Food additive contaminants are chemicals that are intentionally added to a product during the manufacturing process. Many chemicals are added for valid reasons, and need to be monitored to assure they are added according to their usage and specifications, to detect contamination of chemical feed stocks, and for labeling purposes due to potential allergic reactions for consumers. Some examples of these types of chemicals would be nitrate, nitrite, sulfite, and benzoate.

In some cases, however, dangerous or banned chemicals are used to save cost or mislead the consumer. From a safety and regulatory standpoint, unauthorized and banned chemicals need to be detected to assure they are not being used for food products. Examples include Sudan dyes and melamine.

Dionex provides system, column, and detection solutions for determination of a wide variety of food additives.

Nitrate and nitrite are usually added to processed meat products to protect against microorganisms that can cause food poisoning, such as Clostridium botulinum. However, nitrite can react with secondary amines in food products or in the digestive system to form nitrosoamines, a class of carcinogenic compounds. Nitrate, although more stable than nitrite, can act as a reservoir for nitrite. Also, nitrate can readily be converted into nitrite by microbial reduction. Thus, both nitrate and nitrite must be monitored to ensure the quality and safety of meat products.

Nitrate and nitrate in ham can be separated and quantified rapidly using an IC system with an IonPac^® AS11 column and UV detection.

Sulfites are used in foods to preserve the look and taste and to prevent spoilage. However, excessive concentrations can trigger allergic reactions in some people, causing breathing difficulty in minutes after ingestion.

Sulfites occur naturally in almost all wines and are added to wines as preservatives, to prevent spoilage and oxidation. Sulfites are often used as preservatives in foods such as dried fruits and vegetables. Both the EU and the US FDA require that foods containing sulfites be labeled, and the US FDA has banned the use of sulfites in certain foods, such as fresh fruits and vegetables. Ion-exclusion chromatography and pulsed amperometric detection can be used to quantify sulfite in wine and dried foods for regulatory and labeling compliance.

Identification and quantification of sulfite in dried apricots using an IC system and pulsed amperometric detection.

Ion-exclusion chromatography and pulsed amperometric detection can be used to quantify sulfite in wine and dried foods for regulatory and labeling compliance.

Since the early 1900s, benzoate has been used worldwide as a preservative, due to its antimicrobial properties, low toxicity, and absence of taste. Although the US FDA lists benzoate as generally recognized as safe (GRAS), the maximum permitted concentration is 0.1%. The European Union limits benzoate to 0.015% in soft drinks and 0.2% in all other foods. Ion chromatography using an IonPac^® AS18 column and suppressed conductivity detection can be used to determine and quantify benzoate in a variety of liquid food samples.

Determination of benzoate in soy sauce.

The Sudan dyes have been linked to increased cancer risks, and are now banned in most countries around the world. However, some suppliers still turn to these substances to enhance their products’ visual appeal, in spite of the prohibition, because of cost and availability. Sudan dye contamination discovered in 2005 led to the UK's biggest food recall ever.

Sudan dyes in paprika, separated using an Acclaim 120 C18 column and determined using a diode array detector.

Sudan dyes can be determined quickly and easily using an HPLC system with Acclaim 120 C18 column and absorbance detection.

Melamine in Pet Food and Milk

Melamine, a common component of plastic manufacturing, and cyanuric acid, a compound often used for pool chlorination, are closely related chemicals that, by themselves, are non-toxic. However, when combined these components form a toxic, insoluble crystal that causes kidney stones and can lead to renal failure. Because melamine has high nitrogen content, it has been added to low-quality wheat gluten and milk products to make them appear higher in protein.

The Chinese government has established standard test methods for milk and milk powders, using reversed-phase HPLC separation and UV detection. The UltiMate^® 3000 HPLC system and the Acclaim^® 120 C18 column are ideal for these methods.

Melamine in milk powder samples, separated using an Acclaim 120 C18 column. 

Melamine and cyanuric acid can also be separated using an Acclaim Mixed-Mode WAX-1 column and determined either by UV absorption, or using mass spectrometry for increased specificity and sensitivity. Ion chromatography using an IonPac^® CS17 column and detection with UV absorption requires less sample preparation, and provides faster separation.