【行业标准】 进出口粮谷中灭草松残留量检测方法 气相色谱法

中华人民共和国出入境检验检疫行业标准SN/T0292—2010
代替SN0292—1993
进出口粮谷中灭草松残留量检测方法气相色谱法
Determination of bentazon residues in cerealsforimport and exportGC method2010-03-02发布
中华人民共和国
国家质量监督检验检疫总局
合伴网
2010-09-16实施
中华人民共和国出人境检验检疫行业标准
进出口粮谷中灭草松残留量检测方法气相色谱法
SN/T0292—2010
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本标准代替SN0292—1993《出口粮谷中灭草松残留量检验方法》。本标准与SN0292—1993相比主要变化如下：修改了标准的名称；
删去了抽样部分；
修改了气相色谱条件；此内容来自标准下载网
-增加了附录A。
本标准的附录A为资料性附录。
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：中华人民共和国黑龙江出境检验检疫局本标准主要起草人：杨长志、康庆贺、马旭、汤敏顺。本标准于1993年12月28日首次发布，本次为第一次修订。http：//foodmate.netSN/T0292—2010
1范围
进出口粮谷中灭草松残留量检测方法气相色谱法
本标准规定了天米中灭草松残留量的气相色谱检测方法。本标准适用于大来中灭草松残留量的检测2方法提要
SN/T 0292—2010
试样中残留的灭草松先在酸性溶液中用内酮提取，然后氮气吹去内酮，加入硫酸钠溶液，再用正已烷提取。提取液经浓缩，甲基化，硅胶固相萃取柱净化。净化液用气相色谱附电子俘获检测器检测，外标法定量。
3试剂和材料
除另有规定外，所有试剂均为分析纯，水为蒸馏水或相当纯度的水。3.1丙酮：色谱纯。
3.2正已烷：色谱纯。
3.3甲醇：色谱纯。
3.4乙醇。
5无水乙醚：色谱纯。
3.6无水硫酸钠：在650℃灼烧4h.贮于干燥器中备用3.7盐酸。
3.8氢氧化钾。
3.9丙酮-正已烷（2十98，体积比）。3.10
硫酸钠溶液：将20g灼烧过的无水硫酸钠（3.6)溶于去离子水中，稀释至1L。3.11
盐酸溶液：1mol/L。取90mL盐酸（3.7)溶于1000mL去离子水中。3.12氢氧化钾溶液：0.6g/mL，称取60g氢氧化钾（3.8)溶于100mL去离子水中。3.13N-甲基-N-亚硝基-p-甲苯磺酰胺无水乙醚溶液：21.5g/140mL。称21.5gN-甲基-N-亚硝基-p-甲苯磺酰胺溶于140mL.无水乙醚（3.5）中3.14重氮甲烷溶液：将装有10mL氢氧化钾溶液（3.12）、35mL乙醇（3.4）及10mL无水乙醚的混合液的双口蒸馏瓶，置于磁力搅拌器加热板上的水浴中.水温70℃。将搅拌子放人瓶中。接上滴液漏斗和高效冷凝器，冷凝器后串连两个125mL的烧瓶作为接收瓶。在第二个烧瓶中放入10mL无水乙醚，且使人口管插到无水乙醚液面以下。在冰浴中冷却两个接收瓶。边用磁力搅拌边通过滴液漏斗滴加N-甲基-N-亚硝基-p-甲苯磺酰胺无水乙醚溶液（3.13）.滴完全部溶液的时间控制在20min以上。当蒸馏瓶内溶液呈淡黄色时停止蒸馏。将两个接收瓶中的液体合并，在70℃水浴中再蒸馏，其馏出液作为重氮甲溶液。此液密闭置于冰箱中保存，保存期为1个月3.15灭草松标准品：灭草松（bentazon）.C1oH12N2O.S.CASNo.25057-89-0，纯度≥99.5%。3.16灭草松标准储备溶液：准确称取适量灭草松的标准品·用丙酮配成浓度为100μg/mL的标准储备液，标准储备液可在一18℃条件下储存6个月1
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SN/T0292—2010
3.17灭草松标准工作溶液：根据需要再用丙酮稀释成适当浓度的标准工作液，标准工作液可在0℃～4℃条件下储存3个月。
3.18PT-硅胶固相萃取柱：（1.000mg，6mL)或相当者。4仪器和设备
4.1气相色谱仪：配电子捕获检测器。4.2电子天平：感量0.01mg.0.01g4.3固相萃取装置。
4.4粉碎机。
4.5离心机：4000r/min。
4.6旋涡混合器。
氮吹仪。
4.8具塞玻璃离心管：20mL、30mL。4.9具磨口塞刻度试管：15mL。
5试样制备与保存
5.1试样制备
取有代表性样品约500g.用粉碎机粉碎，过0.21mm筛，混匀，装入洁净容器作为试样，密封并标明标记。
5.2试样保存
试样于4℃C以下保存。在制样的操作过程中，应防止样品污染或发生残留物含量的变化6测定步骤
6.1提取
称取试样约10g（精确到0.01g）于30mL离心管中，滴加0.3mL盐酸溶液（3.11)和10mL丙酮（3.1），在旋涡混合器上快速混匀2min，3000r/min离心3min.用尖嘴吸管吸移丙酮层于25mL容量瓶中。再用10mL、5mL丙酮重复提取两次，合并丙酮提取液于同一容量瓶中，并用丙酮定容。准确吸移5mL内酮提取液于20mL离心管中，用氮气吹至2mL然后加人4mL硫酸钠溶液，滴加0.3mI盐酸溶液（1mol/L）和3mL正已烷，在旋涡混合器上高速提取2min，离心3min（3000r/min），用尖嘴吸管吸移上层液于15mL刻度试管中。残液再用3mL正已烷提取一次。合并正已烷提取液于同一刻度试管中，在45℃水浴中用氮气吹干。6.2甲基化
6.2.1样液的甲基化
用0.2mL甲醇溶解残渣，加人过量重氮甲烷溶液（约0.3mL），在25℃水浴中反应5min，然后在45℃水浴中用氮气吹干，用3mL正己烷溶解反应产物6.2.2标准溶液的甲基化
准确吸取适当浓度的标准工作液，在45℃水浴中用氮气流下吹干，以下操作同6.2.1。6.2.3净化
用5mL内酮预处理PT-硅胶固相萃取柱，将甲基化后样液分3次（每次1mL）转移到PT-硅胶固相萃取柱中，弃去流出液。用10mL丙酮-正已烷（3.9）洗脱PT-硅胶固相萃取柱，控制流速在1mL/min～2mL/min，收集10mL洗脱液。洗脱液在45℃水浴中用氮气吹干后，用正已烷溶解并定容至1mL，供气相色谱分析用。
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6.3测定
6.3.1气相色谱条件
SN/T0292—2010
色谱柱：Rtx-1701石英毛细管柱，30m×0.25mm（内径）X0.25μm或相当者；色谱柱温度：初始温度180℃保持3min，以15℃/min升至270℃，保持3min；进样口温度：230℃；
检测器（ECD)温度：320℃；
载气：氮气，纯度大于99.999%，恒流模式，1.2mL/min；进样量：1uL：
进样方式：无分流进样，0.75min后开阀。6.3.2色谱检测
根据样液中被测物的含量情况，选定浓度与样液相近的标准工作溶液。标准工作溶液和样液中灭草松响应值均应在仪器检测线性范围内。标准工作溶液和样液等体积参插进样测定。在上述色谱条件下，灭草松甲酯的保留时间约为7.24min。标准品的色谱图参见附录A中图A.1。6.4空白试验
除不加试样外，均按上述步骤进行。7结果计算和表达
用GC色谱数据处理机或按式（1)计算试样中灭草松残留含量，计算结果需扣除空白值X-AxexV
式中：
-试样中灭草松残留量，单位为毫克每千克（mg/kg）；样液中灭草松甲酯的峰面积；
标准工作液中灭草松甲酯的浓度，单位为微克每毫升（uμg/mL）；样液最终定容体积，单位为毫升（mL）；标准工作液中灭草松甲酯的峰面积；最终样液所代表的试样质量，单位为克（g）。8
测定低限和回收率
8.1测定低限
本方法的测定低限为0.04mg/kg。8.2回收率
样品的添加浓度及回收率的数据见表1。表1样品的添加浓度及回收率的数据样
添加浓度/（mg/kg）
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回收率/%
82.7~91.9
85.5~91.0
80.4~94.8
..（1)
SN/T0292—2010
附录A
（资料性附录）
灭草松甲酯标准品气相色谱图
灭卓松中酪
灭草松甲酯标准品气相色谱图
http：//foodmate.net12
Foreword
SN/T 0292—2010
This standard replace SN 0292—1993\method fordeterminationof bentazon residues in cereals forexport\.
The main technique course and method for determination are not changed in this standard. Comparethis standard with original standard SN 0292—1993,main change of this standard to be as follows:-Revisedthestandardname;
-Samplingpartsiscancelled
The GC operation conditions are modified;-AnnexAof thisstandard isaddedAnnexAofthis standardis aninformativeannexThis standard wasproposed by and isunder the charge of National Regulatory Commission for CertificationandAccreditation.
This standard was drafted by Heilongjiang Entry-Exit Inspection and Quarantine Bureau of the People'sRepublic of China
ThismaindraftersofthisstandardareYangChangzhi,KangQingheOriginal standard was approved on Dec.28,1993 for the first time,amend the standard for the firsttime
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SN/T 0292—2010
Determinationofbentazonresiduesincerealsfor import and exportGC method1
Thisstandard specifiesthemethodof determinationof bentazonresidues inricebyGCThis standard is applicable to thedeterminationofbentazon residues in rice2
Principle
Thebentazon residues in the test sample is extracted inacidic aqueous solution with acetone.Afteracetone is expelled in nitrogen evaporator,sodium sulfate solution is added to the extract,and thenextract with n-hexane,the hexane extract is concentrated to dryness and the residue is methylated.The methylated residue is cleaned up by silica-gel cartridge and analysis by GC with electron capturedetector,using external standard method.3
Reagentsandmaterials
Unless otherwise specified,all regents are analytical pure,\water\ is distilled water or equivalentpurity water.
Acetone:LCgrade
n-hexane：Lgrade
Methanol:LC grade
3.4 Ethanol.
Anhydrousether:LCgrade.
Anhydroussodiumsulfate:Igniteat65o℃for4handstoreinadesiccators.Hydrochloric acid.
Potassiumhydroxide.
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3.9Acetone-hexane solution(2+98,V/V).SN/T0292—2010
3. 10 Sodium sulfate solution:Dissolve 20 g of anhydrous sodium sulfate (3. 6) in water and diluteto1Lwithdeionized water.
3.11Hydrochloric acid solution:1moL/L.Transfer 90 mL of hydrochloric acid (3.7) into a 1000 mLVolumetricflask,dilutetovolumewithdeionized waterandmixwell.3.12Potassiumhydroxidesolution:0.6g/mL.weigh60gofpotassiumhydroxide（3.8)intoa100mLVolumetricflask,dilutetovolumewithdeionizedwaterandmixwell.3.13N-methyl-N-nitroso-p-toluenesulfonamide in anhydrous ether solution:21.5 g/140 mL.weigh21.5g of N-methyl-N-nitroso-p-toluenesulfonamide into a 200 mL Volumetric flask,dilute to volumewith anhydrous ether (3. 5) and mix well.3.14Diazomethane solution:Add35mLof ethanol (3.4)10 mL of anhydrous ether and 10 mL ofpotassium hydroxide solution(3.12)into a double-mouth distillingflask.Immerse the flask in a waterbath (7o ℃)on hot plate with a magnetic stirring device.Place a magnetic stirring bar in the flask.Attach theflask with a dropping funnel and an efficient condenser.Connect the end of the condenserwith two125mL receiving conical flasks in series.Place10 mL of anhydrous ether in the secondaryreceiving conical flask and let the tip of the inlet tube dip below the surface of anhydrous ether.Coolboth receiving flasks in an ice bath.Add dropwise a N-methyl-N-nitroso-p-toluenesulfonamide inanhydrous ether solution (3. 13) through the dropping funnel while stirring the contents of the flaskwith the magnetic stirring bar. It should take more than 20 min to add all of the solution into theflask.When the solution in the distilling flask turns pale yellow,stop the distillation. Combine thecontents of the two receiving flasks and redistill the conbined distillate in a 70 ℃ water bath,thedistillate is the diazomethane solution..The solution is kept in an air-tight container and preserved ina refrigerator not exceeding one month.3.15Bentazonstandard:bentazon.C1oH12N2O3S.CASNo.25057-89-0.Purity≥99.5%3.16Bentazon standard stock solution:Accurately weighanadequateamount ofbentazon standard,dissolve in acetone and prepare a solution of 100 μg/mL as the standard stock solution.The standardstock solution can be preserved in the refrigerator between -18℃ for 6 month.3. 17 Bentazon standard working solution:According to the requirement,dilute a standard workingsolutionof appropriateconcentration withacetone.The standard working solution canbe preservedintherefrigeratorbetweeno℃4℃for3month.3.18PT-silica-gelcartridge:1000mg.6mL.orequivalent.合伙伴网ht
SN/T 0292—2010
Apparatusandequipment
GaschromatographyequippedwithEcD-detector.Electronicbalance：accuratetoo.1mgando.o1g.SPE-12GColumnProcessor.
Centrifuge:4000r/min
Vortex mixer.
Nitrogen evaporator.
Centrifugetubeswithgroundstopper:20mL,30mLGraduated tubes withground stopper:15 mLPreparationandstorageof sample5.1
Preparation of test sample
Take approximately5oo gof representative sample,grind thoroughly with a grinder.let pass througha 0. 21 mm mesh sieve and mix thoroughly. The sample is placed in clean containers as the testsample,which is sealed and labeled.Storage of test sample
Thetest sample should be storedat 4C refrigerator.In the courseof sampling and sample prepara-tion,precautions should be taken to avoid contamination or any factors which may cause the changeofresiduecontent.
Procedure
Extraction
Weighca.10g(accurate to 0.01g)of thetest sample intoa 30 mLcentrifuge tube.Add 0.3mL ofhydrochloric acid solution (3. 11) and 10 mL of acetone (3. 1) and mix at high speed on a vortexhttp:
SN/T0292—2010
mixer for 2 min,and centrifuge at 3 000 r/min for3min.Transfer the acetone layer with capillary-tipped pippet into a 25 mL volumetric flask.The remaining solution is extracted twicemorewith1o mL,5 mL acetone. Combine the acetone extracts into the same volumetric,and dilute to volumewith acetone.Accurately pipet 5 mL of the extract into a 20 mL centrifuge tube,blow to 2 mL innitrogen evaporatorbelow45℃.followedbyaddition of 4mLof sodium sulfatesolution(3.10).Add0.3mLofhydrochloricacid solutionand3mL of n-hexane(3.2),extractonamixer for2minandcentrifuge(3000r/min)for3min.Pipetthesupernateintoa15mLgraduatedtube.Extracttheremaining solution with 3 mL of n-hexane once more. Combine the n-hexane extracts. In the samegraduatedtubeandevaporatetodryness innitrogenevaporatorbelow45℃.6.2Methylation
6.2.1Methylation of the sample solutionDissole the residue in 0. 2 mL of methanol (3. 3),and add an excess of diazomethane solution (aboutO.3mL).Letthemixturereactinawaterbathat25℃for5min.Thereactionmixtureisevaporatedto dryness in nitrogen evaporator below 45 ℃.Dissolve the residue in 3 mL of n-hexane.6.2.2Methylationofthestandard solutionAccuratelypipet1mLofbentazonstandardworkingsolution isevaporatedtodrynessinnitrogenevaporatorbelow45C and proceed accordingto 6.2.1finally,diluteexactlyto volume(1mL)withn-hexane.
Cleanup
Pre-wash PT-silica-gel cartridge with 5 mL acetone.The methylated sample solution in n-hexane istransferredtoPT-silica-gelcartridgeinthreeportions (1mLforeachportion)andthen-hexaneisdiscarded.PT-silica-gel cartridge is eluted at 1mL/min~2 mL/min with10 mL of acetone-hexanesolution (3.9).Collect 10 mL of the eluate and concentrated to dryness in nitrogen evaporator below45℃,andthendiluteexactlytovolume（1mL)withn-hexaneforgaschromatographicanalysis6.3
Determination
GC operationconditions
Column:Rtx-1701fusedquartzcapillarycolumn.30m×0.25mm(i.d.),filmthickness0.25μma)
ortheequivalent；
Column temperature:Initial temperature 180 ℃ hold for 3min,ramp at 15℃/min to 270 ℃,holdb)）
for3min;
Inletstemperature:230；
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