Photometric detection in flow analysis systems using integrated PEDDs

Martina O'Toole; King Tong Lau; Dermot Diamond

doi:10.1016/j.talanta.2005.01.054

Photometric detection in flow analysis systems using integrated PEDDs

Martina O'Toole, King Tong Lau, Dermot Diamond^*

^*Corresponding author for this work

Dublin City University

Research output: Contribution to journal › Article › peer-review

64 Citations (Scopus)

Abstract

A novel inexpensive optical-sensing technique has been developed for colorimetric flow analysis. This sensing system employs two LEDs whereby one is used as the light source and the other as a light detector. The LED used as light detector is reverse biased with a 5-V supply so that the photocurrent generated by the incident light discharges the capacitance. Direct digital output is provided by a simple timer circuit that measures the time taken for this discharge process from 5 V (logic 1) to 1.7 V (logic 0). This sensing concept has been applied in flow analysis by constructing an optical flow cell with a pair of LEDs. Calibration of the integrated optical flow cell using a dye resulted in a linear response that obeys the Beer-Lambert law. The flow rate, dynamic range, sensitivity and limits of detection were investigated. The system was also used for pH determination in the range of pH 2.5-6.8 using bromocresol green (BCG). The pK_a of BCG was successfully determined by this technique.

Original language	English
Pages (from-to)	1340-1344
Number of pages	5
Journal	Talanta
Volume	66
Issue number	5
DOIs	https://doi.org/10.1016/j.talanta.2005.01.054
Publication status	Published - 15 Jun 2005
Externally published	Yes

Keywords

Colorimetric analysis
LEDs
Optical sensing
Transmission measurements
pH sensing

Access to Document

10.1016/j.talanta.2005.01.054

Cite this

@article{1c7ddd59d00c43c495e6588b317f55de,

title = "Photometric detection in flow analysis systems using integrated PEDDs",

abstract = "A novel inexpensive optical-sensing technique has been developed for colorimetric flow analysis. This sensing system employs two LEDs whereby one is used as the light source and the other as a light detector. The LED used as light detector is reverse biased with a 5-V supply so that the photocurrent generated by the incident light discharges the capacitance. Direct digital output is provided by a simple timer circuit that measures the time taken for this discharge process from 5 V (logic 1) to 1.7 V (logic 0). This sensing concept has been applied in flow analysis by constructing an optical flow cell with a pair of LEDs. Calibration of the integrated optical flow cell using a dye resulted in a linear response that obeys the Beer-Lambert law. The flow rate, dynamic range, sensitivity and limits of detection were investigated. The system was also used for pH determination in the range of pH 2.5-6.8 using bromocresol green (BCG). The pKa of BCG was successfully determined by this technique.",

keywords = "Colorimetric analysis, LEDs, Optical sensing, Transmission measurements, pH sensing",

author = "Martina O'Toole and Lau, {King Tong} and Dermot Diamond",

note = "Funding Information: The authors wish to thank Science Foundation Ireland SFI for grant support under the Adaptive Information Cluster Award (SFI 03/IN3/1361). We also acknowledge valuable help and support provided by Dr. William S. Yerazunis, Mitsubishi Electric Research Laboratories, Broadway, Cambridge, MA, USA.",

year = "2005",

month = jun,

day = "15",

doi = "10.1016/j.talanta.2005.01.054",

language = "English",

volume = "66",

pages = "1340--1344",

journal = "Talanta",

issn = "0039-9140",

number = "5",

}

TY - JOUR

T1 - Photometric detection in flow analysis systems using integrated PEDDs

AU - O'Toole, Martina

AU - Lau, King Tong

AU - Diamond, Dermot

N1 - Funding Information: The authors wish to thank Science Foundation Ireland SFI for grant support under the Adaptive Information Cluster Award (SFI 03/IN3/1361). We also acknowledge valuable help and support provided by Dr. William S. Yerazunis, Mitsubishi Electric Research Laboratories, Broadway, Cambridge, MA, USA.

PY - 2005/6/15

Y1 - 2005/6/15

N2 - A novel inexpensive optical-sensing technique has been developed for colorimetric flow analysis. This sensing system employs two LEDs whereby one is used as the light source and the other as a light detector. The LED used as light detector is reverse biased with a 5-V supply so that the photocurrent generated by the incident light discharges the capacitance. Direct digital output is provided by a simple timer circuit that measures the time taken for this discharge process from 5 V (logic 1) to 1.7 V (logic 0). This sensing concept has been applied in flow analysis by constructing an optical flow cell with a pair of LEDs. Calibration of the integrated optical flow cell using a dye resulted in a linear response that obeys the Beer-Lambert law. The flow rate, dynamic range, sensitivity and limits of detection were investigated. The system was also used for pH determination in the range of pH 2.5-6.8 using bromocresol green (BCG). The pKa of BCG was successfully determined by this technique.

AB - A novel inexpensive optical-sensing technique has been developed for colorimetric flow analysis. This sensing system employs two LEDs whereby one is used as the light source and the other as a light detector. The LED used as light detector is reverse biased with a 5-V supply so that the photocurrent generated by the incident light discharges the capacitance. Direct digital output is provided by a simple timer circuit that measures the time taken for this discharge process from 5 V (logic 1) to 1.7 V (logic 0). This sensing concept has been applied in flow analysis by constructing an optical flow cell with a pair of LEDs. Calibration of the integrated optical flow cell using a dye resulted in a linear response that obeys the Beer-Lambert law. The flow rate, dynamic range, sensitivity and limits of detection were investigated. The system was also used for pH determination in the range of pH 2.5-6.8 using bromocresol green (BCG). The pKa of BCG was successfully determined by this technique.

KW - Colorimetric analysis

KW - LEDs

KW - Optical sensing

KW - Transmission measurements

KW - pH sensing

UR - http://www.scopus.com/inward/record.url?scp=19744377395&partnerID=8YFLogxK

U2 - 10.1016/j.talanta.2005.01.054

DO - 10.1016/j.talanta.2005.01.054

M3 - Article

AN - SCOPUS:19744377395

SN - 0039-9140

VL - 66

SP - 1340

EP - 1344

JO - Talanta

JF - Talanta

IS - 5

ER -

Photometric detection in flow analysis systems using integrated PEDDs

Abstract

Keywords

Access to Document

Other files and links

Cite this