Issue link: http://read.dmtmag.com/i/37334
Harvest/Postharvest Portable residue DETECTOR INVENTED New residue-testing equipment might be used in the future in supermarkets to detect chemicals or pathogens. by Richard Lehnert Purdue University graduate student Santosh Soparawalla, left, and postdoctoral researcher Fatkhulla Tadjimukhamedov demonstrate a miniature mass spectrometer used to detect chemicals on store produce. A WE MAKE YOUR JOB EASIER! &!)$(" &!(&)$(" =)667,%2-2',)6:-()*35 2%553:75))53:64%'-2+6 +,-$& .($-( ').(- )( (1/$&& +.(($("" + $ " "!#!"! )0)--)+ )0#.--& ).& )+% +).()" +),-( )()'1!- )$(-)+%, )$(-$$!- )(/ 1)+, + $"#-- .+(1&(*+1 +, :::4,-0&53:2:)0(-2+'31 PHIL BROWN WELDING CORP. ,32) • %; • >-0) ($32/0-2-',-+%2 18 AUGUST 2011 GOOD FRUIT GROWER =!5%'73513827)(9%09) -6%9%-0%&0) =<(5%80-'(5-9)25300)5',%-2 *35032+61337,34)5%7-32 ="6)6);-67-2+75%'735 ,<(5%80-'6<67)1 =(.867%&0),-7',*35(-**)5)27 (5%:&%5,)-+,76 = )%513827)(%8731%7-' &3;67347345)9)2760-(-2+ team of scientists at Purdue University is perfecting a portable device that can quickly detect both chemical residues and bac- terial contamination on fresh fruits and vegetables without complicated laboratory analysis. In a recent trial in a supermarket, university graduate stu- dents armed with the machine were able to identify oranges with residues of the fungicide benzimidazole and apples that had been treated with the scald inhibitor diphenylamine (DPA). The device is a miniature mass spectrometer that weighs 22 pounds compared to the 500-pound versions that are used in laboratories to identify chemical compounds. The small size is one aspect of the new technology Dr. R. Graham Cooks and Dr. Zheng Ouyang and their team have created. Cooks is the Henry Bohn Haas Distin- guished Professor of Chemistry and cofounder of the Purdue Center for Analytical Instrumentation Develop- ment in West Lafayette, Indiana. Ouyang is an assistant professor of biomedical engineering. In an interview with Good Fruit Grower, Cooks said another facet combined with the small size could make this instrument a useful tool in food safety in the future. “The method works without complicated sample collec- tion and preparation,” he said. “That means it can be used in situ, like when walking around in a supermarket.” It’s also fast. The test takes only a few seconds. The field trial focused on finding chemical residues, but Cooks said that in laboratory trials it was also able to detect bacteria like Escherichia coli (E. coli) and salmonella. The work at Purdue dates back nearly a decade. From the start, researchers envisioned a Star Trek-like “tri- corder,” a small instrument that, when pointed at an object, could reveal its chemical composition. Now, instead of tricorder, they use words like iPhone apps— something an ordinary person might use while shopping to scan an apple for chemical residue or bean sprouts for bacteria. Mass spectrometry was developed more than a cen- tury ago and is a commonly used analytical method, but mass spectrometers cost $100,000 and up, are installed in laboratories, and require special sample preparation and analysis in a vacuum chamber. Cooks and his team devel- oped “ambient ionization,” in which a handheld wand dislodges ionized molecules from a surface and vacuums them into the equipment for analysis. It works in open air. The small mass spectrometer works like the larger lab- oratory version, although it is less precise, Cooks said. It www.goodfruit.com Building the Best Since 1964! purdue news service / mark simons