1、BRITISH STANDARD BS3762-3.24: 1988 Analysis of formulated detergents Part3: Quantitative test methods Section3.24 Methods for determination of low molecular mass alcohols content NOTEIt is recommended that this Section be read in conjunction with the information in the “General introduction”, publis
2、hed separately as BS3762-0. UDC 661.185.6:661.72+001.4:543.620.1BS3762-3.24:1988 This British Standard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe Board of BSI and comesintoeffect on 29 January1988 BSI 12-1999 The Committees
3、responsible for this BritishStandard are shown inPart0. The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment 86/53319 DC ISBN 0 580 16291 5 Foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Commi
4、ttee. This standard describes methods of test only and should not be referred to as a specification defining limits of purity. Reference to the standard should indicate that the method of test used is in conformity with BS3762-3.24. A British Standard does not purport to include all the necessary pr
5、ovisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an
6、inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS3762-3.24:1988 BSI 12-1999 i
7、 Contents Page Foreword Inside front cover 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Instrument conditions 1 6 Procedure 1 7 Precision 4 8 Test report 4 Figure 1 Typical chromatogram 3 Publication referred to Inside back coverii blankBS3762-3.24:1988 BSI 12-1999 1 1 Scope This Section of
8、BS3762 describes two methods for the determination of low molecular mass alcohols in liquid detergent formulations. Method1 is intended for the determination of alcohols with a carbon chain of one to four and in a wide range of concentrations. Method2 is for determining methanol and ethanol, from wh
9、ich their ratio can be calculated. NOTEThe title of the publication referred to in this Section is given on the inside back cover. 2 Principle A known mass of acetonitrile(internal standard) in water is added to a known mass of sample and the mixture is subjected to analysis by packed column gas chr
10、omatography. The areas of the acetonitrile and alcohol peaks are obtained from an electronic integrator and the concentration of the alcohol(s) calculated using a response factor derived from calibration solutions. If necessary, the alcohols may be identified by comparison of peak retention times. 3
11、 Reagents The reagents shall be of a recognized analytical grade. Water complying with grade3 of BS3978 shall be used throughout. 3.1 Internal standard acetonitrile aqueous solution, 75mg/10mL approximately. 3.2 Samples of the appropriate alcohols 4 Apparatus Ordinary laboratory apparatus and the fo
12、llowing are required. 4.1 Gas chromatograph, with flame ionization detector and capable of temperature programming, comprising a column capable of producing a chromatogram with resolution similar to, or better than, that shown in Figure 1 (e.g.1.8m 2mm internal diameter glass coil packed with porous
13、 polymer beads,80 to100mesh). NOTEPoropak Q has been found to be a suitable packing. 4.2 Electronic integrator, giving a linear response with adequate sensitivity, and satisfactory correction for deviation of the baseline. 4.3 Syringe, of14L capacity, graduated in0.14L. 4.4 Safety pipette filler 4.5
14、 Sample tubes, 25mL, fitted with screw caps with wadded aluminium inserts. 5 Instrument conditions 5.1 Temperature programme The temperature programme shall be that required for the column(see4.1). NOTEThe following is given as an example: 5.2 Gas flows The carrier gas shall be oxygen-free nitrogen.
15、 NOTEThe instrument manual should be referred to for details of detector gases. 6 Procedure 6.1 Method 1 6.1.1 Preparation of calibration data 6.1.1.1 Pipette10mL of the internal standard acetonitrile solution(3.1) into each of three sample tubes(4.5) using the safety pipette filler(4.4). 6.1.1.2 We
16、igh, to the nearest0.001g, into each tube the following approximate quantities, in mg, of the appropriate alcohols. Cap the tubes before each weighing and finally agitate to mix. NOTEThe above complex mixtures are for use if the type of alcohol(s) present is not known. If the type of alcohol(s) pres
17、ent is known, the mixtures may be simplified accordingly. 6.1.1.3 Inject approximately0.74L of one of the calibration solutions(6.1.1.2) into the gas chromatograph (4.1) operating under the appropriate conditions(seeclause5) and allow the chromatogram to develop. 6.1.1.4 Obtain from the electronic i
18、ntegrator(4.2) the peak areas of the acetonitrile and the appropriate alcohols. initial temperature 170 C ramp rate 10 C/min final temperature 230 C for5min injector temperature 150 C detector temperature 250 C 1 2 3 2-methylpropan-2-ol 75 50 100 2-methylpropan-1-ol 100 50 75 butan-2-ol 50 75 100 bu
19、tan-1-ol 75 100 50 propan-2-ol 100 50 75 propan-1-ol 50 75 100 ethanol 75 100 50 methanol 50 75 100BS3762-3.24:1988 2 BSI 12-1999 6.1.1.5 Calculate the response factor for each alcohol using the following expression: 6.1.1.6 Proceed according to the method described in6.1.1.3 to6.1.1.5 for the other
20、 calibration solutions. 6.1.2 Procedure 6.1.2.1 Test portion. Take a suitable laboratory sample and weigh, to the nearest0.001g, into a sample tube(4.5), a quantity which contains approximately75mg of an alcohol. NOTEIf more than one alcohol is present and the concentration of each is different, it
21、is advisable to prepare new calibration data in which the standards will bracket each alcohol concentration in the sample. 6.1.2.2 Determination. Pipette10mL of the internal standard acetonitrile solution(3.1) into the tube using the safety pipette filler(4.4). Cap the tube and agitate to mix. NOTET
22、he same internal standard acetonitrile solution should be used for both calibration and analysis of sample. Proceed according to the method described in6.1.1.3 and6.1.1.4. 6.1.3 Expression of results. The content of each alcohol present in the sample, expressed as a percentage by mass, is given by t
23、he following expression: 6.2 Method2 6.2.1 Preparation of calibration data 6.2.1.1 Weigh, to the nearest0.001g, into a sample tube(4.5) approximately1g of methanol. 6.2.1.2 Weigh, to the nearest0.001g, into the sample tube approximately9g of water(thus obtaining an approximately10%(m/m) aqueous solu
24、tion of methanol). Cap the tube and agitate to mix. 6.2.1.3 Pipette10mL of the internal standard acetonitrile solution(3.1) into a series of three samples tubes(4.5) using the safety pipette filler(4.4). 6.2.1.4 Weigh, to the nearest0.001g, into each tube the following approximate quantities in mg:
25、Cap the tubes before each weighing and agitate to mix. 6.2.1.5 Inject approximately0.74L of one of the calibration solutions(6.2.1.4) into the gas chromatograph (4.1), operating under the appropriate conditions(seeclause5) and allow the chromatogram to develop. 6.2.1.6 Obtain from the integrator(4.2
26、) the peak areas of the acetonitrile, methanol and ethanol. 6.2.1.7 Calculate the response factor for each alcohol using the following expression. NOTEThe mass of methanol used in this calculation is the calculated mass of pure methanol and not that of the10%solution. 6.2.1.8 Proceed according to th
27、e method described in6.2.1.5 to6.2.1.7 for the other calibration solutions. 6.2.2 Procedure 6.2.2.1 Test portion. Take a suitable laboratory sample and weigh, to the nearest0.001g, into a sample tube(4.5) a quantity which contains approximately70mg of alcohol. 6.2.2.2 Determination, Pipette10mL of t
28、he internal standard acetonitrile solution(3.1) into the tube using the safety pipette filler(4.4). Cap the tube and agitate to mix. where K ROH is the response factor for the alcohol; m AN is the mass of the acetonitrile(in mg); m ROH is the mass of the alcohol (in mg); A AN is the peak area for th
29、e acetonitrile; A ROH is the peak area for the alcohol. where m AN is the mass of the acetonitrile(in mg); m s is the mass of the sample(in mg); A ROH is the peak area for the alcohol; A AN is the peak area for the acetonitrile; K ROH is the mean value of the response factor for the three calibratio
30、n solutions. 1 2 3 methanol solution (see6.2.1.2) 50 30 25 ethanol 90 60 55 where K ROH is the response factor for the alcohol; m AN is the mass of the acetonitrile used(in mg); m ROH is the mass of the alcohol(in mg); A AN is the peak area for the acetonitrile; A ROH is the peak area for the alcoho
31、l.BS3762-3.24:1988 BSI 12-1999 3 Figure 1 Typical chromatogramBS3762-3.24:1988 4 BSI 12-1999 Proceed according to the method described in6.2.1.5 and6.2.1.6. 6.2.3 Expression of results. The contents of each alcohol (methanol and ethanol) present in the sample, expressed as a percentage by mass, is g
32、iven by the following expression. Calculate the methanol/ethanol mass ratio. 7 Precision No precision data are available. 8 Test report The test report shall include the following information: a) a reference to this BritishStandard, i.e.BS3762-3.24:1988; b) a reference to the test method used, i.e.m
33、ethod1 or method2; c) the results expressed in accordance with6.1.3 or6.2.3; d) a complete identification of the sample. where m AN is the mass of the acetonitrile(in mg); m s is the mass of the sample(in mg); A ROH is the peak area for the alcohol; A AN is the peak area for the acetonitrile; K ROH
34、is the mean value of the response factor for the three calibration solutions.BS3762-3.24:1988 BSI 12-1999 Publication referred to BS3978, Specification for water for laboratory use. BS3762-3.24: 1988 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent natio
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