SOP for ESTIMATION OF BORON

PRINCIPLE:

Reaction of Azomethine-H which is the condensation product of H Acid 

(8-amino-naptha-1-ol-3.6-disulphonic Acid) and Salicyladehyde, with dissolved forms of 

borate at a pH above 6. Formation of yellow complex that is measured 

spectrophotometrically at the absorption maximum in the range of 410 nm to 420 nm.  

 Reagent:

Boron free Distilled water

Azomethine H Solution: Weigh accurately 1.0 gm of Azomethine H sodium salt and 3.0 gm L ± Ascorbic acid in to 100 ml volumetric flask. Dissolve in distilled water and make up to the mark. The solution is stable for 1 week when stored in polyethylene bottle at a temperature 4ºC and 6ºC

Stock Borate solution: Dissolve 5.719 gm of boric acid in 1000 ml water.  Store in polyethylene bottle.1 ml of stock = 1.0 mg of borate.

Standard Borate solution: Dilute 10 ml stock solution and dilute to 1000 ml 

with distilled water.  (1ml = 10µm of Borates as B )

 Working Boron Solution: Dilute 10 ml stock solution and dilute to 100 ml with   

distilled water. (1ml = 1.0µ Borates as B)

PROCEDURE: Prepare 0.5, 1, 2, 4, 5 ppm of standard solution of borate form standard 

borate solution of 1 ml = 1 µ of borate. Take 25 ml of each standard, sample and blank as

 distilled water in 100 ml volumetric flask add 10 ml of azomethine H solution to each 

flask and keep at 20ºC ± 1ºC for 2 hrs in dark and make up the volume to 100 ml with 

distilled water .Scan the highest 

             CALCULATION

Boron, mg/L  =                     ABS (Spl)    

                                                         SLOPE

Where,

                                    ABS (Spl) -   Absorbance of sample

                                    SLOPE –      Slope calculated from standard curve

REFERENCE: IS: 13428 – 1998,