8
Figure 15
Resolution and symmetric peaks for sorbic and benzoic acids on an
Ultra Phenyl HPLC column.
lated by the Food andDrug
Administration (FDA). Other products
fall under the guidelines of theUS
Environmental ProtectionAgency (EPA).
Examples of antimicrobial agents are:
quaternary ammonium compounds, sodi-
um hypochlorite, organic acids, alcohols,
iodine, Triclosan, and 4-chloro-3,5-
dimethylphenol (
para
-chloro-
meta
-
xylanol/PCMX).APCMX assay by
HPLC is shown in Figure 14; Figure 15
demonstrates the separation of benzoic
and sorbic acids on anUltra Phenyl
HPLC column.
Preservatives
Preservatives are used to extend product
shelf life. Examples of preservatives
used in cleaning and personal care prod-
ucts areBHT (3,5-di-tert-butyl-4-
hydroxytoluene), BHA (2-& 3- tert-
butyl-4-hydroxyanisole), EDTA (ethyl-
enediamine tetraacetic acid), and glu-
taraldehyde. BHT andBHA are phenolic
antioxidants that can be very effective,
even at low concentrations. These com-
pounds can be analyzed either byGC
(Figure 16) or byHPLC (Figure 17).
LC_0150
Sample:
Inj.:
10µL
Conc.:
100 ppm sorbic acid,
200 ppm benzoic acid
Solvent:
mobile phase
Column:
UltraPhenyl
Catalog #:
9105565
Dimensions: 150 x 4.6mm
Particle size: 5µm
Pore size:
100Å
Conditions:
Mobile phase: 1% acetic acid:methanol
(80:20, v/v)
Flow:
1.2mL/min.
Temp.:
ambient
Det.:
UV@245nm
0
2
4
6
8
10 12
14 16 18 min.
2
1
Figure 14
PCMX in hand soap on a Pinnacle
™
DBC18HPLCcolumn.
1. sorbic acid
2. benzoic acid
0
2
1
4
6
8 min.
PeakList:
1. PCMX (4-chloro-3,5-dimethylphenol)
Column:
Pinnacle
™
DBC18
Catalog #:
9414565
Dimensions:
150 x 4.6mm
Particle Size:
5µm
Pore Size:
140Å
Conditions:
Mobile Phase:
water:methanol (35:65 v/v)
Flow:
1.0mL/min.
Temp.:
ambient
Det.:
UV@ 280nm
Sample:
Inj.:
10µL
Conc.:
5% solution of hand soap inmethanol
SampleDiluent: methanol
SampleTemp.:
ambient
LC_0293
Website :
E-mail
TelNo : 03 9762 2034 . . . inAUSTRALIA
