AminoAcids
HPLC
UltraAqueousC18
OrganicAcids
HPLC
UltraAqueousC18
FOODS, FLAVORS, & FRAGRANCES
14
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Amino Acids, Organic Acids
AminoAcids
Proteins are polymeric materials with molecular
weights greater than 5,000. The basic building
blocks of proteins are amino acids,whichhave the
nutritional properties, but not the functional
properties, of proteins. There are 20 common
amino acids in food systems, categorized as essen-
tial or nonessential amino acids. Derivatization
often is used to provide adequate retention of
amino acids, especially themore hydrophilic com-
pounds. An
Ultra Aqueous C18
reversed phase
HPLC column can separate many amino acids
without derivatization or ion pairing reagents. To
maximize retention, the
UltraAqueousC18
col-
umn can be used with a 100% aqueous mobile
phase without compromising the reproducibility
of the analysis.
OrganicAcids
Organic acids play several important roles in food
and beverage systems. For example, they are
important flavor compounds and indicators of
product quality. In some fruit juices, the organic
acidprofile ismonitored todetermine thepurityof
the fruit juice. Malic acid and citric acid can be
found in fruits,oxalic acid canbe found in spinach
and rhubarb, and tartaric acid is present in grapes.
In food systems, organic acids may be added as
acidulants, to control the pH of the product.
Certain organic acids also can be used as antimi-
crobial agents; for example, propionic acid can be
used to inhibitmold growth.
The analysis of polar organic acids can be difficult
using conventional reversedphaseHPLC columns,
evenwithhighlyaqueousmobilephases.The
Ultra
AqueousC18
columnwas designed for challeng-
ing applications such as this, and provides
enhanced retention and selectivity for organic
acids.
Peak List:
Conc. (mg/mL)
1. tyrosine
0.2
2. phenylalanine 1.6
3. tryptophan
0.4
Sample:
Inj.:
20µL
Solvent:
mobile phase A
Column:
Ultra Aqueous C18
Cat.#:
9178565
Dimensions:
150 x 4.6mm
Particle size:
5µm
Pore size:
100Å
Conditions:
Mobile phases: A: 50mM potassium phosphate,
pH 2.5
B: acetonitrile
5% - 20%B: 0-5min.
20% - 5%B: 5-6min.
Hold at 5%B: 6-13min.
Flow:
1.0mL/min.
Temp.:
30°C
Det.:
UV@254nm
0
2
4
6
8
10
min.
LC_0146
1
2
3
Peak List:
Conc. (µg/mL):
1. malonic acid
500
2. lactic acid
500
3. acetic acid
1000
4. citric acid
1000
5. succinic acid
2000
6. fumaric acid
10
Sample:
Inj.:
10µL
Solvent:
water
LC_0140
1
2
3
4
5
6
min.
0
1
2
3
4
5
Column:
Ultra Aqueous C18
Cat.#:
9178565
Dimensions:
150 x 4.6mm
Particle size:
5µm
Pore size:
100Å
Conditions:
Mobile phase:
50mM potassium
phosphate, pH 2.5:
acetonitrile (99:1)
Flow:
1.5mL/min.
Temp.:
25°C
Det.:
UV@210nm
restek
innovation
!
Monitor amino acidswithout derivatization
or ion pairing reagents.
restek
innovation
!
Monitor acidic food additives
without ion pairing reagents.
CathyGross
HPLCProducts
MarketingManager
