9秒发货/有发票 梧三标准英文版 优质技术翻译  数据库收录:159759 最近更新:2020-06-13  
支付宝/对公账号 首页   询价  购买流程  英文样品 公司简介   购物车

GB 5009.93-2017

标准搜索结果: 'GB 5009.93-2017'
标准号码内文价格(元)第2步交付天数标准名称状态
GB 5009.93-2017 英文版 380 购买 现货,9秒内自动发货PDF,有增值税发票。 食品安全国家标准 食品中硒的测定 有效

   
标准编号: GB 5009.93-2017 (GB5009.93-2017)
中文名称: 食品安全国家标准 食品中硒的测定
英文名称: Food safety national standard -- Determination of selenium in food
行业: 国家标准
中标分类: X09
字数估计: 11,120
发布日期: 2017-04-06
实施日期: 2017-10-06
旧标准 (被替代): SN/T 0860-2000; SN/T 0926-2000; GB/T 21729-2008; GB 5009.93-2010
标准依据: State Health and Family Planning Commission Notice No. 5 of 2017

GB 5009.93-2017
Food safety national standard -- Determination of selenium in food
中华人民共和国国家标准
食品安全国家标准
食品中硒的测定
2017-04-06发布
2017-10-06实施
中华人民共和国国家卫生和计划生育委员会
国 家 食 品 药 品 监 督 管 理 总 局 发 布
前言
本标准代替GB 5009.93-2010《食品安全国家标准 食品中硒的测定》、GB/T 21729-2008《茶叶
中硒含量的检测方法》、SN/T 0860-2000《出口蘑菇罐头中硒的测定方法 荧光分光光度法》和
SN/T 0926-2000《进出口茶叶中硒的检验方法 荧光光度法》。
本标准与GB 5009.93-2010相比,主要变化如下.
---保留氢化物原子荧光光谱法为第一法,荧光分光光度法为第二法;
---增加电感耦合等离子体质谱法为第三法。
食品安全国家标准
食品中硒的测定
1 范围
本标准规定了食品中硒含量测定的氢化物原子荧光光谱法、荧光分光光度法和电感耦合等离子体
质谱法。
本标准适用于各类食品中硒的测定。
第一法 氢化物原子荧光光谱法
2 原理
试样经酸加热消化后,在6mo1/L盐酸介质中,将试样中的六价硒还原成四价硒,用硼氢化钠或硼
氢化钾作还原剂,将四价硒在盐酸介质中还原成硒化氢,由载气(氩气)带入原子化器中进行原子化,在
硒空心阴极灯照射下,基态硒原子被激发至高能态,在去活化回到基态时,发射出特征波长的荧光,其荧
光强度与硒含量成正比,与标准系列比较定量。
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规定的二级水。
3.1 试剂
3.1.1 硝酸 (HNO3).优级纯。
3.1.2 高氯酸 (HClO4).优级纯。
3.1.3 盐酸 (HCl).优级纯。
3.1.4 氢氧化钠 (NaOH).优级纯。
3.1.5 过氧化氢 (H2O2)。
3.1.6 硼氢化钠 (NaBH4).优级纯。
3.1.7 铁氰化钾 [K3Fe(CN)6]。
3.2 试剂的配制
3.2.1 硝酸-高氯酸混合酸(9+1).将900mL硝酸与100mL高氯酸混匀。
3.2.2 氢氧化钠溶液(5g/L).称取5g氢氧化钠,溶于1000mL水中,混匀。
3.2.3 硼氢化钠碱溶液(8g/L).称取8g硼氢化钠,溶于氢氧化钠溶液(5g/L)中,混匀。现配现用。
3.2.4 盐酸溶液(6mol/L).量取50mL盐酸,缓慢加入40mL水中,冷却后用水定容至100mL,
混匀。
3.2.5 铁氰化钾溶液(100g/L).称取10g铁氰化钾,溶于100mL水中,混匀。
3.2.6 盐酸溶液(5+95).量取25mL盐酸,缓慢加入475mL水中,混匀。
3.3 标准品
硒标准溶液.1000mg/L,或经国家认证并授予标准物质证书的一定浓度的硒标准溶液。
3.4 标准溶液的制备
3.4.1 硒标准中间液(100mg/L).准确吸取1.00mL硒标准溶液(1000mg/L)于10mL容量瓶中,加
盐酸溶液(5+95)定容至刻度,混匀。
3.4.2 硒标准使用液(1.00mg/L).准确吸取硒标准中间液(100mg/L)1.00mL于100mL容量瓶
中,用盐酸溶液(5+95)定容至刻度,混匀。
3.4.3 硒标准系列溶液.分别准确吸取硒标准使用液(1.00mg/L)0mL、0.500mL、1.00mL、2.00mL
和3.00mL于100mL容量瓶中,加入铁氰化钾溶液(100g/L)10mL,用盐酸溶液(5+95)定容至刻度,
混匀待测。此硒标准系列溶液的质量浓度分别为0μg/L、5.00μg/L、10.0μg/L、20.0μg/L和
30.0μg/L。
注.可根据仪器的灵敏度及样品中硒的实际含量确定标准系列溶液中硒元素的质量浓度。
4 仪器和设备
注.所有玻璃器皿及聚四氟乙烯消解内罐均需硝酸溶液(1+5)浸泡过夜,用自来水反复冲洗,最后用水冲洗干净。
4.1 原子荧光光谱仪.配硒空心阴极灯。
4.2 天平.感量为1mg。
4.3 电热板。
4.4 微波消解系统.配聚四氟乙烯消解内罐。
5 分析步骤
5.1 试样制备
注.在采样和制备过程中,应避免试样污染。
5.1.1 粮食、豆类样品
样品去除杂物后,粉碎,储于塑料瓶中。
5.1.2 蔬菜、水果、鱼类、肉类等样品
样品用水洗净,晾干,取可食部分,制成匀浆,储于塑料瓶中。
5.1.3 饮料、酒、醋、酱油、食用植物油、液态乳等液体样品
将样品摇匀。
5.2 试样消解
5.2.1 湿法消解
称取固体试样0.5g~3g(精确至0.001g)或准确移取液体试样1.00mL~5.00mL,置于锥形瓶
中,加10mL硝酸-高氯酸混合酸(9+1)及几粒玻璃珠,盖上表面皿冷消化过夜。次日于电热板上加
热,并及时补加硝酸。当溶液变为清亮无色并伴有白烟产生时,再继续加热至剩余体积为2mL左右,
切不可蒸干。冷却,再加5mL盐酸溶液(6mol/L),继续加热至溶液变为清亮无色并伴有白烟出现。
冷却后转移至10mL容量瓶中,加入2.5mL铁氰化钾溶液(100g/L),用水定容,混匀待测。同时做试
5.2.2 微波消解
称取固体试样0.2g~0.8g(精确至0.001g)或准确移取液体试样1.00mL~3.00mL,置于消化管
中,加10mL硝酸、2mL过氧化氢,振摇混合均匀,于微波消解仪中消化,微波消化推荐条件见附录A
(可根据不同的仪器自行设定消解条件)。消解结束待冷却后,将消化液转入锥形烧瓶中,加几粒玻璃
珠,在电热板上继续加热至近干,切不可蒸干。再加5mL盐酸溶液(6mol/L),继续加热至溶液变为清
亮无色并伴有白烟出现,冷却,转移至10mL容量瓶中,加入2.5mL铁氰化钾溶液(100g/L),用水定
容,混匀待测。同时做试剂空白试验。
5.3 测定
5.3.1 仪器参考条件
800℃;炉高8mm;载气流速500mL/min;屏蔽气流速1000mL/min;测量方式标准曲线法;读数方式
峰面积;延迟时间1s;读数时间15s;加液时间8s;进样体积2mL。
5.3.2 标准曲线的制作
以盐酸溶液(5+95)为载流,硼氢化钠碱溶液(8g/L)为还原剂,连续用标准系列的零管进样,待读
数稳定之后,将标硒标准系列溶液按质量浓度由低到高的顺序分别导入仪器,测定其荧光强度,以质量
浓度为横坐标,荧光强度为纵坐标,制作标准曲线。
5.3.3 试样测定
在与测定标准系列溶液相同的实验条件下,将空白溶液和试样溶液分别导入仪器,测其荧光值强
度,与标准系列比较定量。
试样中硒的含量按式(1)计算.
X=
(ρ-ρ0)×V
m×1000
(1)
式中.
X ---试样中硒的含量,单位为毫克每千克或毫克每升(mg/kg或mg/L);
ρ ---试样溶液中硒的质量浓度,单位为微克每升(μg/L);
ρ0 ---空白溶液中硒的质量浓度,单位为微克每升(μg/L);
m ---试样称样量或移取体积,单位为克或毫升(g或mL);
1000 ---换算系数。
当硒含量≥1.00mg/kg(或 mg/L)时,计算结果保留三位有效数字,当硒含量<1.00mg/kg
(或mg/L)时,计算结果保留两位有效数字。
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20%。
8 其他
当称样量为1g(或1mL),定容体积为10mL时,方法的检出限为0.002mg/kg(或0.002mg/L),
定量限为0.006mg/kg(或0.006mg/L)。
9 原理
将试样用混合酸消化,使硒化合物转化为无机硒Se4+,在酸性条件下Se4+与2,3-二氨基萘(2,3-
Diaminonaphthalene,缩写为DAN)反应生成4,5-苯并苤硒脑(4,5-Benzopiaselenol),然后用环己烷萃
取后上机测定。4,5-苯并苤硒脑在波长为376nm的激发光作用下,发射波长为520nm的荧光,测定
其荧光强度,与标准系列比较定量。
10 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规定的二级水。
10.1 试剂
10.1.1 盐酸(HCl).优级纯。
10.1.3 2,3-二氨基萘(DAN,C10H10N2)。
10.1.4 乙二胺四乙酸二钠(EDTA-2Na,C10H14N2Na2O8)。
10.1.5 盐酸羟胺(NH2OH·HCl)。
10.1.6 甲酚红(C21H18O5S)。
10.1.7 氨水(NH3·H2O).优级纯。
10.2 试剂的配制
10.2.1 盐酸溶液(1%).量取5mL盐酸,用水稀释至500mL,混匀。
10.2.2 DAN试剂(1g/L).此试剂在暗室内配制。称取DAN0.2g于一带盖锥形瓶中,加入盐酸溶液
(1%)200mL,振摇约15min使其全部溶解。加入约40mL环己烷,继续振荡5min。将此液倒入塞有
环己烷中荧光降至最低时为止(约纯化5次~6次)。将纯化后的DAN溶液储于棕色瓶中,加入约1cm
厚的环己烷覆盖表层,于0℃~5℃保存。必要时在使用前再以环己烷纯化一次。
注.此试剂有一定毒性,使用本试剂的人员应注意防护。
10.2.3 硝酸-高氯酸混合酸(9+1).将900mL硝酸与100mL高氯酸混匀。
10.2.4 盐酸溶液(6mol/L).量取50mL盐酸,缓慢加入40mL水中,冷却后用水定容至100mL,
混匀。
10.2.5 氨水溶液(1+1).将5mL水与5mL氨水混匀。
10.2.6 EDTA混合液.
a) EDTA溶液(0.2mol/L).称取EDTA-2Na37g,加水并加热至完全溶解,冷却后用水稀释至
b) 盐酸羟胺溶液(100g/L).称取10g盐酸羟胺溶于水中,稀释至100mL,混匀;
c) 甲酚红指示剂(0.2g/L).称取甲酚红50mg溶于少量水中,加氨水溶液(1+1)1滴,待完全溶
解后加水稀释至250mL,混匀;
d) 取EDTA溶液(0.2mol/L)及盐酸羟胺溶液(100g/L)各50mL,加甲酚红指示剂(0.2g/L)
5mL,用水稀释至1L,混匀。
10.2.7 盐酸溶液(1+9).量取100mL盐酸,缓慢加入到900mL水中,混匀。
10.3 标准品
硒标准溶液.1000mg/L,或经国家认证并授予标准物质证书的一定浓度的硒标准溶液。
10.4 标准溶液的制备
加盐酸溶液(1%)定容至刻度,混匀。
10.4.2 硒标准使用液(50.0μg/L).准确吸取硒标准中间液(100mg/L)0.50mL,用盐酸溶液(1%)定
容至1000mL,混匀。
10.4.3 硒标准系列溶液.准确吸取硒标准使用液(50.0μg/L)0mL、0.200mL、1.00mL、2.00mL和
4.00mL,相当于含有硒的质量为0μg、0.0100μg、0.0500μg、0.100μg及0.200μg,加盐酸溶液(1+9)
至5mL后,加入20mLEDTA混合液,用氨水溶液(1+1)及盐酸溶液(1+9)调至淡红橙色(pH1.5~
2.0)。以下步骤在暗室操作.加DAN试剂(1g/L)3mL,混匀后,置沸水浴中加热5min,取出冷却后,
加环己烷3mL,振摇4min,将全部溶液移入分液漏斗,待分层后弃去水层,小心将环己烷层由分液漏
斗上口倾入带盖试管中,勿使环己烷中混入水滴。环己烷中反应产物为4,5-苯并苤硒脑,待测。
注.所有玻璃器皿均需硝酸溶液(1+5)浸泡过夜,用自来水反复冲洗,最后用水冲洗干净。
11.1 荧光分光光度计。
11.2 天平.感量1mg。
11.3 粉碎机。
11.4 电热板。
11.5 水浴锅。
12 分析步骤
12.1 试样制备
同5.1。
准确称取0.5g~3g(精确至0.001g)固体试样,或准确吸取液体试样1.00mL~5.00mL,置于锥
形瓶中,加10mL硝酸-高氯酸混合酸(9+1)及几粒玻璃珠,盖上表面皿冷消化过夜。次日于电热板上
加热,并及时补加硝酸。当溶液变为清亮无色并伴有白烟产生时,再继续加热至剩余体积2mL左右,
切不可蒸干,冷却后再加5mL盐酸溶液(6mol/L),继续加热至溶液变为清亮无色并伴有白烟出现,再
继续加热至剩余体积2mL左右,冷却。同时做试剂空白。
12.3 测定
12.3.1 仪器参考条件
根据各自仪器性能调至最佳状态。参考条件为.激发光波长376nm、发射光波长520nm。
12.3.2 标准曲线的制作
横坐标,荧光强度为纵坐标,制作标准曲线。
12.3.3 试样溶液的测定
将12.2消化后的试样溶液以及空白溶液加盐酸溶液(1+9)至5mL后,加入20mLEDTA混合
液,用氨水溶液(1+1)及盐酸溶液(1+9)调至淡红橙色(pH1.5~2.0)。以下步骤在暗室操作.加DAN
试剂(1g/L)3mL,混匀后,置沸水浴中加热5min,取出冷却后,加环己烷3mL,振摇4min,将全部溶
液移入分液漏斗,待分层后弃去水层,小心将环己烷层由分液漏斗上口倾入带盖试管中,勿使环己烷中
混入水滴,待测。
13 分析结果的表述
试样中硒的含量按式(2)计算.
m1
F1-F0×
F2-F0
(2)
式中.
X ---试样中硒含量,单位为毫克每千克或毫克每升(mg/kg或mg/L);
m1 ---试样管中硒的质量,单位为微克(μg);
F1 ---标准管硒荧光读数;
F0 ---空白管荧光读数;
m ---试样称样量或移取体积,单位为克或毫升(g或mL)。
当硒含量≥1.00mg/kg(或 mg/L)时,计算结果保留三位有效数字;当硒含量<1.00mg/kg
(或mg/L)时,计算结果保留两位有效数字。
14 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20%。
15 其他
当称样量为1g(或1mL)时,方法的检出限为0.01mg/kg(或0.01mg/L),定量限为0.03mg/kg
(或0.03mg/L)。
第三法 电感耦合等离子体质谱法
附 录 A
微波消解升温程序
微波消解升温程序见表A.1。
表A.1 微波消解升温程序
步骤 设定温度/℃ 升温时间/min 恒温时间/min

GB 5009.93-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard -
Determination of selenium in foods
食品安全国家标准
食品中硒的测定
ISSUED ON. APRIL 06, 2017
IMPLEMENTED ON. OCTOBER 06, 2017
Issued by. National Health and Family Planning Commission of the
People’s Republic of China;
China Food and Drug Administration.
How to BUY & immediately GET a full-copy of this standard?
2. Search --> Add to Cart --> Checkout (3-steps);
3. No action is required - Full-copy of this standard will be automatically &
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3
1 Scope .. 4
2 Principle ... 4
3 Reagents and materials ... 4
4 Instruments and equipment .. 6
5 Analysis procedure .. 6
6 Expression of analysis results .. 8
7 Precision ... 8
8 Others ... 8
9 Principle ... 9
10 Reagents and materials ... 9
11 Instruments and equipment .. 11
12 Analysis procedure ... 11
13 Expression of analysis results ... 12
14 Precision ... 13
15 Others ... 13
Annex A Microwave digestion temperature rise program reference conditions
... 14
Foreword
This Standard replaces GB 5009.93-2010 “National food safety standard -
Determination of selenium in foods”, GB/T 21729-2008 “Tea - Determination of
selenium content”, SN/T 0860-2000 “Method for the determination of selenium in
canned mushroom for export - Fluorometry” and SN/T 0926-2000 “Method for the
determination of selenium in tea for import and export - Fluorimetry”.
Compare this Standard with GB 5009.93-2010, the main changes are as follows.
- RETAIN the hydride atomic fluorescence spectrometry as Method I, fluorescence
spectrophotometry as Method II;
- ADD the inductively coupled plasma mass spectrometry as Method III.
National food safety standard -
Determination of selenium in foods
1 Scope
This Standard specifies the determination of selenium content in foods by hydride
atomic fluorescence spectrometry, fluorescence spectrometry and inductively coupled
plasma mass spectrometry.
This Standard applies to the determination of selenium in all types of foods.
Method I -- Hydride atomic fluorescence spectrometry
2 Principle
After the sample is acid-heated and digested, in the 6 mol/L hydrochloric acid medium,
the hexavalent selenium in the sample is reduced to tetravalent selenium. Sodium
borohydride or potassium borohydride is used as the reducing agent to reduce the
tetravalent selenium in the hydrochloric acid medium to hydrogen selenide, which is
introduced by carrier gas (argon) into the atomizer for atomization. In the irradiation of
selenium hollow cathode lamp, the ground-state selenium atoms are excited to a high
energy state. When deactivating back to the ground state, the fluorescence of the
characteristic wavelength is emitted, of which the fluorescence intensity is proportional
to the selenium content. Compare with the standard series.
3 Reagents and materials
Unless otherwise indicated, the reagents used in this method are analytical regents,
and the water is the Grade 2 water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3). excellent regent.
3.1.2 Perchloric acid (HClO4). excellent regent.
3.1.4 Sodium hydroxide (NaOH). excellent regent.
3.1.5 Hydrogen peroxide (H2O2).
3.1.6 Sodium borohydride (NaBH4). excellent regent.
3.1.7 Potassium ferricyanide [K3Fe(CN)6].
3.2 Preparation of reagents
3.2.1 Nitric acid - perchloric acid mixed acid (9 + 1). MIX 900 mL of nitric acid with 100
mL of perchloric acid.
3.2.2 Sodium hydroxide solution (5 g/L). WEIGH 5 g of sodium hydroxide; DISSOLVE
in 1000 mL of water; MIX well.
DISSOLVE in sodium hydroxide solution (5 g/L); MIX well. PREPARE before use.
3.2.4 Hydrochloric acid solution (6 mol/L). WEIGH 50 mL of hydrochloric acid; slowly
ADD to 40 mL of water; COOL; DILUTE with water to 100 mL; MIX well.
3.2.5 Potassium ferricyanide solution (100 g/L). WEIGH 10 g of potassium ferricyanide;
DISSOLVE in 100 mL of water; MIX well.
3.2.6 Hydrochloric acid solution (5 + 95). MEASURE 25 mL of hydrochloric acid; slowly
ADD to 475 mL of water; MIX well.
3.3 Standard
Selenium standard solution. 1000 mg/L, or selenium standard solution at a certain
3.4 Preparation of standard solutions
3.4.1 Selenium standard intermediate solution (100 mg/L). accurately PIPETTE 1.00
mL of selenium standard solution (1000 mg/L) in a 10 mL volumetric flask; ADD
hydrochloric acid solution (5 + 95) to the mark; MIX well.
3.4.2 Selenium standard use solution (1.00 mg/L). accurately PIPETTE 1.00 mL of
selenium standard intermediate solution (100 mg/L) in a 100 mL volumetric flask; ADD
hydrochloric acid solution (5 + 95) to the mark; MIX well.
3.4.3 Selenium standard series solutions. respectively PIPETTE 0 mL, 0.500 mL, 1.00
mL, 2.00 mL and 3.00 mL of selenium standard use solution (1.00 mg/L) in 100 mL
hydrochloric acid solution (5 + 95) to the mark; MIX well for test. The mass
concentrations of the selenium standard series solutions are 0 μg/L, 5.00 μg/L, 10.0
μg/L, 20.0 μg/L and 30.0 μg/L, respectively.
NOTE. The mass concentration of selenium in the standard series solutions may be determined
according to the sensitivity of the instrument and the actual content of selenium in the sample.
potassium ferricyanide solution (100 g/L); ADD water to constant volume; MIX well for
test. At the same time carry out the reagent blank test.
5.2.2 Microwave digestion
WEIGH 0.2 g ~ 0.8 g (to the nearest 0.001 g) of solid sample or accurately PIPETTE
acid and 2 mL of hydrogen peroxide; SHAKE to mix well. DIGEST in the microwave
digestion instrument, and the recommended microwave digestion conditions are
shown in Annex A (set digestion conditions according to different instruments). After
the digestion is completed and cool, TRANSFER the digestion solution into the conical
flask; ADD a few grains of glass beads; continue to HEAT on the electric hot plate to
near dry, it must not be evaporated to dry. ADD 5 mL of hydrochloric acid solution (6
mol/L); continue to HEAT until the solution becomes clear and colorless accompanied
by white smoke; COOL; TRANSFER to a 10 mL volumetric flask. ADD 2.5 mL of
potassium ferricyanide solution (100 g/L); ADD water to constant volume; MIX well for
5.3 Determination
5.3.1 Instrument reference conditions
Adjust the instruments to the best condition according to their performance. Reference
conditions. negative high voltage 340 V; lamp current 100 mA; atomization
temperature 800 °C; furnace height 8 mm; carrier gas flow rate 500 mL/min; shielding
gas flow rate 1000 mL/min; standard curve method of measurement method; peak
area of reading method; delay time 1 s; reading time 15 s; solution adding time 8 s;
sample injection volume 2 mL.
5.3.2 Plotting of standard curve
g/L) as the reducing agent. INJECT sample continuously with the zero tube of the
standard series. After the reading is stable, introduce the selenium standard series
solutions into the instrument according to the order of the mass concentration from low
to high, to measure their fluorescence intensity. The standard curve is plotted by taking
the mass concentration as the abscissa and the fluorescence intensity as the ordinate.
5.3.3 Sample determination
Under the same test conditions as the determination of standard series solutions, the
blank solution and the sample solution are respectively introduced into the instrument,
and the corresponding fluorescence intensity is measured, to compare with the
NOTE. This reagent has a certain toxicity, personnel who use this reagent shall pay attention
to protection.
10.2.3 Nitric acid - perchloric acid mixed acid (9 + 1). MIX 900 mL of nitric acid with
100 mL of perchloric acid.
10.2.4 Hydrochloric acid solution (6 mol/L). MEASURE 50 mL of hydrochloric acid;
slowly ADD to 40 mL of water; COOL; ADD water to 100 mL; MIX well.
10.2.5 Ammonia solution (1 + 1). MIX 5 mL of water with 5 mL of ammonia.
10.2.6 EDTA mixture.
a) EDTA solution (0.2 mol/L). WEIGH 37 g of EDTA-2Na; ADD water and HEAT until
b) Hydroxylamine hydrochloride solution (100 g/L). WEIGH 10 g of hydroxylamine
hydrochloride to dissolve in water; DILUTE to 100 mL; MIX well;
c) Cresol red indicator (0.2 g/L). WEIGH 50 mg of cresol red to dissolve in a small
amount of water; ADD 1 drop of ammonia solution (1 + 1); after completely
dissolved, DILUTE with water to 250 mL; MIX well;
d) Respectively TAKE 50 mL of EDTA solution (0.2 mol/L) and hydroxylamine
hydrochloride solution (100 g/L); ADD 5 mL of cresol red indicator (0.2 g/L);
DILUTE to 1 L with water; MIX well.
10.2.7 Hydrochloric acid solution (1 + 9). MEASURE 100 mL of hydrochloric acid;
10.3 Standard
Selenium standard solution. 1000 mg/L, or selenium standard solution at a certain
concentration certified by the state and awarded the standard substance certificate.
10.4 Preparation of standard solutions
10.4.1 Selenium standard intermediate solution (100 mg/L). accurately PIPETTE 1.00
mL of selenium standard solution (1000 mg/L) in a 10 mL volumetric flask; DILUTE
with hydrochloric acid solution (1 %) to the mark; MIX well.
10.4.2 Selenium standard use solution (50.0 μg/L). accurately PIPETTE 0.50 mL of
selenium standard intermediate solution (100 mg/L); DILUTE with hydrochloric acid
10.4.3 Selenium standard series solutions. accurately PIPETTE 0 mL, 0.200 mL, 1.00
mL, 2.00 mL and 4.00 mL of standard selenium use solution (50.0 μg/L), which are
equivalent to containing 0 μg, 0.010 0 μg, 0.050 0 μg, 0.100 μg and 0.200 μg of
12.3.1 Instrument reference conditions
Adjust the instruments to the best condition according to their performance. The
reference conditions. excitation light wavelength 376 nm, emission light wavelength
520 nm.
12.3.2 Plotting of standard curve
Measure the fluorescence intensity of 4,5-Benzo piaselenol in selenium standard
to high. The standard curve is plotted by taking the mass as the abscissa and the
fluorescence intensity as the ordinate.
12.3.3 Determination of sample solution
After the digested sample solution of 12.2 and the blank solution are added with
hydrochloric acid solution (1 + 9) to 5 mL, ADD 20 mL of EDTA mixture, USE ammonia
solution (1 + 1) and hydrochloric acid solution (1 + 9) to adjust it to pale red-orange
(pH 1.5 ~ 2.0). The following steps are operated in the darkroom. ADD 3 mL of DAN
reagent (1 g/L); MIX well; HEAT in the boiling water bath for 5 min; REMOVE and
COOL; ADD 3 mL of cyclohexane; SHAKE for 4 min; TRANSFER all the solution into
the cyclohexane layer from the top of the separatory funnel into the test tube with a lid.
Do not make cyclohexane mixed with water droplets, for test.
13 Expression of analysis results
The content of selenium in the sample is calculated according to equation (2).
where.
X - the content of selenium in the sample, in milligram...
   
宁德梧三商贸有限公司 | 纳税人识别号:91350900MA32WE2Q2X | 营业执照:营业执照证书
点击联络我们 联系电邮郑文锐销售经理: Sales@gb-gbt.cn | Sales@ChineseStandard.net | 电话郑经理: 18059327808 | 增值税普通发票 / 增值税专用发票样品
对公开户银行:中国建设银行古田支行 | 账号:35050168730700000955 | 账户名称:宁德梧三商贸有限公司 | 大额行号(非必须):105403500207 对公银行账号证书
翻译支持:全资母公司新加坡场测亚洲公司(https://www.ChineseStandard.net 卖欧美后再内销)
网站备案许可:闽ICP备19012676号 http://www.beian.miit.gov.cn
隐私   ·  优质产品   ·  退款政策   ·  公平交易   ·  关于我们