This document discusses various methods for processing food samples to separate analytes from interferents for analysis. Common methods include solvent extraction to separate analytes based on solubility differences, organic matter decomposition through dry ashing or wet digestion to oxidize organic matter, distillation to separate components based on volatility, and salting out to precipitate analytes by reducing solubility. Other chemical separation techniques mentioned are sulfonation, saponification, masking, clarification, decolorization, and concentration. The goal of sample processing is to obtain accurate analytical results by removing potential interferents.

1. Food Sample processing
Vinu Varghese
Asst Professor
Dept of Applied Biotechnology
St Mary’s College Thrissur

2. Sample processing
 Method to separate the analyte from the interferent or removing the interferent for
getting better result

3. Common methods for sample processing
 Solvent extraction method
 Organic matter decomposing method
 Dry ashing
 Wet digestion
 Distillation method
 Salting out method

4. Solvent extraction method
 The principle is to separate the analyte from the Interfernence properties of the
interferent
 Once the analyte is extracted ,undergo HPLC to separate ,identify and quantify the
analyte
 Eg For the determination of Bacillus toxin, alphatoxin is extracted with a common
organic solvent and then by HPLC

5. Organic matter decomposition method
 The principle is to use high temperature treatment to oxidize an decompose the
organic matter in the sample .
 Carbon, Hydrogen and Oxygen will escape along with carbon dioxide and water
 Metal elements and other compounds are released for further determination
 Specific methods are dry ashing and wet digestion

6. Dry ashing
 Place the sample in crucible
 Carbonize under low temperature and low heat
 Ash the sample at a high temperature ( 500oC – 600oC) in a high temperature
furnace ( Muffle Furance)
 for easy ashing sample is melted using nitric acid
 Ashing promoters like ammonium nitrate and sodium nitrate can also be used

7. Muffle Furnace

8. Wet digestion
 Decompose the organic matter in the sample using oxidizing agents like sulphuric
acid ,nitric acid and hydrogen peroxide
 Metal left in the soln will be in an ionic state and the soln is cooled

9. Distillation method
 In this method the difference in volatility of each component in the substance to be
tested is used for separation
 Interferent can be removed and the component to be tested can distilled off
 The distillate is then collected for futher analysis
 Ex kjeldahi method

10. Salting Out Method
 Adding a certain inorganic salt to the solution ,the solubility of the solute in the
original solvent is greatly reduced and precipitated


11. Chemical separation methods
 Sulfonation & Saponification
 Masking Method
 Clarification & Decolorization Method
 Contration

12. Sulfonation and saponification
 Sulfonation is used to treat oil or fat containing samples
 Oil is sulphonated by sulphuric acid
 Ex :analysis of the presence of pesticide in a sample
or
Saponified by alkali

13. Masking method
 Interferent component is converted into noninterfering component using a
masking agent
 Eliminate the interference effect without separating interferent from the analyte
 Common method used in food analysis

14. Clarification and Decolorization
 Clarification is used to separate the turbid material from the sample to eliminate its
effect in the analytical determination by a clarifying agent
 Decolorization is a method of removing coloured substance in a sample that easily
interfere with the measurement by using decolorization agents

15. Concentration Method
 Purified sample is concentrated under particular pressure for removing the
moisture content of the sample