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LOQ
The LOQ of the method was determined by measuring S/N
from a spiked placebo sample of herbal aloe concentrate mango
at the 20 ppb level.
The LOQ met acceptance criteria of not more than 20 ppb.
The S/N for aloins A and B and aloe-emodin were 16.7, 14.3,
and 16, respectively. The LOQ of this method was at 20 ppb.
(This approach was very conservative because a typical LOQ
level requires a S/N of about 10.)
Aloin A and B and Aloe-Emodin Stock
Standard Stability
The stock standard solution of aloinsAand B and aloe-emodin
that was initially prepared was stored in a refrigerator (2–8°C).
After 19 days, the stock standard solution was removed from the
refrigerator and a fresh stock standard solution was prepared.
Both stock standard solutions were diluted and tested. Table 20
shows the recovery of the refrigerated standard calculated
against the fresh standard to determine the stability of the stock
standard solution of aloins A and B and aloe-emodin.
Based on the above test results, the stock standard solution
of aloins A and B and aloe-emodin was stable for 19 days
when stored in the refrigerator at 2–8°C. An expiration date of
2 weeks (14 days) will be assigned to the stock standard when
stored refrigerated at 2–8°C.
Conclusions
The linearity, specificity, precision, accuracy, ruggedness, and
LOD and LOQ test results demonstrated that this test method
for the determination of aloins A and B and aloe-emodin by
HPLC in raw materials and finished products is suitable for its
intended use.
Acknowledgments
We would like to acknowledge Steven Dentali and Andrew
Shao for helpful discussions.
References
(1) Pugh, N., Ross, S.A., Elsohly, M.A., & Pasco, D.S. (2001)
J. Agric. Food Chem.
49
, 1030–1034. doi:10.1021/jf001036d
(2) Aysan, E., Bektas, H., & Ersoz, F. (2010)
Eur. J. Obstet.
Gynecol. Reprod. Biol.
149
, 195–198. doi:10.1016/j
.ejogrb.2009.11.019
(3) Dagne, E. (1996)
Bull. Chem. Soc. Ethiop.
10
, 89–103
(4) International Aloe Science Council (2017) Version 1.0, (search
term: “aloin limit”),
http://www.iasc.org/SearchResults.aspx?Search=aloin+limit
(5)
J. AOAC Int.
99
, 318(2016). doi: 10.5740/jaoacint.
SMPR2015.016
Table 18. Ruggedness test for aloins A and B and aloe-emodin
Analyst
a
,
b
Product
Aloin A, ppb
Aloin B, ppb
Aloe-emodin, ppb
Analysis date
Difference
Analyst 1
Aloe vera WL 5×, lot 1
ND
c
ND
ND
December 10, 2010
NA
d
Analyst 2
Aloe vera WL 5×, lot 1
ND
ND
ND
January 12, 2011
Analyst 1
Aloe vera gel 200×, lot 2
346.8
333.2
23.5
December 10, 2010 4.7% for aloin A
Analyst 2
Aloe vera gel 200×, lot 2
363.5
362.6
27.5
January 12, 2011
8.5% for aloin B
15.7% for aloe-emodin
Analyst 1
Herbal aloe concentrate
mango, lot 3
ND
ND
ND
December 10, 2010
NA
Analyst 2
Herbal aloe concentrate
mango, lot 3
ND
ND
ND
January 12, 2011
Analyst 1
Herbal aloe powder mango,
lot 4
201.2
205.0
<20
December 10, 2010 2.5% for aloin A
Analyst 2
Herbal aloe powder mango,
lot 4
206.3
217.5
<20
January 12, 2011
5.9% for aloin B
NA for aloe-emodin
a
Analyst 1 used the following equipment: HPLC No. 4, Waters Alliance System, Model 2695, Serial No. J07SM4025A and a Phenomenex Synergi
Hydro-RP column, 80 A, 4 µ, 250 × 4.6 mm (Part No. 00G-4375-E0), Serial No. 553344-13.
b
Analyst 2 used the following equipment: HPLC No. 3, Waters Alliance System, Model 2695, Serial No. J07SM4030A and a Phenomenex Synergi
Hydro-RP column, 80 A, 4 µ, 250 × 4.6 mm (Part No. 00G-4375-E0), Serial No. 524451-39.
c
ND = None detected.
d
NA = not available.
Table 19. Typical system suitability results (precision test)
Analyte
R
Tailing factor
Plate count
Aloin A
0.999990
1.0
81176
Aloin B
0.999843
1.0
67627
Aloe-emodin
0.999964
1.1
417385
Table 20. Aloin A and B and aloe-emodin stock standard
solution stability
80 ppb working
standard
Concn expected,
ppb
Concn found, ppb Recovery, %
Aloin A
83.89
81.73
97.4
Aloin B
75.96
75.03
98.8
Aloe-emodin
76.80
80.52
104.8
11