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Design of a flow-through voltammetric sensor based on an antimony-modified silver electrode for determining lithol rubine B in cosmetics.

Lai-Hao W, Shu-Juan H - J Autom Methods Manag Chem (2011)

Bottom Line: For direct current (DC) mode, with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.125 to 1.80 μg/mL was found.The detection limit of our method was approximately 2.0 ng/mL.Findings using HPLC-ECD and HPLC with an ultraviolet detector were comparable.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Chemistry, Chia Nan University of Pharmacy and Science, 60 Erh-Jen Road, Section 1, Jen Te, Tainan 71743, Taiwan.

ABSTRACT
Lithol Rubine B (LRB; the disodium salt of 3-hydroxy-4-[(4-methyl-2-sulfophenyl) azo]-2-naphthalenecarboxylic acid) was detected using high-performance liquid chromatography with an electrochemical (antimony film on silver) detector (HPLC-ECD). For direct current (DC) mode, with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.125 to 1.80 μg/mL was found. The detection limit of our method was approximately 2.0 ng/mL. An antimony-modified silver detector was used to demonstrate that LRB is electrochemically reduced in acidic media and to analyze commercial cosmetics to determine their LRB content. Findings using HPLC-ECD and HPLC with an ultraviolet detector were comparable.

No MeSH data available.


Chromatograms obtained to produce calibration graph for Lithol Rubine B (a) LC-UV, (b) LC-EC. Stationary phase, HyperClone C18 column (particle size 5-μm, 250 mm × 4.6 i.d.); mobile phase, acetonitrile-water (30 : 70, v/v) containing 0.1 mM K2HPO4 (pH 3.97); flow rate 0.5 mL/min. Electrode potential was at −0.6 V versus the Ag/AgCl reference electrode, ultraviolet detector set at 235 nm.
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fig5: Chromatograms obtained to produce calibration graph for Lithol Rubine B (a) LC-UV, (b) LC-EC. Stationary phase, HyperClone C18 column (particle size 5-μm, 250 mm × 4.6 i.d.); mobile phase, acetonitrile-water (30 : 70, v/v) containing 0.1 mM K2HPO4 (pH 3.97); flow rate 0.5 mL/min. Electrode potential was at −0.6 V versus the Ag/AgCl reference electrode, ultraviolet detector set at 235 nm.

Mentions: The calibration plots obtained by plotting the peak area against the concentration of Lithol Rubine B show good linearity over the range 10–80 mg/L. The regression equations were y = 1.17x + 0.387 (correlation coefficient r = 0.9999); the range 0.30–1.2 mg/L and y = 202x + 10.0 (correlation coefficient r = 0.9999) for LC-UV and LC-ED, respectively (Figures 5(a) and 5(b)). Subsequently, we developed a simple and sensitive green electrochemical procedure for determining Lithol Rubine B in real samples. Commercial lipstick was spiked with 0.1, 0.2, or 0.3 mg/L and then analyzed. The calibration plot (Figure 6) shows good linearity. Because it is less expensive than LC-UV analysis, HPLC should be done using a conventional variable wavelength detector to achieve some selectivity and close to the optimum sensitivity of all the colorants. Thus, our proposed analytical method offers a valid and economical alternative to LC-UV detection of Lithol Rubine B.


Design of a flow-through voltammetric sensor based on an antimony-modified silver electrode for determining lithol rubine B in cosmetics.

Lai-Hao W, Shu-Juan H - J Autom Methods Manag Chem (2011)

Chromatograms obtained to produce calibration graph for Lithol Rubine B (a) LC-UV, (b) LC-EC. Stationary phase, HyperClone C18 column (particle size 5-μm, 250 mm × 4.6 i.d.); mobile phase, acetonitrile-water (30 : 70, v/v) containing 0.1 mM K2HPO4 (pH 3.97); flow rate 0.5 mL/min. Electrode potential was at −0.6 V versus the Ag/AgCl reference electrode, ultraviolet detector set at 235 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3094699&req=5

fig5: Chromatograms obtained to produce calibration graph for Lithol Rubine B (a) LC-UV, (b) LC-EC. Stationary phase, HyperClone C18 column (particle size 5-μm, 250 mm × 4.6 i.d.); mobile phase, acetonitrile-water (30 : 70, v/v) containing 0.1 mM K2HPO4 (pH 3.97); flow rate 0.5 mL/min. Electrode potential was at −0.6 V versus the Ag/AgCl reference electrode, ultraviolet detector set at 235 nm.
Mentions: The calibration plots obtained by plotting the peak area against the concentration of Lithol Rubine B show good linearity over the range 10–80 mg/L. The regression equations were y = 1.17x + 0.387 (correlation coefficient r = 0.9999); the range 0.30–1.2 mg/L and y = 202x + 10.0 (correlation coefficient r = 0.9999) for LC-UV and LC-ED, respectively (Figures 5(a) and 5(b)). Subsequently, we developed a simple and sensitive green electrochemical procedure for determining Lithol Rubine B in real samples. Commercial lipstick was spiked with 0.1, 0.2, or 0.3 mg/L and then analyzed. The calibration plot (Figure 6) shows good linearity. Because it is less expensive than LC-UV analysis, HPLC should be done using a conventional variable wavelength detector to achieve some selectivity and close to the optimum sensitivity of all the colorants. Thus, our proposed analytical method offers a valid and economical alternative to LC-UV detection of Lithol Rubine B.

Bottom Line: For direct current (DC) mode, with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.125 to 1.80 μg/mL was found.The detection limit of our method was approximately 2.0 ng/mL.Findings using HPLC-ECD and HPLC with an ultraviolet detector were comparable.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Chemistry, Chia Nan University of Pharmacy and Science, 60 Erh-Jen Road, Section 1, Jen Te, Tainan 71743, Taiwan.

ABSTRACT
Lithol Rubine B (LRB; the disodium salt of 3-hydroxy-4-[(4-methyl-2-sulfophenyl) azo]-2-naphthalenecarboxylic acid) was detected using high-performance liquid chromatography with an electrochemical (antimony film on silver) detector (HPLC-ECD). For direct current (DC) mode, with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.125 to 1.80 μg/mL was found. The detection limit of our method was approximately 2.0 ng/mL. An antimony-modified silver detector was used to demonstrate that LRB is electrochemically reduced in acidic media and to analyze commercial cosmetics to determine their LRB content. Findings using HPLC-ECD and HPLC with an ultraviolet detector were comparable.

No MeSH data available.