Development Of Quantitative Detection Of Several Important Harmful Food Additives Based On Smartphone Of Digital Colorimetric Method

In recent years,food safety problems,especially food pollution or poisoning resulted from the harmful additives such as nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide,were greatly serious.These food harmful additives were carcinogenic and of great harm to the human body.C urrently,the traditional methods detecting thus harmful additives in food requires the professional equipment and the operation is very cumbersome,which can not meet the needs of rapid detection on scene.Therefore,the development of methods that are fast,simple and low cost for the detection of harmful additives in food is necessary.Smartphones-based detection technique is expected to become a new generation of on-site rapid screening tools due to their flexible,convenient,powerful data processing capabilities and the open source app development environment.In this paper,nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide were used as the research object and the corresponding spectrophotometric method was developed.On this basis,the four test cards were further developed and the corresponding Photoshop digital colorimetric method were developed.Through the smart phone detection system,multiple samples of simultaneous testing was achieved and the simple,fast and low-cost quantitative detection for the harmful additives was realized.The main research contents are as follows:(1)The spectrophotometric detection methods of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide were established respectively.After the discolor and the detection system were investigated and optimized,the precision of the method was measured.The linear ranges of the four spectrophotometry were 0.025-4.0?g/mL,0.25-5.0?g/mL,2.5-40.0?g/mL and 0.5-20.0?g/mL respectively.The linear equations were y=0.6382 x+0.0598,y=0.3393 x-0.0704,y=0.0168 x-0.0563 and y=0.1307 x+0.2319 respectively.The correlation coefficients were R~2=0.9998,R~2=0.9988,R~2=0.9984 and R~2=0.9974 respectively.The coefficient of variation of intra-assay and inter-assay were less than 15%and the linear equations were very approximative,thus indicating the established spectrophotome tric a good reproducibility and high precision.(2)On the basis of spectrophotometric methods,four kinds of test cards of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide were developed.The color of test cards changed after chemical reaction,and the gray value of new color was obtained by the Photoshop software and corresponding formula and eventually converted to gray different value.Thus,the Photoshop digital colorimetric detection method of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide were developed.The linear ranges of the digital colorimetric method were 0.5-20.0?g/mL,0.5-40.0?g/mL,10.0-100.0?g/mL and 1.0-50.0?g/mL respectively.The linear equations were y=5.7481 x-0.6527,y=0.5013 x+1.9433,y=0.9726 x-4.5143 and y=1.9362 x+7.7108 respectively.The recoveries of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide ranged from 87.96%to 118.54%,from 91.52%to 113.54%,from 93.84%to119.13%,from 92.14%to 117.69%respectively.The coefficients of variation were5.45%-13.98%,6.82%-11.86%,3.43%-11.92%and 6.61%-13.56%respectively.Four kinds of test cards had good specificity apart from the interference of a small number of preservatives and ions.It indicated that the effect of the test cards was superior and the corresponding digital colorimetric detection method based on Photoshop was accurate and reliable.(3)We have developed a smartphone detection system for rapid quantitative detection of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide.This system consists of two parts:smartphone application and portable optical device.The smartphone detection app is written to capture pictures of the reaction zone of the test cards of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide firstly,then calculate the gray different value of each test card,finally obtain the concentrations of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide in samples on the basis of the obtained gray different values of samples and directly display the results on the phone screen.To provide uniform illumination for four kinds of test cards and eliminate the influence of ambient light,a portable optical device is designed by 3DMax and printed using a 3D printer.Then the white LED lights and battery were put in the respective components.(4)The digital colorimetric detection method based on smart phone was developed and the corresponding detection methods of nitrite,formaldehyde,sodium formaldehyde sulfoxylate and hydrogen peroxide in the samples were realized.The recoveries of nitrite in Chinese cabbage and mustard ranged from 87.96%to 109.81%and the coefficient of variation ranged from 5.45%to 13.98%.The recoveries of formaldehyde in yuba and sugar ranged from 82.63%to 115.20%and the coefficient of variation ranged from 5.76%to13.72%.The recoveries of sodium formaldehyde sulfoxylate in noodles and rice flour ranged from 82.91%to 97.06%and the coefficient of variation ranged from 3.61%to9.57%.The recoveries of hydrogen peroxide in Chinese cabbage and apples ranged from84.40%to 104.62%and the coefficient of variation ranged from 6.62%to 11.73%.Compared with spectrophoto metry,the linearity coefficients were R~2=0.9751,R~2=0.9955,R~2=0.9815 and R~2=0.9751 respectively,indicating good consistency between the two methods.The results detected by the digital colorimetric detection method based on smart phone of the ten actual samples were compared to the HPLC,showing good consistency,which verify the accuracy and reliability of this method.