Increasingly, large amounts of seafood, such as shrimp is being imported into many countries including the United States. (Here is a USDA chart listing shrimp imports by volume and dollars.) Seafood can be legally treated with polyphosphates and citrate to help preserve it before it reaches the consumer. Even though polyphosphates are not considered injurious to human health, many countries set limits on the amounts of polyphosphates that can be added to shrimp and other seafood including the United Nations Food and Agricultural Organization (FAO). Here is the U.S. Department of Commerce’s Seafood Inspection Program handbook (downloadable PDF).
Here, we present Application Note 1007: Determination of Mono-, Di-, and Tripolyphosphates and Citrate in Shrimp by Ion Chromatography, (downloadable PDF) authored by application chemists in our Bangkok Applications Lab and should be of interest to government labs responsible for inspecting seafood and food analysis labs that assay for polyphosphate.
Our application library does contain two earlier applications which describe excellent ion chromatography (IC) methods for determining both small and large polyphosphates:
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- Application Note 71,Determination of Polyphosphates Using Ion Chromatography with Suppressed Conductivity Detection, (downloadable PDF)
- Application Update 172, Determination of Polyphosphates Using Ion Chromatography, (downloadable PDF)
But, Application Note 1007 was developed as some customers might only need to analyze for a few analytes. AN1007 describes the use of online sample preparation with sample pretreatment cartridge (Thermo Scientific Dionex InGuard HRP cartridge) to remove hydrophobic components from the shrimp sample before separation of the small polyphosphates and citrate on a Reagent-Free IC (RFIC) system (Thermo Scientific Dionex ICS-3000 system) outfitted with an anion-exchange column (Thermo Scientific Dionex IonPac AS11 column). The combination of the inline sample preparation and RFIC system saves analyst time and reduces error.
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