Studies on Residual Alkylbenzenesulfonate (ABS) in Vegetables and Fruits

Abstract

We carried out the determination of residual ABS remained in vegetable and fruits treated with the chemical detergent.
1) Chemical method
There are few reports on the determination of ABS contained in vegetables and fruits, but in this case we adopted the following method; a sample sliced and miced as finely as possible is extracted with alcohol containing hydrochloric acid. After evaporating alcohol from the alcoholic extract, the residual fluid is adjusted to pH 10 and filtered. The filterate is washed with petroether. The petroether-washed liquid is treated according to Longwell and Maniece method.
As a result of our experiments we could find the following.
Vegetables: The residual detergent was 20-70ppm after soaking a sample in 0.05 per cent ABS solution (usual concentration for use) for 1-5 minutes, but when once washed with water after soaking, the residuals were decreased to 4-13ppm, when 3 times to 2-7ppm.
Hurt vegetables showed a larger amount of the residues as compared with normal ones.
Fruits: 0.5-2ppm of the residues were found to remain in a sample after washing with water.
In the case of strawberry as a sample, it was found the longer time of soaking the more residues of the detergent.
On the contrary apples showed no more than 0.5ppm of the residual detergent after soaking in the solution within 1-5 minutes.
2) Radiochemical method
As a result of our radiochemical experiments, when 10g of spinach was soaked in 150ml of 0.05 per cent ABS solution containing labeled sodium alkylbenzenesulfonate for 10 seconds, and washed again with 300ml of water, we found 2ppm of ABS remained in the sample. And when soaked for 30 minutes under the same conditions, 12ppm of ABS in the sample.