MadSci Network: Chemistry

Re: Are there ways to test foods for sulfur dioxide, if so how?

Date: Wed May 31 10:37:16 2000
Posted By: Alfred Bushway, Professor of Food Science
Area of science: Chemistry
ID: 958693802.Ch

Hi Beth,

I will try and provide some information that might assist you with your project. As you already know sulfur dioxide and other sulfiting agents are permited as food additives. When one analyzes foods for these compounds we usually look for residual sulfite. The methods that are used in the industry require sophisticated analytical equipment (High Performance Liquid Chromatographs). There are test strips sold which can be used to estimate the sulifite content in liquids. You might be able to adapt them to solid food products by extracting the foods with water, filtering and using the strips to determine the sulifite concentration in the filtrate. You can purchase these test strips from Fisher Scientific ( They are called Quant* Test Strips and are found on page 1935 of the Fisfer catalog. The price is $38.53 for 100 test strips. I hope this information proves to be of assistance, and good luck with your project.


Al Bushway

Professor of Food Science


Admin note:
Don Schaffner adds the following:

An FDA training manual on the web:

lists two sulfur dioxide test methods. Here is an excerpt from the online manual.

------------------------------------------ Sulfites

A. Introduction

Sulfur dioxide and sodium and potassium bisulfites and metabisulfites are used in foods as antioxidants and bleaching agents. Sulfites are commonly used as preservatives in dried fruits and as bleaching agents in the processing of maraschino cherries.

This exercise requires the trainee to determine the amount of sulfite, calculated as sulfur dioxide, present in a preserved food.

B. Assignment

The trainer will provide a sample of dried fruit preserved with sulfides. Determine the amount of sulfite present. as sulfur dioxide. using the Monier-Williams Procedure (with Modifications), also referred to as the Optimized Monier-Williams Procedure published in the Federal Register, Vol. 51, No. 131, July 9, 1986, pp. 25017-20. Also perform the AOAC gravimetric determination. 962.16C.

C. References

1. Federal Register, Vol. 51, No. 131, July 9, 1986, pp. 25012-26.

2. AOAC Official Methods of Analysis." 15th ed., 1990: 962.16C.


A good librarian should be able to get copies of both documents via interlibrary loan.

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