PMID- 18969936
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20121002
LR  - 20081030
IS  - 1873-3573 (Electronic)
IS  - 0039-9140 (Linking)
VI  - 65
IP  - 5
DP  - 2005 Mar 15
TI  - Spectrophotometric determination of ascorbic acid using copper(II)-neocuproine 
      reagent in beverages and pharmaceuticals.
PG  - 1226-32
LID - 10.1016/j.talanta.2004.08.048 [doi]
AB  - The proposed method for ascorbic acid (Vitamin C) (AA) determination is based on 
      the oxidation of AA to dehydroascorbic acid with a 
      Cu(II)-2,9-dimethyl-1,10-phenanthroline (neocuproine (Nc)) reagent in ammonium 
      acetate-containing medium at pH 7, where the absorbance of the formed 
      bis(Nc)-copper(I) chelate is measured at 450nm. This chelate was formed 
      immediately and the apparent molar absorptivity for AA was found to be 1.60 x 
      10(4)dm(3)mol(-1)cm(-1). Beer's law was obeyed between 8.0 x 10(-6) and 8.0 x 
      10(-5)M concentration range. The relative standard deviation for 90mug AA was 3%. 
      The Cu(II)-Nc reagent is a milder and therefore more selective oxidant than the 
      conventional Fe(III)-1,10-phenanthroline (phen) reagent used for the same assay. 
      This feature makes the proposed method superior for real samples such as fruit 
      juices containing weak reductants such as citrate, oxalate and tartarate that 
      otherwise produce positive errors in the Fe(III)-phen method when equilibrium is 
      achieved. The developed method was applied to a number of commercial fruit 
      juices, pharmaceutical preparations containing Vitamin C, and red wine. The 
      meta-bisulfite content of wine was removed with an anion exchanger at pH 3 prior 
      to analysis, and a difference extractive-spectrophotometric method of AA assay in 
      wine was developed so as to suppress the interferences caused by wine 
      anthocyanins and polyphenols. The findings of the developed method for fruit 
      juices and pharmaceuticals were also statistically compared with those of HPLC so 
      as to establish it as a reliable novel method.
FAU - Guclu, Kubilay
AU  - Guclu K
AD  - Istanbul University, Faculty Chemistry Department, Avcilar, 34320 Istanbul, 
      Turkey.
FAU - Sozgen, Kevser
AU  - Sozgen K
FAU - Tutem, Esma
AU  - Tutem E
FAU - Ozyurek, Mustafa
AU  - Ozyurek M
FAU - Apak, Resat
AU  - Apak R
LA  - eng
PT  - Journal Article
PL  - Netherlands
TA  - Talanta
JT  - Talanta
JID - 2984816R
EDAT- 2008/10/31 09:00
MHDA- 2008/10/31 09:01
CRDT- 2008/10/31 09:00
PHST- 2004/04/27 00:00 [received]
PHST- 2004/07/27 00:00 [revised]
PHST- 2004/08/25 00:00 [accepted]
PHST- 2008/10/31 09:00 [pubmed]
PHST- 2008/10/31 09:01 [medline]
PHST- 2008/10/31 09:00 [entrez]
AID - S0039-9140(04)00532-6 [pii]
AID - 10.1016/j.talanta.2004.08.048 [doi]
PST - ppublish
SO  - Talanta. 2005 Mar 15;65(5):1226-32. doi: 10.1016/j.talanta.2004.08.048.