Batch and hydrodynamic monitoring of vitamin C using novel periodate selective sensors based on a newly synthesized Ni(II)-Schiff bases complexes as a neutral receptors.
A highly selective membrane electrodes based on a two newly synthesized nickel (II) Schiff bases, [NiL(1)] and [NiL(2)] where L(1) and L(2) are N,N/bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H(2)L(1)) and N,N/bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H(2)L(2)) were used as a neutral carrier ionophores for static and hydrodynamic potentiometric mode of operations for the determination of periodate. Under static mode of operation, the sensors displayed a near-Nernstian slope of -66.1+/-0.8 and -59.9+/-1.1mV decade(-1) of activity and detection limits to 5.2x10(-6) and 7.3x10(-6)molL(-1) for the sensors based on [NiL(1)] and [NiL(2)], respectively. Under hydrodynamic mode of operation (FIA), the slope of the calibration plot, limit of detection, and working linear range were -71.1mV decade(-1) of activity, 7.3x10(-6) and 1.0x10(-5) to 1.0x10(-3)molL(-1), respectively. The response time of the sensors in whole concentration ranges was very short (<10s). The response of the sensors was independent on the pH range of 3-8. A tubular version was further developed and coupled to a flow injection system for ascorbic acid (AA) determination in beverages and pharmaceutical preparations. This approach was achieved by selecting a 50-cm reactor and an overall flow of 3mLmin(-1), and injecting volume 100microL of AA standards in a 1.0x10(-4)molL(-1) IO(4)(-) solution. Under these conditions, a linearity range of 2-13microgmL(-1), with a slope of 4.97mV (mg/L)(-1) (r(2)=0.9995), detection limit 0.9mgL(-1) and a reproducibility of +/-1.1mV (n=5) was recorded. This simple and inexpensive flow injection analysis manifold, with a good potentiometric detector, enabled the analysis of approximately 50 samples h(-1) without requiring pretreatment procedures. An average recovery of 98.8% and a mean standard deviation of 1.3% were obtained.
Aziz
Ayman A Abdel
AA
Chemistry Department, Faculty of Science, Ain Shams University, Cairo, Egypt.
Kamel
Ayman H
AH
D001205:Ascorbic Acid / Q000032:analysis* / Q000737:chemistry; D001628:Beverages / Q000032:analysis; D004566:Electrodes; D008567:Membranes, Artificial; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010504:Periodic Acid / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry
D008567:Membranes, Artificial; D009942:Organometallic Compounds; D004364:Pharmaceutical Preparations; D010504:Periodic Acid; D009532:Nickel; C009288:metaperiodate; D001205:Ascorbic Acid