Decreasing the uncertainty of gas chromatographic quantification using the solvent’s signal in the method of external standard

Погрешности результатов количественных газохроматографических определений способами, предполагающими использование абсолютных площадей хроматографических пиков, в том числе внешнего стандарта, «чувствительны» к воспроизводимости дозирования проб. Эффективным приемом компенсации таких погрешностей является введение в анализируемые образцы дополнительных стандартов и замена абсолютных площадей пиков их отношениями к площадям пиков стандартов. Важно, что в качестве дополнительных стандартов можно использовать любые компоненты образцов, в том числе входящие в их состав растворители. В модифицированном варианте количественного анализа способом внешнего стандарта растворитель можно использовать, даже если его пики регистрируются в «усеченном» виде в результате ограничения выходных сигналов усилителя. Использование относительных площадей пиков не требует никаких дополнительных операций с образцами, кроме регистрации площадей пиков растворителя. Сравнение обычного и модифицированного вариантов способа внешнего стандарта показывает, что замена абсолютных значений площадей пиков отношениями площадей пиков целевого аналита и растворителя не влияет на характеристики точности определений по критерию «введено-найдено», но уменьшает случайную составляющую погрешности определений в 2-3 раза. Обсуждается проблема повышения достоверности подобных статистических оценок, для чего представляется целесообразным изменение «дизайна» экспериментальных операций. Вместо последовательных анализов однотипных образцов предпочтительнее использовать параллельные определения, что можно достичь, например, при выполнении практических работ студентами.Uncertainties of the results of quantitative determinations in gas chromatography using the methods based on the absolute peak areas (including the external standard method) are rather “sensitive” to the reproducibility of injections. The effective way to compensate for such errors is to introduce the additional standards into the samples, followed by replacing the absolute peak areas by their ratios to peak areas of the standards. It is important to underline that any constituents of the samples can be used as additional standards, including the solvents. Solvents can be used for these purposes even if the heights of their peaks are restricted when the analytical signals exceed the amplifier limits. Using the relative peak areas does not require any extra sample processing besides the registration of peak areas for solvents. Comparing the commonly known and modified methods of external standard demonstrates that using the relative peak areas instead of the absolute ones does not influence the overall precision of determinations (according to the criterion “introduced-determined”) but improve the reproducibility by 2-3 times. The problem of increasing the reliability of such statistical evaluations of results is discussed and to solve it, it is proposed to change the “design” of the experiments. Instead of series of successive analyses of similar origin samples, the use of parallel determinations is preferable. This can be realized, for example, during the fulfillment of student’s practical works.Студенческая практическая работа, результаты которой составили предмет настоящего сообщения, выполнена с использованием оборудования Ресурсного Центра «Методы анализа состава вещества» Санкт-Петербургского государственного университета. Авторы благодарят сотрудников Центра за содействие.The students’ work, the results of which are discussed in this paper, was carried out using the equipment of the “Methods of analysis of substance’s composition” Resource Centre at St. Petersburg State University. The authors are grateful to the staff of this Center for their assistance

FEATURES SOCIAL SITUATION OF DEVELOPMENT IN THE PRESCHOOL CHILD

The article investigates specific features of the social situation of development of preschool children. On the basis of the system analysis described the main components of the social situation of development, shows the genesis of their formation during the first seven years of life. The authors concluded that the social situation of development of the preschool child develops at the intersection of four gradually expand the scope of social development in the preschool child: self-image, family, peers, adult world. The dynamics of the image I appears Strezhnev vector of social development, it is determined by self-oriented, self-control and attitude. The development of the sphere of interaction with adults and peers ensures the formation of social concepts in direct life experience of the child, his interaction with other people

STUDENTS ' MEMICAL PROFICIENCES IN THE CONTEXT OF EDUCATIONAL PROFESSIONAL ACTIVITY

The article actualizes the problem of memory development and mnemonic abilities of students, as an important component of cognitive activity, which ensures the quality and effectiveness of education. On the basis of the theoretical analysis of scientific and psychological research and their own pedagogical experience, the authors consistently reveal the essence of mnemonic activity, the structure, factors that determine its development, ways and means of its improvement. An attempt has been made to study the regularities and mechanisms of the development of the mnemonic abilities of students in the conditions of the establishment of secondary vocational education. The results obtained by the authors show a low level of development of memory abilities, demonstrated by students against the background of a general decrease in cognitive interests and motives for learning activity. The conclusion is drawn about the need for special work aimed at optimizing mnemonic abilities, proposing concrete ways and methods for training and developing memory in the educational process and outside it. Attention is focused on the need to develop professional skills and competences, cognitive abilities that have their own specifics from the standpoint of specific professional activities

THE USE OF THE ECOLOGICAL CALENDAR IN THE PROCESS OF ACQUAINTANCE OF OVER-FIVE PRESCHOOL CHILDREN WITH SEASONAL CHANGES IN NATURE

Introduction: The article examines the important problem of the formation of pre-schoolers' views on the change of seasons, patterns and features of seasonal changes in nature. The approaches to solving this problem existing in science are stated briefly, the specificity of pre-schoolers' learning of temporary and seasonal ideas is revealed. Theoretically, the effectiveness of the application of the ecological calendar in the work on the environmental education of pupils of 5-6 years is proved experimentally.Materials and methods: The results of an experimental study of the effectiveness of the application of the ecological calendar for the familiarization of children of over-five  preschool age with seasonal changes in nature, obtained on the basis of the use of diagnostic tools, are presented on the basis of  S.N. Nikolaeva and OA Solomennikova on revealing the level of the formation of knowledge about the seasons.Results: Based on the research of M.M. Ushakova, S.N. Nikolaeva and other authors the main content of the ecological calendar adapted for over-five preschoolers is presented, the main ecological dates (dates of solstices), events and holidays of ecological orientation, state holidays identified, taking into account the climatic and geographical conditions of the Nizhny Novgorod region, the requirements of the GEF preschool education, the interests of children. Some of the most effective forms and methods of working with children on acquaintance with environmental dates are described.Discussion and conclusions: On a concrete factual material, the expediency of using the calendar of ecological dates as an orderly system of annual events in nature in the work on making familiar 5-6 years preschoolers with seasonal changes in nature is shown. The obtained data convince that children of the senior preschool age are able to assimilate complex knowledge about the rhythm and cyclic nature of processes