IPT09 ANALYSIS OF FOOD FLAVOURING AGENTS Last Revised:
May 2015
1. PURPOSE This exercise determines the concentration of the major flavour component of almond essence by UV absorption spectrophotometry. 2. REAGENTS & EQUIPMENT 2.1
Phenylmethanal (benzaldehyde) 2.2
Ethanol 2.3
Almond essence 2.4
UV spectrophotometer and quartz cells 3. PROCEDURE 3A. Standard preparation 3.1
Make up 1 L of 10% ethanol in a beaker, using a measuring cylinder to measure out the ethanol. 3.2
Weigh accurately 0.5 g of phenylmethanal into a small beaker, dissolve in 20 mL of pure ethanol and transfer to a 50 mL volumetric flask. Make up to the mark with ethanol. 3.3
Pipette 1 mL of the phenylmethanal solution from step 3.2 to a 100 mL volumetric flask. Make up to the mark with 10% ethanol. 3.4
Pipette 2, 5 and 10 mL of the standard in step 3.3 to 100 mL volumetric flasks. Make up to the mark with 10% ethanol. 3B. Sample preparation 3.5
Pipette 1 mL of essence, in triplicate, into 100 mL volumetric flasks. 3.6
To one flask, pipette 1 mL of the phenylmethanal standard made in step 3.2, as a recovery check. 3.7
Make up to the mark with 10% ethanol. 3.8
Pipette 2 mL of each solution into 100 mL volumetric flasks. 3.9
Make up to the mark with 10% ethanol. 3C. Analysis 3.10
Use the Cary UV/VIS for this task. In Simple Reads, choose User Collect and enter the following formula: =READ(249)‐0.5*(READ(222)_READ(350)) 249 nm is the analytical , and 222 and 350 nm deal with matrix error. 3.11
Measure the absorbance of each solution, using 10% ethanol as a blank. Reporting 

enter the data into the spreadsheet found on the subject website. record the final results – average %w/v, % recovery and % relative precision – on your Results Sheet