California Code of Regulations › Title 3 - Food and Agriculture › Division 3 - Economics › Chapter 1 - Fruit and Vegetable Standardization › Subchapter 4 - Fresh Fruits, Nuts and Vegetables › Article 2 - Inspection Procedures › Section 1370.16 - Alkali Solutions, Procedure for Testing

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
The 0.1562 normal hydrochloric acid for testing the
						strength of solutions used for testing citrus can also be used to check the
						strength of the 0.1333 normal sodium hydroxide solution used for testing grape
						maturity.
PROCEDURE FOR CHECKING THE STRENGTH OF CITRUS AND
						GRAPE TESTING SODIUM HYDROXIDE SOLUTIONS
By means of a volumetric pipette transfer 25.00
						milliliters (ml.) of 0.1562 normal hydrochloric acid to the titrating flask. Do
						not blow out the liquid remaining in the tip of the pipette, but touch the
						pipette tip to the surface of liquid in the flask to remove the adhering
						drop.
Add phenolphthalein indicator solution to the titrating
						flask, and then add the alkali solution to be tested from the burette,
						agitating the contents of the titrating flask continuously if possible. As the
						end-point is approached and the indicator color starts to spread through the
						liquid, add the alkali solution dropwise, swirling the flask to mix the entire
						contents before adding additional alkali.
The true end-point is a faint but persistent pink color,
						not a deep red.
Table 1. Citrus Maturity Testing Solution (0.1562
						Normal)
Ml. citrus testing soln. required to
								neutralize 25.00 ml. of 0.1562 normal hydrochloric acid
Normality of the citrus testing
								solution
Citric acid equivalent gram per ml.
25.00..........................
0.1562
0.01000
25.10..........................
0.1556
0.00996
25.20..........................
0.1550
0.00992
25.30..........................
0.1543
0.00988
25.40..........................
0.1537
0.00984
25.50..........................
0.1531
0.00980
25.60..........................
0.1525
0.00976
25.70..........................
0.1519
0.00972
25.80..........................
0.1514
0.00969
25.90..........................
0.1508
0.00965
26.00..........................
0.1502
0.00962
Table II. Grape Maturity Testing Solution (0.1333
						Normal)
Ml. citrus testing soln. required to
								neutralize 25.00 ml. of 0.1562 normal hydrochloric acid
Normality of the grape testing
								solution
Tartaric acid equivalent gram per
								ml.
29.30..........................
0.1333
0.01000
29.40..........................
0.1328
0.00996
29.50..........................
0.1324
0.00993
29.60..........................
0.1319
0.00989
29.70..........................
0.1315
0.00986
29.80..........................
0.1310
0.00983
29.90..........................
0.1306
0.00980
30.00..........................
0.1302
0.00977
30.10..........................
0.1297
0.00973
30.20..........................
0.1293
0.00970
30.30..........................
0.1289
0.00967
The keeping qualities of the 0.1562 N hydrochloric acid
						standard are excellent when the bottle is kept properly closed to avoid
						evaporation and out of direct sunlight. Unused titrating solutions should never
						be returned to the bottle, but discarded to minimize the hazard of
						contamination. There should be a slight change in normality of the acid in a
						six-month period. Sodium hydroxide solutions do not keep as well but tend to
						become weaker as they age. They should be checked with the standard acid as
						frequently as necessary to assure the operator that their strength is
						known.
1. New
						section filed 7-7-55; effective thirtieth day thereafter (Register 55, No.
						10).
2. Renumbering from Section
						1382 filed 1-21-75; effective
						thirtieth day thereafter (Register 75, No. 4).