HOME   Cart(0)   Quotation   About-Us Tax PDFs Standard-List Powered by Google www.ChineseStandard.net Database: 189760 (2 Nov 2024)

SN/T 3927-2014 PDF in English


SN/T 3927-2014 (SN/T3927-2014, SNT 3927-2014, SNT3927-2014)
Standard IDContents [version]USDSTEP2[PDF] delivered inName of Chinese StandardStatus
SN/T 3927-2014English135 Add to Cart 0-9 seconds. Auto-delivery. Determination of sodium thiocyanate in dairy products for export Valid
Standards related to (historical): SN/T 3927-2014

SN/T 3927-2014: PDF in English (SNT 3927-2014)

SN/T 3927-2014 Determination of sodium thiocyanate in dairy products for export 2014-04-09 ~ {jj" ~'4\"www cntw315 corn ll!.i< 'i4006982315 20 14-11-0 1 ~Mi! Foreword The standard are compiled according as the GB/T 1.1-2009. The standard was proposed by and is under the charge of the Certification and Accreditation Admin- istration of the People's Republic of China. The standard was drafted by Shandong Entry-Exit Inspection and Quarantine Bureau of the People's Republic of China, Shanxi Entry-Exit Inspection and Quarantine Bureau of the People's Republic of China, Hunan Academy of Inspection and Quarantine. The standard was mainly drafted by Hu Qiaoru, Yang Lijun, Wang Jing, Dulijun, Cui Fengj ie, Song Xiaohua,Cong Weihong,Liu Yumin,Fu Yingwen,Cui He,Zhai Jinyi,Zhao Youyou,Liu Hongyan, Yao Yating, Huang zhiqiang. Determination of sodium thiocyanate in dairy products for export 1 Scope This standard specifies the ion chromatographic method and gas chromatographic method for the de- termination of sodium thiocyanate in dairy products of export. This standard is applicable to the determination of sodium thiocyanate in sterilized milk, pasteurized milk, yoghurt, formula milk, milk beverage,milk powder, formula milk powder, cheese and condensed milk of export. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references,only the edition cited applies. For undated references, the latest edition of the ref- erenced document (including any amendments) applies. GB/T 6682 Water for analytical laboratory use-Specification and test method Ion chromatography 3 Principle The sample was extracted and precipitated protein with acetonitrile, then the extract was cleaned, separated by anion exchange column, potassium hydroxide solution as eluent. The determination was aceieved by ion chromatography equipped with conductance detector,qualitatified with the retention time and quantified by external standard method. 4 Reagents and materials Unless otherwise specified, the reagents used should be analytical pure. And the water should comply with the requirement of GB/T 6682 (first class water). 4.1 Sodium thiocyanate standard CNaSCN,CAS No..540-72-7) .purity;?..99.99%. tate protein at room temperature and then centrifuge at 6 OOO r/min for 10 min. Accurately pipette 1.0 ml (V2 ) of the supernatant into a color comparison tube with cap,dillute to 10 ml (V3 ) with water, shake it on the vortex mixer and take the extract to filter through a 0.22 µm membrane, then cleaned by SPE column(for example Guard II RP column) ,discard the first 3 ml of solution and take the middle section of the filtrate for Ion chromatography determination. If the sodium thiocyanate exceeds the range of the standard curve, the sample amount should be reduced or the multiple should be increased. 7 .1.2 Solid sample Accurately weigh 1.0 g test sample (accurate to 0.01 g) into a color comparison tube with cap, add 4 g water and shake it on the vortex mixer for 2 min, then dillute to 10 ml( V1 )with acetonitrile. Mix it well on the vortex, then stand for 20 min to precipitate prettied at room temperature and then cen- trifuge at 6 OOO r/min for 10 min. Accurately pipette 1.0 ml ( V2 ) of the supernatant into a color comparison tube with cap,dillute to 10 ml ( V3) with water,shake it on the vortex mixer and take the extract to filter through a 0.22 µm membrane, then cleaned by SPE column(for example Guard II RP column) ,discard the first 3 ml of solution and take the middle section of the filtrate for Ion chro- matography determination. If the sodium thiocyanate exceeds the range of the standard curve, the sample amount should be reduced or the multiple should be increased. 7 .2 Chromatography operating conditions 7.2.1 Chromatography column. hydroxide selective, high-capacity anion exchange column compatible with gradient elution,for example Ion Pac® AS 16,4 mm x 250 mm (with Ion Pac® AG 16,4 mm x 50 mm guard column). 7 .2.2 The temperature of column. 30 °C. 7.2.3 Eluent. potassium hydroxide solution, the concentration of 45 mmol/l-60 mmol/l,utilizing a gradient elution program (0.00 min-13.00 min,45.0 mmol/l;13.00 min-18.00 min,60.0 mmol/l; 18.00 min-23.00 min,45.0 mmol/l). 7 .2.4 Suppressor. ASRS-300 4 mm anion suppressor; external water suppression mode (flow rate. 1.5 ml/min) ,suppression current is 112 mA-149 mA. 7.2.5 Flow rate. 1.0 ml/min. 7 .2.6 Injection volume. 100 µL. 7 .2. 7 Detector. conductance detector. 7 .3 Standard curve According to need, dilute sodium thiocyanate (SCN-) standard work solution with water step by step,and prepare serial standard work sol1Jtion of applicable concentrations (referred linear range. a) Chromatographic column. capillary column, BP10 25 m x 0.32 mm (id) x 0.50 µm(film thickness); b) Temperature programme.40 °C (keep 5 min) ,50 °C /min to 200 °C (keep 2 min); c) Carrier gas. Nitrogen (purity~99.999%); d) Injection port temperature. 150 °C; e) Detector temperature.260 °C; f) Split ratio.100. 1; g) Flow rate.1.0 ml/min. 15.3 Standard Curve Accurately pipette 10 ml of the sodium thiocyanate standard work solution (12.8) into headspace bottle,add 0.1 ml Chloramine T solution and mix for test. The standard solution are determined ac- cording to chromatography operating conditions (15.2). Based on the chromatogram,draw the stand- ard curve with the concentration of sulfur dioxide as abscissa and the response of the peak area (or peak high) as ordinate, and calculate the linear regression equation condition, the retention time of sodium thiocyanate ion derivative is about 2.50 min, For chromatogram of the standard see Figure A.2 in Annex A. 15.4 Sample analysis The standard solution and the sample are determined according to chromatography operating condi- tions (15.2) ,and the quantitative analysis is conducted on the basis of peak area of sodium thiocya- nate ion derivative with external standard method. The responses of the standard solution and the sample should be in the linearity of the instrument. 15.5 Blank test The operation of the blank test is the same as the described in the method of determination, but with the omission of sample addition. 15.6 Calculation and result presentation The content of sodium thiocyanate in the test sample is calculated by Formula (2) . X =Cc - c 0 ) x V x 1 OOO ...( 2 ) mx1000 ......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.