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标准编号: GB 5009.270-2023 (GB5009.270-2023)
中文名称: 食品安全国家标准 食品中肌醇的测定
英文名称: (National food safety standards Determination of chlorate and perchlorate in food)
行业: 国家标准
中标分类: X09
字数估计: 8,882
发布日期: 2023-09-06
实施日期: 2024-03-06
发布机构: 中华人民共和国国家卫生健康委员会、国家市场监督管理总局
范围: 本标准规定了食品中氯酸盐和高氯酸盐的液相色谱-串联质谱测定方法。本标准适用于蔬菜及其制品、水果及其制品、谷物及其制品、肉及肉制品、水产品、蛋及蛋制品、乳及乳制品、调味品、饮料类、婴幼儿配方食品和婴幼儿辅助食品、茶叶中氯酸盐和高氯酸盐的测定。

GB 5009.270-2023 中文版: 食品安全国家标准 食品中肌醇的测定
GB 5009.270-2023 英文版: (National food safety standards Determination of myo-inositol in food)
中 华 人 民 共 和 国 国 家 标 准
食品安全国家标准
食品中肌醇的测定
2023-09-06发布
2024-03-06实施
中华人民共和国国家卫生健康委员会
国 家 市 场 监 督 管 理 总 局 发 布
前言
本标准代替GB 5009.270-2016《食品安全国家标准 食品中肌醇的测定》。
本标准与GB 5009.270-2016相比,主要变化如下:
---气相色谱法调整为第一法,微生物法调整为第二法;
---增加了附录B、附录C;
---修改了气相色谱法的适用范围、硅烷化试剂、样品前处理方法和仪器参考条件;
---修改了微生物法的原理表述、菌种的名称及制备方法、设备材料和测试步骤。
食品安全国家标准
食品中肌醇的测定
1 范围
本标准规定了食品中肌醇(环己六醇,myo-inositol)的测定方法。
第一法气相色谱法适用于婴幼儿配方食品、特殊医学用途配方食品、乳及乳制品和饮料中肌醇的
测定。
第二法微生物法适用于食品中肌醇的测定。
第一法 气相色谱法
2 原理
试样中的肌醇用水提取,经乙醇沉淀,上清液离心干燥后,与硅烷化试剂衍生,衍生物经正己烷提
取,采用气相色谱分离,氢火焰离子化检测器检测,外标法定量。
3 试剂和材料
除非另有说明,本方法所用试剂均为分析纯,水为GB/T 6682规定的一级水。
3.1 试剂
3.1.1 无水乙醇(C2H6O)。
3.1.2 95%乙醇(C2H6O)。
3.1.3 乙腈(C2H3N)。
3.1.4 正己烷(C6H14)。
3.1.5 三甲基氯硅烷(C3H9ClSi)。
3.1.6 六甲基二硅胺烷(C6H19NSi2)。
3.1.7 N,N-二甲基甲酰胺(C3H7NO)。
3.1.8 无水硫酸钠(Na2SO4)。
3.2 试剂配制
3.2.1 70%乙醇:量取700mL无水乙醇,用水定容至1000mL,混匀。
3.2.2 硅烷化试剂:分别吸取三甲基氯硅烷、六甲基二硅胺烷、N,N-二甲基甲酰胺,按体积比为1∶2∶8
混合,超声混匀,临用现配。
注:硅烷化试剂若出现白色浑浊现象,需重新配制。
3.3 标准品
肌醇标准品(C6H12O6,CAS号:87-89-8):纯度≥99%,或经国家认证并授予标准物质证书的标
准品。
3.4 标准溶液配制
3.4.1 肌醇标准储备液(1.00mg/mL):称取已于105℃±2℃干燥至恒重的肌醇标准品100mg(精确
至0.1mg),用25mL水溶解,95%乙醇定容至100mL,混匀,2℃~8℃贮存,有效期1个月。
3.4.2 肌醇标准工作液(0.100mg/mL):准确移取5.00mL肌醇标准储备液,用70%的乙醇定容至
50mL,混匀,临用现配。
4 仪器和设备
4.1 气相色谱仪:配氢火焰离子化检测器。
4.2 分析天平:感量为0.1mg和1mg。
4.3 离心机:转速≥4000r/min。
4.4 烘箱:温度精度为±2℃。
4.5 恒温水浴:温度精度为±2℃。
4.6 旋转蒸发仪。
4.7 涡旋振荡器。
4.8 超声波仪。
4.9 氮吹仪。
5 分析步骤
5.1 试样制备
5.1.1 溶解
称取混合均匀的固体试样1g或液体试样12g(精确至1mg)于100mL锥形瓶中,固体试样用
12mL40℃~45℃的温水溶解,超声提取10min。将上述处理过的试样溶液转入50mL容量瓶中,
用95%乙醇定容至刻度,混匀,静置沉淀20min。若试样出现块状沉淀而非絮状沉淀现象,可重新称取
样品,用30mL40℃~45℃温水重新溶解样品,加乙腈定容至刻度,混匀,静置沉淀20min。沉淀结束
后,吸取10mL上清液,以不低于4000r/min的转速离心5min后,准确移取5.00mL上清液至
25mL旋蒸瓶或螺口玻璃瓶中,待干燥。
5.1.2 干燥
向待干燥试样中加入适量无水乙醇,在不超过80℃下采用旋转蒸发仪或氮吹仪浓缩至近干,于
100℃烘烤1h,取出冷却至室温,待衍生。
5.1.3 衍生
向干燥后的试样中加入10mL硅烷化试剂,超声5min,于25mL螺口玻璃瓶中密封混匀,于80℃
水浴中反应75min,其间每隔20min取出振荡一次。结束后冷却至室温,加入5mL正己烷,涡旋
2min,待静置分层后,取3mL正己烷萃取液于预先加入少许无水硫酸钠的离心管中,涡旋后以不低于
4000r/min的转速离心5min后,将溶液转移至进样瓶中,即得试样测定液,供气相色谱仪测定。
5.2 肌醇标准测定液制备
分别吸取0.200mL、0.400mL、0.600mL、0.800mL、1.00mL、2.00mL肌醇标准工作液(0.100mg/mL)于
0.020mg、0.040mg、0.060mg、0.080mg、0.100mg、0.200mg。
注:可根据样品中肌醇含量,调整肌醇标准测定液的浓度范围。
5.3 仪器参考条件
仪器参考条件如下:
a) 检测器:氢火焰离子化检测器。
b) 色谱柱:石英毛细管柱(5%苯基-甲基聚硅氧烷,柱长30m,内径0.25mm,膜厚0.25μm),或
具同等性能的色谱柱。
c) 进样口温度:260℃。
d) 检测器温度:300℃。
f) 进样量:1.0μL。
g) 载气:高纯氮气。
h) 载气流速:1mL/min。
i) 氢气流量:40mL/min。
j) 空气流量:400mL/min。
k) 参考程序升温:见表1。
5.4 标准曲线的制作
将肌醇标准测定液分别注入气相色谱仪中,以肌醇标准测定液中肌醇的质量为横坐标,测得的峰面
积为纵坐标,绘制标准曲线。肌醇标准品衍生物的气相色谱图参见附录A图A.1。
将试样测定液注入气相色谱仪中,测得保留时间和峰面积。试样测定液中肌醇衍生物的保留时间
与肌醇标准品衍生物的保留时间相比,相对偏差应在±0.5%以内。试样测定液中肌醇的质量根据标准
曲线得到。
6 分析结果的表述
试样中肌醇的含量按式(1)计算。
7 精密度
在重复性条件下获得的两次独立测定结果的绝对差值不得超过算术平均值的10%。
8 其他
固体样品称样量为1g,定容体积为50mL时,检出限为1.0mg/100g,定量限为3.0mg/100g。
第二法 微 生 物 法
9 原理
肌醇是酿酒酵母菌(Saccharomycescerevisiae)生长所必需的营养素,在一定条件下,酿酒酵母菌的
生长与肌醇含量呈对应关系,以标准工作曲线为参照,根据待测液吸光度值,即可计算出待测试样中肌
醇的含量。
10 设备和材料
10.1 设备
10.1.1 天平:感量为0.1mg,1mg和0.1g。
10.1.2 pH计:精度为±0.01。
10.1.4 恒温培养箱:30℃±1℃。
10.1.5 振荡培养箱:30℃±1℃,振荡频率140r/min~160r/min。
10.1.6 高压蒸汽灭菌器:121℃(0.10MPa~0.12MPa);125℃(0.13MPa~0.15MPa)。
10.1.7 恒温仪(或水浴锅):100℃±1℃。
10.1.8 离心机:转速≥2000r/min。
10.1.9 冰箱:2℃~5℃。
10.1.10 涡旋振荡器。
10.1.11 均质器。
10.2 材料
10.2.2 试管:18mm ×180mm。
10.2.3 无菌吸管:10mL(具0.1mL刻度)或10mL微量移液器及吸头。
10.2.4 锥形瓶:200mL或250mL。
10.2.5 容量瓶(A类):50mL,100mL,250mL。
10.2.6 漏斗:直径90mm。
10.2.7 定量滤纸:直径90mm。
注:玻璃仪器使用前,用活性剂(月桂磺酸钠或家用洗涤剂加入到洗涤用水中即可)对硬玻璃测定管及其他必要的
玻璃器皿进行清洗,清洗后200℃干热2h。
11 培养基和试剂
11.1 培养基
11.1.1 麦芽浸粉琼脂培养基:见附录B中B.1。
11.1.2 麦芽浸粉液体培养基:见附录B中B.2。
11.1.3 肌醇测定培养基:见附录B中B.3。
注:商品化合成培养基按使用说明进行配制。
11.2 试剂及菌种
11.2.1 氯化钠(NaCl)。
11.2.2 氢氧化钠(NaOH)。
11.2.3 盐酸(HCl)。
11.2.5 酿酒酵母菌(Saccharomycescerevisiae)ATCC9080,或其他经验证的等效标准菌株。
11.3 试剂配制
11.3.1 无菌氯化钠溶液(0.85%):称取8.5g氯化钠溶解于1000mL水中,分装试管,每管10mL,
121℃ 灭菌15min。
11.3.2 盐酸溶液(1mol/L):量取90mL浓盐酸,定容至1000mL,混匀。
11.3.3 盐酸溶液(0.44mol/L):量取39.6mL浓盐酸,定容至1000mL,混匀。
11.3.4 氢氧化钠溶液(15mol/L):称取300g氢氧化钠溶解于水中,冷却后定容至500mL,混匀。
11.3.5 氢氧化钠溶液(1mol/L):称取40g氢氧化钠溶解于水中,冷却后定容至1000mL,混匀。
11.4 标准品
准品。
11.5 标准溶液配制
11.5.1 肌醇标准储备液(0.2mg/mL):肌醇标准品置于五氧化二磷的干燥器中干燥24h以上,称取
50mg上述肌醇标准品(精确至0.1mg)至100mL烧杯中,用水溶解后转移至250mL棕色容量瓶中,
稀释至刻度,混匀,2℃~8℃贮存。有效期1个月。
11.5.2 肌醇标准中间液(10μg/mL):准确移取5.00mL肌醇标准储备液,用水定容至100mL棕色容
量瓶中,2℃~8℃贮存。临用现配。
11.5.3 肌醇标准工作液(1μg/mL和2μg/mL):准确移取10.00mL肌醇标准中间液两次,分别用水
定容至100mL棕色容量瓶和50mL棕色容量瓶中。临用现配。
12.1 菌种制备
12.1.1 菌种复苏
将酿酒酵母菌接种到麦芽浸粉琼脂培养基斜面上,30℃±1℃培养16h~24h后,再转接2代~
3代以增强活力,制备成贮备菌种,贮存于4℃冰箱中,保存期不得超过2周。
12.1.2 菌悬液制备
临用前将贮备菌种接种到新的麦芽浸粉琼脂培养基斜面上,30℃±1℃培养16h~24h。再将斜
面培养物转接一环到10mL麦芽浸粉液体培养基中,30℃±1℃培养20h~24h。将上述10mL新鲜
培养物充分振荡混匀,转移至离心管中,2000r/min离心15min,弃去上清液。加入10mL无菌0.85%
氯化钠溶液,混合重悬。重复离心和重悬步骤2次,制成10mL菌悬液备用。
悬液浓度,使其透光率在60%~80%,1h内使用。
12.2 试样制备及提取
谷物类等固体试样需粉碎、研磨、过筛(筛板孔径0.3mm~0.5mm);肉及肉制品等试样用均质器
制成食糜;果蔬等试样需均质混匀;液体试样测定前振摇混合。试样临用现制。
准确称取试样适量,以含肌醇0.5mg~2.0mg为宜。一般新鲜果蔬、内脏、生肉等肌醇含量较高的
食品称取1g(精确至0.001g);谷类、豆类等肌醇含量较低的食品称取5g(精确至0.001g);一般营养
素补充剂、复合营养强化剂称取0.1g~0.5g(精确至0.001g);液体饮料或流质、半流质试样称取5g~10g
(精确至0.001g),置于250mL锥形瓶中。固体试样加入80mL盐酸溶液(0.44mol/L),液体或半固体
试样加入100mL盐酸溶液(0.44mol/L),混匀。
2mL氢氧化钠溶液(15mol/L),冷却。用氢氧化钠溶液(1mol/L)或盐酸溶液(1mol/L)调pH至5.2±0.1,
转入一定体积V(根据样品中肌醇含量调整,一般为250mL)容量瓶中,用水定容至刻度。混匀,滤纸过
滤,收集滤液。必要时进一步调整稀释倍数f,使待测液肌醇的浓度在0.1μg/mL~1.0μg/mL范围
内,作为试样提取液。
12.3 标准溶液的配制
按表2分别加入水、肌醇标准工作液和肌醇测定培养基于培养管中,每管平行制备3份。
12.4 待测液的配制
12.5 灭菌
在12.3和12.4中所有需培养的试管内分别加入一粒玻璃珠,盖上试管帽,121℃高压灭菌5min

GB 5009.270-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Determination of Inositol
in Foods
ISSUED ON. SEPTEMBER 6, 2023
IMPLEMENTED ON. MARCH 6, 2024
Issued by. National Health Commission of the People’s Republic of China;
State Administration for Market Regulation.
Table of Contents
Foreword... 3
1 Scope... 4
Method I - Gas Chromatography... 4
2 Principle... 4
3 Reagents and Materials... 4
4 Instruments and Equipment... 5
5 Analytical Procedures... 6
6 Expression of Analysis Results... 8
7 Precision... 8
8 Others... 8
Method II - Microbiological Method... 9
9 Principle... 9
10 Reagents and Materials... 9
11 Culture Media and Reagents... 10
12 Analytical Procedures... 11
13 Expression of Analysis Results... 14
14 Precision... 15
15 Others... 15
Appendix A Gas Chromatogram... 16
Appendix B Culture Media and Reagents... 17
Appendix C Four-parameter Logistic Curve Fitting Equation... 20
National Food Safety Standard - Determination of Inositol
in Foods
1 Scope
This Standard specifies the methods for the determination of inositol (myo-inositol) in foods.
Method 1 - gas chromatography is applicable to the determination of inositol in infant
formulas, formulas for special medical purposes, milk and dairy products, and beverages.
Method 2 - microbiological method is applicable to the determination of inositol in foods.
Method I - Gas Chromatography
2 Principle
The inositol in the specimen is extracted with water and precipitated with ethanol. After the
supernatant is centrifuged and dried, it is derivatized with a silanization reagent. The
derivative is extracted with n-hexane, separated by gas chromatography and detected by a
hydrogen flame ionization detector. Adopt the external standard method for quantitative
determination.
3 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are all analytically pure,
and the water is Grade-1 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Absolute ethanol (C2H6O).
3.1.2 95% ethanol (C2H6O).
3.1.3 Acetonitrile (C2H3N).
3.1.4 n-Hexane (C6H14).
3.1.5 Trimethylchlorosilane (C3H9ClSi).
3.1.6 Hexamethyldisilazane (C6H19NSi2).
3.1.7 N, N-dimethylformamide (C3H7NO).
3.1.8 Anhydrous sodium sulfate (Na2SO4).
3.2 Preparation of Reagents
3.2.1 70% ethanol. measure-take 700 mL of absolute ethanol, use water to reach a constant
volume of 1,000 mL, and evenly mix it.
3.2.2 Silanization reagent. respectively draw-take trimethylchlorosilane,
hexamethyldisilazane and N, N-dimethylformamide, mix them in a volume ratio of 1. 2. 8,
and conduct ultrasonic mixing. Prepare it right before use.
NOTE. if the silanization reagent appears white and turbid, it needs to be prepared again.
3.3 Reference Material
Inositol reference material (C6H12O6, CAS. 87-89-8). purity  99%, or a standard substance
certified by the state and awarded a reference material certificate.
3.4 Preparation of Standard Solutions
3.4.1 Inositol standard stock solution (1.00 mg/mL). weigh-take 100 mg (accurate to 0.1 mg)
mL of water to dissolve it, and use 95% ethanol to reach a constant volume of 100 mL, and
evenly mix it. Store it at 2 C ~ 8 C. It shall remain valid for 1 month.
3.4.2 Inositol standard working solution (0.100 mg/mL). accurately transfer-take 5.00 mL of
inositol standard stock solution, use 70% ethanol to reach a constant volume of 50 mL, and
evenly mix it. Prepare it right before use.
4 Instruments and Equipment
4.1 Gas chromatograph. equipped with a hydrogen flame ionization detector.
4.2 Analytical balance. with a division value of 0.1 mg and 1 mg.
4.3 Centrifuge. with a speed  4,000 r/min.
4.5 Constant-temperature water bath. with a temperature accuracy of  2 C.
4.6 Rotary evaporator.
4.7 Vortex oscillator.
4.8 Ultrasonoscope.
4.9 Nitrogen blower.
5 Analytical Procedures
5.1 Specimen Preparation
5.1.1 Dissolution
Weigh-take 1 g of solid specimen or 12 g of liquid specimen (accurate to 1 mg) that has been
warm water to dissolve it, and perform ultrasonic extraction for 10 minutes. Transfer the
above treated specimen solution into a 50 mL volumetric flask, use 95% ethanol to reach a
constant volume to the scale, and evenly mix it; let it stand to precipitate for 20 minutes. If
the specimen has lumpy, rather than flocculent precipitate, re-weigh the sample, and use 30
mL of 40 C ~ 45 C warm water to re-dissolve the sample, add acetonitrile to reach a
constant volume to the scale and evenly mix it; let it stand to precipitate for 20 minutes.
After the precipitation is completed, draw-take 10 mL of the supernatant, at a speed not
lower than 4,000 r/min, centrifuge it for 5 min, then, accurately transfer-take 5.00 mL of the
supernatant to a 25 mL rotary evaporation bottle or screw-top glass bottle and reserve it for
5.1.2 Drying
Add an appropriate amount of absolute ethanol to the specimen to be dried, at a temperature
not higher than 80 C, use the rotary evaporator or nitrogen blower to concentrate it to near
dryness. At 100 C, bake it for 1 h. Take it out to cool to room temperature and reserve it for
derivatization.
5.1.3 Derivatization
Add 10 mL of the silanization reagent to the dried specimen, conduct ultrasound for 5
minutes, seal and evenly mix it in a 25 mL screw-top glass bottle. In 80 C water bath, react
for 75 minutes, during which, take it out and oscillate once every 20 minutes. After it is over,
stratification, then, take 3 mL of n-hexane extracting solution into a centrifuge tube that has
been pre-added with a little anhydrous sodium sulfate, vortex, then, at a speed not lower than
4,000 r/min, centrifuge for 5 min. Then, transfer the solution into a sample injection bottle to
obtain the specimen determination solution to be determined by the gas chromatograph.
5.2 Preparation of Inositol Standard Determination Solutions
Respectively draw-take 0.200 mL, 0.400 mL, 0.600 mL, 0.800 mL, 1.00 mL and 2.00 mL of
inositol standard working solution (0.100 mg/mL) into rotary evaporation bottles or screw-
top glass bottles. The other analytical procedures are the same as 5.1.2 and 5.1.3.The
inositol content in the obtained standard determination solutions is respectively. 0.020 mg,
NOTE. the concentration range of the inositol standard determination solutions can be adjusted
Method II - Microbiological Method
9 Principle
Inositol is an essential nutrient for the growth of Saccharomyces cerevisiae. Under certain
conditions, there is a corresponding relation between the growth of Saccharomyces
cerevisiae and the inositol content. Taking the standard working curve as a reference, in
accordance with the absorbance value of the solution to be tested, the inositol content in the
specimen to be tested can be calculated.
10 Reagents and Materials
10.1.1 Balance. with a division value of 0.1 mg, 1 mg and 0.1 g.
10.1.2 pH meter. with an accuracy of  0.01.
10.1.3 Spectrophotometer (at a wavelength of 550 nm).
10.1.4 Constant-temperature incubator. 30 C  1 C.
10.1.5 Oscillation incubator. 30 C  1 C, with an oscillation frequency of 140 r/min ~ 160
r/min.
10.1.6 High-pressure steam sterilizer. 121 C (0.10 MPa ~ 0.12 MPa); 125 C (0.13 MPa ~
0.15 MPa).
10.1.7 Thermostat (or water bath). 100 C  1 C.
10.1.9 Refrigerator. 2 C ~ 5 C.
10.1.10 Vortex oscillator.
10.1.11 Homogenizer.
10.2 Materials
10.2.1 Glass beads. with a diameter of about 5 mm.
10.2.2 Test tube. 18 mm  180 mm.
10.2.3 Sterile pipette. 10 mL (with a scale of 0.1 mL) or 10 mL micropipette and tip.
10.2.4 Conical flask. 200 mL or 250 mL.
10.2.5 Volumetric flask (Type A). 50 mL, 100 mL and 250 mL.
10.2.7 Quantitative filter paper. with a diameter of 90 mm.
NOTE. before using the glass instrument, use an active agent (add sodium laurel sulfonate or
household detergent to the washing water) to clean the hard glass measuring tube and
other necessary glassware. After cleaning, dry heat at 200 C for 2 hours.
11 Culture Media and Reagents
Unless it is otherwise specified, the reagents used in this Method are all analytically pure,
and the water is Grade-2 water specified in GB/T 6682.
11.1 Culture Media
11.1.1 Malt extract agar culture medium. see B.1 in Appendix B.
11.1.3 Culture medium for inositol determination. see B.3 in Appendix B.
NOTE. commercial synthetic media can be prepared in accordance with the instructions.
11.2 Reagents and Strain
11.2.1 Sodium chloride (NaCl).
11.2.2 Sodium hydroxide (NaOH).
11.2.3 Hydrochloric acid (HCl).
11.2.4 Phosphorus pentoxide (P2O5).
11.2.5 Saccharomyces cerevisiae ATCC 9080, or other validated equivalent standard strains.
11.3 Preparation of Reagents
dissolve it in 1,000 mL of water, and divide it into test tubes, with 10 mL in each tube. At
121 C, sterilize for 15 minutes.
11.3.2 Hydrochloric acid solution (1 mol/L). measure-take 90 mL of concentrated
hydrochloric acid, reach a constant volume of 1,000 mL and evenly mix it.
11.3.3 Hydrochloric acid solution (0.44 mol/L). measure-take 39.6 mL of concentrated
hydrochloric acid, reach a constant volume of 1,000 mL and evenly mix it.
11.3.4 Sodium hydroxide solution (15 mol/L). weigh-take 300 g of sodium hydroxide and
dissolve it in water. After cooling, reach a constant volume of 500 mL and evenly mix it.
11.3.5 Sodium hydroxide solution (1 mol/L). weigh-take 40 g of sodium hydroxide and
11.4 Reference Material
Inositol reference material (C6H12O6, CAS. 87-89-8). purity  99%, or a standard substance
certified by the state and awarded a reference material certificate.
11.5 Preparation of Standard Solutions
11.5.1 Inositol standard stock solution (0.2 mg/mL). place inositol reference material in a
phosphorus pentoxide desiccator to dry for more than 24 hours, weigh-take 50 mg (accurate
to 0.1 mg) of the above-mentioned inositol reference material into a 100 mL beaker, use
water to dissolve it, then, transfer it to a 250 mL brown volumetric flask. Dilute to the scale
and evenly mix it. Store it at 2 C ~ 8 C. It shall remain valid for 1 month.
of inositol standard stock solution, use water to reach a constant volume in a 100 mL brown
volumetric flask. Store it at 2 C ~ 8 C. Prepare it right before use.
11.5.3 Inositol standard working solution (1 g/mL and 2 g/mL). accurately transfer-take
10.00 mL of inositol standard intermediate solution twice, respectively use water to reach a
constant volume in a 100 mL brown volumetric flask and a 50 mL brown volumetric flask.
Prepare it right before use.
12 Analytical Procedures
12.1 Preparation of Strain
12.1.1 Strain recovery
   
相关标准:  GB 5009.265-2021  GB 5009.259-2023
 
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