農產品中農藥殘留量標準分析方法之建立－－加保扶、大滅松及乃力松檢驗法

ANALYTIC METHODS FOR DETERMINING THE RESIDUES OF CARBOFURAN, DIMETHOATE AND NALED IN CROPS

行政院衛生署于77年4月公告增訂殘留農藥安全容許量標準。農藥種類已達127種，作物類別則分為18類。配合此公告需研訂標準檢驗法以為執行檢驗與管理之依據，本計劃的目的為建立加保扶、大滅松及乃力松之標準檢驗方法。加保扶檢驗為檢體經溶媒抽取、淨化後，檢液注入高效液相層析系統直接衍生化，並使用螢光偵測器偵測。敏感度10ppb 。對十四類規定加保扶限量之農作物作外添加回收試驗，翠玉瓜和木瓜添加濃度為0.05、0.1及0.2ppm，其平均回收率範圍分別如下：翠玉瓜72.1～87.3%；木瓜81.7～87.6%。米、玉米、綠豆、甘藍菜、蘿蔔、蕃茄、芒果、蘋果、柑桔等作物添加濃度為0.25、0.5及1.0ppm，其平均回收率範圍分別如下：米85.6～88.2%；玉米72.0～76.9%；綠豆80.1～85.2%；甘藍菜81.1～86.8%；蘿蔔79.7～87.2%；蕃茄72.6～73.6%；芒果70.0～75.3%；蘋果75.7～81.3%；柑桔62.1～67.9%。小白菜、茶葉添加濃度為0.5、1.0及2.0ppm，其平均回收範圍分別如下：小白菜83.7～86.9%；茶葉72.1～74.0%。楊桃添加濃度為1.0、2.0及4.0ppm，平均回收率在74.8～78.1%之間。大滅松之檢驗方法為檢體、經溶媒萃取，矽膠快速層析管柱（Sep-pak silica cartridge）淨化，最後以氣相層析儀（G.C.-FPD）分析。敏感度5ppb。針對規定大滅松限量之檢體作外添加回收試驗，米添加濃度為0.025、0.05及0.1ppm，其平均回收在82.8～86.5%之間。芒果、小白菜、木瓜添加濃度為0.5、1.0及2.0ppm，其個別平均回收範圍如下：芒果84.6 ～92.8%；小白菜84.5～86.8%；木瓜94.8～102.6%。柑桔添加濃度為1.0、2.0及4.0ppm，其平均回收在73.7～78.2%之間。乃力松分析方法為檢體酸化，以正己烷萃取，再轉溶入水層，以二氯甲烷抽取，最後採氣相層析儀分析。敏感度0.1ppm。針對規定乃力松限量之農作物作外添加回收試驗，小白菜、甘藍菜、胡瓜、茶葉等檢體添加濃度皆為0.5、1.0及2.0ppm，其個別平均回收範圍如下：小白菜91.8～93.7%，甘藍菜84.9～91.7%；胡瓜74.7～76.2%，茶葉72.2～73.4%。試驗結果顯示加保扶、大滅及乃力松三種農藥標準曲線及回收曲線皆有良好的線性關係，同時檢驗方法靈敏度可達殘留容許量標準以下，且其回收率及再現性良好，為理想之標準檢驗方法。

A high pressure liquid chromatographic method for determinging residues of carbofuran in crops and gas-liquid chromatographic methods for determination of dimethoate and naled residues in crops were developed. Carbofuran residues were extracted from crops by homogenizing with acetonitrile. The extracts were cleaned up by liquid-liquid partitioning and florisil column, then separated on a reverse phase LC column, using an acetonitrile-water mobile phase. The carbofuran in the elutes were fllowed by an in-line post-column hydrolysis to yield methylamine, and the formation of a flourophore with ophthalaldehyde and 2-mercaptoethanol prior to fluorescence detection. Fourteen crops which had been set with tolerance were each fortified with carbofuran standard at the level of 0.05-4.0ppm. And the average recoveries ranged from 62.1% to 88.2%. The detection limit of HPLC method was 10ppb. Acetonitrile are used to extract dimethoate residues from crops. The extracts were evaporated with rotatory evaporator to move acetonitrile. The aqueous residues were partitioned with dichlorome thane. The organo extracts were further cleaned up by silica cartridge, and finally determined by GC-FPD. Five crops which had been set with tolerance were each fortified with dimethoate standard at the level of 0.025-4.0ppm, and the average recoveries ranged from 73.7% to 102.6%. The detection limit of GC method was 5ppb. Naled residues were extracted from crops by homogenizing with n-hexane. Nonpolar plant coextractives were partitioned into dichloromethane. then analyzed by GC-FPD. Four crops which had been set with tolerance were each fortified with naled standard at the level of 0.5-2.0ppm. and the average recoveries ranged from 72.2% to 93.7%. The detection limit of GC method for determination of naled residue was 0.1ppm.