Investigation into the predictive performance of colorimetric sensor strips using RGB, CMYK, HSV, and CIELAB coupled with various data preprocessing methods: a case study on an analysis of water quality parameters

Journal of Analytical Science and Technology

Table 1 Detail of colorimetric strips used in this investigation

Analyte	No. of sensors	Concentration range	Concentrations of training samples	Concentrations of validation samples
Manganese ion (Mn²⁺)	1	0, 2, 5, 20, 50, and 100 (ppm)	0.00, 3.00, 7.00, 15.00, 25.00, 45.00, 60.00, 80.00, and 100.00	2.00, 5.00, 10.00, 20.00, 35.00, 50.00, 70.00, and 90.00
Copper ion (Cu²⁺)	1	0, 10, 30, 100, and 300 (ppm)	0.00, 10.00, 30.00, 80.0, 120, 170.00, 200.00, and 300.00	5.00, 20.00, 40.00, 100.00, 150.00, 180.00, and 2500.0
Iron ion (Fe²⁺/Fe³⁺)	1	0, 2, 5, 10, 25, 50, and 100 (ppm)	0.00, 3.00, 7.00, 15.00, 25.00, 45.00, 60.00, 80.00, and 100.00	2.00, 5.00, 10.00, 20.00, 35.00, 50.00, 700.00, and 90.00
Nitrate (NO₃^-)	1	0,10, 25, 50, 100, 250, and 500 (ppm)	0.00, 10.00, 20.00, 30.0, 50.0, 100.00, 200.0, 350.00, and 500.00	5.00, 15.00, 25.00, 40.0, 75.0, 150.00, 250.00, and 450.00
Phosphate (PO₄^3-)	1	0, 3, 10, 25, 50, and 100 (ppm)	0.00, 2.00, 5.00, 10.00, 20.00, 30.00, 50.0, 70.0, 90.00, and 100.00	1.00, 3.00, 7.00, 15.00, 25.00, 40.00, 60.00, and 80.00
Sulfate (SO₄^2-)	4	< 200, > 400, > 800, > 1200, and > 1600 (ppm)	0.00, 200.00, 400, …, 1600	100,300, 500, …, 1500
Total hardness (CaCO₃)	5	< 54, > 90, > 180, > 270, > 360, and > 445 (ppm)	0.00, 59.00, 75.00, 100.00, 137.00, 250.00, and 450.00	50.00, 62.00, 87.00, 106.00, 150.00, 200.00, and 375.00
pH	4	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14	0.93, 2.86, 4.70, 6.66, 9.10, 10.97, and 12.66	1.83, 3.85, 5.83, 7.20, 9.64, and 11.76