| Abstract | Korištenjem slijedne analize injektiranjem uz spektrofotometrijski detektor optimizirana je i vrednovana nova metoda određivanja N-acetil-L-cistein etil estera (NACET). Temelji se na redoks reakciji u
kojoj NACET sudjeluje kao reducens pri čemu nastaje ljubičasto obojeni [Cu(BCA)2]+ kompleks koji pokazuje
apsorpcijski maksimum pri = 562 nm. Univarijantnom metodom odabrani su optimalni parametri protočnog
sustava koji omogućuju pouzdano -6određiv-a1nje NACET-a uz -1jednostrano injektiranje reagensa u
koncentracijskom području od 8,0 × 10 mol L do 1,0 × 10-4 mol L te uz dvostrano injektiranje reagensa u
koncentracijskom području od 6,0 × 10-6 mol L-1 do 1,0 × 10-4 mol L-1. Linearno dinamičko područje je uz
jednostrano injektiranje reagensa definirano jednadžbom: y = 3483,4x + 0,0063, uz koeficijent linearne regresije
R2 = 0,9900, dok je uz dvostr2ano injektiranje reagensa definirano jednadžbom: y = 3879,8x --10,0045, uz
koeficijent linerane regr6esije R-1 = 0,9994. Određene su granica dokazivanja (2,22 × 10-6 mol L ) i granic-a6
određivanja (7,46 × 10- mol L ) za određiva6nje NAC-ET-a uz jednostrano te granica dokazivanja (1,60 × 10
mol L-1) i granica određivanja (5,34 × 10- mol L 1) za određivanje NACET-a uz dvostrano injektiranje
reagensa. Ponovljivost signala ima relativno standardno odstupanje od 2,51 % uz jednostrano injektiran reagens
te 1,66 % uz dvostrano injektiran reagens. Utvrđeno je i da naizmjeničnim injektiranjem otopina standarda koje
su sadržavale različite koncentracije NACET-a ne dolazi do prenošenja signala, bez obzira na analizirane
koncentracije NACET-a. Navedeno se odnosi na određivanje NACET-a uz jednostrano te uz dvostrano
injektiranje reagensa. Tvari koje se uobičajeno nalaze u sastavu farmaceutskih pripravaka ne interferiraju. |
| Abstract (english) | A novel sequential injection spectrophotometric method for the determination of N-acetyl-L-
cysteine ethyl ester (NACET) was developed and validated. The method is based on a redox re+action in which
the reduction of [Cu(BCA)2]2+ complex by NACET occurs forming a violet [Cu(BCA)2] complex with
absorption maximum at = 562 nm. Univariate method was used to select optimal parameters of the flow system
for a successfull and reliable determination of NACET by standard sampling in the concentration range of the
selected analyte of 8.0 × 10-6 mol L--61 to 1.0-× 10-4 mol L-1 and by-1sandwich sampling in the concentration range
of the selected analyte of 6.0 × 10 mol L 1 to 1.0 × 102-4 mol L . Linear dynamic range obtained 2by standard
and sandwich sampling was y = 3483.4x + 0.0063 (R = 0,9900) and y = 3879.8x-6- 0.0045 (R = 0,9994)
respecti1vely. Limit of detection and limit of quantification were found to be 2.22 × 10 mol L-1 and 7.46 × 10-6
mol L- for standard sam1pling. For sandwich sampling limit of detection and limit of quantification were found
to be 1.60 × 10-6 mol L- and 5.34 × 10-6 mol L-1. The reproducibility or precision of the method was evaluated
by examining the relative standard deviation which was 2.51 % for standard and 1.66 % for sandwich sampling.
The obtained results are considered to be satisfactory. Injection of standard solutions containing different
concentrations of NACET did not cause signal carryover for standard and sandwich sampling. Comonly present
compounds that acompany similar thiols in their pharmaceautical preparations did not show an interfering effect. |
