Scientist Profile


Edna C. Quinto

Chemical Sensors, University of Santo Tomas Gold and Silver Series Award (2001)

Expertise: Chemical Sensors

Dr. Edna C. Quinto is recognized for her important contributions in the field of Chemical Sensors A researcher of the National Research Council of the Philippines (NRCP) recently reported a new method of detecting calcium crystals in urine to determine whether a patient is a “stone” or “non-stone” former. Crystals in urine are a form of salts, majority of which are calcium oxalate, which eventually form kidney stones. The conventional method only determines the amount of stone present in urine using a microscope. Dr. Edna C. Quinto, a research professor at the Chemical Engineering Department of the University of Santo Tomas (UST), presented the features of this device her team developed during the Scientific Session of the NRCP Division of Chemical Sciences on July 26, 2016 at UST in España, Manila. Dr. Quinto is an active regular member of the said division. According to Dr. Quinto this technique only requires 5 mL of urine sample to do the test compared with the conventional detection methods that demand robust laboratory analyses that are expensive and work-intensive. In the US, the present urine calcium tests require a 24-hour urine collection. In this research, Dr. Quinto used an LED (light source) and a photoresistor to detect changes in the sample by measuring the amount of light that is absorbed by the precipitate formed when calcium ions in urine is mixed with a known amount of ammonium oxalate. She explained that when the presence of calcium oxalate is high in the urine sample, the light absorbance also tends to be high. This method helped Dr. Quinto determine “stone formers” from “non-stone formers.” Kidney stone formation or nephrolithiasis is considered a debilitating medical condition as hard masses of crystals that are also present in the urinary tract may cause excruciating pain, infection and in severe cases, bleeding. The Senate Committee on Health and Demography estimated in 2011 that 2 million Filipinos may have kidney stones that are left undetected. In Filipinos, the prevalence of kidney stones rises dramatically as men enter their 40s and continues to rise into their 70s. For women, the prevalence of kidney stones peaks in their 50s. Dr. Quinto said that this test is very practical not only because it requires small amount of urine sample but it is also cost-effective. She said that the system costs less than a thousand pesos for consumables such as the LED lights and the photoresistor. The most expensive parts of the system are the power supply and the digital voltmeter. This study is very promising that Dr. Quinto also found that the method can also be employed in detecting water hardness, thus offering practical applications to improve water quality standards. While the technique seems to offer so much potentials and applications, Dr. Quinto said that the methodology needed to be tightened up and standardized as her research team aims for a technology patent and an upgrade by automation using a data logger. Once patented, Dr. Quinto gave an assurance that the technology will be rolled out for use by other government agencies involved in health and nutrition research.


Faculty Researcher, RCNS, Thomas Aquinas Research Complex, University of Santo Tomas, Espana, Manila

Faculty, Faculty of Engineering, UST


    • National Research Council of the Philippines, Associate Member
    • Philippines Institute of Chemical Engineers, Member, Metro Manila Academe Chapter


    • Fu Jen Cahtolic University, Taipei, Taiwan, Teaching Assistant, 1975-1979
    • St. Paul College, Quezon City, Faculty, 1980-1981


    • Silver Series 1994-1996, University of Santo Tomas, Gold and Silver Series Awards, 13 October 1998
    • Silver Series 1998-2000 , University of Santo Tomas Gold and Silver Series Award, 28 Februray 2001


    • Development of a trimethylamine sensitive film based on bromthymol blue, and its application on fish sample: Lapu-lapu (Epinephelus Malabaricus) [Completed]
    • Optical sensor enhancement and confirmation of a CO sensor [Completed]
    • Development of an ammonia-amine sensor based on bromthymol blue, and polyaniline: A confirmation study [completed]
    • Application of the Polyaniline Film sensor on fish samples: Dalagang Bukid (Pterocaesio digramma, Bangus (Chanos,chanos) [On-going]

Papers Presented

    • Monitoring of an Amine Sample using a pH Sensitive Film Sensor, S & T Poster Exhibit, Thomas Aquinas Research Complex, UST
    • Electrochromic Polyaniline as an Ammonia Gas Optical Sensor , Research Colloquium, Research Center for the Natural Thomas Aquinas Research Complex, UST
    • Development of an Optical Sensor for Total Volatile Base Nitrogen Based on Polyaniline, S&T Research Poster Exhibit Research Center for the Natural Sciences, UST
    • Development of Trimethylamine Sensor Based on Bromthymol Blue employing Lapu-lapu (Epinephelus malabaricus), Undergraduate Research Symposium Research Center for the Natural Sciences, UST
    • Determination of the Effectiveness of a Polyaniline-based Optical Sensor for Trimethylamine in Dalagang Bukid (Pterocaesio digramma), S & T Undergraduate Research Symposium
    • Development of a fish packaging sensor based on polyaniline, S&T Undergraduate Research Colloquium


    • University of Santo Tomas, Espana St., Sampaloc Manila, MSc. in Chemistry, 1993
    • University of Santo Tomas, Espana St., Sampaloc Manila, Doctor of Philosophy in Chemistry, 2009


    • Quinto, Edna C. and Sevilla, F. III, (2007) Development of an Ammonia Sensor based on bromthymol blue
    • Acta Manilana Volume 55
    • Quinto, E.C., Rodriguez, N.V., (1999) An optical sensor for lead based on immobilized dithizone
    • Philippine Journal of Science Volume 128, No. 4
    • Quinto, E., Sevilla, F. III, (2005) Optical sensor for ammonia based on polyaniline
    • Asian Conference on New Techniques in Pharmaceutical and Biomedical Research IEEE 2005 Paper No. 57


    • Chemical Sensors, 1995 N-1996 Mr, University of Manchester (fomerly UMIST) at Dept of Instrumentation and Analytical Science