Flow-injection spectrophotometric determination of novalgin in pharmaceuticals using micellar medium.
A sensitive flow-injection (FI) procedure with spectrophotometric detection in a micellar medium is proposed for the determination of novalgin. The method is based on the instantaneous formation of a red-orange product (lambda(max) = 510 nm) after the reaction between novalgin and p-dimethylaminocinnamaldehyde (p-DAC) in a dilute acid medium. The sensitivity of this reaction was increased by a factor of 5.6 in the presence of sodium dodecyl sulfate (SDS). Experimental design methodologies were used to optimize the chemical and FI variables. The calibration curve was linear in the range of 1.45 x 10(-6) to 2.90 x 10(-5) mol L(-1) with an excellent correlation coefficient (r = 0.9999). The detection limit was 1.31 x 10(-7) mol L(-1) (n = 20, RSD = 2.0%). No interferences were observed from the common excipients. The results obtained by the proposed method were favorably compared with those given by the iodometric reference method at 95% confidence level.
Weinert
Patrícia Los
PL
Instituto de Química-UNESP, P. O. Box 355, CEP 14801-970, Araraquara, SP, Brazil.
Fernandes
João Roberto
JR
Pezza
Leonardo
L
Pezza
Helena Redigolo
HR
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis*; D004177:Dipyrone / Q000032:analysis*; D017022:Flow Injection Analysis; D007202:Indicators and Reagents; D008823:Micelles; D019999:Pharmaceutical Solutions; D012015:Reference Standards; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007202:Indicators and Reagents; D008823:Micelles; D019999:Pharmaceutical Solutions; D013607:Tablets; D004177:Dipyrone