1.适用范围
        本标准适用于大米中杀虫双、沙蚕毒素的残留量测定。本方法低检出限为0.1ng。
        2.原理概要
        大米样品经0.1mol/L盐酸提取后，在碱性溶液中，转化成沙蚕毒素，以三氯甲烷提取后，蒸除三氯甲烷，用甲醇定容1mL，以FPD-GC测定。
        3.主要仪器和试剂
        3.1.主要试剂
        0.1mol/L盐酸、0.1mol/L氢氧化钠、0.1mol/L硫化钠水溶液。
        甲醇（重蒸）、无水乙醇、无水硫酸钠。。
        三氯甲烷：重蒸加无水乙醇，使含1％乙醇。
        杀虫双标准溶液：称取杀虫双23.8mg，以甲醇溶解，稀释100mL，每毫升中杀虫双含量相当于沙蚕毒素100μg。        根据需要，吸取一定量上述标准溶液，以甲醇稀释一定体积，配制成应用液。杀虫双转化：相当于沙蚕毒素4μg的杀虫双，按下述条件转化，终浓度为每毫升含2μg沙蚕毒素。
        沙蚕毒素标准溶液：称取沙蚕毒素草酸盐16.00mg，以甲醇溶解，稀释100mL，每毫升含沙蚕毒素100μg，根据需要，吸取一定量上述标准溶液，以甲醇稀释一定体积，配制成应用液。
        3.2.仪器
        台式离心机、旋转蒸发器、玻璃蒸馏器、氮气蒸发器、微量注射器
        气相色谱仪(具火焰光度检测器)、一般玻璃仪器(略)。
        4.过程简述
        4.1.样品处理：
        称取大米样品5g，加10mL 0.1mol/L盐酸溶液，在振荡器上振荡30min，于1600r/min离心10min，将上清液倒于带盖量筒中，再以10mL 0.1mol/L盐酸洗涤样品，如此重复三次。合并盐酸提取液，调节pH8.5～9，加0.1mol/L硫化钠溶液2mL放置过夜，加2倍样品液体积的三氯甲烷于分液漏斗中，剧烈振摇1min，静置分层。将三氯甲烷层经无水硫酸钠滤于三角瓶中，在旋转蒸发器中45℃蒸除氯仿，剩余少许时，立即取出，用甲醇定容1mL，待测定。
        4.2.气相色谱条件：
        色谱柱：3mm(内径)×2m玻璃柱；填装涂有1.5％ OV-17 Chromosorb.W(80～100目)的担体。
        温度 柱温：160℃；汽化室温：200℃；FPD检测器温：170℃。
        气体速度：载气(氮气)流速：70mL/min；氢气流速：150mL/min；空气流速：50mL/min。
        其他条件：仪器灵敏度：×102；衰减：×32；纸速：0.5cm/min。
        4.3.测定：
        按上述色谱条件调试仪器，待仪器稳定后，用微量注射器注入样品或标准液，以保留时间为定性指标。取杀虫双转化后相当于0.5、1、2、3、4、5ng的沙蚕毒素，注入色谱仪中，测量峰高。以杀虫双含量为横坐标，峰高为纵坐标，在双对数坐标纸上绘制工作曲线，根据样品的峰高定量。

        5.结果计算

        式中：X——样品中杀虫双含量，mg/kg；
                 B——测得样品的峰高(或面积)值，查标准曲线后得到的沙蚕毒素量，ng；
                 V——定容体积，mL；
                 A——进样量，μL；
                 m——样品质量，g。
        杀虫双分子量为355，沙蚕毒素分子量为149，将测得的沙蚕毒素量乘以2.38，即为杀虫双含量。
        7.度
        大米样品添加回收实验结果的变异系数小于20％。
        8.其他

名称：玻璃柱
规格：3mm（内径）*2m
型号：1.5%OV-17/Chromosorb W(80-100目）
应用：GB/T 5009.114-2003 大米中杀虫双残留量的测定
适用于岛津各种型号的气相色谱仪GC2010，GC-2014

1. Scope of application

        This standard is applicable to the determination of the residues of ciprofloxacin and necrotoxin in rice. The minimum detection limit of this method was 0.1 ng.

        2. Principle outline

        After the rice sample was extracted with 0.1mol/L hydrochloric acid, it was converted into necrotoxin in an alkaline solution, extracted with chloroform, evaporated to remove chloroform, made up to 1mL with methanol, and determined by FPD-GC.

        3. Main instruments and reagents

        3.1. Main reagents

        0.1mol/L hydrochloric acid, 0.1mol/L sodium hydroxide, 0.1mol/L sodium sulfide aqueous solution.

        Methanol (re-distilled), anhydrous ethanol, anhydrous sodium sulfate. .

        Trichloromethane: redistilled and added absolute ethanol to make 1% ethanol.

        Insecticidal double standard solution: Accurately weigh 23.8 mg of insecticidal bisulfite, dissolve it in methanol, and dilute to 100mL. The content of insecticidal bisulfite per ml is equivalent to 100 μg of necrotoxin. As required, draw a certain amount of the above standard solution, dilute it with methanol to a certain volume, and prepare an application solution. Insecticidal double transformation: Insecticidal double equivalent to 4 μg of necrotoxin was transformed according to the following conditions, and the final concentration was 2 μg of necrotoxin per milliliter.

        Neretoxin standard solution: Accurately weigh 16.00 mg of necrotoxin oxalate, dissolve it in methanol, and dilute to 100 mL. Each milliliter contains 100 μg of necrotoxin. As needed, draw a certain amount of the above standard solution and dilute it to a certain volume with methanol. , formulated into an application solution.

        3.2. Instruments

        Benchtop centrifuges, rotary evaporators, glass stills, nitrogen evaporators, microinjectors

        Gas chromatograph (with flame photometric detector), general glass instrument (omitted).

        4. Brief description of the process

        4.1. Sample processing:

        Weigh 5 g of rice sample, add 10 mL of 0.1 mol/L hydrochloric acid solution, shake on a shaker for 30 min, centrifuge at 1600 r/min for 10 min, pour the supernatant into a graduated cylinder with a lid, and wash the sample with 10 mL of 0.1 mol/L hydrochloric acid , and so on three times. Combine the hydrochloric acid extracts, adjust the pH to 8.5-9, add 2 mL of 0.1 mol/L sodium sulfide solution and leave overnight, add 2 times the volume of the sample solution in chloroform, shake vigorously for 1 min, and let stand for stratification. The chloroform layer was filtered through anhydrous sodium sulfate into a conical flask, and the chloroform was evaporated at 45°C in a rotary evaporator. When there was a little remaining, it was taken out immediately, and the volume was made up to 1 mL with methanol, to be determined.

        4.2. Gas chromatography conditions:

        Chromatographic column: 3mm (inner diameter)×2m glass column; packed with a carrier coated with 1.5% OV-17 Chromosorb.W (80-100 mesh).

        Temperature Column temperature: 160°C; vaporization room temperature: 200°C; FPD detector temperature: 170°C.

        Gas velocity: carrier gas (nitrogen) flow rate: 70 mL/min; hydrogen flow rate: 150 mL/min; air flow rate: 50 mL/min.

        Other conditions: Instrument sensitivity: ×102; Attenuation: ×32; Paper speed: 0.5cm/min.

        4.3. Determination:

        Adjust the instrument according to the above chromatographic conditions. After the instrument is stable, inject the sample or standard solution with a micro-syringe, and take the retention time as the qualitative index. Take the necrotoxin equivalent to 0.5, 1, 2, 3, 4, and 5 ng after the insecticidal double transformation, inject it into the chromatograph, and measure the peak height. Taking the content of insecticidal double as the abscissa and the peak height as the ordinate, draw the working curve on the double logarithmic coordinate paper, and quantify according to the peak height of the sample.

        5. Result calculation

        In the formula: X——Insecticide content in the sample, mg/kg;

                 B——The peak height (or area) value of the measured sample, the amount of necrotoxin obtained after checking the standard curve, ng;

                 V——constant volume, mL;

                 A——Injection volume, μL;

                 m——sample mass, g.

        The molecular weight of the insecticidal double is 355, and the molecular weight of the necrotoxin is 149. Multiply the measured amount of the neretoxin by 2.38, which is the content of the insecticidal double.

        7. Precision

        The coefficient of variation of the experimental results of adding and recovering rice samples was less than 20%.

        8. Others

name: glass column

Specifications: 3mm (inner diameter) * 2m

Model: 1.5%OV-17/Chromosorb W (80-100 mesh)

Application: GB/T 5009.114-2003 Determination of Pesticide Residues in Rice

Suitable for various types of Shimadzu gas chromatographs GC2010, GC-201