Vpliv kalibracije na merilno negotovost določitve kalcija v morski vodi

Šušteršič, Maja (author), Gros, Nataša (mentor)

V delu smo ovrednotili vpliv kalibracije na rezultate in merilno negotovost določitve kalcija v morski vodi z ionsko kromatografijo. Določitev je bila izvedena na podlagi kalibracijskega standarda s kalcijevo soljo in na podlagi kombiniranega standarda, ki posnema matrico vzorca. Merilno negotovost smo ovrednotili s pristopom od spodaj navzgor. Priprava vzorca in delovnih kalibracijskih raztopin je vključevala redčenje. Za vrednotenje negotovosti odmerjanja volumna smo uporabili gravimetrično metodo. Razlika v določitvi masne koncentracije kalcijevih ionov v morski vodi je bila signifikantna. Višjo masno koncentracijo smo določili pri uporabi kalibracijskega standarda s kalcijevo soljo. Merilna negotovost je bila večja pri določitvi s kombiniranim kalibracijskim standardom. Največji prispevek k merilni negotovosti ima negotovost interpolacije rezultata iz enačbe premice.

• Language: Slovenian
• Keywords: določitev kalcija, morska voda, ionska kromatografija, kalibracija, merilna negotovost
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2024
• PID: 20.500.12556/RUL-154184
• COBISS.SI-ID: 183349251
• Publication date in RUL: 30.01.2024

Secondary language

• Language: English
• Title: Calibration influence on the measurement uncertainty of calcium determination in seawater

Abstract

Here were evaluated the results and the measurement uncertainty of the determination of calcium in seawater by ion chromatography. The determination was performed on the basis of a calibration standard with calcium salt and on the basis of a combined standard that took into account the matrix of the sample. Bottom-up approach was used to evaluate the measurement uncertainty. Preparation of sample and working calibration standards included dilution. Gravimetric method was used to evaluate the uncertainty of volumetric operations. The difference in the mass concentration of calcium ions in seawater obtained with these two different approaches was significant. Higher mass concentration was determined by using a calibration standard with calcium salt. Measurement uncertainty was higher when combined calibration standard was involved. The uncertainty of interpolation of the results from linear regression equation represented the largest contribution to the measurement uncertainty.

• Keywords: calcium determination, seawater, ion chromatography, calibration, measurement uncertainty