A novel on‐chip solution enabling rapid analysis of melamine and chloramphenicol in milk by smartphones

Abstract

Ubiquitous food security control is desirable. However, the analysis methods, such as those for milk, are highly based on manual analysis, leading to low efficiency. Thus, we report a multilayer paper-based microfluidic chip transforming chromatic readout to electric signals. First, colloidal gold immunochromatographic assays (GICA) are used to achieve the colorimetric occurrence.Secondly, the test (T) lines and control (C) lines are patterned to encode different EAN-8 barcode. Furthermore, accurate scanning is accomplished by the automatic threshold segmentation.These technologies make the digital determination of melamine (MEL) and chloramphenicol (CAP) by phone readily accessible. Results indicate that the accurate machine-scanning can be assured when MEL and CAP is above 30 ng/mL and 6 ng/mL in milk respectively. The detection time is under 8 min, and the stable storage life is over 90 days. Therefore, this simple chip allows rapid, machine-readable, electric-recordable diagnostic directly from chromatic assays with satisfying stability, specificity and accuracy. Practical applicationsThis article illustrates a method used to determine the concentration of melamine and chloramphenicol in milk. When melamine and chloramphenicol is above 30 and 6 ng/ml in milk, the produced EAN-8 barcode can be recognized with high accurate level, compared with international standards, the results are acceptable and sensitive. This method is highly intellectual and environmentally friendly, with the disposable materials and instant smartphone-readable EAN-8 results patterns. This article demonstrates a multilayer paper chip based on EAN-8 encoding rules, colloidal gold nanoparticles, and immunochromatographic assays. The EAN-8 format assay is achieved by color-development occurrence of colloidal GICA in different encoding areas of EAN-8 code, and the analysis device, namely smartphone, is accessible by almost every individual. Therefore, this chip can pave a potential way for massive health control and digital automated analysis for daily life and industrial manufacture.

Smartphone-based optical assays in the food safety field

“…Examples are (i) a SBD for pesticide (methyl parathion) detection in apples with a LOD of 200 ng.mL −1 [ 41 ], (ii) a SBD for E. Coli detection in drinking water with positive detection from 10 6 CFUs ( Fig. 3 f) [ 52 ] and, (iii), a SBD for melamine & chloramphenicol detection in milk with a LOD of 30 ng.mL −1 for melamine and 6 ng mL −1 for chloramphenicol [ 53 ] ( Table 2 ). The concept of utilising QR barcodes is powerful because it utilises existing software and can be exploited for analyses by end-users using a plethora of smartphone models.…”

“…However, further validation of these devices is needed. For instance, only [ 53 ] conducted an interference study. Moreover, verification of inter-phone variation is lacking and is needed to complete the readiness of this technique.…”

Handheld Spectral Sensing Devices Should Not Mislead Consumers as Far as Non-Authentic Food Is Concerned: A Case Study with Adulteration of Milk Powder

“…In that regard, liquid chromatography-tandem mass spectrometry (LC-MS/MS) is often considered as a reference and used for validating simple tests [ 33 , 34 ], thereby ensuring the accuracy of those. Smartphone-based sensors that rely on optical detection principles have recently emerged [ 35 , 36 ] ( Figure 6 ), and they represent an attractive technological opportunity that combines rapid testing, connectivity, customization, and portability.…”

Detection of Melamine Based on the Fluorescence Changes of Nitrogen-Doped Carbon Dots

“…At present, there are a number of detection methods for melamine, such as enzyme-linked immune sorbent assay (ELISA) [9,10], colloidal gold immune-chromatographic assays (GICA) [11], high performance liquid chromatography (HPLC) [12,13], liquid chromatography-mass spectrometry (LC-MS) [14,15], gas phase chromatography-mass spectrometry (GC-MS) [16,17], electrospray ionizationmass spectrometry (ESI-MS) [18], and near-infrared (NIR) [19]. ese methods have the advantages of high sensitivity and high accuracy.…”