Solid-Phase Extraction Coupled to a Paper-Based ... - ACS Publications

Feb 22, 2018 - Department of Environmental and Radiological Health Sciences,. ‡. School of Biomedical Engineering,. §. Department of Mechanical. En...
0 downloads 9 Views 3MB Size
Subscriber access provided by UNIV OF SCIENCES PHILADELPHIA

Article

Solid-Phase Extraction Coupled to a Paper-Based Technique for Trace Copper in Drinking Water Casey W. Quinn, David Cate, Daniel Miller-Lionberg, Thomas Reilly, John Volckens, and Charles S. Henry Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b05436 • Publication Date (Web): 22 Feb 2018 Downloaded from http://pubs.acs.org on February 22, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 21

Environmental Science & Technology

Solid-Phase Extraction Coupled to a Paper-Based Technique for Trace Copper in Drinking Water Casey W. Quinn†, David M. Cate‡, Daniel D. Miller-Lionberg║, Thomas Reilly III║, John Volckens*†§, and Charles S. Henry*‡┴ # †Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA; ‡School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado 80523, USA; §Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523, USA; ║Access Sensor Technologies, LLC, Fort Collins, Colorado 80524, USA; ┴ Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA; #Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, Colorado 80523, USA 1

TOC Graphic

2

ACS Paragon Plus Environment

1

Environmental Science & Technology

Page 2 of 21

3

4

ABSTRACT

5

Metal contamination of natural and drinking water systems poses hazards to public and

6

environmental health. Quantifying metal concentrations in water typically requires sample

7

collection in the field followed by expensive laboratory analysis that can take days to weeks to

8

obtain results. The objective of this work was to develop a low-cost, field-deployable method to

9

quantify

trace

levels

of

copper

in

drinking

water

by

coupling

solid-phase

10

extraction/preconcentration with a microfluidic paper-based analytical device. This method has

11

the advantages of being hand-powered (instrument-free) and using a simple ‘read by eye’

12

quantification motif (based on color distance). Tap water samples collected across Fort Collins,

13

CO were tested with this method and validated against ICP-MS. We demonstrate the ability to

14

quantify the copper content of tap-water within 30% of a reference technique at levels ranging

15

from 20 to 500,000 ppb. The application of this technology, which should be sufficient as a rapid

16

screening tool, can lead to faster, more cost-effective detection of soluble metals in water

17

systems.

18

ACS Paragon Plus Environment

2

Page 3 of 21

19

Environmental Science & Technology

INTRODUCTION

20

Recent municipal1 and environmental2 water contamination events have highlighted public

21

health concerns regarding water quality. Events like those in Flint, MI and the Gold King Mine

22

in Colorado have produced considerable outrage3,

23

improved monitoring.5 Affected stakeholders have placed particular emphasis on increasing the

24

spatial and temporal resolution of monitoring, in an effort to promote more effective risk

25

communication (and control efforts) during a contamination event.6,

26

methods for trace metals analysis, however, rely on expensive equipment and time-intensive

27

procedures. Therefore, a need exists for water quality monitoring methods that are rapid, low-

28

cost, and scalable to the needs not only of regulatory agencies but also the general public.

4

and have increased public demand for

7

Standard reference

29

Microfluidic paper analytical devices (µPADs) represent an emerging technology platform that

30

shows promise for scalable, low-cost monitoring of water quality. Most µPAD applications have

31

focused on medical diagnostics,8-10 but this technology is also well poised to make advances in

32

environmental monitoring.11 The present work focuses on µPAD detection of Cu in drinking

33

water. Although low-levels of Cu intake are essential for human and aquatic health, high levels

34

of intake can be toxic.12,

35

monitoring of Cu in drinking water under the 1991 Copper and Lead rule14 and also under the

36

National Recommended Aquatic Life Criteria.15 The current EPA Action Level (concentration

37

that when exceeded warrants remedial action) for Cu in drinking water is 1.3 ppm.16 Although

38

colorimetric intensity17-26 and distance-based27-28 µPADs have been developed for Cu, these

39

existing designs have limitations. Intensity-based µPADs require the evaluation of the color hue

40

and/or intensity, which can be difficult to access accurately without the aid of imaging

41

equipment and software. Distance-based µPADs are easier to evaluate in the field as they can be

13

The U.S. Environmental Protection Agency (EPA) requires

ACS Paragon Plus Environment

3

Environmental Science & Technology

Page 4 of 21

42

read by eye; however, such methods, to date, cannot detect Cu concentrations at or below the

43

EPA limit of 1.3 ppm.

44

Solid-phase extraction of metal ions has been previously demonstrated as a sample preparation

45

technique for Flame Atomic Absorption Spectrometry,29-31 X-Ray Fluorescence,32,

33

46

Reflectance Spectroscopy,34-36 and for intensity-based µPADs.37 In this work, EmporeTM

47

chelation disks were used to extract the metal ions from the sample to reduce the potential for

48

interferences from sample matrix effects and to preconcentrate Cu from tap water samples for

49

subsequent quantification using a distance-based µPAD. While we focused on Cu, the method

50

has broad utility to other types of analytes.38 Once captured, the Cu was extracted from the disk

51

with 100 µL of acid and eluted onto a distance-based µPAD for direct quantification. Using this

52

approach, a detection limit of 20 ppb was achieved, approximately two orders of magnitude

53

lower than methods without preconcentration. Finally, Cu levels were measured in drinking

54

water from multiple sites and gave good agreement for paired samples analyzed by ICP-MS.

55

EXPERIMENTAL METHODS

Diffuse

56

Chemicals. Ultrapure water (18.2 MΩcm) from a Mill-Q system was used for the preparation

57

of solutions and cleaning of supplies and equipment (Merck Millipore, Darmstadt, Germany).

58

Analytical-grade chemical reagents were used. Copper(II) sulfate pentahydrate, dithiooxamide

59

(98.5%), and hydroxylamine hydrochloride were purchased from Sigma-Aldrich (St. Louis, MO,

60

USA). Sodium acetate, nitric acid, sodium hydroxide, glacial acetic acid, and isopropanol were

61

obtained from Fisher Scientific (Pittsburgh, PA, USA).

62

µPAD Fabrication. The distance-based µPAD design39 and dithiooxamide Cu detection ink

63

reported by Cate et. al.27 were leveraged in this work. The µPAD was created on Whatman

ACS Paragon Plus Environment

4

Page 5 of 21

Environmental Science & Technology

64

(grade 4) filter paper (GE Healthcare Bio-Sciences, Pittsburgh, PA, USA) using a red wax

65

barrier to enhance visibility of the colorimetric product. The distance-based µPAD design is

66

shown in the supporting materials (Figure S1). In brief, red wax barriers (46 devices per 8”x11”

67

sheet) were printed on filter paper using a wax printer (Xerox ColorQube 8860). Next, a

68

piezoelectric ink-jet printer (Epson R280) deposited the dithiooxamide reagent along the flow

69

channel according to a pre-determined gradient (five printing cycles in all) with more reagent

70

deposited near the sample addition zone and decreasing amounts of reagent along the detection

71

zone. The reagent gradient improves the linear response by offsetting the Lucas-Washburn40

72

capillary flow as found by Cate et. al.27 For this work, dithiooxamide was printed as two

73

gradients (Figure S1) in series. At the midpoint of the detection zone a second identical gradient

74

was started; this second gradient provided a visible warning indication for the presence of high

75

Cu concentrations (Figure S1). After printing, a 350 nL aliquot of 10%(w/w) hydroxylamine was

76

pipetted onto the pretreatment zone. Next, the Whatman paper was placed inside a lamination

77

sheet and passed through a laminator (Apache AL13P) six times at 340°F to melt the wax

78

through the paper and to seal the device. The wax barrier and the plastic laminate sheets provide

79

hydrophobic barriers to confine the sample flow within the channel and to prevent evaporation

80

during analysis. A 3 mm hole was then punched into each device to form a sample addition zone;

81

clear packing tape was applied to the underside of each hole creating a small reservoir for sample

82

addition.

83

Preconcentration and µPAD Analysis. The sample workflow for analysis of Cu is depicted

84

in Figure 1. Standard solutions prepared from analytic reagents were used to calibrate the

85

method.

ACS Paragon Plus Environment

5

Environmental Science & Technology

1 Sample Draw

2 Sample Preconcentration

3 Acid Elution

4 pH Adjustment

Page 6 of 21

6 Quantification

5 Sample Addition

86 87

Figure 1: Schematic for sample collection, preconcentration, and µPAD analysis in six steps: 1)

88

Sample water is drawn into a syringe, 2) Sample water is passed through an EmporeTM chelation

89

disk for metal capture, 3) A drop of acid is passed through the EmporeTM chelation disk,

90

releasing the metal ions back into solution and depositing them into a micro-centrifuge tube

91

containing pre-mixed amounts of base and buffer, 4) A pH adjusted aliquot is pulled from the

92

centrifuge tube 5) The aliquot is added to the distance-based µPAD, 6) After 30 min (once the

93

sample has fully been wicked along the length of the µPAD), the color formation distance is read

94

to determine the sample concentration.

95

Sample Preconcentration. Initial development of the preconcentration technique leveraged

96

work by Gazda et. al.,35 which used a polystyrene-divinylbenzene EmporeTM solid-phase

97

extraction Chelation disk (3M) housed in a 13 mm Millipore Swinnex filter holder; however,

98

modifications were made to optimize this technique. We used computer-aided design software

99

(SolidWorks® ANSYS, Inc., Canonsburg, PA, USA) and rapid-prototype machining to develop

100

a holder that is chemically resistant (made from Sabic Ultem 1000 thermoplastic) and thus,

101

reusable with 10 mm chelation disks. Head space for the chelation disk was integrated into the

102

upper portion of the filter holder to accommodate the swelling that occurs when the disk is

ACS Paragon Plus Environment

6

Page 7 of 21

Environmental Science & Technology

103

wetted; this feature reduces the amount of backpressure during preconcentration (Figure 1 step

104

2). Drain manifold tracks were added to the lower portion of the filter holder and a polyether

105

ether ketone (PEEK) mesh was used to eliminate blockage of the outlet of the filter cartridge. As

106

a result, the holder allows for a high acid extraction efficiency (Figure 1, step 3) with a minimal

107

acid wash volume. The final preconcentration design consisted of a 10 mm punch of solid-phase

108

extraction chelation disk (3M) paired with a 10 mm punch of fine woven PEEK mesh which

109

were placed inside the custom holder (Figure 2).

110

Copper was adsorbed to the disk by passing a 30-mL aqueous sample through the EmporeTM

111

chelation disk by hand with a disposable syringe. Each 30-mL sample required approximately

112

five minutes to complete the preconcentration (Figure 1, steps 1-3). Most of that time was

113

attributed to the sample preconcentration (Figure 1, step 2) due to the limited flow rate of the

114

chelation disk; estimated flow rates were comparable to the 3M documentation (400 ppb, n=5) were found in

ACS Paragon Plus Environment

13

Environmental Science & Technology

Page 14 of 21

226

some of the oldest buildings on campus are shown in Figure 6 (orange/red dots), and are likely

227

the result of old infrastructure and/or pipe corrosion.

228 229

Figure 6: Cu concentrations by sample location. Inset shows all samples collected across Fort

230

Collins (n=33) in August of 2015. The Colorado State University main campus is enclosed with

231

the red dotted lines on the inset, and the samples (n=19) collected there are displayed on the main

232

map. Maps were generated with the ggmap44 library using R 3.4.1 (R Core Team, Vienna,

233

Austria).

234

Implications for Metal Detection in Water Sources. A preconcentration technique coupled

235

with a distance-based µPAD with minimal equipment requirements has been developed. This

236

new method can be used for quantitative detection of Cu at parts-per-billion levels in water and

237

has been validated against ICP-MS. Although both qualitative and quantitative colorimetric kits

ACS Paragon Plus Environment

14

Page 15 of 21

Environmental Science & Technology

238

for Cu detection are commercially available (in addition to aforementioned laboratory methods),

239

the distance-based measurement described here offers several key advantages. For example,

240

distance-based detection is more precise than existing low-cost methods that rely on color chart

241

comparisons.48 Although a single measurement is limited to a smaller range of concentrations

242

(e.g. 20-375 ppb when using a 188× preconcentration factor), one can adapt the method to

243

measure a wide range of Cu concentrations (from approximately 20 to 500,000 ppb) by adjusting

244

the volume of sample that is preconcentrated and/or adjusting the aliquot volume that is added to

245

the µPAD.

246

The implementation of a second gradient along the µPAD detection region provides a warning

247

indicator that the optimal detection range has been exceeded (Figure 3); this line also may be

248

used to alert a user that Cu concentrations have reached or exceeded action limits. Finally, the

249

output from the µPAD can be easily captured using a smartphone for long-term data storage, the

250

advantages of which have been described in a number of reports.49-57 A phone application similar

251

to these could be developed to measure the length of the color formation and automatically

252

report that data back to a central data server. Adding this functionality would allow the

253

image/results to be quickly relayed back to a central location.

254

There are several limitations worth noting. 1) The color formation produced by the Cu-

255

dithiooxamide complex is relatively faint especially when Cu concentrations are low (Figure 3).

256

The use of another complexing reagent with higher molar absorptivity would improve

257

readability. Bathocuproine has been successfully used in µPADs for the detection of Cu;22

258

however, the development of a bathocuproine ink compatible with an ink-jet printer has yet to be

259

developed. Silver nanoparticles (AgNP) have been used with traditional µPADs to detect ppb

260

levels of Cu.23 The use of AgNP could be a potential candidate for future work and improve the

ACS Paragon Plus Environment

15

Environmental Science & Technology

Page 16 of 21

261

sensitivity of the method; however, deposition of the AgNP on the µPAD and immobilization of

262

the Cu-AgNP complex would need to be considered. Recent work has successfully demonstrated

263

the use of Meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin sulfonate (TDMPzP), a water-

264

soluble porphyrin derivative for Cu detection using a distance-based µPAD.28 The TDMPzP

265

ligand provides a very visible response to Cu and future work will likely try to couple this µPAD

266

motif with the preconcentration technique to quantify ppb Cu in water. 2) The distance-based

267

µPAD demonstrated in this work required 30 minutes to complete sample wicking and color

268

formation. The Cu-TDMPzP color formation will help reduce the quantification time by

269

providing a distinct color formation. Work is also underway to reduce the time to transport the

270

sample aliquot along the length of the µPAD measurement zone. 3) Currently Cu is the only

271

analyte that has been evaluated with this method; however, there is potential to extend this

272

method to other metals. For example, colorimetric reagents have been described for arsenic,58

273

chromium,17 nitrate/nitrite,59 and lead,37 all of which are regulated in drinking water by the U.S.

274

Environmental Protection Agency.

275

The preconcentration-µPAD system has the potential to provide water quality experts,

276

technicians, and other stakeholders with a tool that can provide quick and inexpensive analysis of

277

a large number of water samples. This method will not eliminate the need for standard laboratory

278

sample analysis; however, this method can be used for the identification of a pollutant source in

279

a river section, provide spatial-temporal feedback during accidental events (similar to the Gold

280

King Mine incident), or provide municipalities with a cost-effective means to implement a

281

monitoring network without a substantial investment of resources.

282

ASSOCIATED CONTENT

ACS Paragon Plus Environment

16

Page 17 of 21

Environmental Science & Technology

283

Supporting Information.

284

The following file is available free of charge.

285

One 16-page PDF document containing 4 figures, 1 equation, 8 tables, and 1 method.

286

AUTHOR INFORMATION

287

Corresponding Authors

288

*Phone: 1-970-491-2852. Fax: 1-970-491-1801. E-mail: [email protected] (C.S.H.).

289

Phone: 1-970-491-6341. E-mail:[email protected] (J.V.).

290

ORCID

291

Charles S. Henry: 0000-0002-8671-7728

292

Casey W. Quinn: 0000-0002-6802-5250

293

Notes

294

The authors declare no competing financial interest.

295

ACKNOWLEDGMENT

296

This work was supported by grant 1415655 from the National Science Foundation and a State of

297

Colorado Advanced Industries Grant. The authors wish to thank all of the volunteers whom

298

provided water samples from their homes.

299

REFERENCES

300 301 302 303 304 305 306

1. Butler, L. J.; Scammell, M. K.; Benson, E. B., The Flint, Michigan, Water Crisis: A Case Study in Regulatory Failure and Environmental Injustice. Environmental Justice 2016, 9, (4), 9397. 2. Emergency Response to August 2015 Release from Gold King Mine. http://www.epa.gov/goldkingmine (accessed Jan. 2018), 3. Rodriguez-Freire, L.; Avasarala, S.; Ali, A.-M. S.; Agnew, D.; Hoover, J. H.; Artyushkova, K.; Latta, D. E.; Peterson, E. J.; Lewis, J.; Crossey, L. J.; Brearley, A. J.; Cerrato,

ACS Paragon Plus Environment

17

Environmental Science & Technology

307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351

Page 18 of 21

J. M., Post Gold King Mine Spill Investigation of Metal Stability in Water and Sediments of the Animas River Watershed. Environmental Science & Technology 2016, 50, (21), 11539-11548. 4. Bellinger, D. C., Lead Contamination in Flint — An Abject Failure to Protect Public Health. New England Journal of Medicine 2016, 374, (12), 1101-1103. 5. Rutt, R. L.; Bluwstein, J., Quests for Justice and Mechanisms of Suppression in Flint, Michigan. Environmental Justice 2017, 10, (2), 27-35. 6. Scully, J. R., The Corrosion Crisis in Flint, Michigan: A Call for Improvements in Technology. The Bridge of the National Academy of Engineering 2016, 46, (2), 9-29. 7. Drinking Water Action Plan; United States Environmental Protection Agency: Washington D.C., 2016. 8. Yang, Y.; Noviana, E.; Nguyen, M. P.; Geiss, B. J.; Dandy, D. S.; Henry, C. S., PaperBased Microfluidic Devices: Emerging Themes and Applications. Analytical Chemistry 2017, 89, (1), 71-91. 9. Cate, D. M.; Adkins, J. A.; Mettakoonpitak, J.; Henry, C. S., Recent developments in paper-based microfluidic devices. Anal Chem 2015, 87, (1), 19-41. 10. Yetisen, A. K.; Akram, M. S.; Lowe, C. R., Paper-based microfluidic point-of-care diagnostic devices. Lab Chip 2013, 13, (12), 2210-51. 11. Meredith, N. A.; Quinn, C.; Cate, D. M.; Reilly, T. H., 3rd; Volckens, J.; Henry, C. S., Paper-based analytical devices for environmental analysis. Analyst 2016, 141, (6), 1874-87. 12. Council, N. R., Copper in Drinking Water. The National Academies Press: Washington, DC, 2000; p 162. 13. Dorsey, A.; Ingerman, L. Toxicological Profile for Copper; United States Department of Health and Human Services: Atlanta, GA, 2004. 14. Lead and Copper Rule. https://www.epa.gov/dwreginfo/lead-and-copper-rule (accessed Jan. 2018), 15. Aquatic Life Criteria. https://www.epa.gov/wqc/national-recommended-water-qualitycriteria-aquatic-life-criteria-table (accessed Jan. 2018), 16. Drinking Water Contaminants. http://water.epa.gov/drink/contaminants/ (accessed Jan. 2018), 17. Cate, D. M.; Nanthasurasak, P.; Riwkulkajorn, P.; L’Orange, C.; Henry, C. S.; Volckens, J., Rapid Detection of Transition Metals in Welding Fumes Using Paper-Based Analytical Devices. Annals of occupational hygiene 2014, 58, (4), 413-423. 18. Chaiyo, S.; Siangproh, W.; Apilux, A.; Chailapakul, O., Highly selective and sensitive paper-based colorimetric sensor using thiosulfate catalytic etching of silver nanoplates for trace determination of copper ions. Analytica chimica acta 2015, 866, 75-83. 19. Hossain, S. Z.; Brennan, J. D., β-Galactosidase-based colorimetric paper sensor for determination of heavy metals. Analytical chemistry 2011, 83, (22), 8772-8778. 20. Jayawardane, B. M.; Cattrall, R. W.; Kolev, S. D., The use of a polymer inclusion membrane in a paper-based sensor for the selective determination of Cu (II). Analytica chimica acta 2013, 803, 106-112. 21. Li, M.; Cao, R.; Nilghaz, A.; Guan, L.; Zhang, X.; Shen, W., “Periodic-Table-Style” Paper Device for Monitoring Heavy Metals in Water. Analytical chemistry 2015, 87, (5), 25552559. 22. Mentele, M. M.; Cunningham, J.; Koehler, K.; Volckens, J.; Henry, C. S., Microfluidic paper-based analytical device for particulate metals. Anal Chem 2012, 84, (10), 4474-80.

ACS Paragon Plus Environment

18

Page 19 of 21

352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396

Environmental Science & Technology

23. Ratnarathorn, N.; Chailapakul, O.; Henry, C. S.; Dungchai, W., Simple silver nanoparticle colorimetric sensing for copper by paper-based devices. Talanta 2012, 99, 552-557. 24. Rattanarat, P.; Dungchai, W.; Cate, D.; Volckens, J.; Chailapakul, O.; Henry, C. S., Multilayer paper-based device for colorimetric and electrochemical quantification of metals. Analytical chemistry 2014, 86, (7), 3555-3562. 25. Sadollahkhani, A.; Hatamie, A.; Nur, O.; Willander, M.; Zargar, B.; Kazeminezhad, I., Colorimetric disposable paper coated with ZnO@ ZnS core–shell nanoparticles for detection of copper ions in aqueous solutions. ACS applied materials & interfaces 2014, 6, (20), 1769417701. 26. Liu, L.; Lin, H., Paper-Based Colorimetric Array Test Strip for Selective and Semiquantitative Multi-Ion Analysis: Simultaneous Detection of Hg2+, Ag+, and Cu2+. Analytical Chemistry 2014, 86, (17), 8829-8834. 27. Cate, D. M.; Noblitt, S. D.; Volckens, J.; Henry, C. S., Multiplexed paper analytical device for quantification of metals using distance-based detection. Lab on a Chip 2015, 15, (13), 2808-2818. 28. Pratiwi, R.; Nguyen, M. P.; Ibrahim, S.; Yoshioka, N.; Henry, C. S.; Tjahjono, D. H., A selective distance-based paper analytical device for copper(II) determination using a porphyrin derivative. Talanta 2017, 174, 493-499. 29. Saxena, R.; Meena, P. L.; Tiwari, S., Determination of copper in industrial water by innovative flow injection flame atomic absorption spectrometry. Instrumentation Science & Technology 2016, 44, (2), 210-222. 30. Díaz-de Alba, M.; Galindo-Riaño, M. D.; García-Vargas, M., Solid phase extraction of copper traces using poly(styrene-divinylbenzene) membrane disks modified with pyridoxal salicyloylhydrazone in water samples. Talanta 2012, 100, 432-438. 31. Baytak, S.; Kasumov, V. T., Preconcentration and Determination of Copper (II) by Novel Solid-Phase Extraction and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry. Analytical Letters 2017, 50, (1), 105-116. 32. Abe, W.; Isaka, S.; Koike, Y.; Nakano, K.; Fujita, K.; Nakamura, T., X‐ray fluorescence analysis of trace metals in environmental water using preconcentration with an iminodiacetate extraction disk. X‐Ray Spectrometry 2006, 35, (3), 184-189. 33. Hou, X.; Peters, H. L.; Yang, Z.; Wagner, K. A.; Batchelor, J. D.; Daniel, M. M.; Jones, B. T., Determination of trace metals in drinking water using solid-phase extraction disks and Xray fluorescence spectrometry. Applied spectroscopy 2003, 57, (3), 338-342. 34. Fritz, J. S.; Arena, M. P.; Steiner, S. A.; Porter, M. D., Rapid determination of ions by combined solid-phase extraction–diffuse reflectance spectroscopy. Journal of Chromatography A 2003, 997, (1), 41-50. 35. Gazda, D. B.; Fritz, J. S.; Porter, M. D., Determination of nickel (II) as the nickel dimethylglyoxime complex using colorimetric solid phase extraction. Analytica Chimica Acta 2004, 508, (1), 53-59. 36. Gazda, D. B.; Fritz, J. S.; Porter, M. D., Multiplexed colorimetric solid-phase extraction: determination of silver (I), nickel (II), and sample pH. Analytical chemistry 2004, 76, (16), 48814887. 37. Satarpai, T.; Shiowatana, J.; Siripinyanond, A., Paper-based analytical device for sampling, on-site preconcentration and detection of ppb lead in water. Talanta 2016, 154, 504510.

ACS Paragon Plus Environment

19

Environmental Science & Technology

397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442

Page 20 of 21

38. Souza-Silva, É. A.; Jiang, R.; Rodríguez-Lafuente, A.; Gionfriddo, E.; Pawliszyn, J., A critical review of the state of the art of solid-phase microextraction of complex matrices I. Environmental analysis. TrAC Trends in Analytical Chemistry 2015, 71, 224-235. 39. Cate, D. M.; Dungchai, W.; Cunningham, J. C.; Volckens, J.; Henry, C. S., Simple, distance-based measurement for paper analytical devices. Lab on a Chip 2013, 13, (12), 23972404. 40. Washburn, E. W., Phys. Rev 1921, 17, 273. 41. Empore™ Solid Phase Extraction Disks - Technical Information; Chelating - 6208HB 98-0504-1677-9; 3M: Eagan, MN, 2009. 42. Soylak, M.; Erdogan, N. D., Copper (II)–rubeanic acid coprecipitation system for separation–preconcentration of trace metal ions in environmental samples for their flame atomic absorption spectrometric determinations. Journal of hazardous materials 2006, 137, (2), 10351041. 43. Jacobs, W. D.; H. Yoe, J., Simultaneous spectrophotometric determination of traces of cobalt, nickel and copper with dithio-oxamide. Analytica Chimica Acta 1959, 20, 332-339. 44. Kahle, D.; Wickham, H., ggmap: Spatial Visualization with ggplot2. R Journal 2013, 5, (1). 45. Noblitt, S. D.; Berg, K. E.; Cate, D. M.; Henry, C. S., Characterizing nonconstant instrumental variance in emerging miniaturized analytical techniques. Analytica Chimica Acta 2016, 915, 64-73. 46. 2016 Drinking Water Quality Report For Calendar Year 2015; Colorado State University: Fort Collins, CO, 2016. 47. 2016 Drinking Water Quality Report For Calendar Year 2015 City of Fort Collins: Fort Collins, CO, 2016. 48. HACH Copper Color Disc, 0-4 mg/L. https://www.hach.com/copper-color-disc-0-4-mgl/product?id=8276546107 (accessed Jan. 2018), 49. Chang, B.-Y., Smartphone-based Chemistry Instrumentation: Digitization of Colorimetric Measurements. Bulletin of the Korean Chemical Society 2012, 33, (2), 549-552. 50. Fronczek, C. F.; San Park, T.; Harshman, D. K.; Nicolini, A. M.; Yoon, J.-Y., Paper microfluidic extraction and direct smartphone-based identification of pathogenic nucleic acids from field and clinical samples. RSC Advances 2014, 4, (22), 11103-11110. 51. Lopez-Ruiz, N.; Curto, V. F.; Erenas, M. M.; Benito-Lopez, F.; Diamond, D.; Palma, A. J.; Capitan-Vallvey, L. F., Smartphone-based simultaneous pH and nitrite colorimetric determination for paper microfluidic devices. Anal Chem 2014, 86, (19), 9554-62. 52. Martinez, A. W.; Phillips, S. T.; Carrilho, E.; Thomas III, S. W.; Sindi, H.; Whitesides, G. M., Simple telemedicine for developing regions: camera phones and paper-based microfluidic devices for real-time, off-site diagnosis. Analytical chemistry 2008, 80, (10), 3699-3707. 53. Mudanyali, O.; Dimitrov, S.; Sikora, U.; Padmanabhan, S.; Navruz, I.; Ozcan, A., Integrated rapid-diagnostic-test reader platform on a cellphone. Lab Chip 2012, 12, (15), 267886. 54. Sicard, C.; Glen, C.; Aubie, B.; Wallace, D.; Jahanshahi-Anbuhi, S.; Pennings, K.; Daigger, G. T.; Pelton, R.; Brennan, J. D.; Filipe, C. D., Tools for water quality monitoring and mapping using paper-based sensors and cell phones. Water research 2015, 70, 360-369. 55. Thom, N. K.; Lewis, G. G.; Yeung, K.; Phillips, S. T., Quantitative Fluorescence Assays Using a Self-Powered Paper-Based Microfluidic Device and a Camera-Equipped Cellular Phone. RSC Adv 2014, 4, (3), 1334-1340.

ACS Paragon Plus Environment

20

Page 21 of 21

443 444 445 446 447 448 449 450 451 452

Environmental Science & Technology

56. Wang, Y.; Ge, L.; Wang, P.; Yan, M.; Yu, J.; Ge, S., A three-dimensional origami-based immuno-biofuel cell for self-powered, low-cost, and sensitive point-of-care testing. Chem Commun (Camb) 2014, 50, (16), 1947-9. 57. Yetisen, A. K.; Martinez-Hurtado, J.; Garcia-Melendrez, A.; da Cruz Vasconcellos, F.; Lowe, C. R., A smartphone algorithm with inter-phone repeatability for the analysis of colorimetric tests. Sensors and Actuators B: Chemical 2014, 196, 156-160. 58. Nath, P.; Arun, R. K.; Chanda, N., A paper based microfluidic device for the detection of arsenic using a gold nanosensor. RSC Advances 2014, 4, (103), 59558-59561. 59. Jayawardane, B. M.; Wei, S.; McKelvie, I. D.; Kolev, S. D., Microfluidic paper-based analytical device for the determination of nitrite and nitrate. Anal Chem 2014, 86, (15), 7274-9.

453

ACS Paragon Plus Environment

21