Validacija atomskog apsorpcijskog spektrofotometra AA - 7000 za analizu cinka u serumu

master's thesis

• Title (english): Validation of the atomic apsorption spectrophotometer AA - 7000 for the analysis of serum zinc
• Author: Sara Randić
• Mentor: Dunja Rogić (mentor)
• Committee member: Dunja Rogić (predsjednik povjerenstva)
• Committee member: Mila Lovrić (član povjerenstva)
• Committee member: Željka Vogrinc (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of medical biochemistry and haematology); Zagreb
• Defense date and country: 2020, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Medical Biochemistry

Abstract

Cink je jedan od najbitnijih oligoelemenata u ljudskom tijelu koji djeluje kao kofaktor u više od 300 metaloenzima. Do
deficita cinka u organizmu uglavnom dolazi zbog smanjenog unosa, keliranja lijekovima ili različitih bolesti dok je
hipercinkemija puno rjeđa. Mjerenjem koncentracije cinka u krvi može se pratiti njegov sadržaj u tijelu. Referentna
metoda za mjerenje cinka u krvi je atomska apsorpcijska spektrofotometrija, no zbog veće dostupnosti i jednostavnosti
se u većini laboratorija cink rutinski određuje kolorimetrijskim metodama. Cilj ovog istraživačkog rada bio je
validirati metodu za određivanje cinka u krvi na novom atomskom apsopcijskom spektrofotometru AA – 7000 tvrtke
Shimadzu u Kliničkom zavodu za laboratorijsku dijagnostiku KBC Zagreb. Postupak validacije obuhvatio je
ispitivanje preciznosti, istinitosti, granice kvantifikacije i linearnosti, usporedbu s dosad korištenom metodom i
provjeru deklariranih referentnih intervala. Dobiveni rezultati za nepreciznost (iz dana u dan i u seriji) te sustavnu
pogrešku (bias) u skladu su s kriterijima prihvatljivosti prema Westgardu. Rezultati ispitivanja granice kvantifikacije
su pokazali da se metodom atomske apsorpcijske spektrofotometrije na uređaju AA – 7000 može pouzdano mjeriti
koncentracije cinka u serumu od 3,06 umol/L što je prihvatljivo za rutinski rad. Ispitivanje linearnosti napravljeno
pomoću pet kalibratora pokazalo je da uređaj AA – 7000 daje rezultate ispitivanja proporcionalne koncentraciji analita
bez dodatnog razrjeđenja uzorka čime je potvrđena dobra linearnost. Rezultati usporedbe ispitivane metode s ranije
korištenom kolorimetrijskom metodom su pokazali da ne postoje konstantne niti proporcionalne razlike između dvije
navedene metode i da se rezultati mjerenja cinka u serumu pacijenata različitih dobi i spola na oba analizatora mogu
smatrati jednakim. Određivanjem cinka u 20 uzoraka seruma zdravih pacijenata metodom atomske apsorpcijske
spektrofotometrije na uređaju AA-7000 provjereni su referentni intervali, a iz Gaussove krivulje je vidljivo da se
dobivene vrijednosti nalaze unutar očekivanog raspona. Na temelju rezultata ovog istraživanja može se zaključiti da se
uređaj AA – 7000 tvrtke Shimadzu može uvesti u rutinsku primjenu za analizu cinka u serumu.

Abstract (english)

Trace elements (also called oligoelements) make up 0,1% of an organisms body mass. They can be divided into
essential oligoelements which are crucial for the normal body function and non-essential oligoelements which can
become toxic in high concentrations. One of the main oligoelements is Zinc (Zn) which acts as a cofactor of more than
300 metalloenzymes. Zinc deficiency is more common than hyperzincemia, and it is mostly caused by a low uptake
and chelating drugs. It is also a symptom of many diseases. Although many clinical laboratories still use, colorimetric
methods to determine the serum concentration of zinc because of their availability and simplicity, atomic apsorption
spectroscopy is considered the standard, reference method.The main purpose of this research was to validate the AA–
7000 atomic apsorption spectrophotometer in order to confirm that it can be used in the rutine testing of serum Zn
concentrations at the Department of Laboratory Diagnostics at the University Hospital Center Zagreb. AAS method
validation included tests of precision, trueness, linearity and limits of quantification (LOQ) as well as comparing the
AA – 7000 analyser to the older Cobas 6000 c501 analyser and checking the reference intervals for serum Zn
concentrations.The calculated imprecisions and bias are in accordance with the desireable specifications according to
Westgard. Through testing the lower limit of quantification it was confirmed that concentrations of serum Zinc as low
as 3,06 umol/L can be determined with a high degree of precision and trueness. Comparing the two analysers using the
Passing-Bablock and Bland-Altman plots it was concluded that no constant or proportional differences can be found
between the two methods and that we can cosider the results obtained by these two analysers equal. The correlation
coefficient was calculated to be greater than 0,990 and therefore the linearity of the method was confirmed. The
generally accepted reference intervals were also confirmed by reading from the Gauss curve. Based on this research it
was confirmed that the atomic apsorption spectrophotometer AA – 7000 analyser from Shimadzu can incorporated
into the routine laboratory practice for the analysis of serum zinc concentrations.

• Keywords: elementi u tragovima; cink; serum; validacija; preciznost; točnost; granica kvantifikacije; Passing i Bablok; Bland i Altman; linearnost; referentni interval
• Keywords (english): trace elements; zinc; serum; validation; precision; trueness; limit of quantification; Passing – Bablok; Bland – Altman; linearity; reference interval
• Language: croatian
• URN:NBN: urn:nbn:hr:163:174583
• Study programme: Title: Medical biochemistry; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra medicinske biokemije (magistar/magistra medicinske biokemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-02-21 13:24:37