Page 88 - Application Notebook - Solution for Food Safety

Application No. AD-0095
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 Results and Discussion Fig. 2 shows the calibration curves of the six compounds
established with 1 μL injection volume. The linearity
Method Development 2
with correlation coefficient (R ) greater than 0.999 across
The six preservatives were well-separated as sharp the wide calibration range of 0.008 to 200 mg/L was
peaks between 1.7 min and 5.1 min as shown in Fig. 1. obtained for the six compounds.
The total run time of the UHPLC method is 8.5 mins,
which is several times faster than the HPLC method The repeatability of the method was evaluated at the
levels S2 and S5. The peak area %RSD for the six
3,
4
2,
reported * * * . It is worth to note that two wavelengths
were selected for quantitative data processing, i.e., compounds were lower than 5.1 % and 0.3 % respectively
(Table 3).
240 nm for benzonic acid and 260 nm for the rest five
4
compounds * .
Table 3 Results of Repeatability Evaluation Using Working
Standard S2 and S5 (n=6, 1μL Injection)
Conc. Conc.
Compound RSD% RSD%
(mg/L) (mg/L)
Benzoic acid 2.0 1.1 60.0 0.2
Sorbic acid 0.08 1.5 60.0 0.2
Methyl paraben 0.1 1.2 2.4 0.2
Ethyl paraben 0.1 3.8 3.0 0.2
Propyl paraben 0.1 3.2 3.0 0.2
Butyl paraben 0.1 5.1 3.0 0.3
The LOD and LOQ of the method, and peak identification
criteria (RT & λ Max) are summarized in Table 4. The results
were obtained from the mixed standard S1 (Fig. 3). The
Chromatograms of Mixed Standard (S3) with 1 μL high sensitivity achieved, i.e., LOQs ranging at 8 to
Injection Volume on Nexera X2 10 μg/L of the compounds except benzoic acid
(280 μg/L), is attributed partially to the use of a high
sensitivity SPDM30A detector with using a capillary cell
of 85 mm optical path.

Table 4 LOD (S/N=3), LOQ (S/N=10) and Peak Identification
Citeria of UHPLC Method Obtained from S1 Chromatogram
Conc. LOD LOQ
Compound RT λMax
(μg/L) (μg/L) (μg/L)
Benzoic acid 200 1.702 238 90 280
Sorbic acid 8 2.183 257 2.7 8
Methyl paraben 10 2.866 258 3 10
Ethyl paraben 10 3.687 257 3 10
Propyl paraben 10 4.445 258 3 10
Butyl paraben 10 5.091 256 3 10

Chromatogram of Mixed Standard S1 (1 μL)

Calibration Curves of Six Preservatives
at Concentration S1 to S9 (see Table 1)