samples have been made according to the above requirements, and have been used as standardized samples by the National Accreditation Organization of Laboratories to verify the capability of tea. Not only does it have a lower cost, but its uniformity has been guaranteed from the beginning.
(ii) Pre-treatment and Grinding of Gross Tea
Gross tea that has just been processed usually contains some debris. In order to ensure uniform quality standards for the whole batch of tea, there is an urgent need to pick up all the tea leaves, and remove the stems and stones, etc., which can avoid the impact of these impurities on the indicators. International standards for physical and chemical testing of tea samples require the use of ground tea leaves, therefore, under the precondition of pre-treatment, it is necessary to grind the samples of gross tea. Before grinding, firstly, the grinding equipment should be cleaned up, secondly, a small part of the sample is put into the grinding, and clean up these grinding samples. Finally, to start the formal grinding of the sample, select the aperture of 0.6 mm to 1 mm between the sieve on the grinding of the sample for screening and will be used as a preparation sample.
(C) Homogenizing and Dispensing of Ground Samples
The preparation of standardized samples is different from that used in normal testing. A large number of samples are prepared at one time, and in order to ensure that the samples have a high degree of homogeneity, it is necessary to mix the screened ground samples well before the dispensing operation. After mixing the samples, the samples are placed in dry and clean equipment, and the caps are tightly closed to provide an airtight, dry, and sunlight-avoidant environment for preserving the tea samples.
(iv) Test for homogeneous stability of the samples
More than 10 samples were randomly selected from the overall samples and then tested for homogeneity. The test of uniformity can be done using the items to be tested, selecting items that are representative or sensitive to uneven samples. For each sample taken, it is tested more than 2 times under constant environmental conditions by the same tester. The results of the test are analyzed by applying a one-way variance to fully verify that there will be no significant variability between the samples, and only then can it be proved that they are homogeneous samples. In the uniformity test work of the samples required to verify the capability of tea, the relevant items such as total ash and crude fiber were selected to test the uniformity. Due to the correct preparation of uniform samples in the previous work, the results of the above test of uniformity were verified by applying one-way variance to show that they are uniform. The above tea items are stable in a closed and dry environment, therefore, the samples applied to the above items can not be stabilized.
(E) Detection of characteristic values
Detection of a characteristic value, through the need to have the ability to test tea dozens of laboratories, according to the national regulations of the test method, the application of the joint testing method between the various laboratories, the joint determination of the corresponding trait value. That is, according to the methods specified in the relevant guidelines, statistics and calculations of each laboratory to obtain test results, and ultimately determine the standardized samples of each characteristic value embodied in the measurement of uncertainty.
Third, the development of physical and chemical test samples of tea
China is currently working on a variety of capabilities to carry out the program verification, in the verification of the tea capacity of the various activities, the participating units have a very high degree of enthusiasm, to participate in the individual project laboratories more than a hundred. In the process of carrying out the work, the staff is y aware of the preparation of a large number of samples is very difficult, in the process of sample preparation, how to ensure that the samples have the uniformity and its effective testing and other work consumes a lot of financial resources and energy. Therefore, the relevant staff believe that by virtue of the verification of tea capacity this opportunity to increase the number of samples prepared for verification. As each validation of tea capacity after the remaining samples have passed the uniformity test, while in the process of validation of capacity to obtain further confirmation; through the validation of capacity can produce a number of excellent laboratories with a high level of technology. Therefore, the standardization of samples for the value, the value can be based on the shift to these laboratories to provide the test-related data. For example: a sample of relevant items can be required for the standard value of the median value of each laboratory to determine the value of the standardized IQR is defined as the standard deviation. If the scientific and effective application of these resources, not only can greatly reduce the preparation and verification of tea standardized samples of the costs required, but also to promote the results of the value of the more infinitely close to the real value, in line with the quality inspection units on the physical and chemical inspection of tea standard samples generated requirements.
Conclusion
At present, in the preparation of tea standard samples, tea workers have a wealth of professional tea background advantages, but to verify the tea ability to enhance the standardized samples of tea, but also to the relevant research procedures to make a further analysis and understanding, in order to be able to prepare a stable result, accurate value, uniform samples at the same time, give full play to the legal effect of the standardized samples of tea, but also for the quality inspection units to meet the requirements of the physical and chemical testing of tea. Tea standardized samples, but also for the development of China's tea quality control work to contribute their strength.
References:
[1]GB/T8303-2002. Preparation of Tea Ground Sample and Determination of its Dry Matter Content [M]. National Standard of the People's Republic of China, 2009.
[2]CNAS-GL03. Guidelines for the Evaluation of Homogeneity and Stability of Proficiency Testing Samples [M]. China National Accreditation Service for Conformity Assessment 2008.
Physical and Chemical Inspection Technology Thesis Part III: Based on the work process of the "Food Physical and Chemical Inspection Technology" course teaching process design
Food Physical and Chemical Inspection Technology as a food nutrition and detection of one of the major important core courses, the teaching of the course will have a direct impact on the quality of the training of the students [], therefore, the need for course Teaching process design, to develop students' learning enthusiasm, initiative and creativity, mobilize students' interest in learning, so as to improve the classroom effect of teaching, the teaching process is the overall comprehensive embodiment of knowledge, experience, methodology, and ability, the teaching process not only to reflect the ways and means of doing things, but also to pay attention to the mastery and application of knowledge [1-2]. In order to improve the teaching of the course, this paper on the "food physical and chemical inspection technology" course teaching process design, through the teaching process design to ensure that the teaching effect of the classroom, to achieve the enterprise requirements of the talent training goals.
First, the development of food physical and chemical inspection technology course
The development of food physical and chemical inspection technology course is oriented to the work process of physical and chemical inspection of enterprises, the physical and chemical inspection of the work process is designed as a corporate job needs of the work task, and the work task as a carrier for the design of the learning situation, to determine the development of the process, the specific first of all, the food nutrition and testing professional research, write a research report, analyze the research report, and the study report, the study report, the study report, the study report, the study report, and the study report. Research, write a research report, analyze the vocational ability and work ability required by the enterprise physical and chemical inspection jobs, according to the requirements of the vocational ability and work ability, analyze the course structure of food physical and chemical inspection technology, optimize the curriculum system of the course, so as to analyze the teaching content of the course, develop the course standard and experimental training guide, and then carry out the teaching design.
Second, the selection of teaching content and course content structure
In the selection of teaching content of food physical and chemical inspection technology course, according to the national and local food business industry development and higher vocational food nutrition and detection of professional training objectives, in accordance with the food physical and chemical inspection of the job requirements of students' knowledge, ability, quality, according to the ? Enough, necessary? Principle to select the teaching content, in accordance with the principle of vocational, practical selection of food physical and chemical training teaching projects.
Third, the design of the teaching process of food physical and chemical inspection technology
The teaching process of food physical and chemical inspection technology courses using specific tasks to lead the entire process of student learning, in accordance with the process of physical and chemical inspection of food jobs to design the teaching process of the course, from the jobs required to select the physical and chemical inspection project, inspection project selection is completed, the student According to the test project to find information for the program design, program design to determine out, the need for teachers and students *** with repeated discussions, modifications, through the implementation of the program, according to determine the program, the students in the teacher's guidance to complete the preparatory work of the experimental training, and then began to operate the practical training operation, the operation is completed, the results of the practical training to analyze, and then a wide range of teachers and students to collect the views of the students, and finally the teacher to feedback problems to the students. Finally, the teacher will feedback the problem to the students to avoid the same kind of error next time. The design of the teaching process of the course "Food Physical and Chemical Inspection Technology" is shown in Figure 1.
Figure 1 The design of the teaching process of Food Physical and Chemical Inspection Technology
Fourth, the implementation of the work process based on project-oriented, task-driven teaching method