{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T18:46:21Z","timestamp":1768416381583,"version":"3.49.0"},"reference-count":43,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2022,10,15]],"date-time":"2022-10-15T00:00:00Z","timestamp":1665792000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Princess Nourah Bint Abdulrahman university"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Azo compounds such as the Sudan dyes I\u2013IV are frequently used illegally as colorants and added to a wide range of foods. These compounds have been linked to a number of food safety hazards. Several methods have been proposed to detect food contamination by azo compounds and most of these are laboratory based; however, the development of reliable and portable methods for the detection and quantification of food contaminated by these chemicals in low concentration is still needed due to their potentially carcinogenic properties. In this study, we investigated the ability of surface enhanced Raman scattering (SERS) combined with chemometrics to quantify Sudan I\u2013IV dyes. SERS spectra were acquired using a portable Raman device and gold nanoparticles were employed as the SERS substrate. As these dyes are hydrophobic, they were first dissolved in water: acetonitrile (1:10, v\/v) as single Sudan dyes (I\u2013IV) at varying concentrations. SERS was performed at 785 nm and the spectra were analyzed by using partial least squares regression (PLS-R) with double cross-validations. The coefficient of determination (Q2) were 0.9286, 0.9206, 0.8676 and 0.9705 for Sudan I to IV, respectively; the corresponding limits of detection (LOD) for these dyes were estimated to be 6.27 \u00d7 10\u22126, 5.35 \u00d7 10\u22125, 9.40 \u00d7 10\u22126 and 1.84 \u00d7 10\u22126 M. Next, quadruplex mixtures were made containing all four Sudan dyes. As the number of possible combinations needed to cover the full concentration range at 5% intervals would have meant collecting SERS spectra from 194,481 samples (214 combinations) we used a sustainable solution based on Latin hypercubic sampling and reduced the number of mixtures to be analyzed to just 90. After collecting SERS spectra from these mixture PLS-R models with bootstrapping validations were employed. The results were slightly worse in which the Q2 for Sudan I to IV were 0.8593, 0.7255, 0.5207 and 0.5940 when PLS1 models (i.e., one model for one dye) was employed and they changed to 0.8329, 0.7288, 0.5032 and 0.5459 when PLS2 models were employed (i.e., four dyes were modelled simultaneously). These results showed the potential of SERS to be used as a high-throughput, low-cost, and reliable methods for detecting and quantifying multiple Sudan dyes in low concentration from illegally adulterated samples.<\/jats:p>","DOI":"10.3390\/s22207832","type":"journal-article","created":{"date-parts":[[2022,10,17]],"date-time":"2022-10-17T03:43:58Z","timestamp":1665978238000},"page":"7832","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Simultaneous Multiplexed Quantification of Banned Sudan Dyes Using Surface Enhanced Raman Scattering and Chemometrics"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2149-9990","authenticated-orcid":false,"given":"Taghrid S.","family":"Alomar","sequence":"first","affiliation":[{"name":"Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia"},{"name":"Centre for Metabolomics Research, Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9656-0437","authenticated-orcid":false,"given":"Najla","family":"AlMasoud","sequence":"additional","affiliation":[{"name":"Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia"},{"name":"Centre for Metabolomics Research, Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK"}]},{"given":"Yun","family":"Xu","sequence":"additional","affiliation":[{"name":"Centre for Metabolomics Research, Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9062-6298","authenticated-orcid":false,"given":"Cassio","family":"Lima","sequence":"additional","affiliation":[{"name":"Centre for Metabolomics Research, Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK"}]},{"given":"Baris","family":"Akbali","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ, UK"},{"name":"Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan"}]},{"given":"Simon","family":"Maher","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2230-645X","authenticated-orcid":false,"given":"Royston","family":"Goodacre","sequence":"additional","affiliation":[{"name":"Centre for Metabolomics Research, Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/j.trac.2017.03.001","article-title":"Application of magnetic molecularly imprinted polymer as a versatile and highly selective tool in food and environmental analysis: Recent developments and trends","volume":"90","author":"Ansari","year":"2017","journal-title":"Trends Anal. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"131857","DOI":"10.1016\/j.foodchem.2021.131857","article-title":"Fast sequential multi element analysis of lead and cadmium in canned food samples using effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) coupled with high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS)","volume":"375","author":"Chaikhan","year":"2022","journal-title":"Food Chem."},{"key":"ref_3","first-page":"232","article-title":"A new cloud point extraction procedure for determination of trace amount crystal violet in wastewater by UV-VIS. Spectrometry","volume":"38","author":"Bisgin","year":"2015","journal-title":"Oxid. Commun."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"127561","DOI":"10.1016\/j.foodchem.2020.127561","article-title":"Ultrasound-assisted development of stable grapefruit peel polyphenolic nano-emulsion: Optimization and application in improving oxidative stability of mustard oil","volume":"334","author":"Nishad","year":"2021","journal-title":"Food Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"756","DOI":"10.1016\/j.foodchem.2007.01.010","article-title":"A rapid HPLC method for determination of Sudan dyes and Para Red in red chilli pepper","volume":"105","author":"Alasalvar","year":"2007","journal-title":"Food Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1049","DOI":"10.1080\/19440049.2020.1726500","article-title":"Optical screening for presence of banned Sudan III and Sudan IV dyes in edible palm oils","volume":"37","author":"Andoh","year":"2020","journal-title":"Food Addit. Contam."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2747","DOI":"10.1016\/j.chroma.2010.02.038","article-title":"A review of analytical techniques for determination of Sudan I\u2013IV dyes in food matrixes","volume":"1217","author":"Rebane","year":"2010","journal-title":"J. Chromatogr. A"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"13857","DOI":"10.1021\/jp0516846","article-title":"Anisotropic metal nanoparticles: Synthesis, assembly, and optical applications","volume":"109","author":"Murphy","year":"2005","journal-title":"J. Phys. Chem. B"},{"key":"ref_9","unstructured":"Gurr, E. (2012). Synthetic Dyes in Biology, Medicine and Chemistry, Elsevier."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"5570","DOI":"10.1021\/ac0603577","article-title":"Visual detection of Sudan dyes based on the plasmon resonance light scattering signals of silver nanoparticles","volume":"78","author":"Wu","year":"2006","journal-title":"Anal. Chem."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1080\/10739149.2021.1982726","article-title":"Ultrasound assisted deep eutectic solvent based liquid phase microextraction for the preconcentration and spectrophotometric determination of amaranth (E123) in water and food samples","volume":"50","author":"Soylak","year":"2022","journal-title":"Instrum. Sci. Technol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1016\/j.scitotenv.2010.09.010","article-title":"Cancer in the Sudan: An overview of the current status of knowledge on tumor patterns and risk factors","volume":"423","author":"Awadelkarim","year":"2012","journal-title":"Sci. Total Environ."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"T1225","DOI":"10.1111\/1750-3841.12482","article-title":"Determination of tert-butylhydroquinone in vegetable oils using surface-enhanced Raman spectroscopy","volume":"79","author":"Pan","year":"2014","journal-title":"J. Food Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1016\/j.anifeedsci.2016.08.014","article-title":"A preliminary evaluation of the use of mid infrared spectroscopy to develop calibration equations for determining faecal composition, intake and digestibility in sheep","volume":"221","author":"Lyons","year":"2016","journal-title":"Anim. Feed Sci. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/j.foodcont.2013.09.014","article-title":"Analyses of phosmet residues in apples with surface-enhanced Raman spectroscopy","volume":"37","author":"Fan","year":"2014","journal-title":"Food Control"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"560","DOI":"10.1080\/19476337.2021.1925746","article-title":"Rapid Determination of Sudan Dyes in chilli products using ultra high performance supercritical fluid chromatography-photodiode array detection","volume":"19","author":"Nie","year":"2021","journal-title":"CYTA J. Food"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"977","DOI":"10.1016\/j.supflu.2010.09.029","article-title":"Determination of Sudan dyes in food samples using supercritical fluid extraction\u2013capillary liquid chromatography","volume":"55","author":"Zougagh","year":"2011","journal-title":"J. Supercrit. Fluids"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"739","DOI":"10.1016\/j.foodchem.2012.11.004","article-title":"Electrochemical determination of Sudan I in food samples at graphene modified glassy carbon electrode based on the enhancement effect of sodium dodecyl sulphonate","volume":"138","author":"Ma","year":"2013","journal-title":"Food Chem."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"730","DOI":"10.1016\/j.snb.2013.12.020","article-title":"Utilizing polyethyleneimine-capped silver nanoclusters as a new fluorescence probe for Sudan I\u2013IV sensing in ethanol based on fluorescence resonance energy transfer","volume":"193","author":"Chen","year":"2014","journal-title":"Sens. Actuators B Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"521","DOI":"10.15625\/0868-3166\/29\/4\/14178","article-title":"Detection of a Sudan dye at low concentrations by surface-enhanced Raman spectroscopy using silver nanoparticles","volume":"29","author":"Dao","year":"2019","journal-title":"Commun. Phys."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"466","DOI":"10.1016\/j.apsusc.2015.05.149","article-title":"Quaternized chitosan\/silver nanoparticles composite as a SERS substrate for detecting tricyclazole and Sudan, I","volume":"351","author":"Chen","year":"2015","journal-title":"Appl. Surf. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"7285","DOI":"10.1021\/jp908892n","article-title":"Quantitative analysis of the banned food dye Sudan-1 using surface enhanced Raman scattering with multivariate chemometrics","volume":"114","author":"Cheung","year":"2010","journal-title":"J. Phys. Chem. C"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Le Ru, E., and Etchegoin, P. (2008). Principles of Surface-Enhanced Raman Spectroscopy: And Related Plasmonic Effects, Elsevier.","DOI":"10.1016\/B978-0-444-52779-0.00005-2"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1002\/jrs.3046","article-title":"The distributions of enhancement factors in close-packed and nonclose-packed surface-enhanced Raman substrates","volume":"43","author":"Fang","year":"2012","journal-title":"J. Raman Spectrosc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.saa.2011.11.027","article-title":"Surface Enhanced Raman Spectroscopy (SERS) and multivariate analysis as a screening tool for detecting Sudan I dye in culinary spices","volume":"87","author":"Marsal","year":"2012","journal-title":"Spectrochim. Acta A Mol. Biomol. Spectrosc."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1016\/j.jhazmat.2011.07.118","article-title":"Vertically aligned Ag nanoplate-assembled film as a sensitive and reproducible SERS substrate for the detection of PCB-77","volume":"211","author":"Zhu","year":"2012","journal-title":"J. Hazard Mater."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1019","DOI":"10.1039\/b502540k","article-title":"Rapid monitoring of antibiotics using Raman and surface enhanced Raman spectroscopy","volume":"130","author":"Clarke","year":"2005","journal-title":"Analyst"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3391","DOI":"10.1021\/j100214a025","article-title":"Adsorption and surface-enhanced Raman of dyes on silver and gold sols","volume":"86","author":"Lee","year":"1982","journal-title":"J. Phys. Chem. A"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1016\/S0266-8920(97)00013-1","article-title":"Improvements to and limitations of Latin hypercube sampling","volume":"13","author":"Huntington","year":"1998","journal-title":"Probabilistic Eng. Mech."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1016\/j.foodchem.2018.08.038","article-title":"Rapid quantification of the adulteration of fresh coconut water by dilution and sugars using Raman spectroscopy and chemometrics","volume":"272","author":"Richardson","year":"2019","journal-title":"Food Chem."},{"key":"ref_31","first-page":"211","article-title":"Principal component analysis: Concept, geometrical interpretation, mathematical background, algorithms, history, practice","volume":"Volume 2","author":"Brown","year":"2009","journal-title":"Comprehensive Chemometrics: Chemical and Biochemical Data Analysis"},{"key":"ref_32","unstructured":"Martens, H., and Naes, T. (1992). Multivariate Calibration, John Wiley & Sons."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"772","DOI":"10.1366\/0003702894202201","article-title":"Standard normal variate transformation and de-trending of near-infrared diffuse reflectance spectra","volume":"43","author":"Barnes","year":"1989","journal-title":"Appl. Spectrosc."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1007\/s11306-011-0330-3","article-title":"Double-check: Validation of diagnostic statistics for PLS-DA models in metabolomics studies","volume":"8","author":"Saccenti","year":"2012","journal-title":"Metabolomics"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"318","DOI":"10.1016\/j.aca.2006.08.018","article-title":"Determination of low analyte concentrations by near-infrared spectroscopy: Effect of spectral pretreatments and estimation of multivariate detection limits","volume":"581","author":"Blanco","year":"2007","journal-title":"Anal. Chim. Acta"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"5706","DOI":"10.1039\/c2cs35138b","article-title":"Fingerprinting food: Current technologies for the detection of food adulteration and contamination","volume":"41","author":"Ellis","year":"2012","journal-title":"Chem. Soc. Rev."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Efron, B., and Tibshirani, R.J. (1994). An Introduction to the Bootstrap, CRC Press.","DOI":"10.1201\/9780429246593"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1007\/s11694-011-9106-8","article-title":"Determination of chloramphenicol and crystal violet with surface enhanced Raman spectroscopy","volume":"5","author":"Lai","year":"2011","journal-title":"Sens. Instrum. Food Qual. Saf."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"734","DOI":"10.1021\/ar800249y","article-title":"A unified view of surface-enhanced Raman scattering","volume":"42","author":"Lombardi","year":"2009","journal-title":"Acc. Chem. Res."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"5605","DOI":"10.1021\/jp800167v","article-title":"A unified approach to surface-enhanced Raman spectroscopy","volume":"112","author":"Lombardi","year":"2008","journal-title":"J. Phys. Chem. C"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3718","DOI":"10.1021\/nn300629z","article-title":"Controlling assembly of mixed thiol monolayers on silver nanoparticles to tune their surface properties","volume":"6","author":"Stewart","year":"2012","journal-title":"ACS Nano"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1070","DOI":"10.1021\/ac00079a024","article-title":"Rapid and quantitative analysis of the pyrolysis mass spectra of complex binary and tertiary mixtures using multivariate calibration and artificial neural networks","volume":"66","author":"Goodacre","year":"1994","journal-title":"Anal. Chem."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/j.foodcont.2014.03.047","article-title":"The feasibility of using near infrared and Raman spectroscopic techniques to detect fraudulent adulteration of chili powders with Sudan dye","volume":"48","author":"Haughey","year":"2015","journal-title":"Food Control"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/20\/7832\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T00:54:38Z","timestamp":1760144078000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/20\/7832"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,10,15]]},"references-count":43,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2022,10]]}},"alternative-id":["s22207832"],"URL":"https:\/\/doi.org\/10.3390\/s22207832","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,10,15]]}}}