Frequency-selective absorbance detection: Refractive index and turbidity compensation with dual-wavelength measurement

Eom, In Yong; Dasgupta, Purnendu Κ.

doi:10.1016/j.talanta.2005.11.033

Cited by 15 publications

(15 citation statements)

References 26 publications

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“…Light‐emitting diodes (LEDs) have been widely used as a light source by replacing conventional light sources and/or a monochromator in many optical measurements because of their wide range of emission wavelength covering from the infrared (IR) to ultraviolet (UV), good stability in light intensity ( i . e ., lower fluctuation in intensity), and narrow emission bands …”

Section: Introductionmentioning

confidence: 99%

“…Elimination of optical filter can enhance the sensitivity of an optical measurement system because optical filters reduce light intensity registered on a photodetector. Light level should be converted to electrical signals and any photodetector is surrounded by many different types of electrical noises so higher light intensity is usually preferred to get higher sensitivity …”

Section: Introductionmentioning

confidence: 99%

“…Light-emitting diodes (LEDs) have been widely used as a light source by replacing conventional light sources and/or a monochromator in many optical measurements because of their wide range of emission wavelength covering from the infrared (IR) to ultraviolet (UV), good stability in light intensity (i.e., lower fluctuation in intensity), and narrow emission bands. [1][2][3][4][5] In all optical sensing instruments, a proper photodetector should be employed to extract qualitative and quantitative information from samples by measuring light intensity of a light source or luminescence light from an analyte. It is not widely known that an LED also can detect light.…”

Section: Introductionmentioning

confidence: 99%

“…Light level should be converted to electrical signals and any photodetector is surrounded by many different types of electrical noises so higher light intensity is usually preferred to get higher sensitivity. 2 LEDs are originally designed to be used as a light source not as a photodiode. Therefore, the sensing ability of light varies from an LED to another.…”

Section: Introductionmentioning

confidence: 99%

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Spectral Responses of Light‐Emitting Diodes as a Photodiode and Their Applications in Optical Measurements

Shin

Kim

Eom

2016

Bulletin Korean Chem Soc

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Spectral responses of four light‐emitting diodes (LEDs) were investigated because their uses as a photodiode are growing these days. An LED showed reasonable sensitivity to shorter wavelengths which the LED emits. Their spectral response ranges are same or relatively wider than their emission range. In addition, LEDs were used as detectors to analyze test dyes with absorbance measurement technique or with fluorescence measurement technique. Absolute noise level of 0.0001 absorbance unit was observed with the blue LED (nominal λmax = 455 nm) photodiode. Phosphate amount in Kumho River (located in Gyeongsan, South Korea) was determined using IR LED (nominal λmax = 805 nm) as a photosensor. A green LED (nominal λmax = 520 nm) was used to excite rhodamine B (excitation λmax = 560 nm, emission λmax = 575 nm) and red LEDs (nominal λmax = 660 nm) were used to detect fluorescence light emitted from the fluorescence dye. The LOD of rhodamine B was found to be 26 nM with four red LEDs as a photodiode and without using optical filters.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spectral Responses of Light‐Emitting Diodes as a Photodiode and Their Applications in Optical Measurements

Shin

Kim

Eom

2016

Bulletin Korean Chem Soc

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“…In a later modification, instead of the LED, the common leg of a bifurcated fiber optic (FO, http://www.dolan-jenner.com) was the light source. The two free distal ends of the FO were coupled to a 583 and a 653 nm LED (signal and reference), 42,43 respectively driven at 30 and 31 mA. The two LEDs were alternately turned on and off at 0.33 Hz (1.5 s on-period, each) controlled via an N-channel logic level MOSFET switch (IRLI530N, www.irf.com) (the schematic appears in Figure S10 in the SI).…”

Section: Methodsmentioning

confidence: 99%

Rapid Point of Care Analyzer for the Measurement of Cyanide in Blood

Ohira

Mishra

et al. 2011

Anal. Chem.

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A simple, sensitive optical analyzer for the rapid determination of cyanide in blood in point of care applications is described. HCN is liberated by the addition of 20% H3PO4 and is absorbed by a paper filter impregnated with borate-buffered (pH 9.0) hydroxoaquocobinamide Hereinafter called cobinamide). Cobinamide on the filter changes color from orange (λmax = 510 nm) to violet (λmax = 583 nm) upon reaction with cyanide. This color change is monitored in the transmission mode by a light emitting diode (LED) with a 583 nm emission maximum and a photodiode detector. The observed rate of color change increases 10x when the cobinamide solution for filter impregnation is prepared in borate-buffer rather than in water. The use of a second LED emitting at 653 nm and alternate pulsing of the LEDs improve the limit of detection by 4x to ~ 0.5 μM for a 1 mL blood sample. Blood cyanide levels of imminent concern (≥ 10 μM) can be accurately measured in ~ 2 min. The response is proportional to the mass of cyanide in the sample – smaller sample volumes can be successfully used with proportionate change in the concentration LODs. Bubbling air through the blood-acid mixture was found effective for mixing of the acid with the sample and the liberation of HCN. A small amount of ethanol added to the top of the blood was found to be the most effective means to prevent frothing during aeration. The relative standard deviation (RSD) for repetitive determination of blood samples containing 9 μM CN was 1.09% (n=5). The technique was compared blind with a standard microdiffusion-spectrophotometric method used for the determination of cyanide in rabbit blood. The results showed good correlation (slope 1.05, r2 0.9257); independent calibration standards were used.

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Accuracy Improvement When Determining Copper(II) Ions With Zincon at Acidic Condition

Lee

Kim

Eom

2020

Bulletin Korean Chem Soc

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2-Carboxy-2 0-hydorxy-5 0-sulfoformazylbenzene has been widely used to determine Cu(II) ions. In general, basic pH condition is preferred to enhance the reactivity between metal ions and zincon. But acidic condition can be applied for copper determination because Cu(II) cannot lose reactivity at acidic condition. Also, pH = 5 condition can minimize the interference from zinc which is found together with copper in many samples. However, zincon can be precipitated at acidic condition. We minimized precipitation problem by adding cyclohexanone or the use of lower buffer concentration. Using this approach, accuracy was improved from −17.7 to 242.5% to −0.4% to 22.0%. A very linear calibration curve (r 2 = 0.9999) was obtained for the copper concentration range of 30-2002 ng/mL. This method was successfully applied to determine copper concentration from discharged water samples. No significant interference was observed and the estimated LOD (S/N = 3) is 5.5 ng/mL.

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Frequency-selective absorbance detection: Refractive index and turbidity compensation with dual-wavelength measurement

Cited by 15 publications

References 26 publications

Spectral Responses of Light‐Emitting Diodes as a Photodiode and Their Applications in Optical Measurements

Spectral Responses of Light‐Emitting Diodes as a Photodiode and Their Applications in Optical Measurements

Rapid Point of Care Analyzer for the Measurement of Cyanide in Blood

Accuracy Improvement When Determining Copper(II) Ions With Zincon at Acidic Condition

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