Prinya Masawat

An iPhone-based digital image colorimeter for detecting tetracycline in milk

An iPhone-based digital image colorimeter (DIC) was fabricated as a portable tool for monitoring tetracycline (TC) in bovine milk. An application named ColorConc was developed for the iPhone that utilizes an image matching algorithm to determine the TC concentration in a solution. The color values; red (R), green (G), blue (B), hue (H), saturation (S), brightness (V), and gray (Gr) were measured from each pictures of the TC standard solutions. TC solution extracted from milk samples using solid phase extraction (SPE) was captured and the concentration was predicted by comparing color values with those collected in a database. The amount of TC could be determined in the concentration range of 0.5-10 μg mL(-1). The proposed DIC-iPhone is able to provide a limit of detection (LOD) of 0.5 μg mL(-1) and limit of quantitation (LOQ) of 1.5 μg mL(-1). The enrichment factor was 70 and color of the extracted milk sample was a strong yellow solution after SPE. Therefore, the SPE-DIC-iPhone could be used for the assay of TC residues in milk at the concentration lower than LOD and LOQ of the proposed technique.

Green Determination of Total Iron in Water by Digital Image Colorimetry

ABSTRACT A green iOS digital image colorimeter was fabricated for the determination of total iron in natural water. A mobile application operating on an iOS device was designed using Euclidean distance theory to perform iron determination. The application records the components of the color by storing red, green, and blue values as well as calculating the hue, saturation, brightness, and gray values using standard color theory. The component values obtained from the images of orange solutions of iron(II) complex with 1,10-phenanthroline were collected in a database and used for evaluation of the total iron concentration in water samples. Under the optimal conditions for solid-phase extraction used for sample preconcentration, the enrichment factor was 8.18. The iron concentration was determined by this device for concentrations from 0.01 to 1.0 ppm. The iOS digital image colorimeter achieved a limit of quantitation of 0.1 ppm. The accuracy and precision of the iOS digital image colorimeter were validated using a certified reference material, riverine water. The instrumentation was used for the analysis of natural water samples.

Rapid Low-Cost Determination of Lead(II) in Cassava by an iPod-Based Digital Imaging Colorimeter

Abstract An iPod-based digital image colorimeter was developed for the determination of lead(II) in cassava. The method is based on the color values of a lead(II) solution following its reaction with dithizone. Lead(II) from cassava was extracted using an ultraviolet-digestion unit followed by the color-forming reaction and image capture using the ColorConc application operated on an iPod touch. The concentration was predicted by comparing the color values with those collected in a database. The time needed for complete digestion was 30 min. The determined concentrations of lead(II) were from 0.10 to 1.00 µg mL−1. The limits of detection and quantitation were 0.0120 and 0.0399 µg mL−1, respectively. The recovery values were 105 ± 7.07% and 109 ± 6.61% at 0.2 µg mL−1 and 0.4 µg mL−1 lead(II) (n = 5). The reported method was demonstrated to be simple, accurate, rapid, precise, and low cost.