Tentative Translation

JAS
0008
JAPANESE AGRICULTURAL
STANDARD
Determination of the lutein in Spinach－High-performance liquid chromatographic method

Date of Establishment: 2019-1-31
Date of Revision: 2019-6-27

Ministry of Agriculture, Forestry and FisheriesPrecautions for using English version of JAS
This English translation has been made by the drafting party etc., based on the original text (Japaneseversions), and has been posted on the Website of Incorporated Administrative Agency Food andAgricultural Materials Inspection Center(FAMIC), with permission of the publisher of the original text
(Ministry of Agriculture, Forestry and Fisheries).
The translation is made in consideration of technical contents, but it is aimed to provide information whenusing JAS original text, and is not recognized as having the same effects as the original text.
If there is any doubt in the translation, please follow the original.
FAMIC is not responsible for inconvenience by using only the translation.
Incorporated Administrative Agency
Food and Agricultural Materials Inspection Center0008：2019

Contents

Page

1Scope…………………………………………………………………………………………………………………..1
2 Normative references………………………………………………………………………………………………..1
3 Principle……………………………………………………………………………………………………………...1
4 Reagents………………………………………………………………………………………………………..…….2
5 Apparatus………………………………………………………………………………………………………….....4
6 Preparation of test samples………………………………………………………………………………………....5
7 Procedure…………………………………………………………………………………………………………….6
7.1 Saponification………………………………………………………………………………………………….…..6
7.2 Extraction of lutein……………………………………………………………………………………………...6
7.3 Dissolution………………………………………………………………………………………………….……6
7.4 Determination……………………………………………………………………………………………………..6
8 Calculation…………………………………………………………………………………………………………..7
8.1 General……………………………………………………………………………………………………….……7
8.2 Quantitation………………………………………………………………………………………………….……7
8.3 Expression of results………………………………………………………………………………………….…...89 Precision…………………………………………………………………………………………………………..….8
9.1 Interlaboratory test…………………………………………………………………………………………...…...8
9.2 Repeatability………………………………………………………………………………………….....…………8
9.3 Reproducibility……………………………………………………………………………………….....…………8
10 Quality control………………………………………………………………………………………………….…..8
11 Test report………………………………………………………………………………………………………......8
Annex A (informative) Results of interlaboratory tests…………………………………………………………..10
Annex B (informative) Typical HPLC chromatograms…………………………………………………………...11
Annex C (informative) The procedure purifying chromatograms………………………………………………..13
Bibliography…………………………………………………………………………………………………….....…14

10008：2019

JAS
0008：2019Japanese Agricultural Standard

Determination of the lutein in Spinach－High-performance liquid chromatographic method
Warning —Persons using this Standard should be familiar with normal laboratory practice.
does not purport to address all the safety problems associated with its use.

This standard

It is the responsibility of the userof this standard to establish appropriate safety and health practices and to ensure compliance with any
national regulatory conditions.
1

Scope

This document specifies a high-performance liquid chromatographic test method of lutein in the edible part ofspinach (Spinacia oleracea L.)(fresh spinach and frozen one after blanching).
2

Normative references

The following documents are referred to in the text in such a way that some or all of their contents requirements ofthis document. For undated references, the latest edition of the referenced document (including any amendments)
applies.
ISO 648

Laboratory glassware — Single-volume pipettes

ISO 1042

Laboratory glassware — One-mark volumetric flasks

ISO 8655-2 Piston-operated volumetric apparatus — Part2:Piston pipettes
JIS K 0115

General rules for molecular absorptiometric analysis

JIS K 0124

General rules for high performance liquid chromatography

JIS K 0557

Water used for industrial water and wastewater analysis

JIS K 8034

AcetoneJIS K 8101

Ethanol(99,5)

JIS K 8150

Sodium chloride

JIS K 8359

Ammonium acetate

JIS K 8361

Ethyl acetate (Reagent)

JIS K 8574 Potassium hydroxide
JIS K 8780 Pyrogallol

3

JIS K 8848

HexaneJIS K 8891

Methanol

JIS K 8987

Sodium sulfate

Principle

20008：2019

The test portion of ground spinach which is homogenized with pyrogallol ethanol is saponified with potassiumhydroxide. The lutein is extracted by hexane and ethyl acetate mixture.
The lutein in the extract is determined by high-performance liquid chromatograph (HPLC) with ultraviolet-visible
absorption detector.
4

Reagents

Use only reagents recognized analytical grade, unless otherwise specified.
Warning — It is the responsibility of users of this standard to comply with legal regulations regarding the useof reagents.
4.1

Water, conforming to grade A3 or A4 of JIS K 0557.

4.2

Lutein, of minimum mass fraction,

4.3

Ethanol, of minimum mass fraction, (C2H5OH)

99,5 %, according to JIS K 8101.

4.4

Pyrogallol, of minimum mass fraction, (C6H6O3)

99,0 %, according to JIS K 8780.

4.5

Potassium hydroxide, of minimum mass fraction, (KOH)

4.6

Sodium chloride, of minimum mass fraction, (NaCl)

99,5 %, according to JIS K 8150.

4.7 Hexane , of minimum mass fraction, (CH3 (CH2)4CH3)

96,0 %, according to JIS K 8848.

(C40H56O2)

95,0%.

4.8

Ethyl acetate, of minimum mass fraction, (CH3COOC2H5)

4.9

Methanol, HPLC grade.

4.10

Acetonitrile, HPLC grade.

4.11

Ethanol(HPLC), HPLC grade.

4.12

Ammonium acetate, according to JIS K 8359.

4.13

Nitrogen, of volume fraction, (N2) 99,5%.

4.14

2,6-di-tert-butyl-p-cresol(BHT), of minimum mass fraction,

4.15

Pyrogallol ethanol,

85,0 %, according to JIS K 8574.

99,5 %, according to JIS K 8361.

(C6H2 (OH)(C(CH3)3)2CH3) 98%.

Dissolve 30 g of pyrogallol (4.4) per 1,0 l of ethanol (4.3). Prepare it when necessary.
4.16

Potassium hydroxide (water) solution,
Dissolve 60 g of potassium hydroxide (4.5) per 100 ml of water (4.1).
Warning— Since irritating gas is generated, work should be done in a place with good ventilation
inside a fume cupboard etc.

4.17

Sodium chloride (water) solution,
Dissolve 10 g of sodium chloride (4.6) per 1,0 l of water (4.1).

4.18

Hexane / ethyl acetate mixture,Mix 9 parts per volume of hexane (4.7) with 1 part per volume of ethyl acetate (4.8).

4.19

BHT ethanol,
Dissolve 1,0 g of BHT (4.14) per 1,0 l of ethanol (4.11).

4.20
4.20.1

HPLC mobile phases
Mobile phase A, acetnitrile / methanol mixture containing ammonium acetate.
Dissolve 5,0g of ammonium acetate (4.12) per 1,0 l of methanol (4.10). Mix 4 parts per volume of thissolution with 15 parts per volume of acetonitrile. Degas the mixture before use.

30008：2019

NOTE Degassing prevents troubles of gases, then gives stable flow and background.
4.20.2

Mobile phase B, ethanol.
Degas ethanol (4.11) before use.
NOTE Degassing prevents troubles of bubbles, then improves baseline stability and reduce noise.

4. 21

Lutein stock standard solution,
Prepare a solution containing lutein (4.2) in ethanol (4.11) at a concentration of 100 µg /ml. Transfer thissolution into a labelled bottle with screw cap, then store at –20 °C or lower under light-shielded condition.
NOTE Lutein stock standard solution is sometimes degraded gradually.
Remove from freezer before use, allow it to attain to room temperature and mix.

4.22
4.22.1

Standard solutions
GeneralPrepare lutein standard solutions of 4 or more stepwise concentrations.
A standard solution for absorbance measurement (4.22.2) and a series of the following standard solutions(4.22.3) should be prepared from a single bottle of the lutein stock standard solution (4.21). Every time eachlutein stock standard solution is returned to normal temperature, prepare the standard solution forabsorbance measurement and measure the concentration of that on the same day. Discard the remaining
stock standard solution after used, and do not reserve.

4.22.2Standard solution for absorbance measurement,
Dilute the lutein stock standard solution (4.21) 50-fold with ethanol (4.3) using the single volume pipette(5.6) or the piston pipette (5.7) and volumetric flask (5.5). This solution is used for absorbancemeasurement.
NOTE In the interlaboratory tests described in Annex A, 0,200 ml of lutein stock standard solution wastransferred into a 10 ml volumetric flask using the piston pipette.
Set up and operate the spectrometer (5.14) in accordance with the manufacturer’s instructions.
Measure the concentration of standard solution for absorbance measurement by using a spectrometer at
445 nm with ethanol as reference.
The lutein concentration of the stock standard solution in μg/ml, ρ, is given by the formula:ρ=

A×V1 ×10 000

ε×V2

where
A is the absorbance of standard solution for absorbance measurement determined at 445 nm(ethanol ,1 cm cell );ε is the absorption coefficient of lutein in concentration 1% and optical pathlength 1 cm, 2 550[5];V1 is used volumetric flask’s capacity, in ml;
V2 is the volume, in ml, of used stock standard solution;
Note In the interlaboratory tests described in Annex A, V1 is 10 and V2 is 0,200.

40008：2019

After calculation, proceed
4.22.3

immediately in accordance with 4.22.3.

A series of standard solution
Using a single volume pipette(5.6) or a piston pipette (5.7), transfer lutein stock standard solution (4.21)
into glass vessels (5.9).
Evaporate the solutions just to dryness under a stream of nitrogen gently.
Dissolve the contents in glass vessels completely by BHT ethanol (4.19).
Note1 In the interlaboratory tests described in Annex A, test tube mixier was used for about 10 seconds.
Transfer the dilute standard solutions into vials (5.13).
The lutein concentration of the dilute standard solution in μg/ml, ρi, is given by the formula:

ρi =

ρ×V3
V4

where
ρ is the concentration of lutein stock standard solution (4.21), in μg/ml;
V3 is the volume of lutein stock standard solution (4.21) , in ml,;
V4 is the volume of BHT ethanol (4.19), in ml;
NOTE2 In the interlaboratory tests described in Annex A, each lutein standard solutions were prepared
1,0, 2,0, 5,0, 10 and 20 µg/ml concentration.
Perform HPLC analysis (7.4.2) on the day of preparation.
5

Apparatus

Usual laboratory apparatus and, in particular, the following.
5.1

Analytical balances, capable of weighing to an accuracy of ±0,1mg more than 200 g.

5.2

Centrifuge tubes, glass or polypropylene, of about 50 ml capacity, with the lid, keeping the space for enoughmix and centrifugation at 400×g is possible.
Use the stopper or screw type lid to which a packing of a material resistant to organic solvents and strong basic
solutions is attached.

5.3

Vertical Shaker, for bobbing or back-and-forth motion holding tube.

5.4

Centrifuge, capable of 400×g.

Warning — To prevent accidents, operate the centrifuge according to the instruction manual of theequipment.
5.5

One-mark volumetric flasks, to cover the volume range for standard dilution and sample extract dissolution,of ISO1042, class A.

5.6

Single volume pipettes, to cover the volume range for standard dilutions, of ISO648, class A.

5.7

Piston pipettes, to cover the volume range for standard dilutions, of ISO 8655-2, type A.

50008：2019

5.8

Water bath, capable of being maintained at (70±3) °C and size for centrifuge tube rack.

5.9

Glass vessels, amber, to cover the volume range for lutein stock standard dilutions.

5.10

Round-bottomed flasks, of 100 ml capacity, with ground neck and amber, usable evaporation.

5.11

Rotary evaporator, with water bath and vacuum control, for evaporation of solvent, for example hexane,
ethyl acetate and ethanol.

5.12 Membrane filters, for organic solutions, made of polytetrafluoroethylene (PTFE), with a pore size of lessthan 0,20 µm. The filter and the housing are unitary, and the material of the housing is resistant to organic
solvents.
5.13

Vials, suitable for HPLC to be used. Amber and deactivated glass, with deactivated insert vials in them, orother glass-made ones that have been checked for no influence. The septum of the lid was coated with PTFE or
PTFE.

5.14

Spectrometer, capable measuring wavelengths 445 nm, holding cells (5.15).

5.15

Cells, quartz glass or glass, of optical path length 1 cm, and they should have stoppers.

When multiple cells

are used, use the ones that guaranteed to have same optical characteristic.
5.16

HPLC apparatus

5.16.1High-performance liquid chromatograph, equipped to perform binary gradient elution or switchingsolvent line manually with a thermostatically controlled column compartment, an ultraviolet-visible detector
set at 445 nm, and data collection / integration system.

5.16.2Chromatographic column for HPLC, reverse-phase C30 (Triacontyl) columns, with the following
characteristics:—length: 250 mm;—internal diameter: 4,6 mm;—spherical particle size: 5 μm
Lutein shall elute within 15 min. Confirm that retention time of the lutein and the peak of lutein does notoverlap with those of other peaks according to 7.4.
When a guard column is used, select the one matching to the C30 (Triacontyl) column.

6
6.1

Preparation of test samples
Mince the sample of fresh spinach removed the roots and weigh it in the container like a homogenizer cup.

When the sample is frozen spinach that is only blanched, weigh it in the container. Record the weight in 3 significant
figures.
6.2

Add pyrogallol ethanol (4.15) about 3 times mass of sample (6.1) and weigh it in 3 significant figures.

6.3

Pulverize it using homogenizer or the like. This is used as a test sample.

6.4

Proceed immediately in accordance with 7.1, or store frozen the test samples at –20 °C or lower.

If test samples are stored at –20 °C or lower, transfer all of them or a portion of them after stirring homogeneously
into the amber glass sealed containers soon after pulverized. Remove the test samples stored at –20 °C or lower fromthe freezer before use, allow them to room temperature and mix well.
NOTE It has been confirmed that the test samples will remain stable for at least 6 month when stored
frozen at –20 °C to –30 °C.

60008：20197

Procedure

7.1

Saponification

7.1.1

Weigh, to the nearest 10 mg, approximately 2 g of the test sample (6) into a tube (5.2). Add 10 ml ofpyrogallol ethanol (4.15) to the tube.
7.1.2

Add 1 ml of potassium hydroxide (water) solution (4.16) to a tube, mix gently. Place the tube in a constanttemperature water bath (5.8) set at 70 °C, heat the tube for 30 min mixing every 5 min. Allow the centrifuge tube tocool to room temperature.
7.2

Extraction of lutein

7.2.1

Add 20 ml of sodium chloride (water) solution (4.17) and 12 ml of hexane / ethyl acetate mixture (4.18) to a

tube (7.1.2) and mix.
7.2.2

Mix hard the contents for 5 min by vertical shaker (5.3).

Separate the contents by the centrifuge(5.4) at 400×g for 5 min. Transfer the supernatant into a round-bottomed
flask (5.10).
7.2.3

Add 12 ml of hexane / ethyl acetate mixture to the liquid left in the tube. Repeat steps 7.2.2. Transfer thesupernatant in the same round-bottomed flask which the 7.2 supernatant was transferred.
7.2.4

Repeat steps 7.2.3.

7.2.5

Evaporate almost the solvent in a round-bottomed flask (7.2.4) at less than 40 °C by vacuum rotating

evaporator (5.11). Then evaporate the solvent under a gentle stream of nitrogen (4.13).
7.3

Dissolution

Dissolve the contents of the round-bottom flask (7.2.5) completely, using BHT ethanol (4.19). Then transfer thesolution completely to a volumetric flask.
NOTE 1 10 ml of one-mark volumetric flasks were used in the interlaboratory tests described in Annex A.
Add to the mark with BHT ethanol and mix. Filter through a membrane filter (5.12) and transfer filtrate into the vials(5.13). This filtrate is used as sample extract.
Perform HPLC measurement (7.4.2) on the day of preparation or store the sample extract at –20 °C or lower.
NOTE 2 It has been confirmed that the sample extract will remain stable for at least 12 days when stored at–30°C to –20 °C.
Remove the stored sample extract stored at –30 °C to –20 °C from the frozen before use and mix well.
7.4

Determination

7.4.1

HPLC operating conditions

Set up the chromatograph (5.16) in accordance with the manufacturer's instructions and adjust it as follows.
a) Flow rate of the mobile phase (4.20): 1,0 ml/minb) Temperature of the column (5.16.2) set at 40 °Cc) UV-VIS detector set at 445 nm.
d) Volume injected: 10 µle)Binary gradient conditions: 95 % mobile phase A (4.20.1) and 5 % mobile phase B (4.20.2) for 15 min frominjections of sample extract, then increase the volume ratio of mobile phase B to 95 % in order to elute quickly
other analyte from the column.

70008：2019

Then reset to 95 % mobile phase A and 5 % mobile phase B, and allow to equilibrate for 10 min before next
injection. If a lutein peak is not disturbed by those of other components, the washing time , equilibrate time andvolume ratio of solvents may be changed.
NOTE In the interlaboratory tests described in Annex A, the elution programme as detailed in Table 1 ormanual switching solvent lines with solvents that were mixed as table 1 beforehand were used.
Table 1 — Binary gradient programmeTime (min)Mobile phase A

Mobile phase B

(%)

(%)

0 to 1595

5

15 to 30

595

30 to 40

95

5NOTE The values given are for guidance only.

7.4.2

HPLC analysis

Allow the entire system to run appropriately to stabilize it. Confirm that the fluctuation of base line gives nohindrance for determination of lutein by a blank run under the specified condition (7.4.1). Then inject a series ofstandard solutions (4.22.3) onto the column, followed by an equal volume of the sample extract solutions (7.3).
7.4.3

Identification

Identify the individual lutein peak in the sample chromatograph by comparing retention times with those obtained
from the standard solutions under the same chromatographic conditions (7.4.1).
NOTE Typical HPLC chromatogram of a ‘Spinach’ extract can be found in Annex B.
8

Calculation

8.1

GeneralQuantitative determination is performed by the external standard method with integration of the peak area, which isthen related to the corresponding value for the standard substance.
For the peaks of impurities, take appropriate measures according to the perpendicular or tangent method prescribed
by JIS K 0124.
8.2

Quantitation

Obtain the areas of lutein in each of a series of standard solutions (4.22.4). Construct linear calibration graphs foreach standard of the lutein concentrations (µg/ml) against the peak areas obtained from the data collection/integration
system. The correlation coefficient of the linear calibration is required to be more than 0,995.
Calculate the concentration (µg/ml) of lutein from the areas of each sample solutions by the calibration curve. The
lutein content, Wi, expressed as a percentage by mass on ‘Spinach’ sample, is given by the formula:

80008：2019

Wi =

C×V5
Wsp
W×
Wsp ＋Wet

where
C is the concentration of lutein in the the diluted sample extract, in µg/ml;
V5 is the constant volume (ml) at the time of dissolution, in the interlaboratory tests, that is, 10;
W is the mass, in g, of the sample test portion(7.1.1);
Wsp is the mass, in g, of the sample spinach in preparation (6.1);
Wet is the mass, in g, of the pyrogallol ethanol in preparation(6.2);
NOTE In the interlaboratory tests described in Annex A, V5 is 10.
8.3

Expression of results

Express the results to two significant figures
99.1

Precision
Interlaboratory test

Details of the interlaboratory test to determine the precision of the method are summarized in Annex A. The values
derived from this interlaboratory test might not be applicable to concentration ranges (65 mg/kg to 1,5×102
mg/kg)and matrices other than those given.
9.2

Repeatability

The absolute difference between two independent single test results, obtained using the same method on identical test
material in the same laboratory by the same operator using the same equipment within a short interval of time, may
be expected in not more than 5 % of cases be greater than the repeatability limit (r) values[2] given in Table A.1 onaverage as long as the specified operation is definitely done[1].
9.3

Reproducibility

The absolute difference between two single test results, obtained using the same method on identical test material indifferent laboratories with different operators using different equipment, may be expected in not more than 5 % ofcases be greater than the reproducibility limit (R) values[2] given in Table A.1 on average as long as the specified
operation is definitely done[1].
10Quality control

The laboratory is required to have internal quality control procedures for tests.
11

Test report

The test report shall include at least the following information:a)a reference to this JAS standard;

90008：2019b)

identification of the sample;c)the date of the test;d)the results of the test.

100008：2019

Annex A
(informative)
Results of interlaboratory tests
Interlaboratory tests in accordance with IUPAC protocol[3], carried out in 2017 in Japan, gave the statistical results
shown in Tables A.1. Some samples from which the root tops of commercially available ‘Spinicia oleracea L.’ wasremoved, 50 g, were added 30 g/L pyrogallol ethanol with 3 times of sample mass as an antioxidant, and were
grinded at 5 000 r/min for 5 min by homogenizer.
After homogeneity [4] was confirmed, pulverized samples were used as a test sample. Since lutein may be easily
degraded, it was used after purified as described in Annex C. The experimental protocol, standard stock solutions andtest samples were supplied to the participating laboratories by the Food and Agricultural Materials Inspection Center(FAMIC). All laboratories, respectively, tested a total of 10 test samples (5 pairs of blind duplicates) according to theexperimental protocol.

Table A.1 — Precision data
Sample identification

Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

Number of participating laboratories

12

12

12

12

12

Number of accepted test results

10

11

12

12

12

Mean lutein content, mg/kg (mass fraction),

64,9

71,8

88,8

119

150

Repeatability standard deviation sr, mg/kg

3,3

3,6

6,7

4,8

5,1

Repeatability relative standard deviation, %

5,1

5,0

7,5

4,1

3,4

Repeatability limit r (r = 2,8 sr), mg/kg

9,2

10

19

13

14

Reproducibility standard deviation sR, mg/kg

3,6

5,4

12

7,5

6,8

Reproducibility relative standard deviation, %

5,6

7,5

13

6,4

4,6

Reproducibility limit R (R = 2,8 sR), mg/kg

10

15

33

21

19

11
0008：2019

Annex B(informative)
Typical HPLC chromatograms 1)

Key

X

Retention time, minYResponse, AU

1LuteinFigureB.1 — Lutein standard

HPLC Condition
HPLC operating conditions in accordance with 7.4.1 and the following.

a）Chromatographic column : YMC® Carotenoid 2)b）Binary gradient conditions: Table 1
1)

The fluctuation between 18 min and 33 min coused from switching of flow lines. There are cases that some baselines arehigh and others are low.
2)

YMC® Carotenoid is an example of a suitable column available commercially.

This information is given for theconvenience of users of this standard and does not constitute an endorsement of this product.

120008：2019

Key
Retention time, min
Y Response, AU
X

1LuteinFigure B.2 — ‘Spinach’ extract

HPLC Condition
HPLC operating conditions in accordance with 7.4.1 and the following.

a）Chromatographic column : YMC® Carotenoidb）Binary gradient conditions: Table 1

130008：2019

Annex C
(informative)
The procedure of purifying lutein
C.1 General
This annex specifies a procedure of purifying lutein by silica gel column chromatography that is used as standard
stock solutions in the interlaboratory test described in annex A.
C.2 Reagentsa)

Packing materials, with a particle size of 150 μm to 425 μm, for column chromatography.

b)

Lutein, specified in 4.2.

c)Acetone, according to JIS K 8034.

d)

Hexane, specified in 4.7.

e)Sodium sulfate, according to JIS K 8987.

f)Ethyl acetate, specified in 4.8.

g)

Nitrogen, specified in 4.13.

h)Eluent A, specified in 4.18.

i)Eluent B, mix 7 parts per volume of hexane (4.7) with 3 part per volume of ethyl acetate (4.8).

j)Eluent C, mix 6 parts per volume of hexane (4.7) with 4 part per volume of ethyl acetate (4.8).

C.3 Apparatusa)

Chromatographic tubes, cylindrical glass tube, of 15 mm to 20 mm diameter and more than 30 cm length, witha stopcock.

b)

Wools, absorbent cotton or glass wool, plug in the bottom of chromatography tubes (C.3 a)) and capable ofpreventing outflow of packing materials (C.2 a)).

c)Round-bottomed flasks, specified in 5.10.

d)Vacuum rotating evaporator, specified in 5.11.

C.4 Procedurea)

Mix about 10 g of packing materials (C.2 a)) and a small amount of hexane. Place wool (C.3 b)) in the bottomof a chromatographic tube (C.3 a)) and then poured the mixture into it.

b)

Prepare a lutein (4.2) solution in acetone (4.11). Transfer this solution into the chromatographic tube (C.4 a)).
Lutein solutions can be mixed with a small amount of packing materials, then evaporate its solvent before
transferred into the chromatographic tube (C.4 a)).

c)

Place about 3 g of sodium sulfate (C.2 e)) above the adsorbent layer in the chromatographic tube (C.4 b)).

d)

Add 100 ml of eluent A (C.2 h)), 100 ml of eluent B (C.2 i)), 100 ml of eluent C (C.2 j)) and 100 ml of ethyl
acetate (4.8) in this order. Collect orange-coloured eluent in the round-bottomed flask (5.10).
NOTE The colour of eluent changes as colourless, yellow, orange and yellow in this order.

e)

Evaporate almost solvent in a round-bottomed flask (C.4 d)) at less than 40 °C by vacuum rotating evaporator(5.11). Then evaporate the solvent just under a gentle stream of nitrogen.

140008：2019

Bibliography[1] ISO 5725-1:1994

Accuracy (trueness and precision) of measurement methods and results — Part 1:Generalprinciple and definitions
NOTE The expression of the repeatability limit and reproducibility limit referred to section 7.1.5.
[2] ISO 5725-6:1994

Accuracy (trueness and precision) of measurement methods and results — Part 6:Use inpractice of accuracy value
NOTE The calculation of the repeatability limit and reproducibility limit referred to section 4 “Determination oflimits”.
[3] Horwitz, W., Protocol for the design, conduct and interpretation of method-performance studies, Pure Appl.
Chem., 1995, 67(2), p. 331-343[4] Thompson, M., et al., The International Harmonized Protocol for the Proficiency Testing of Analytical Chemistry
Laboratories. Pure Appl.Chem. 78(1), 145-196 (2006)
NOTE The method of homogeneity referred to section 3.11 “Testing for sufficient homogeneity and stability”.
[5] Britton, G., Liaaen-Jensen, S., Pfander, H. ed.,Carotenoids handbook, Birkhauser Verlag, Basel/Boston/Berlin,
2004
NOTE The absorption coefficient of lutein referred to “MAIN LIST 133(Lutein) Spectroscopic data”.