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Hindawi Journal of Analytical Methods in Chemistry Volume 2023, Article ID 3400863, 13 pages https://doi.org/10.1155/2023/3400863 Research Article An Environmentally Friendly Compact Microfluidic Hydrodynamic Sequential Injection System Using Curcuma putii Maknoi & Jenjitt. Extract as a Natural Reagent for Colorimetric Determination of Total Iron in Water Samples 1 2 Maneerat Namjan , Natcha Kaewwonglom , 1 2,3 Chonlada Dechakiatkrai Theerakarunwong , Jaroon Jakmunee , and Wanpen Khongpet Program of Chemistry, Faculty of Science and Technology, Nakhon Sawan Rajabhat University, Nakhon Sawan 60000, Tailand Laboratory for Analytical Instrumentation and Electrochemistry Innovation, Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Tailand Environmental Science Research Center,and Center of Excellence for Innovation in Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Tailand Correspondence should be addressed to Wanpen Khongpet; email@example.com Received 23 July 2022; Revised 16 November 2022; Accepted 15 December 2022; Published 13 January 2023 Academic Editor: Leandro Wang Hantao Copyright © 2023 Maneerat Namjan et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te miniaturization of analytical systems and the utilization of nontoxic natural extract from plants play signifcant roles for green analytical chemistry methodology. In this work, the microfuidic hydrodynamic sequential injection (HSI) with the LED- phototransistor colorimetric detection system has been proposed to create an ecofriendly and low-cost miniaturized analytical system for online determination of iron in water samples using Curcuma putii Maknoi & Jenjitt. extracts as high stability and good selectivity of a natural reagent. Te proposed method was designed for online solution mixing and colorimetric detection on a microfuidic platform. Te Curcuma putii Maknoi & Jenjitt. extracts and standard/samples were sequentially aspirated to fll the channel before entering the built-in fow cell. Te intensity of iron-Curcuma putii Maknoi & Jenjitt. extract complex was monitored under the optimum conditions of fow rate, sample volume, mixing zone length, and aspiration sequences, by altering the gain control of the colorimetric detector to achieve good sensitivity. Te results demonstrated a good performance of the green −1 analytical systems. A linear calibration graph in the range of 0.5–6.0 mg L was obtained with a limit of detection at an adequate −1 −1 level of 0.11 mg L for water samples with a sample throughput of 30 h . Te precise and accurate measurement results were achieved with relative standard deviations in the range of 1.61–1.72%, and percent recoveries were found in the range of 90.6–113.4. Te proposed method ofers cost-efective, easy operation over an appropriate analysis time (2 min/injection) with good sensitivity and is environmentally friendly with low consumption of solutions and the use of high stability and good selectivity of nontoxic reagents. Te achieved method was demonstrated to be a good choice for routine analysis. and industrial wastes are essential parameters for the exis- 1. Introduction tence of iron in natural water such as rivers, lakes, and Iron is one of the most important metals in the environ- groundwater. Te iron level in groundwater can be increased mental geochemical, industrial, and biological processes. It by the dissolution of iron compounds in soils or ferrous can be chemically combined with many other elements to boreholes and handpump components through leaching form iron ores. Te natural deposits and refning of iron ores from home water drinking, cooking, washing, cleaning, and 2 Journal of Analytical Methods in Chemistry (-OH) bonded directly to an aromatic ring and are capable of agricultural purposes [1, 2]. Generally, iron exists in natural −1 fresh waters in the range of 0.5 to 50 mg L . Te presence of binding or chelating with metal ions. Tus, plant extracts containing phenolic compounds can be used as a natural iron above the certain level produces a reddish color of water, metallic taste, a distinct odor, turbidity, and a ten- complexing agent for metal ions. dency to stain clothes. In submerged paddy felds, a ferric ion Curcuma putii Maknoi & Jenjitt. is a new species dis- is reduced to the more soluble ferrous ion under the con- covered in central Tailand . Te leaves of this species ditions of low pH and anaerobic environment. Te excess are rich in phenolic compounds that have antioxidant ac- ferrous form can lead to cytotoxicity in rice as it is absorbed tivity. Tese compounds contain a large number of OH by the roots and accumulated in plant tissues, leading to groups and a strong ability to complex with metals. Con- tissue destruction and yield loss [3, 4]. Terefore, monitoring sequently, it is possible that Curcuma putii Maknoi & Jenjitt. of the iron levels in water is extremely essential for water extract could be applied as a great complexing agent with high stability, good selectivity, and sensitivity for iron quality evaluation and water pollution control to determine the suitability of water for consumption and other appli- quantifcation by the microfuidic HSI system. Terefore, in this work, the combination of a compact cations. Te recommended limit of iron in groundwater and drinking water by the World Health Organization (WHO) is and cost-efective microfuidic HSI and Curcuma putii −1 0.3 mg L Maknoi & Jenjitt. extract was proposed for the determination . Water for irrigation the iron levels above 0.1 mg −1 L may cause drip emitter clogging irrigation [5, 6]. of total iron in water samples based on a green chemical Various analytical techniques have been developed for analysis process. Te proposed method exhibited higher the determination of iron in water samples. Tese methods stability than the other plant extracts that have previously include ultraviolet-visible spectrophotometry (UV-Vis) been reported for iron determination and ofered good [7, 8], atomic absorption spectroscopy (AAS) , liquid sensitivity with a homemade colorimetric detection device. chromatography , potentiometry , and voltammetry Te special feature of the detector is its ability to adjust its sensitivity using a gain-adjustable signal. Typically, there is . Among these techniques, UV-Vis spectrophotometry is the analysis instrument with easy operation and simple no distinction in the narrow concentration range since the generated signals all have the same shade. In this work, colorimetric detection in the visible region with several reagents to form color complexes and can be encountered in amplifcation of the signal with adjustable gain can assist to almost every laboratory. However, this technique involves distinguish a small concentration range. Te satisfactorily high cost and large sizes that consume high amounts of selectivity and reproducibility results were achieved with chemicals. Moreover, complete chemical reactions are im- a portable device and an environmentally friendly approach portant for the detection of the products. Tus, microfuidic which is suitable for water quality monitoring. technology is currently of interest for the development of a detection system with portability advantages, low-cost 2. Materials and Methods integrated miniaturized devices, providing a low solution consumption. To obtain automatic operation and sufcient 2.1. Chemicals and Materials. All chemicals were of ana- sensitivity of the detection device, fow-based analytical lytical reagent grade, and deionized water was used for the systems such as fow injection (FI), sequential injection (SI), preparation of all solutions throughout the experiment. A −1 and hydrodynamic sequential injection (HSI) have gained stock standard solution of iron (II) at 1000 mg L was more attention recently for good alternative choices. Among prepared by dissolving 0.7022 g of ammonium ferrous these fow-based techniques, HSI presents an excellent sulfate hexahydrate (Sigma-Aldrich, England) in water system in terms of cost, chemical consumption, and auto- containing 1.0% (v/v) concentrated sulfuric acid (BDH, matic operation. However, its drawbacks revealed to human England); then, the volume was adjusted to 100 mL. Te −1 health and environmental concerns because most of the stock standard solution of iron (III) at 1000 mg L was reagents are toxic such as Tiron, 1,10 phenanthroline, 2-(5- prepared in the same way with 0.1 g of ferric chloride (BDH, bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl) England). A series of working standard solutions were amino] aniline, ferrozine, nitroso-R, 4,7-diphenyl-1,10- prepared daily by diluting the stock standard solution to the phenanthroline, bathophenanthroline, 2,2′-bipyridine, desired concentrations. Acetate bufer (0.2 M, 500 mL) deferiprone, thiocyanate, and 3-hydroxy-1,2-dimethyl- pH 4.8 was prepared by dissolving 7.21 g of sodium acetate 4(1H)-pyridinone [2, 13–15]. To solve this problem, a nat- trihydrate (Carlo Erba, Italy) in water containing 2.72 mL of ural reagent along with a microfuidic HSI system for the acetic acid (Carlo Erba, Italy). determination of iron is considered as a remarkable tech- nique. Te use of natural extract ofers safer and greener colorimetric reagents for humans and the ecosystem. Some 2.2. Curcuma putii Maknoi & Jenjitt. Extraction. Dry Cur- plant extracts were utilized as natural reagents in con- cuma putii Maknoi & Jenjitt. leaves of 1.0 g were extracted junction with digital images by a mobile phone and FI with 40 mL of 70% (v/v) ethanol using ultrasonic for 1 hour system for iron determination such as green tea , guava and subsequently fltered through a flter paper (Whatman leaves , and Phyllanthus emblica Linn.  that showed No. 4). For ongoing usage during the day, the fltrate was successful quantitative analysis in real samples. In all of these maintained at room temperature. Te extract was prepared plant extracts, phenolic compounds were found as common from fresh Curcuma putii Maknoi & Jenjitt. leaves daily, and active compounds. Tey are comprised of a hydroxyl group the concentration of the total phenolic component was also Journal of Analytical Methods in Chemistry 3 determined before use. Te use of the same extraction 2.4. Stability Study of the Curcuma putii Maknoi & Jenjitt. methods with the same batch of Curcuma putii Maknoi & Extract. Te Curcuma putii Maknoi & Jenjitt. extract was Jenjitt. leaves was one of these criteria. Te total phenolic prepared in the suitable extract solvent from the previous contents of Curcuma putii Maknoi & Jenjitt. extracts were experiment and let to stand in the brown bottle at room quantifed using the Folin–Ciocalteau assay  and were temperature for 0–7 hours and up to 30 days before mixing −1 −1 found to be 2,021 mg L (80.33± 2.12 mg/g dry weight), with 10 mg L of iron (III). Te mixtures were prepared as which was employed in the experiment. previously described. Finally, the absorption spectra were Te most active compounds of phenolic compounds, measured to investigate absorption characteristics. including favonoids and tannins, have the ability to chelate metal ions. Tis research believed that favonoids or tannins 2.5. Microfuidic HSI Design and Assembly. Te microfuidic were the major compounds in Curcuma putii Maknoi & HSI colorimetric system (Figure 1) was designed for the Jenjitt. extract for chelating with metal. Terefore, the ferric determination of total iron using Curcuma putii Maknoi & test and Shinoda’s test procedures were used for tannins and Jenjitt. extract as a natural reagent. It consisted of a 5.0 mm favonoids determination, respectively [21, 22]. Moreover, thickness black polymethyl methacrylate (PMMA) platform tannins are generally classifed into hydrolysable (gallo- (80 mm × 140 mm) that contained a microfuidic channel tannins and ellagitannins), condensed, and complex tannins. (0.5 mm width × 0.5 mm deep) and a built-in fow cell with Terefore, the analysis of tannins in Curcuma putii Maknoi a laser cutting machine (MK2230, Mass Business Co. Ltd., & Jenjitt. was preliminarily studied using the acid butanol Tailand) for online sampling and reagents mixing and test, nitrous acid test , and potassium iodate test . product detection, 1.0 mm thickness clear PMMA Te acid butanol test is specifc for condensed tannins, (80 mm × 140 mm) as a top cover on the platform, and forming a red-orange to red-crimson product. Hydrolysable peristaltic pump (Ismatec, Model ISM796B-230 V, Swit- tannins ellagitannins can be determined with a nitrous acid zerland) ftted with Tygon pump tubings (1.14 mm i.d.) test, which forming a red or pink color and slowly changing which were connected to PTFE tubing in each port of the color to purple or blue while potassium iodate can also be microfuidic channel on the platform. All ports were con- used for the detection of gallotannins, forming pink color. nected with 2-way solenoid valves (Biochem Valve, To confrm the major active compound in Curcuma putii 075T2NC12-32, 20 PSI 12 VDC, USA) or a 3-way solenoid Maknoi & Jenjitt. extract, liquid chromatography-mass valve (NResearch, HP161T031, 12 VDC 100 PSI, USA) spectrometry (LC-MS) was used for the identifcation of which was controlled by Control Solenoid Valve 3.0 software phenolic compounds. Tis method mainly aims to identify of a homemade controller connected to the personal the compounds present in the extracts. LC-MS was used computer to detect the fow of solutions by turning on/of under the following instrumental operating conditions: the valves, and a simple homemade light-emitting diode column-Hypersil GOLDTM PFP (100 × 2.1 mm i.d., 1.9μm), phototransistor (LED-PT)-based colorimetric detector using mobile phase: (A) 0.1% formic acid in water and (B) meth- a red LED (maximum emission: 660 nm) as a light source anol, gradient elution: 0% B in A for 2 min, linear increasing which was assembled in a built-in fow cell in the micro- from 0% B in A to 100% B in A for 8 min, and 100% B for fuidic platform, and a data acquisition unit (eDAQ 2 min, fow rate 1 mL/min, and detection: UV 254 nm. Australia). 2.3.StudyoftheCurcumaputiiMaknoi&Jenjitt.Extract-Iron 2.6.DetectionofTotalIron. First of all, the microfuidic HSI −1 Complex Formation. In this study, 10 and 100 mg L colorimetric system (Figure 1) was cleaned thoroughly of both iron (II) and iron (III) complexes with Curcuma putii with deionized water by switching solenoid valves Maknoi & Jenjitt. extracts were extracted by using various (SV1–SV5) to the fow cell position for 2 minutes and solvents including deionized water, acetate bufer (pH 4.8), propelling the carrier solution (acetate bufer) for and ethanol in order to study the extraction efciency. Te 2 minutes. Ten the Curcuma putii Maknoi & Jenjitt. procedure is briefy described as follows: Both 2.5 mL extract was aspirated into the microfuidic channel on the −1 standard solutions of iron (II) and iron (III) of 1,000 mg L platform for 6 seconds by a peristaltic pump, 2-way so- were mixed with 10 mL of Curcuma putii Maknoi & Jenjitt. lenoid valve 2 (SV2), and 3-way solenoid valve 5 (SV5, extract in three extraction solvents (water, acetate bufer position “out”) while 2-way solenoid valves 1, 3, and 4 (SV1, SV3, SV4) were closed. In this step, the solution was pH 4.8, and ethanol) and adjusted to the fnal volume of 25 mL with acetate bufer. After 30 min, the mixtures of flled into the zone A (50 μL, R1), and the excess volume was discarded into the reservoir for waste collection. Te each extraction solvent were scanned for absorption spectra measurement at the visible range of 500–800 nm using aspiration of the standard solution of iron (III)/sample a UV-Vis spectrophotometer (Termo Fisher Scientifc, solution (75 μL zone B, S) and Curcuma putii Maknoi & USA). Te Curcuma putii Maknoi & Jenjitt. extracted Jenjitt. extract (50 μL zone C, R2) were similarly operated without iron was used as a blank solution. Te complex as previously described, but 2-way solenoid valve 3 (SV3) −1 formation of both 10 mg L iron (II) and iron (III) with and 2-way solenoid valve 4 (SV4) were opened for 8 and Curcuma putii Maknoi & Jenjitt. extracts were prepared 6 seconds to fll in the zone B and zone C, respectively. −1 Tus, the sequence of solution zones was R1 S R2, re- similarly but with 100 mg L standard solutions of iron (II) and iron (III). spectively, for efcient mixing between the natural 4 Journal of Analytical Methods in Chemistry Phototransistor Flow cell 10 mm Injection Open R1 S R2 Carrier MX Carrier R1 S R2 W LED Close Close Close Close SV1 Phototransistor Colorimeter zone zone zone MX A B C R2 R1 S FC/D Carrier Carrier Interface LED SV5 SV2 SV3 SV4 out In pump R1 S R2 A B C D E F controller Figure 1: Te schematic of the microfuidic HSI system for determination of total iron, using acetate bufer solution as a carrier, where S � standard/sample, R1 and R2 � natural reagent, MX � mixing zone, FC � fow cell, D � homemade LED/phototransistor colorimeter, SV � solenoid valve, and W � waste. reagent and standard/sample solution. Finally, injection usage to reduce metal ion sorption from the sample storage step, all solution zones were pushed by acetate bufer bottle. Te samples were analyzed within 24 hours after carrier stream through the mixing zone with 2-way so- sampling. lenoid valve 1 (SV1) into the fow cell with 10 mm path To investigate the efcient detection of the proposed length to monitor the color of complex formation and method for the determination of total iron, the standard record the signal profles continuously on a personal samples were prepared using the known concentration of the computer. Each new cycle was continuously operated with iron standard solution to give three standard samples that the control solenoid valve 3.0 software of a homemade contained iron (II), iron (III), and iron (II) plus iron (III). −1 controller. In addition, the solution aspiration was con- Each sample has the fnal concentration of 2.0 mg L as trolled by opening only one 2-way solenoid valve per step a reference value. and switching 3-way solenoid valve 5 at the position “out” while switching 3-way solenoid valve 5 at the position “in” 3. Results and Discussion for colorimetric detection of Curcuma putii Maknoi & Jenjitt. extract-iron complex formation. 3.1. Preliminary Study 3.1.1. Identifcation of Phenolic Compounds in Curcuma putii 2.7. Sample Preparation. Water samples were collected of Maknoi & Jenjitt. Identifcation of phenolic compounds was diferent sources including well water samples and tap water performed according to screening methods of the Shinoda’s from Sakae Krang Sub-District, Mueang District, Uthai test, ferric test, acid butanol test, nitrous acid test, and Tani, Tailand. Samples were fltered through a Whatman potassium iodate test. Te results are shown in Table 1. In the flter paper No. 6 and kept in polyethylene bottles at 4 C. All test for favonoids with Shinoda’s test procedure, the result bottles were rinsed with 10% (v/v) of nitric acid or sulfuric was found that the formation of brown color appear that acid and triple-rinsed with distilled water before further indicated the presence of favonoids. Tannins detection with Journal of Analytical Methods in Chemistry 5 3.1.2. Curcuma putii Maknoi & Jenjitt. Extract-Iron Complex ferric test procedure was tested with 2.0% (w/v) of ferric chloride, resulting in a greenish-brown precipitates Formation. Te absorption spectra of iron (III), iron (II), and Curcuma putii Maknoi & Jenjitt. extract in water, acetate appearing in the extract. It is possible that the phenolics detected were tannins. Some research reported that the ferric bufer, and ethanol were recorded using UV-Vis spectro- test could be used to distinguish hydrolysable tannins from photometer (Termo Fisher Scientifc, USA) in the range of condensed tannins. Condensed tannins give greenish-brown 500–800 nm. Figures 4(a)–4(c) represent the absorption precipitates while hydrolysable tannins form bluish-black spectra of Curcuma putii Maknoi & Jenjitt. extract-iron color and precipitates . Terefore, it is possible that the complexes in water, acetate bufer, and ethanol, re- extracts contain condensed tannins. To confrm that Cur- spectively. Te results indicated that the use of water and acetate bufer as the extraction solvents (Figures 4(a) and cuma putii Maknoi & Jenjitt. extract contains condensed tannins (e.g., catechin and gallocatechin), the extract was 4(b)) might not be able to extract the active species from the Curcuma putii Maknoi & Jenjitt., which was the main active tested using acid butanol, nitrous acid, and potassium io- date. Te formation of a crimson product with the acid component for chelating with iron. It could also be possible that the formation of iron and the active site of the active butanol test indicates the presence of condensed tannins in Curcuma putii Maknoi & Jenjitt. while hydrolysable tannins species did not appear, resulting in no signifcant detection (ellagitannins and gallotannins) with nitrous acid and po- of iron complex absorption in the 650–700 nm region, and tassium iodate tests, gave negative results. Terefore, the their absorption spectra were similar to those of iron preliminary conclusion is that the phenolic compounds in standard solution prepared in water and acetate bufer. In Curcuma putii Maknoi & Jenjitt. including favonoids and ethanol, both iron (II) and iron (III) could bind to the active condensed tannins were obtained. site of the active species of Curcuma putii Maknoi & Jenjitt. a blue-green or brown color appears and exhibits the Te species of phenolic compounds in Curcuma putii Maknoi & Jenjitt. was confrmed by LC-MS. Te results maximum absorption at 667 nm as shown in Figure 4(c). However, the absorbances values of iron (III) complexes are shown in Table 2 and Figure 2. Te Curcuma putii Maknoi & Jenjitt. extract contains favonoids, condensed were higher than those of iron (II) complexes. Tis is probably due to the fact that the iron (III)-Curcuma putii tannins, and other compounds consistent with the pre- liminary results of screening methods. Te major com- Maknoi & Jenjitt. complex has a higher molar absorptivity pounds of Curcuma putii Maknoi & Jenjitt. extract were and stronger afnity. Tus, iron (III) standard solution was miquelianin (quercetin 3-O-glucuronide) with the re- chosen for the construction of calibration curves for further tention time of 5.37 which is a species of natural favonoid studies and determination of total iron by the microfuidic and metabolite of quercetin. Tis compound has the HSI colorimetric system in order to obtain the best sensi- carbonyl group in the C ring and multiple hydroxyl tivity for water sample monitoring by using the microfuidic system. groups and has several chelating sites for the complexa- tion of metals. Te possible chelating site of iron consists Some research studies reported that some chemicals (e.g., favonoids and tannins) could reduce iron (III) to iron of the C4-carbonyl-C5-hydroxy and the ortho-dihydroxyl (3′,4′-dihydroxyl or catechol) groups . Terefore, it is (II). Terefore, to test for the reducing efect of the sample, possible that quercetin 3-O-glucuronide is the main active preliminary studies were conducted to investigate some compound in Curcuma putii Maknoi & Jenjitt. for iron chemicals (e.g., favonoid, tannin, steroid, and terpenoids.) chelation. Te proposed mechanisms of iron reactions found in the Curcuma putii Maknoi & Jenjitt. extract. From with quercetin 3-O-glucuronide is shown in Figures 3(a) the report based on the phenanthroline method, iron (III) and 3(b). Quercetin is a strong chelating agent with both did not form a reddish complex with phenanthroline but iron (II) and iron (III). Iron attached to the 4-carbonyl only with iron (II) as it appeared to show the absorption group of C ring and 5-hydroxyl group of A ring, resulting spectra at about 510 nm  or 500± 20 nm . Tus, if the active species in Curcuma putii Maknoi & Jenjitt. extract in the break of double bond and deprotonation to gen- erate the two Fe-O bonds. Te next possible site is the could reduce iron (III) to iron (II), a reddish complex of iron (II) and phenanthroline would be formed, leading to the 3′,4′-dihydroxyl site, either one or both H atoms can be removed from hydroxyl groups and bonded with iron. absorption spectra at about 500± 20 nm. In the experiment, Moreover, iron (II) and iron (III) ions are most likely iron (III) was mixed with Curcuma putii Maknoi & Jenjitt. chelated with two quercetin molecules in 1 : 2 and 1 : 1 extract and 3.0% (w/v) phenanthroline. Te mixing pro- ratios, respectively. However, the formation of iron- cedure is similar to that in Section 2.3 but phenanthroline quercetin or metal-ligand complex depends on pH, sol- was added before adjusting the fnal volume. In addition, the −1 vent, oxidizing agent, and reactant forms [24, 26]. desired fnal concentrations were 1.0 and 10 mg L of iron Several studies have reported that quercetin has (III) and 3.0% (w/v) of phenanthroline. Tis mixed solution a stronger afnity for iron (III) than for iron (II) [27–29]. was scanned across the regions of 400–800 nm to compare Furthermore, iron (III) at pH 5.0 could oxidize sufciently with other various groups such as iron (III)-Curcuma putii to be reduced to iron (II) by quercetin (Figure 4(b)) . Maknoi & Jenjitt. extract, iron (III)-phenanthroline, Cur- Bijlsma et al. reported the reduction of iron (III) to iron cuma putii Maknoi & Jenjitt. extract-phenanthroline, and (II) through the transfer of electrons from the favonoid Curcuma putii Maknoi & Jenjitt. extract. Te results in- (catechol group) to iron and the favonoid is oxidized to dicated that Curcuma putii Maknoi & Jenjitt. extract has a semiquinone radical, and fnally to a quinone . a natural reducing efect (Figure 5). Te addition of 6 Journal of Analytical Methods in Chemistry Table 1: Colorimetric test results. Methods Positive/Negative Colour observed Ferric test + Greenish-brown Shinoda’s test + Brown Acid butanol test + Crimson Nitrous acid test − Brownish-yellow Potassium iodate test − Brown + positive test, − negative test. Table 2: Characterization of compounds from Curcuma putii Maknoi & Jenjitt. extract by the LC-MS analysis. Molecular No Proposed compounds Retention time Formula m/z Weight 1,5-anhydro-1-[5,7-dihydroxy-2-(4-hydroxyphenyl)-4-oxo-4H-chromen-8- 1 3.67 C H O 578.1420 577.1346 30 26 12 yl]-2-O-[(2E)-3-(4-hydroxyphenyl)-2-propenoyl] hexitol 2 Catechin 3.69 C H O 290.0787 289.0715 15 14 6 3 p-coumaric acid glucoside 3.76 C H O 326.0999 325.0927 15 18 8 4 1-naphthol glucuronide 3.76 C H O 320.0893 319.0820 16 16 7 5 (+)-gallocatechin 3.77 C H O 306.0737 305.0664 15 14 7 6 Sinapinic acid-O-glucuronide isomer 3.99 C H O 400.1004 399.0931 17 20 11 7 Heptaethylene glycol 4.13 C H O 326.1940 349.1832 14 30 8 8 Catechin 4.32 C H O 290.0789 289.0716 15 14 6 9 8-O-methylfusarubin 4.50 C H O 320.0894 319.0820 16 16 7 10 p-coumaric acid glucoside 4.54 C H O 326.0999 325.0927 15 18 8 11 3,5,6,7-Tetrahydroxy-2-(4-hydroxyphenyl)-2,3-dihydro-4H-chromen-4-one 4.66 C H O 304.0583 303.0510 15 12 7 12 Leucyl-leucyl-norleucine 4.67 C H N O 357.2627 358.2700 18 35 3 4 13 Epiafzelechin 4.68 C H O 274.0841 275.0913 15 14 5 14 Guibourtinidol-(4alpha->6)-catechin 4.72 C H O 546.1523 545.1449 30 26 10 15 3,4-methylenesebacic acid 5.32 C H O 226.1205 249.1097 12 18 4 16 Miquelianin 5.37 C H O 478.0745 477.0671 21 18 13 17 Isoquercetin 5.44 C H O 464.0954 463.0880 21 20 12 18 Rutin 5.47 C H O 610.1527 609.1455 27 30 16 19 Bergaptol 5.62 C H O 202.0265 201.0192 11 6 4 20 Trifolin 5.66 C H O 448.1005 447.0931 21 20 11 21 Flaviolin 5.78 C H O 206.0215 205.0143 10 6 5 7-hydroxy-9-methoxy-6-(1,3,4-trihydroxy-2-butanyl)-1,2-dihydrocyclopenta 22 5.95 C H O 350.0997 349.0925 17 18 8 [c]chromene-3,4-dione 23 Dodecyltrimethylammonium 5.99 C H N 227.2612 228.2685 15 33 24 Bis(2-ethylhexyl) amine 6.09 C H N 241.2766 242.2839 16 35 25 3-tert-butyladipic acid 6.19 C H O 202.1206 201.1133 10 18 4 26 Prometryn 6.93 C H N S 241.1363 242.1436 10 19 5 27 3-oxolauric acid 6.97 C H O 214.1569 237.1461 12 22 3 28 trans-2-Dodecenoylcarnitine 7.29 C H NO 341.2566 342.2639 19 35 4 29 N,N-Bis(2-hydroxyethyl)dodecanamide 7.70 C H NO 287.2461 310.2354 16 33 3 30 3,5-di-tert-Butyl-4-hydroxybenzaldehyde 7.88 C H O 234.1620 235.1693 15 22 2 31 10,16-dihydroxyhexadecanoic acid 8.41 C H N O 342.2882 343.2955 19 38 2 3 (Similar to: (1S,8S,9S,10S,13R)-6,9,10-trimethyl-2-oxo-4,14-dioxatetracyclo- 32 8.42 C H NO 239.2249 240.2322 15 29 tetradeca-3(7),5-dien-8-yl acetate; Δmass: 38.1571 Da) (Similar to: (1S,8S,9S,10S,13R)-6,9,10-trimethyl-2-oxo-4,14-dioxatetracyclo- 33 8.53 C H O 330.1831 329.1758 20 26 4 tetradeca-3(7),5-dien-8-yl acetate; Δmass: −64.9062 Da) 34 5,5′-diisopropyl-2,2′-dimethyl-3,3′,4,4′-biphenyltetrol 9.58 C H NO 255.2560 256.2633 16 33 35 Hexadecanamide 9.72 C H O 330.2770 353.2662 19 38 4 Journal of Analytical Methods in Chemistry 7 Table 2: Continued. Molecular No Proposed compounds Retention time Formula m/z Weight 36 L-α-PALMITIN 9.91 C H O 390.2769 413.2661 24 38 4 37 Bis(2-ethylhexyl) phthalate 9.94 C H O 282.2559 281.2486 18 34 2 38 Oleic acid 10.39 C H O P 670.4573 669.4496 37 67 8 (2R)-1-(Palmitoyloxy)-3-(phosphonooxy)-2-propanyl (9Z,12Z,15Z)-9,12,15- 39 10.46 C H O 446.3760 469.3651 29 50 3 octadecatrienoate 40 13-hydroxy-alpha-tocopherol 10.79 C H O 444.3591 477.3917 29 48 3 140.0 mAU 125.0 112.5 100.0 87.5 75.0 62.5 50.0 37.5 25.0 12.5 min -3.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 Time [min] Figure 2: Chromatogram of the Curcuma putii Maknoi & Jenjitt. extract. 4′ 2/3+ Fe HO O 3′ O A C O C H O 6 9 6 5 4 OO 2/3+ Fe (a) OO O 3+ Oxidative coupling +Fe 3+ Fe BB B Decomposition 2+ 2+ +Fe RR O R +Fe OH O (b) Figure 3: Te proposed complexation mechanism of quercetin 3-O-glucuronide and iron. (a) Possible chelating sites of iron (iron (III) or iron (II)) ions on quercetin 3-O-glucuronide. (b) Oxidation of the favonoid 3ʹ,4ʹ-dihydroxyl (catechol group) site to a semiquinone-type radical and possibly to a quinone . Absorbance [mAU] 8 Journal of Analytical Methods in Chemistry 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0.0 0.0 500 550 600 650 700 750 800 500 550 600 650 700 750 800 Wavelength (nm) Wavelength (nm) natural extract natural extract iron (III) 10 mg/L-natural extract iron (III) 10 mg/L-natural extract iron (III) 100 mg/L-natural extract iron (III) 100 mg/L-natural extract iron (II) 10 mg/L-natural extract iron (II) 10 mg/L-natural extract iron (II) 100 mg/L-natural extract iron (II) 100 mg/L-natural extract (a) (b) 1.0 0.8 0.6 0.4 0.2 0.0 500 550 600 650 700 750 800 Wavelength (nm) natural extract iron (III) 10 mg/L-natural extract iron (III) 100 mg/L-natural extract iron (II) 100 mg/L-natural extract iron (II) 10 mg/L-natural extract (c) Figure 4: (a) Te absorbance spectra of the Curcuma putii Maknoi & Jenjitt. extract-iron complex in water. (b) Te absorbance spectra of the Curcuma putii Maknoi & Jenjitt. extract-iron complex in acetate bufer solution. (c) Te absorbance spectra of the Curcuma putii Maknoi & Jenjitt. extract-iron complex in ethanol. phenanthroline into the solution that contained Curcuma initial signal by the initial signal and multiplying the result putii Maknoi & Jenjitt. extract and iron (III) clearly caused by 100, both did not exceed 10%. For more than 20 days, the a reddish color, resulting in an appearance of absorption results provided 5.23% for the deviation between the initial spectra at about 502 nm wavelength. signal to the fnal signal (stored for 30 days) and 13.84% for the percentage diference between the initial signal and the fnal signal (stored for 30 days), respectively. Te results 3.1.3. Stability of the Curcuma putii Maknoi & Jenjitt. indicated that Curcuma putii Maknoi & Jenjitt. extract has Extract. Curcuma putii Maknoi & Jenjitt. extract was pre- a high stability of the determination of total iron, while other pared and left for 0–7 hours and up to 30 days before being plant extracts whose stability has been reported at least −1 mixed with 10 mg L of iron (III). Te absorbances values within 4 and 72 hours (3 days) [16, 17]. are recorded as shown in Figures 6(a) and 6(b). Te de- viation between the initial signal (frst measurement point) to the extract signal after 20 days of storage was 3.93% Te 3.2. Optimization. Te microfuidic HSI colorimetry was percentage diference of signal between the initial signal used for determination of total iron by varying important (frst measurement point) and the extract storage signal for parameters of experimental conditions, such as fow rate, 20 days was 9.55%, which is calculated by dividing the sample volume, mixing zone length, and aspiration se- diference between the target signal (storage 20 days) and the quences. Te investigated parameter was varied while the Absorbance Absorbance Absorbance Journal of Analytical Methods in Chemistry 9 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 400 500 600 700 800 Wavelength (nm) natural extract iron (III) 10 mg/L-phenanthroline natural extract-iron (III) 10 mg/L natural extract-iron (III) 10 mg/L-phenanthroline natural extract-phenanthroline natural extract-iron (III) 1 mg/L-phenanthroline Figure 5: Te absorbance spectra studies for the reducing efect of Curcuma putii Maknoi & Jenjitt. extract (natural extract). 0.50 0.50 0.45 0.45 0.40 0.40 0.35 0.35 0.30 0.30 0.25 0.25 0.20 0.20 0.15 0.15 0.10 0.10 0.05 0.05 0.00 0.00 0 1234567 0 2468 10 12 14 16 18 20 22 24 26 28 30 Time (h) Time (day) (a) (b) −1 Figure 6: Stability of Curcuma putii Maknoi & Jenjitt. extract. (a) 0–7 hours. (b) 0–30 days before mixing with 10 mg L of iron (III) solutions. others were fxed. Te iron (III) standard solutions of 3.2.2. Efect of Sample Volume. Te sample volumes were −1 0.0–6.0 mg L were employed during optimization. Ten, controlled with the microfuidic channel on the platform the optimum conditions were selected to obtain high sen- which was designed in accordance with calculating length, sitivity and sufciency for total iron determination. width, and depth of the S zone position to obtain volume in the range of 25–150μL, as shown in Figure 7(b). Te sen- sitivity increased with the increase in sample volume up to 3.2.1. Efect of Flow Rate. Flow rate was the one of infu- 75μL, then remained constant. Tus, to achieve high sen- encing parameters on the sensitivity of Curcuma putii sitivity and sampling rate, a sample volume of 75μL was Maknoi & Jenjitt. extract-iron complex detection because it selected for further studies. afected solution dispersion in a microfuidic platform. Te results shown in Figure 7(a) indicate that a low fow rate led to a longer time for both solution aspiration and the 3.2.3. Efect of Mixing Zone Length. In order to achieve an movement into the detector, resulting in a large dispersion efcient mixing of sample and reagent, the carrier was re- which could reduce the sensitivity and the sample quired for the fow cell throughput, leading to maximum throughput. Te outcome of increasing fow rate from 0.1 to sensitivity for product detection. Te mixing zone lengths of −1 1.0 mL min was a decrease in dispersion thus causing 50–200 cm were studied. Te results shown in Figure 7(c) −1 higher sensitivity. However, at fow rate above 1.0 mL min , also indicate that the sensitivity increased with the increase a lower sensitivity was obtained due to the limited reaction of mixing zone length up to 75 cm and rapidly decrease from −1 time. So, a fow rate of 1.0 mL min was selected. 75 to 200 cm because increasing the length of the mixing Absorbance Absorbance Absorbance 10 Journal of Analytical Methods in Chemistry 0.10 0.20 0.08 0.16 0.06 0.12 0.04 0.08 0.02 0.04 0.00 0.00 0.0 0.5 1.0 1.5 2.0 2.5 0 25 50 75 100 125 150 -1 Flow rate (mL min ) Sample volume (µL) (a) (b) 0.20 0.16 0.12 0.08 0.04 0.00 0 50 100 150 200 Mixing zone length (cm) (c) Figure 7: Efect of (a) fow rate, (b) sample volume, and (c) mixing zone length on sensitivity of iron (III) determination. zone led to extremely large dispersion of the detection zone, approximately 1.7 mL/operation of waste as shown in Fig- −1 resulting in lower sensitivity. Tus, a 75 cm mixing zone ure 8. Te limit of detection was achieved at 0.11 mg L , length was chosen because it provided the highest sensitivity. which was calculated by dividing three times standard de- viation of the intercept by the slope of the calibration graph. Te precision was evaluated by the aspiration of iron (III) −1 3.2.4. Efect of Aspiration Sequence. Te aspiration se- standard solutions of 0.5, 2.0, and 6.0 mg L for 11 repli- quences of the solution are studied by using four patterns cates, that obtained relative standard deviation percentages with diferent carrier solutions as shown in Table 3. Te (%RSD) of 1.72, 1.63, and 1.61, respectively, resulting in high results revealed that the pattern of reagent (zone R), sample precision of the measurements. Te percentages of recovery (zone S), and reagent (zone R), using a natural reagent as were studied by spiking the diluted water samples and the a carrier provided the highest sensitivity. However, some standard samples with known diferent concentrations of −1 drawbacks often occurred during the experiment operation iron (III) solution (1.0 and 3.0 mg L ). Te results are such as the color of the natural reagent easily and quickly summarized in Table 4, indicating that the percentage of adhered to the microfuidic channel. Tis caused small recovery was in the range of 90.6–113.4 with satisfactory colloids that were retained in the fow cell, resulting in an accuracy and correspondence with the AOAC unstable signal, unreliable, and faulty results. To compro- acceptable range. mise between sensitivity and reduce these drawbacks, the sequence of reagent (R), sample (S), and reagent (R) with 3.4. Interference Study. Te efects of some interference acetate bufer as a carrier (No. 2) was selected. species on iron determination were studied, especially cations 2+ 2+ 2+ 2+ 2+ 3+ 2+ and anions such as Zn , Cu , Mn , Cd , Ni , Cr , Co , 2+ + 2+ 2+ 3+ − + − − 3− 3.3. Analytical Characteristics of the Microfuidic HSI Col- Pb , Na , Ca , Mg , Al , NH , Cl , NO , NO , and PO . 4 2 3 4 orimetric System. Te analytical characteristics of the Tese species of known concentration were added to iron (III) microfuidic HSI colorimetric system using Curcuma putii standard solution containing a fxed concentration of 1.0 mg −1 Maknoi & Jenjitt. extract as a natural reagent include lin- L to evaluate the tolerance limit of interference species on earity ranges, the limit of detection (LOD), the precision, iron detection. Te tolerance limit was defned as the maxi- and the accuracy. Te selected conditions were obtained as mum of interference species concentration that caused the previously studied. A linear calibration graph in the range of iron concentration deviation of less than ±5% of the iron −1 2 0.5–6.0 mg L (y � 0.1586x − 0.0109, r � 0.9992) was con- concentration without interference. It was found that there −1 −1 + 2+ structed with a sample throughput of 30 h and was no interference in excess of 500 mg L of Na , Ca , and -1 Sensitivity (V Lmg ) -1 Sensitivity (V Lmg ) -1 Sensitivity (V Lmg ) Journal of Analytical Methods in Chemistry 11 Table 3: Study on aspiration sequences. a 2 No Carrier solution Sequence Calibration graph equation r 1 deionized water R/S/R y � 0.0301x + 0.1368 0.9964 2 Acetate bufer R/S/R y � 0.1586x − 0.0109 0.9992 3 Natural reagent R/S/R y � 0.3253x − 0.2195 0.9746 4 Standard/sample solution S/R/S y � 0.1094x + 0.1678 0.9931 R and S represent natural reagent and standard/sample, respectively. -1 -1 6.0 mg L 4.0 mg L -1 1.0 mg L -1 -1 2.0 mg L 0.5 mg L Blank 0 200 400 600 800 1000 1200 1400 Time (s) Figure 8: Response profle for the determination of iron (III) using the microfuidic HSI colorimetric system. Table 4: Concentration of total iron in water samples and percent recoveries. −1 −1 Sample Iron added (mg L ) Iron found (mg L ) Recovery (%) 0 3.085 — 1 1 4.151 106.6 3 6.301 107.2 0 1.076 — 2 1 2.111 103.5 3 4.351 109.2 0 0.661 — 3 1 1.751 109.0 3 3.379 90.6 0 2.359 — 4 1 3.398 103.9 3 5.630 109.0 0 2.477 — 5 1 3.446 96.9 3 5.879 113.4 0 2.003 — 6 1 2.976 97.3 3 5.102 103.3 0 2.083 — 7 1 3.108 102.5 3 4.819 91.2 0 2.089 — 8 1 3.037 94.8 3 5.063 99.1 − −1 3+ −1 2+ 3− Cl , 100 mg L of Al , 50 mg L of Mg and PO , 25 mg Tus, it could be considered to have no interference efect in −1 −1 + −1 2+ −1 L of NO , 10 mg L of NH , 5 mg L of Cu , 1.0 mg L this case. 2+ 2+ 2+ 2+ 2+ of Mn , Zn , Ni , Cd , and Pb , indicating that some 2+ 2+ 2+ 2+ 2+ species (Mn , Zn , Ni , Cd , and Pb ) had a positive or 3.5. Application to Real Samples. Te microfuidic HSI negative efect that interfered the determination of total iron. system combining a natural reagent from Curcuma putii However, these species were absent in the studied samples. Maknoi & Jenjitt. extract (new plant species) was applied to Signal (V) 12 Journal of Analytical Methods in Chemistry Table 5: Comparison of the proposed method and spectrophotometric method for the determination of total iron in water samples. −1 a Total iron (mg L ) Sample Proposed method Spectrophotometric method 1 6.17± 0.08 6.94± 0.01 2 2.15± 0.01 1.93± 0.01 3 1.32± 0.13 1.11± 0.03 4 11.79± 0.05 12.08± 0.09 5 9.91± 0.08 9.40± 0.07 6 2.00± 0.13 1.94± 0.01 7 2.08± 0.03 2.11± 0.01 8 2.09± 0.06 2.19± 0.01 Mean of triplicate results. determine iron ion in water samples. Comparing the spec- 4. Conclusions trophotometric method that used 1,10 phenanthroline as A compact microfuidic HSI system for homemade colori- a chromogenic reagent and hydroxylamine as a reducing metric detection using Curcuma putii Maknoi & Jenjitt. agent, the results as shown in Table 5 indicate that the extract was proposed as a green analytical methodology for proposed microfuidic HSI-Curcuma putii Maknoi & Jenjitt. iron quantifcation. Te extract was nontoxic, low in cost, extract system had good correlation with the had high stability (stable for at least 20 days) with good spectrophotometric method. Considering the linear selectivity, and was an easily available reagent that could be regression equations (y � 0.9779x + 0.0824) of the applied to the microfuidic HSI system. Te developed correlation graph between both methods, where X and Y method ofered high accuracy and precision as well as represented the results obtained from spectrophotometric sufcient sensitivity with the adjustable gain control de- and the microfuidic HSI methods, the slope was close to 1 tection device and optimum conditions without the need to and r value was 0.9918. Moreover, both methods were also purify natural reagents prior to use. Te proposed method compared using the t-test at 95% confdent level . It was provided cost-efective, easy operation with an appropriate found that there was no signifcant diference among all water analysis time (2 min/injection) and environmental pro- samples (t � 2.36, t � 0.16, DOF � 7). Moreover, critical calculated tection with low consumption of solutions and chemical when comparing the amount of total iron obtained from usage reduction. Terefore, it could be considered as an standard samples (sample numbers 6–8) with the amount of −1 alternative analytical method for routine analysis of total total iron (2.0 mg L ) obtained from iron (II) and iron (III) iron in water samples. standard solutions, it was found that there was no signifcant diference. All results indicated that the proposed microfuidic HSI-Curcuma putii Maknoi & Jenjitt. extract system gave Data Availability a comparable performance to the spectrophotometric method. Moreover, the proposed method could reduce Te data used to support the fndings of this study are in- some major drawbacks of the standard spectrometric cluded within the article. method. Te frst point, the proposed method successfully determined total iron in water samples with microliter- Conflicts of Interest volumes of nontoxic reagents and samples, while the stan- dard spectrometric method required volume of milliliter of Te authors declare that they have no conficts of interest. highly toxic reagents. It indicated that the proposed method produced less toxic waste and was more environmentally Acknowledgments friendly. Te second avail, the detection device of the pro- Tis work was supported by Research and Development posed method is much cheaper than a standard spectrometric instrument and could be easily fabricated. Besides, the au- Institute, Nakhon Sawan Rajabhat University, Tailand, the Royal Golden Jubilee (RGJ) Ph.D. Program [PHD/0157/ tomatic operation of the detection system could shorten the analysis time, which is convenient for routine work. However, 2558], PERCH-CIC, and Chiang Mai University. 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