1、Professional Standard of the Peoples Republic of Chinafor Import and Export Commodity InspectionSN0493-1995Method for the determination of trichlorfonresidues in cereals for export1 Scope and field of applicationThis standard specifies the methods of sampling,sample preparation and determination of
2、trichlorfonresidues by gas chromatography in cereals for export.This standard is applicable to the determination of trichlorfon residues in unpolished rice for export.2 Sampling and sample preparation2.1 Inspection lotEach inspection lot should not exceed 4000 bags(200t).The characteristics of the c
3、argo within the same inspection lot,such as packing,mark,origin,specifica-tion,grade etc.,should be the same.2.2 Quantity of sample takenThe number of bags to be sampled shall be calculated according to the formula(1):a=/N(1)whereN-total number of bags in a lot;a-number of bags to be sampled.Note:If
4、 value a is with decimal,round off the decimal part,which is added as unity to the integral part of a.2.3 Sampling tools2.3.1 Metallic sampler:Length(including handle):55cm;diameter:1.5 cm;groove length:longer thanhalf the diagonal length of the bag.2.3.2 Sampling shovel.2.3.3 Plate for quartering.2
5、.3.4 Sample can(bag):which can be sealed.2.3.5 Cloth(or other suitable material)sheet:For sample dividing(quartering).2.4 Sampling procedure2.4.1 Sampling by emptying outDraw 10 percent of the number of bags specified in 2.2(not less than 3 bags)at any part of the pile atrandom.Unseam and open the b
6、ag,and lay it on a clean cloth sheet(or other clean sheet).Grasp tight twocorners of the bag bottom and raise up to an angle of 45,tug backward for ca 1 m until all content of thebag is emptied out.Check the appearance,odour of the goods and whether the goods are moldy,rottenApproved by the State AdministrationImplemented from Jan.1,1996of Import and Export Commodity In-spection of the Peoples Republic ofChina on Nov.28,19954
