Table 2.
Summary of microfluidic paper-based analytical device (μPAD) applications in detecting chemical hazards in food matrices.
| Analyte | Food Matrix | Sample Preparation | Liquid Phase | Principle and Format | Paper Type | Fabrication Method | Barrier Material | Note | Ref. |
|---|---|---|---|---|---|---|---|---|---|
| Paraoxon (organophosphate pesticide) | Milk, apple juice, head lettuce, apple | Adjust apple juice pH, swab surface of lettuce and apple into water | Aqueous | Acetylcholinesterase (AChE) inhibition, colorimetric bidirectional lateral flow strip | Whatman No. 1 | Paper-cutting, inkjet-printing of reagents | - | Silica assisted reagent trapping, sampling method issue | [34] |
| Pirimicarb (carbamate pesticide) | Lettuce, brown rice | PBS buffer extraction (10 min) or QuEChERS method | Aqueous, acetonitrile | AChE inhibition, colorimetric | Whatman No. 1 | Cutting | - | Sample preparation details not reported | [37] |
| Methyl-paraoxon (organophosphate pesticide) | Cabbage, green mussel | QuEChERS method | Aqueous (4% methanol) | AChE inhibition, colorimetric | Whatman No. 4 | Polymer screen-printing method | Polystyrene | Nanoceria (CeO2) coated μPAD | [38] |
| Dichlorvos (organophosphate pesticide) | Cucumber, tomato, cabbage | Water eluting & filtration | Aqueous | Chemiluminescence, lateral flow | Whatman Grade 3MM CHR chromatography paper | Cutting, home-made reagent dispensing equipment | - | Incorrect sampling | [35] |
| Tomato skin, cabbage leaf | Chemiluminescence, molecularly imprinted polymers | [36] | |||||||
| Nitrite | Red cubilose | 75 °C water extraction 5 min, centrifugation 30 min | Aqueous | Griess-color nitrite assay | Whatman No. 1 | UV-lithography | Octadecyltrichlorosilane | Sample preparation details not specified | [39] |
| Nitrite | Ham, sausage | 100 °C water extraction (1 h) | Aqueous | Griess-color nitrite assay | JProlab JP40 filter paper | Stamping | Paraffin | - | [41] |
| Cu(II) | Tomato juice, rice | Centrifuge & filtration (tomato juice), 4 h acid digestion & oxidation (rice) | Aqueous | Catalytic etching of silver nanoplates by thiosulfate in presence of Cu2+, colorimetric | Whatman No. 1 | Wax printing | Xerox Color Qube printing wax | - | [42] |
| Cu(II), Pb(II), Cd(II) | Rice, fish | 4 h acid digestion, pH adjustment, filtration | Aqueous | Electrochemistry for Pb(II), Cd(II) | Whatman No. 1 | Wax printing (pattern), screening-printing (electrochemical ink) | Xerox Color Qube printing wax | Cu(II)detection [42] incorporated | [40] |
| Clenbuterol (veterinary drug) | Milk | No | Aqueous | Competitive ELISA, HRP labeled | Chromatography paper | Wax printing, screening-patterning | Xerox Color Qube printing wax, paraffin | - | [43] |
| Formaldehyde (illegal preservative) | Dried goods | Micro-distillation | Aqueous | Hantzsch reaction, fluorescent formaldehyde-Acetoacetanilide complex | Advantec No. 1 | Wax printing | Xerox Color Qube printing wax | - | [44,45] |
| l-glutamate | Instant soup | No | Aqueous | Dehydrogenase catalyzed color change | Chromatography paper | No pattern | - | - | [46] |
| “Genotoxic activity of pollutants” | Grilled chicken | Dimethyl sulfoxide (DMSO) extraction | DMSO | Electrochemiluminescence | Whatman No. 1 | Screening-printing | Wax from commercial wax paper | Large variation, analyte not specified | [47] |