Objective: This article describes the application and the performance of a cheap, simple and portable device that can be used for colorimetric quantitative determination of captopril (CPT) in pharmaceutical preparations. Methods: The sensor is a light detector resistor (LDR) placed into a black PTFE cell and coupled to a low cost multimeter (Ohmmeter). The instrument has been tested and is easy and fast to use. The quantitative study is based mainly on reduction of ammonium molybdate by captopril, in the presence of sulphuric acid, producing a green-yellow compound (λmax 407 nm). The calibration curves were obtained by plotting the electric resistance of the LDR against the CPT concentration on the range of 4.60 × 10-4 to 1.84 × 10-3 mol l-1 with a good coefficient of determination (R2 = 0.9962). Results: Statistical analysis of the obtained results showed no significant difference between the proposed methodology and the official reported method as evident from the t-test and variance ratio at 95% confidence level. Conclusion: The results of this study demonstrate that the instrument can be used for simple, accurate, precise, fast, in situ and low-cost colorimetric analysis of captopril in pharmaceuticals products.64194198Florey, K., (1988) Analytical Profiles of Drug Substances, , New York: Academic PressBrunton, L., Chabner, B., Knollman, B., (2010) Goodman and Gilman's The Pharmacological Basis of Therapeutics, , 20th ed. New York: Mcgraw-HillGuerrero, R.S., Vives, S.S., Calatayud, J.M., Fluorimetric determination of captopril by flow injection analysis (1991) Microchem J, 43 (3), pp. 176-180Zhang, X.R., Baeyens, W.R.G., Weken, G.V.D., Calokerinos, A.C., Nakashima, K., Chemiluminescence determination of captopril based on a rhodamine B sensitized cerium(IV) method (1995) Anal Chim Acta, 303 (1), pp. 121-125Zhang, Z.D., Baeyens, R.G.W., Zhang, X.R., Weken, T.V.D., Chemiluminescense flow injection analysis of captopril applying a sensitized rhodamine 6G method (1996) J Pharmaceut Biomed Anal, 14 (8), pp. 939-945Xinrong, Z., Baeyens, W.R.G., Weken, G.V.D., Calokerinos, A.C., Nakashima, K., Chemiluminescence analysis of captopril: Comparison between luminol and rhodamine B-sensitized cerium(IV) methods (1995) J Pharmaceut Biomed Anal, 13 (4-5), pp. 425-429Economou, A., Themelis, D.G., Theodoridis, G., Tzanavaras, P.D., Sensitive determination of captopril by flow injection analysis with chemiluminescence detection based on the enhancement of the luminol reaction (2002) Anal Chim Acta, 463 (2), pp. 249-255Walily, A.F.M.E., Razak, O.A., Belal, S.F., Bakry, R.S., Utilization of carbon disulphide for the analytical determination of betahistine hydrochloride and captopril in their pharmaceutical preparations (1999) J Pharmaceut Biomed Anal, 21 (2), pp. 439-449Reis, M.E., Attia, F.A., Kenawy, I., Indirect determination of captopril by AAS (2000) J Pharmaceut Biomed Anal, 23 (2), pp. 249-254Mirza, T., Tan, H.S., Determination of captopril in pharmaceutical tablets by anion-exchange HPLC using indirect photometric detectiona study in systematic method development (2001) J Pharmaceut Biomed Anal, 25 (1), pp. 39-52Kok, R.J., Visser, J., Moolenaar, F., Zeeuw, D., Meijer, D.K.F., Bioanalysis of captopril: Two sensitive high-performance liquid chromatographic methods with pre-or post-column fluorescent labeling (1997) J. Chromatogr B, 693 (1), pp. 181-189Jankowski, A., Skorek, A., Krzyr Ko, K., Zarzycki, P.K., Ochocka, R.J., Lamparczyk, H., Captopril: Determination in blood and pharmacokinetics after single oral dose (1995) J Pharmaceut Biomed Anal, 13 (4-5), pp. 655-660Sypniewski, S., Bald, E., Determination of captopril and its disulphides in whole human blood and urine by highperformance liquid chromatography with ultraviolet detection and pre-column derivatization (1996) J. Chromatogr A, 729 (1-2), pp. 335-340Bald, E., Sypniewski, S., Determination of thiol drugs in pharmaceutical formulations as their 5-pyridinium derivatives by high-performance liquid chromatography with ultraviolet detection (1997) Fresenius J Anal Chem, 358 (4), pp. 554-555Cavrini, V., Gatti, R., Dipietra, A.M., Raggi, M.A., HPLC Determination of thiol drugs in pharmaceutical formulations using ethacrynicacid as a pre-column ultraviolet derivatization reagent (1987) Chromatographia, 23 (9), pp. 680-683Cavrini, V., Gotti, R., Andrisano, V., Gatti, R., 1, 1'-[ethenylidenebis(sulfonyl)]bis-benzene: A useful prechromatographic derivatization reagent for HPLC analyses of thiol drugs (1996) Chromatographia, 42 (9-10), pp. 515-520Favaro, G., Fiorani, M., Determination of pharmaceutical thiols by liquid chromatography with electrochemical detection: Use of an electrode with a conductive carbon cement matrix, chemically modified with cobalt phthalocyanine (1996) Anal Chim Acta, 332 (2-3), pp. 249-255Liu, Y.C., Wu, H.L., Kou, H.S., Chen, S.H., Wu, S.M., Derivatization gaschromatographic determination of captopril (1995) Anal Lett, 28 (8), pp. 1465-1481Fraga, J.M.G., Abizanda, A.I.J., Moreno, F.J., Leon, J.J.A., Application of principal component regression to the determination of captopril by differential pulse polarography with no prior removal of dissolved oxygen (1998) Talanta, 46 (1), pp. 75-82Stefan, R.I., van Staden, J.F., Aboul-Enein, H.Y., On-line assay of Scaptopril using an amperometric biosensor/sequential injection system (2000) Anal Chim Acta, 411 (1-2), pp. 51-56Palomeque, M.E., Band, B.S.F., Flow injection biamperometric determination of captopril (2002) J Pharmaceut Biomed Anal, 30 (3), pp. 547-552Mohamed, M.E., Aboul-Enein, H.Y., Amperometric and conductimetric methods for simultaneous determination of captopril and bendroflumethiazide (1985) Anal Lett, 18 (20), pp. 2591-2603(2007) USP-The United States Pharmacopeia: The National Formulary, , 25th ed. Rockville: The United States Pharmacopeial Convention-Twinbrook ParkwayMohamed, M.E., Aboulenein, H.Y., Gadkariem, E.A., Potentiometric and visual titrimetric methods for analysis of captopril and its pharmaceutical forms (1983) Anal Lett Pt B, 16 (1), pp. 45-55El-Brashy, A., Titrimetric determination of captopril in dosage forms (1995) Acta Pharm Hung, 65 (3), pp. 91-93Stefan, R.I., van Staden, J.K.F., Aboul-Enein, H.Y., A new construction for a potentiometric, enantioselective membrane electrode-its utilization to the S-captopril assay (1999) Talanta, 48 (5), pp. 1139-1143Pimenta, A.M., Araujo, A.N., Montenegro, M.C.B.S.M., Sequential injection analysis of captopril based on colorimetric and potentiometric detection (2001) Anal Chim Acta, 438 (1-2), pp. 31-38Ribeiro, P.R.S., Santini, A.O., Pezza, H.R., Pezza, L., Potentiometric determination of captopril in pharmaceutical formulations (2003) Eclet Quim, 28 (1), pp. 39-44Hillaert, S., Van den Bossche, W., Determination of captopril and its degradation products by capillary electrophoresis (1999) J Pharmaceut Biomed Anal, 21 (1), pp. 65-73Nikolic, K., Velasevic, K., Conductometric determination of captopril (1989) Pharmazie, 44 (2), pp. 155-156Nikolic, K., Valasevic, K.S., Coulometric determination of captopril (1991) Acta Pol Pharm, 48 (1-2), pp. 5-7Sarna, K., Fijalek, Z., Voltammetric and electrochemical quartz crystal microbalance study of antithyroid drugs (1997) Chem Anal.-Warsaw, 42 (3), pp. 425-433Ribeiro, P.R.S., Pezza, L., Pezza, H.R., A simple and environmentally friendly reflectometric method for the rapid quantitative analysis of captopril in pharmaceutical formulations (2011) Eur J Anal Chem, 6 (2), pp. 90-103Askal, H.F., New spectrophotometric methods for determination of captopril bulk drug and tablets (1991) Talanta, 38 (10), pp. 1155-1158Ashour, F.M.S., Salama, F.M., Aziza, M.A.E., A colorimetric method for the determination of captopril (1990) J Drug Res, 19 (1-2), pp. 323-326Albero, M.I., Sanchezpetreno, C., Garcia, M.S., Rodenas, V., Determination of captopril in pharmaceutical samples by flowinjection analysis (1993) J Pharmaceut Biomed Anal, 11 (10), pp. 887-891Jovanovic, T., Stanovic, B., Koricanac, Z., Spectrophotometric investigation on complex-formation of captopril with palladium(II) and its analytical application (1995) J Pharmaceut Biomed Anal, 13 (3), pp. 213-217Tzanavaras, P.D., Themelis, D.G., Economou, A., Theodoridis, G., Reversed flow-injection manifold for the spectrophotometric determination of captopril based on its inhibitory effect on the Co(II)-2, 2′-dipyridyl-2-pyridylhydrazone complex formation (2002) Talanta, 57 (3), pp. 575-581Sanghavi, N.M.S., Samarth, M.M., Matharu, R., Singh, P.S., Colorimetric estimation of captopril and its formulations (1991) Indian Drugs, 28 (4), pp. 189-191Sastry, C.S.P.S., Sailaja, A., Rao, T.T., Determination of captopril by two simple spectrophotometric methods using oxidative coupling reaction (1991) Pharmazie, 46 (6), pp. 465-557Karlicek, R., Solich, P., Flow-injection spectrophotometric determination of captopril using on-line solid phase extraction (1998) Pharmazie, 53 (8), pp. 549-551El-Ashry, S., Ibrahim, F., Colorimetric determination of captopril in dosage forks (1992) Anal Lett, 25 (9), pp. 1657-1672Ribeiro, P.R.S., Pezza, L., Pezza, H.R., Tognolli, J.O., Spectrophotometric determination of captopril through charge transfer complex formation using fractional factorial and central composite design (2011) Lat Am J Pharm, 30 (6), pp. 1158-1166Ribeiro, P.R.S., Pezza, L., Pezza, H., A simple spectrophotometric method for the determination of captopril in pharmaceutical preparations using ammonium molybdate (2010) Eclet Quim, 35 (3), pp. 179-188Silva, F.C.M., Matos, O.R., Ribeiro, P.R.S., Development and validation of a new, simple and sensitive spectrophotometric method for the determination of captopril in marketed dosage formulations (2014) Lat Am J Pharm, 33 (1), pp. 142-150Rossi, A.V., He, X.W., Tubino, M., A simple, portable and low cost device for a colorimetric spot-test quantitative analysis (2000) Anal Lett, 33 (9), pp. 1885-1898Wang, L.Q., Dang, G.C., Zheng, L.P., Yuan, K.Z., A simple optical fiber reflectance spectrophotometer and its application in identification of pigments on relics (2000) Chinese J Anal Chem, 28 (4), pp. 513-517Acharya, Y.B., Jayaraman, A., Sun photometry using photodiode open-circuit voltage measurements (1995) Rev Sci Instrum, 66 (8), pp. 4087-4090Richter, E.M., Rocha, F.R., Angnes, L., Multímetro interfaceado de baixo custo para aquisição de dados (2004) Quim Nova, 27 (2), pp. 313-314Ooba, S., An automatic titrator for measurement of exchange capacity and titration curve of ion-exchanger (1991) Bunseki Kagaku, 40 (4), pp. 87-90Watanabe, K., Okada, K., Oda, H., Katsu, T., Development of a portable cocaine-selective electrode (1997) Bunseki Kagaku, 46 (12), pp. 1019-1023Richter, E.M., de Jesus, D.P., Neves, C.A., do Lago, C.L., Angnes, L., Aplicações eletroanalíticas com eletrodos de prata confeccionados a partir de CDs graváveis (2003) Quim Nova, 26 (6), pp. 839-843Barnard, W.R., Kelley, J.C., Gidden, R., Eberhard, W.H., A lecture room digital multimeter (1968) J Chem Educ, 45 (3), pp. 206-208Vreman, H.J., Stevenson, D.K., Oh, W., Fanaroff, A.A., Wright, L.L., Lemons, J.A., Semiportable electrochemical instrument for determining carbon-monoxide in breath (1994) Clin Chem, 40 (10), pp. 1927-1933Sevilla, F., Alfonso, R.L., Andres, R.T., The electrician's multimeter in the chemistry teaching laboratory: Part 2: Potentiometry and conductimetry (1993) J Chem Educ, 70 (7), pp. 580-584Yue, F., Ngin, T.S., Hailin, G., A novel paper pH sensor based on polypyrrole (1996) Sensor Actuat B-Chem, 32 (1), pp. 33-39Arnold, M.A., Fiber-optic chemical sensors (1992) Anal Chem, 64 (21), pp. 1015-1025Seitz, W.R., Sepaniak, M.J., Chemical sensors based on immobilized indicators and fiber optics (1988) Crit Rev Anal Chem, 19 (2), pp. 135-173Skoog, D.A., Holler, F.J., Nieman, T.A., (2002) Princípios de análise instrumental, , 5th ed. Porto Alegre: BookmanLong, G.L., Winefordner, J.D., Limit of detection a closer look at the IUPAC definition (1983) Anal Chem, 55 (7), pp. 712-715Araujo, P., Key aspects of analytical method validation and linearity evaluation (2009) J Chromatogr B, 877 (23), pp. 2224-2234Bratinova, S., Raffael, B., Simoneau, C., (2009) Guidelines for performance criteria and validation procedures of analytical methods used in controls of food contact materials, , 1st ed. Luxembourg: Office for Official Publications of the European CommunitiesMiller, J.C., Miller, J.N., (1993) Estadística para Química Analítica, , 2nd ed. Delaware: Addison-Wesley Iberoamericana S. AHorwitz, W., Evaluation of analytical methods used for regulation of foods and drugs (1982) Anal Chem, 54 (1), pp. 67-76(1993) Peer verified methods program: Manual on policies and procedures, , AOAC-Association of Official Analytical Chemists, 1st ed. Arlington: AOAC International