1、lS 中华人民共和国出入境检验检疫行业标准SN/T 1055-2002 出口坚果中氧化苯丁锡残留量检验方法原子眼收分光光度法Method for the determination of fenbutatin oxide residues in nuts for export-Atomic absorption spectrophotometric method 2002 -01-16发布2002 - 06 -01实施中华人民共和国发布国家质量监督检验检疫总局SN /T 1055-2002 前本标准是按照GB/T1.1-1993(标准化工作导则第1单元:标准的起草与表述规则第1部分:标准编写的
2、基本规定和SN/T0001-1995(出口商品中农药、兽药残留量及生物毒素检验方法标准编写的基本规定的要求进行编写的，其中测定方法是参考国内外有关文献，经研究、改进和验证后而制定的。本标准同时制定了抽样和制样方法。本标准的测定低限，是在参考若干国家及国际组织对商品中氧化苯丁锡最高残留限量(MRL)的规定和测定方法灵敏度的基础上而确定的。本标准由国家认证认可监督管理委员会提出并归口。本标准起草单位:中华人民共和国北京出入境检验检疫局。本标准主要起草人:王嘉瑞、邹连生、刘岩、张世忠。本标准首次发布。1 范围中华人民共和国出入境检验检疫行业标准出口坚果中氧化苯丁锡残留量检验方法原子吸收分光光度法Me
3、thod for the determination of fenbutatin oxide residues in nuts for export Atomic absorption spectrophotometric method SN /T 1055-2002 本标准规定了出口坚果中氧化苯丁锡残留量检验的抽样、制样和原子吸收分光光度测定方法。本标准适用于出口栗子、核桃等坚果中氧化苯丁锡残留量的检验。2 抽样和制样2. 1 抽样批次以同种类、同等级为一抽样批次，每个抽样批次不得大于50t 0 2. 2 抽样数量50件及以下抽取5件。51 100件按件数的10%抽取。101 500件以10
4、0件抽取10件为基础，其余件数按6%抽取。501 1 000件以500件抽取34件为基础，其余件数按3%抽取。计算样件数量时，不足-件者按一件计。每件抽样数量应基本一致，核桃不得少于20颗，每批样品不得少于500颗;栗子每件抽样数量不得少于500g，每批样品不得少于4kg。2. 3 试样制备将所取原始样品缩分出1峙，取可食部分，经样品均质器碎化，均分成2份，装入洁净容器内，作为试样，密封，并标明标记。2.4 试样保存将试样于18CC冷冻保存。注:在抽样和制样的操作过程中，必须防止样品受到污染或发生残留物含量的变化。3 测定方法3. 1 方法提要以二氯甲皖-冰乙酸混合溶剂，提取试样中氧化苯丁锡残
5、留，提取液经离心分离，浓缩至干后，残渣用湿法消化，溶解定容后，用配有氢化物发生系统、外焰加热石英管原子化器的原子吸收分光光度计测定，外标法定量。3.2试剂和材料除另有注明外，试剂均为分析纯，水为去离子水。3.2.1 提取剂:二氯甲:皖-冰乙酸，6+4CV/V)。中华人民共和国国家质量监督检验检疫总局2002-01-16批准2002- 06-01实施1 SN/T 1055-2002 3. 2. 2 浓硫酸:优级纯。3.2.3 过氧化氢:30%，优级纯。3.2.4 甲基紫指示剂:0.1 g甲基紫溶于100mL水中。3. 2. 5 广范pH试纸。3.2.6 10 mol/L氢氧化铀榕液:40g氢氧化
6、铀榕于100mL水中。3. 2. 7 腆化饵溶液:20g腆化饵溶于100mL水中。3.2.8 硫酸溶液:5mL浓硫酸溶于1000 mL水中(氢化物发生系统用)。3. 2. 9 o. 025 mol/L氢氧化铀溶液:1. 0 g氢氧化铀溶于1000 mL 水中。3. 2. 10 棚氢化铀榕液:10.0 g棚氢化铀溶于1000 mL o. 025 mol/L的氢氧化铀溶液中(氢化物发生系统用)。3.2. 11苯。3.2.12 氧化苯丁锡标准品:纯度97%。3.2. 13 氧化苯丁锡标准溶液:根据标准品的纯度计算后，准确称取适量的氧化苯丁锡标准品，用苯配成浓度为1.000 mg/mL的标准储备榕液1
7、00mL，分装于10mL的刻度试管中保存。再配制浓度为0.0100 mg/mL的标准工作溶液100mL，分装于10mL的刻度试管中保存。3. 3 仪器和设备3.3.1 原子吸收分光光度计:配有氢化物发生系统和外焰加热石英管原子化器。3. 3. 2 容量瓶:100mL。3. 3. 3 刻度试管:具磨口塞，10mL。3. 3. 4 样品均质器。3. 3. 5 振蔼器。3. 3. 6 离心瓶:具磨口塞，50mL。3.3.7 离心机:LD4-2型医用离心机，或能与离心瓶相配合的其他类型。3. 3. 8 凯氏烧瓶:250 mLo 3. 3. 9 比色管:具磨口塞，25mL。3. 3. 10 玻璃珠:直径
8、约5mm。3.3. 11 电热套:220V , 200 VA，容积1000 mL。3. 3. 12 电调压器:0220V , 1000 VA。3.4 测定步骤3.4.1 提取称取试样约5g(精确到0.1g)于离心瓶内，加.25mL二氯甲皖-冰乙酸提取剂，振荡45min，振荡频率为180次/min。离心5min，转速为2000 r /nin 0将上清液转移至凯氏瓶中，转移时，用离心瓶塞挡住任何浮渣(果仁皮)流出。再用25mL提取剂做第2次提取，用20mL提取剂做第3次提取(第3次提取的振荡时间减为20min)。合并全部上清液于凯氏瓶中。3.4.2 蒸发加4粒玻璃珠于上述凯氏烧瓶中，在风力强劲的通
9、风柜中，用电调压器和电热套，蒸发凯氏烧瓶中的溶剂。初始蒸发阶段，电压限定在140V，以防喷溅，蒸发到液量约为10mL以下时，电压调定到160 V继续加热蒸发，直至残留的油脂或者固体残渣的颜色变为棕黑色或黑色为止，取出，放冷约2 min。为确保安全，整个蒸发期间，周围不得使用明火。3. 4. 3 r肖化3. 4. 3. 1 炭化于上述凯氏烧瓶中，加入2mL浓硫酸(残渣为油脂时，加2.5mL浓硫酸)，再置凯氏瓶于通风柜里的电热套中，加热炭化残渣，电压限定在160V，以防过热，对油脂残渣而言，炭化到刚产生大量黑色泡2 沫为止，取出，放冷2min。3. 4. 3. 2 消化SN /T 1055-200
10、2 加入10mL过氧化氢于上述凯氏瓶中，置凯氏瓶于通风柜里的电热套中，加热消化残渣，电压限定在160V，以防反应过于激烈，至过氧化氢作用完全时，立即取出(不得延误，延误将导致硫酸熬于)，放冷2mino重复加过氧化氢，直至消化液变为无色透明时为止，取出，放冷2mino 注:对油脂残渣而言，在过氧化氢第一次作用完全时，出现激烈的炭化反应，同时产生大量的黑色泡沫，此时应立即取出凯氏瓶，放冷2min，然后再从加过氧化氢开始，重复消化操作。过氧化氢作用完全时，反应的激烈程度，一次比一次缓和，产生的黑色泡沫的量，一次比一次少。未消化掉的残液的颜色，也一次比一次浅，由最初的黑色，变为深棕色、浅棕色、黄色、浅
11、黄色直至最后消化完全时，残液变为无色。3.4.3.3 消化凯氏瓶颈上的残留物加入20mL过氧化氢于上述凯氏瓶中，凯氏瓶放回通风柜里的电热套中，电压调定到200V，消化至溶液冒白烟，呈透明无色，元任何微小气泡时为止，以确保过氧化氢被完全分解，并确保硫酸不被挥发至干。取出凯氏瓶，放冷后，供配制原子吸收测试溶液用。I3.4.4 标准工作挥手液的消化按5g试样量计算，从浓度为0.0100 mg/mL的氧化苯丁锡标准工作溶液中，准确吸取0.00，0.10 , 0.20 , 0.30 , 0.40 mL(相当于试样中氧化苯丁锡含量为0:00，0.20，0.40，0.60，0.80mg/kg)，分别放入一组
12、编号的凯氏烧瓶中，各加入4粒玻璃珠，在风力强劲的通风柜中，用电热套和电调压器，电压调定在140V，加热挥发凯氏烧瓶中的榕剂至干，取出放冷，加入0.5mL浓硫酸，20mL过氧化氢，电压，调定在200V，加热消化，消化至溶液冒白烟，呈透明元色，无微小气泡时为止，以确保过氧化氢被完全分解，并确保硫酸不被挥发至干。取出凯氏瓶，放冷后，供配制原子吸收测试搭液用。3.4.5 原子吸收测试溶液的配制3. 4. 5. 1 肖化残液的搭解和定量转移分3次，每次5mL水，分别榕解、洗涤凯氏烧瓶中的标准和试样的消化残液，定量转移至比色管中，供降低酸度和定容使用。3. 4.5.2 降低测试溶液的酸度并定容降低酸度操作
13、，应逐一在比色管中进行，以防止指示剂过早加入而失效。往比色管中加入6滴甲基紫指示剂，摇匀，用10mol/L的氢氧化铀溶液，分次加入，降低溶液的酸度，并不断用流水冷却比色管，榕液由黄色，变为黄绿色、绿色直至蓝色为止。降低酸度的操作，必须一次完成，中间不得中断，否则指示剂在低酸度条件下很快退色失效，使降低酸度的操作失败。为确保酸度不会降低过头显碱性，用广范pH试纸检验一下调酸后的洛液，试纸显示酸色即可。再加入5mL腆化饵榕液，用水稀释至25mL刻度线，摇匀，静置5min后，进行原子吸收测定。3. 4. 6 测定3.4.6.1 原子吸收测定条件-._-/ / / / 配有氢化物发生系统、外焰加热石英
14、管原子化器的原子吸收分光光度计的测定条件如下:a)波长:224.6口m;b)狭缝宽度:1. 30口m;c)灯电流:12.5mA; d)火焰:空气乙快焰;e)燃气流量:2.0L/min; f)空气压强:160kPa; g)空气流量:15.0 L/min; h)时间恒定值:2.00 S; i)测量时间:15.0 的3 SN /T 1055-2002 j)延迟时间:5的k)测量次数:2; 1)浓度单位:mg/kgC样品中氧化苯丁锡的含量单位); m)进样体积:5mL。3.4.6.2 原子吸收测定按照设定好的仪器测试条件，测定每份标准的测试溶液和试样的测试溶液的原子吸收吸光度。3.4.7 空白试验除不
15、加试样外，均按上述测定步骤进行。3.4.8 结果计算与表述用原子吸收分光光度计的数据处理机，或按式(1)计算试样中氧化苯丁锡的残留量:式中:X一一试样中氧化苯丁锡残留量，mg/kg;A一一试样的原子吸收吸光度测定值;Ao-一空白试验原子吸收吸光度测定值;是一一标准曲线线性回归方程斜率，Cmg/kg)-l。4 方法的测定低限、回收率4.1 测定低限本方法的测定低限为0.10mg/kg。4.2 回收率. C 1 ) 回收率的试验数据:试样中氧化苯丁锡的添加浓度在O.100. 80 mg/kg范围时，回收率为87.5%110. 0%。4 SN/T 1055-2002 Foreword This st
16、andard was drafted in accordance with the requirement of GB/T 1. 1-1993 Directives for the work of standardization-Unit 1 : Drafting and presentation of standards-Part 1: General rules for drafting standards and SN/T 0001-1995General rules for drafting the standard methods for the determination of p
17、esticide , veterinary drug residues and biotoxins in commodities for export回The method of determination of this standard was drafted by referring to relational domestic and foreign literature through research , modification and verification .In addition , methods of samplng and sample preparation ar
18、e also specified in this standard. The limit of determination in this standard is defined on the basis of the current international maxi. mum limits for fenbutatin oxide residues in foodstuffs and the sensitivity of the method. This standard was proposed by and is under the charge of National Regula
19、tory Commission fol Certilication and Accreditation. This standard was drafted by Beijing Bureau for Entry-Exit Inspection and Quarantine of the Peo ple s Republic of China. The main drafters of this standard are Wang Jiarui , Zou Lianshe吨，LiuYan , Zhang Shizhong. This standard is a professional sta
20、ndard promulgated for the first time. Note:币IsEnglish version , a translation from the Chinese text , is solely for guidance. F D Professional Standard of the People s Republic of China for Entry-Exit Inspection and Quarantine Method for determination of fenbutatin oxide residues in nuts for export一
21、Atomic absorption spectrophotometric method 1 Scope SN/T 1055-2002 This standard specifies the method of sampling , sample preparatioh and determination of fenbu-tatin oxide residues in nuts for expo同bythe atomic absorption spectrophotometry. This standard is applicable to the determination of fenbu
22、tatin cxide residues in nuts such as sweet nut, walnut for export. 2 Sampling and sample preparation 2.1 Inspection lot An inspection lot should be same wpe and same grade, each lot shou|d not be more than 50 tons-2.2 Ouantity of sample taken Number of piece in each inspection lot 运5051 - 100 101 -
23、500 501 - 1 000 Minimum number of iece to be opened 5 10% 10 piece of 100 piece + 6% remainder piece. 34 piece of/500 piece + 3% remainder piece. When calculate the number of piece , less than one piece should be assumed as one piece. The quantity taken from one piece should be same , for walnut, sh
24、ould not be less than 20 grains a piece; for sweetnut, should not be less than 500 grams a piece. For one inspection lot, the quantity of sample taken should not be less than 4 kg. 2.3 Preparation of test sample The combined primary sample is reduced to 1 kg , the edible portion is blended , and the
25、n divided into two equal portions. Each po同ionis placed in a clean container as the test sample , which is Approved by General Administration of Oualit Supervision ,lnspection and Ouarantine of the People s Republic of China on 2002-01-16 6 Implemented from 2002-06-01 SN/T 1055-2002 sealed and label
26、ed. 2.4 Storage of test sample The test samples should be stored at - 18C . Note: In the course of sampling and test sample preparatio口，precaution must be taken to avoid the contamination or any factors which may cause the change of residues content. 3 Method of determination 3.1 Principle After the
27、 sample is extracted by the dichloromethane-glacial acetic acid mixed solvent, the solution is centrifuged , separated , and concentrated to dryness , the dryness residue is digested by sulfuric acid and oxide reagents , then the digested solution is diluted to a definite volume. Finally , the solu
28、tion is analyzed by the atomic absorption spectrophotometer equiped with a hydride formation system and an external flame heating qua同ztube for the atomic vapor formation , using external standard method for the quantitative determination. 3.2 Reagents and materials Unless otherwise specified , the
29、purit of all of reagents is A. R. , the water is distilled water. 3.2.1 Extraction reagent: dichloromethane-glacial acetic acid ,6 + 4( V /V). 3.2.2 Concentration sulfuric acid: High class purity. 3.2.3 Hydrogen peroxide:30% , high c1ilsS purity. 3.2.4 Methyl violet indicator solution:Q.1 gram methy
30、l violet is dissolved in 100 mL water. 3.2.5 Universal indicator paper:pH 1 -14. 3.2.6 10 mol/L solution of. so;fium hydroxide:40igram sodium Irydroxide is dissolved in 100 mL water. / 3.2.7 Potassium iodide solution :20 grams potassium iodide is dissolved in 100 mL water. 3.2.8 Solution of sulfuric
31、 acid: 5 mL concentrated sulfuric acid dissolved in 1 000 mL water (to be used for hydride formation system) . 3.2.9 0.025 mol/L solution of sodium hydroxide: 1.0 gram sodium hydroxide is dissolved in 1 000 mL water. 3.2.10 Sodium borohydried: 10.0 gram sodium borohydride is dissolved in 1 000 mL 0.
32、025 mol/ L solution of sodium hydroxide (to be used for hydride formation system). 7 SN/T 1055-2002 3.2.11 Benzene. 3.2.12 Fenbutatin oxide standard material: Purity:注97%.3.2.13 Fenbutatin oxide standard solution: After the calculation according to the purity of fenbu tatin oxide , accurately weigh
33、adequate amount of fenbutatin oxide standard material , dissolved in benzen and prepare 100 mL solution of the concentration as 1.000 mg/mL, divided into the 10 mL graduated test tubes as the standard stock solution. Then prepare again 100 mL solution of the concentration as 0.010 0 mg/mL, divided i
34、nto the 10 mL graduated test tubes as the standard working solution. 3.3 Apparatus and equipment 3.3.1 The atomic absorption spectrophotometer: Equipped with a hydride formation system and an external flame heating quartz tube for atomic vapor formation . 3.3.2 Measuring flask: 100 mL. 3.3.3 Graduat
35、ed test tube:10 mL, with ground stopper. 3.3.4 Sample homogenizer. 3.3.5 Shaker. 3.3.6 Centrifuge bottle:50 mL, with ground stopper. 3.3.7 Centrifuger: LD-4 model , or other model that can match with the centrifuge bottle. 3.3.8 Kjeldahls flask:250 mL. 3.3.9 Colorimetric test tube:25 mL,with ground
36、stopper. 3.3.10 Glass pearl:about 5 mm diameter. 3.3.11 Electrical heating mantle:220 V ,200 VA, size 1 000 mL. 3.3.12 Voltage adjuster:O 220 V , 1 000 VA. 3.4 Procedure 3.4.1 Extraction Weigh ca 5 9 of the test sample (accurate to O. 1 g) into a centrifuge bottle , add 25 mL dichloromethane-glacial
37、 acetic acid mixed extract reagent and stopper, the bottle is shaken for 45 8 SN/T 1055-2002 min. by a shaker, shaking frequency is about 180 times/min. Then the centrifuge bottle is cen trifuged for 5 min by a centrifuger, rotating speed is about 2 000 r/min , then the clean solution is decanted in
38、to the Kjeldahl s flask , during the decanting , the floating dregs (such as peel of kernel) is kept off by ground stopper of centrifuge bottle to prevent decanting out. Then the test sample is extracted second time by 25 mL, third time by 20 mL extract reagent (during third extracting , the shaken
39、time is reduced as 20 min). AII of the clean solutions are combined into the Kjeldahl s flask. 3.4.2 Evaporation Add 4 pellets of glass pearls into the above Kjeldahl s flask , in the draught chamber with a strong wind power, heat the Kjeldahl s flask by the electrical heating mantle and the voltage
40、 adjuster to evaporate the extract solvent. During the initial evaporating , the voltage is kept at 140 V to prevent erupting.When the volume of solvent is less than 10 mL,the voltage is increased to 160 V to con tinue heating for evaporation , when the color of residue (oil or solid residue) is ge忧
41、ingdark brown or dark, stop heating , take out the flask to cool about 2 min. For safety reason , guarantee no flame exist on the surrounding during the whole evaporating. 3.4.3 Digestion 3.4.3.1 Carbonization Add 2 mL concentrated sulfuric acid (for oil residue , add 2.5 mL)into above Kjeldahls fla
42、sk , then put it back into the electrical heating mantle in the draught chamber, heat the flask to carbonize the residue ,the voltage is adjusted as 160 V to prevent over heat. For oil residue , the carbonizing should not stop until a great number of dark foam just is occur, then the flask is taken
43、out to cool about 2 min. 3 .4.3.2 Digestion Add 10 mL hydrogen peroxide into the above Kjeldahl s flask , then put it back into the electrical heating mantle in the draught chamber, heat and digest the content in flask , the voltage is adjusted as 160 V to prevent the reaction from too drastically.
44、When the hydrogen peroxide is reacted out, take out the flask right away (should not delay, if delay, the sulfuric acid will be dried out) to cool about 2 min. Repeat adding the hydrogen peroxide operation and don t stop until the digested residue liquid has become clear and transparent , take out t
45、he flask to cool about 2 min. Note: For oil residue , when the hydrogen peroxide is reacted out for the first time , the violent carbonizing reaction is occurred , at the same time a great number of dark foam is occurred , at this time the flask should be taken out to cool about 2 min , then repeat
46、the digestion operation with adding the peroxide hydrogen. Whenever the hy drogen peroxide is reacted out , the reaction is more gentle than last time is , the amount of dark foam is less than last time is ,the color of residue liquid is lighter than last time is , it is progressively ge忧ingfrom ini
47、tial black, to dark brown , light brown , yellow , light yellow , and finally the color of residue liquid is colorless and transparent. 9 SN/T 1055-2002 3.4.3.3 Digestion of residue on the inside wall of the neck of Kjeldahl s flask Add 20 mL hydrogen peroxide into the above Kjeldahl s flask , then
48、put it back into the electrical heating mantle in the draught chamber , the voltage is adjusted as 200 V , continue to digest till the solution has become clear and transparent , and produces the white smog , does not appear any mi cro-bubble , to ensure that residue hydrogen peroxide has decomposed
49、 out, but the sulfuric acid has not be dried out, then take out the flask to cool. The cool digested residue liquid will be pre pared into testing solution for AAS. 3.4.4 Digestion of standard working solution After calculate the each volume of standard working solution according to the amount of 5 9 test sample , then accurateltake out 0.00, 0.10,0.20,0.30,0.40 mL (They are equivalent to fenbutatin oxide content in the test samples separately is 0.00 , 0.20, 0.40, 0.60 , 0.80 mg/kg.)
