ALN-01

B rown et al .: J ournal of AOAC I nternational V ol . 97, N o . 5, 2014  1327

Table 3. Precision results summary of the test materials

Analyte (Aloin)

RSDr, %

HorRat (0.3–2.0) a

Mean b

Matrix

TM1 – Inner leaf juice dry powder A

A B

TM2 – Inner leaf dry juice powder B

A

1.5

6.62

6.33

B

2.0

6.62

8.64

TM3 – Nondecolorized leaf dry juice powder

A

1.4

26.20

4.89

B

1.8

24.80

6.30

TM4 – Decolorized inner leaf dry juice powder

A

B

TM5 – Powder capsule

A

1.0

4.73

4.44

B

0.6

4.73

2.74

TM6 – Nondecolorized leaf juice

A

0.3

23335

1.21

B

0.3

23265

1.09

TM7 – Decolorized leaf juice

A

B

TM8 – Nondecolorized inner leaf juice

A

1.3

13889

4.92

B

1.2

14000

4.51

TM9 – Decolorized inner leaf juice concentrate

A

B

a  HorRat values between 0.3 and 2.0 are considered acceptable according to AOAC guidelines for SLVs. b  µg/g For solid samples and µg/mL for liquid samples.

materials. It should be noted that quantification of the treated test materials (i.e., low level aloin content) was done using a four- point calibration curve (i.e., 0.3, 0.5, 1, and 5 µg/mL) since linear regression does not give equal weight to the calibration points especially at low levels when a seven-point calibration curve is used. The r 2 for the four-point calibration curve was ≥99.9%. Alternatively, a weighted least square calibration curve could have been used using all seven points, which would produce results comparable to the four-point calibration curve.

Materials tested included treated and nontreated powder and liquid/juice.

Selectivity

There was adequate resolution (Rs > 2.0) of the aloins from each other as well as from neighboring eluted compounds.

Linearity

All of the standard curves produced throughout the course of the study appeared linear upon visual inspection. The coefficients of determination (r 2 ) were ≥99.9%, therefore considered linear and acceptable for quantifying the aloins in the different test

LOD and LOQ

By the IUPAC method, the LODs for aloinA and aloin B were

Table 4. Negative control spike recovery results for aloin A and aloin B in a (a) liquid matrix and (b) solid matrix Level 1 Level 2 Level 3 Aloin A Aloin B Aloin A Aloin B Aloin A Aloin B (a) Liquid matrix x Recovery, a % 106.26 95.01 104.74 90.17 105.45 92.70 RSDr, % 4.30 1.83 0.75 0.15 0.84 0.57 (b) Solid matrix x Recovery, % 108.86 91.50 100.20 84.41 105.71 88.06 RSDr, % 0.98 3.84 3.17 0.23 1.95 1.81 a x = Mean value of three replicate samples.