TBHQ
Amalfi TBHQ is an antioxidant which offers excellent solubility in fats and oils. Used alone or in combination with other Amalfi antioxidants it adds stability to fats, oils, cereals and packaging materials.
TBHQ
tert-Butylhydroquinone; Mono-tert-butylhydroquinone
C10H14O2
Formula wt 166.22
INS: 319
CAS: [1948-33-0]
Description
A white, crystalline solid having a characteristic odor. It is soluble in alcohol and in ether, but is practically insoluble in water.
Functional Use in Foods: Antioxidant.
Requirements
Identification: Dissolve a few mg of the sample in 1 mL of methanol, and add a few drops of a 25% solution of dimethylamine in water. A pink to red color is produced.
Assay: Not less than 99.0% of C10H14O2.
t-Butyl-p-benzoquinone: Not more than 0.2%
2,5-Di-t-butylhydroquinone: Not more than 0.2%
Heavy Metals (as Pb): Not more than 10 mg/kg.
Hydroquinone: Not more than 0.1%.
Melting Range: Between 126.5o and 128.5o.
Toluene: Not more than 0.0025%.
Ultraviolet Absorbance (polynuclear hydrocarbons): Passes test.
Tests
Assay: Transfer about 170 mg of the sample. previously ground to a fine powder and accurately weighed, into a 250-mL, wide-mouth Erlenmeyer flask, and dissolve in 10 mL of methanol. Add 150 mL of water, 1mL of 1 N sulfuric acid, and 4 drops of diphenylamine indicator (3 mg of p-diphenylaminesulfonic acid sodium salt per mL of 0.1 N sulfuric acid), and titrate with 0.1 N ceric sulfate to the first complete color change from yellow to red violet. Record the volume, in mL, of 0.1 N ceric sulfate required as V. Calculate the percentage of C10H14O2 in the sample, uncorrected for hydroquinone (HQ) and 2,5-di-tert-butylhydroquinone (DTBHQ), by the formula
8.311N ( V - 0.1 mL ) / W
in which 0.1 mL represents the volume of ceric sulfate solution consumed by the primary oxidation products of tert-Butylhydroquinone ordinarily present in the sample; N is the exact normality of the ceric sulfate solution; and W is the weight of the sample taken, in g. Record the uncorrected percentage thus calculated as A. If HQ and DTBHQ are present in the sample, they will be included in the titration. Calculate the corrected percentage of C10H14O2 in the sample by the formula
A - ( % HQ x 1.51 ) - ( % DTBHQ x 0.75)
using the respective values for percentage of HQ and percentage of DTBHQ as determined under 2,5-Di-t-butylhydroquinone and Hydroquinone.
t-Butyl-p-benzoquinone:
Standard Preparation Transfer about 10 mg of FCC Mono-tertiary-butyl-p-benzoquinone Reference Standard, accurately weighed, into a 10-mL volumetric flask, dissolve in chloroform, dilute to volume with the same solvent, and mix.
Sample Preparation Transfer about 1 g of the sample, previously reduced to a fine powder in a high-speed blender and accurately weighed, into a 10-mL volumetric flask, dilute to volume with chloroform, and shake for 5 min to extract the t-butyl-p-benzoquinone. Filter through a Millipore filter or equivalent, before use in the Procedure below.
Procedure Fill the reference cell with chloroform and the sample cell with the Standard Preparation, place the cell in the respective reference and sample beams of the spectrophotometer, and record the infrared spectrum from 1600 to 1775 cm-1. On the Spectrum draw a background line from 1612 to 1750 cm-1, and determine the net absorbance (AS) of the standard Preparation at 1659cm-1. Similarly, obtain the spectrum of the Sample Preparation, and determine its net absorbance (AU) at 1659 cm-1. Calculate the percentage of t-butyl-p-benzoquinone in the sample by the formula
100 x ( AU / AS ) x ( WS / WU )
in which WS is the exact weight, in mg, of the Reference Standard taken, and WU is the exact weight, in mg, of the sample taken.
2,5-Di-t-butylhydroquinone and Hydroquinone:
Stock Solutions Weigh accurately about 50 mg each of hydroquinone (HQ), 2,5-di-t-butylhydroquinone (DTBHQ), and methyl benzoate (internal standard), transfer into separate 50-mL volumetric flasks, dilute to volume with pyridine, and mix.
Calibration Standards Into separate 10-mL volumetric flasks add 0.50, 1.00, 2.00, and 3.00 mL of the HQ stock solution, then to each flask add 2.00 mL of the methyl benzoate (internal standard) stock solution, dilute each to volume with pyridine, and mix. In the same manner prepare four DTBHQ calibrating solutions. Prepare the trimethylsilyl derivative of each solution as follows: Add 9 drops of calibration solution to a 2-mL serum vial, cap the vial, evacuate with a 50-ml gas syringe, add 250 µL of N,O-bis-trimethylsilylacetamide, and heat at about 80o for 10 min. Chromatograph 10-µL portions of each standard in duplicate, and plot the concentration ratio of HQ to internal standard (X-axis) against the response ratio of HQ to internal standard (Y-axis). Plot the same relationships between DTBHQ and the internal standard.
Sample Preparation and Procedure Transfer about 1 g of the sample, accurately weighed, into a 10-mL volumetric flask, add 2.00 mL of the methyl benzoate internal standard stock solution, dilute to volume with pyridine, and mix. Prepare the trimethylsilyl derivative as described above under Calibration Standards, and then chromatograph duplicate 10-µL portions to obtain the chromatogram. The approximate peak times, in min, are methyl benzoate, 2.5; TMS derivative of HQ, 5.5; TMS derivative of tert-Butylhydroquinone, 7.3; TMS derivative of DTBHQ, 8.4.
Calculation Determine the peak areas (response) of interest by automatic integration or manual triangulation. Calculate the response ratio of HQ and DTBHQ to internal standard. From the calibration curves determine the concentration ratio of HQ and DTBHQ to internal standard, and calculate the percentage of HQ and the percentage of DTBHQ in the sample by the formula
A = Y x I x 10 / S
in which A is the percentage of HQ or the percentage of DTBHQ in the sample; Y is the concentration ratio (X-axis on calibration curve); I is the percentage (w/v) of internal standard in the Sample Preparation; and S is the weight of sample taken, in g.
Packaging and storage Store in well-closed containers.
Reference: FCC IV
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