1、BRITISH STANDARD BS 6455:1984 Method for Monitoring the levels of residual solvents in flexible packaging materials UDC 621.798.156:542.62.06BS6455:1984 This British Standard, having been prepared under the directionof the Packaging and Freight Container Standards Committee, was published under the
2、authority of the Board of BSIand comes into effect on 29February 1984 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference PKM/586 Draft for comment 81/61913 DC ISBN 0 580 13596 9 Committees responsible for this British Standard The preparation of this Br
3、itish Standard was entrusted by the Packaging and Freight Container Standards Committee (PKM/-) to Technical Committee PKM/586, upon which the following bodies were represented: Association of Board Makers British Aluminium Foil Rollers Association British Carton Association British Paper and Board
4、Industry Federation (PIF) British Plastics Federation Chemical Industries Association Film Converters Association Flexible Packaging Association Food Manufacturers Federation Incorporated Glass Manufacturers Federation Institute of Packaging Ministry of Agriculture, Fisheries and Food Packaging and
5、Industrial Films Association Shipowners Refrigerated Cargo Research Association Society of British Printing Ink Manufacturers Transparent Cellulose Wrapping Committee Amendments issued since publication Amd. No. Date of issue CommentsBS6455:1984 BSI 08-1999 i Contents Page Committees responsible Ins
6、ide front cover Foreword ii 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Selection and preservation of test samples 2 6 Procedure without internal standard 2 7 Procedure with internal standard 5 8 Expression and calculation of results 6 9 Test report 6 Figure 1 125 ml (nominal) vial 2 Figure
7、 2 Typical chromatogram produced by a twelve-component calibrationsolution 3 Figure 3 Typical syringe cleaning apparatus 4 Figure 4 Characteristic pattern of chromatogram peaks produced byhydrocarbon solvents 6 Publications referred to Inside back coverBS6455:1984 ii BSI 08-1999 Foreword This Britis
8、h Standard has been prepared under the direction of the Packaging and Freight Container Standards Committee, at the request of the Film Converters Association. Initially, consideration was given to the preparation of a general method for the measurement of residual solvents in packaging materials, b
9、ut, after detailed discussion by the responsible BSI committee, it was decided that the greatest need was for a rapid method of monitoring the levels of residual solvents in flexible packaging materials, primarily for process control purposes. Attention is drawn to the need to ensure that adequate v
10、entilation is provided in any area where testing is to be carried out, to reduce the possibility of inhaling solvent vapour. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance
11、 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, pages i and ii, pages1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had
12、amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6455:1984 BSI 08-1999 1 1 Scope This British Standard describes a method for monitoring the levels of certain residual volatile solvents in unprinted and gravure or flexographic printed papers, films,
13、foils and laminates intended for packaging. The method is suitable for monitoring the presence of at least the following solvents: NOTE 1Methyl ethyl ketone and tetrahydrofuran have very similar retention times and cannot be resolved by this method. However, the presence of both solvents in any one
14、sample rarely occurs. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Principle A standard area of flexible packaging material is incubated in a sealed glass vial under closely controlled conditions of time and temperature. The amount of solve
15、nt released into the head-space is determined by transferring a sample of the head-space to a gas chromatograph. NOTEThe incubation conditions described do not release all the residual solvent, but the amount released is reproducible. Use of the specified incubation containers and syringes minimizes
16、 the loss of the released solvent through leaks. An internal standard solvent may be used to indicate that no loss of released solvent has occurred during a particular incubation/injection sequence. 3 Reagents 3.1 General. All reagents shall be of recognized analytical reagent quality. 3.2 Standard
17、calibration solution, preferably consisting of equal volumes of the following solvents: acetone ethanol isopropanol ethyl acetate tetrahydrofuran (or methyl ethyl ketone) isopropyl acetate N-propanol N-propyl acetate isobutanol N-butanol toluene 2-ethoxy-ethanol Prepare 100 ml to 200 ml of the calib
18、ration solution by adding the solvents in order of increasing volatility, so that changes in proportion due to evaporation are minimized. Store the calibration solution in a well-sealed metal or glass container, and dispense small quantities as required, so that there are less changes in proportion
19、due to preferential evaporation of more volatile solvents. Renew the calibration solution at regular intervals, because of preferential evaporation of more volatile solvents. Laboratories carrying out comparison tests shall use the same calibration solution. NOTE 1The composition of the calibration
20、solution can be monitored by comparing the peak height of the most volatile solvent with that of a less volatile one. NOTE 2Small quantities of the calibration solution may beprepared using a 1 ml or 2 ml glass or glass/polytetrafluoroethylene (PTFE) syringe. NOTE 3If the presence of a limited numbe
21、r of solvents is being determined, a solution of between six and twelve components may be used. 3.3 Internal standard, containing no significant impurities; examples are N-propyl acetate and isoamyl acetate. NOTEThe internal standard may be diluted to an appropriate level using a suitable diluent, e
22、.g. tertiary butanol or amyl acetate. 4 Apparatus Ordinary laboratory apparatus together with the following. 4.1 125 ml nominal capacity (150 ml actual capacity) vials 1) , fitted with inert butyl or silicone rubber seals and aluminium crimp tops. The seals shall be gas-tight during incubation and s
23、hall permit samples of the head-space gas to be withdrawn by hypodermic syringe for subsequent analysis. (SeeFigure 1.) 4.2 Crimping tool 1) , for sealing the vials. 4.3 Seal removing tool 1) . 4.4 Templates, 100 mm 100 mm and 50 mm 100 mm. 4.5 Scalpel, or sharp knife. 4.6 Disposable glass micropipe
24、ttes, capacity 1 4l. 4.7 Thermostatically controlled oven in accordance with BS 2648 and BS 3421, fitted with circulating fan and set to a temperature of 120 C. 4.8 Thermostatically controlled oven, set to a temperature of 60 C. acetone 2-ethoxy-ethanol tetrahydrofuran isopropanol N-propanol isoprop
25、yl acetate toluene ethyl acetate ethanol Methyl ethyl ketone (butanone) N-propyl acetate isobutanol 1) For information on the availability of suitable apparatus, apply to Enquiry Section (London), British Standards Institution, enclosing a stamped addressed envelope for reply.BS6455:1984 2 BSI 08-19
26、99 4.9 1 ml syringe, gas-tight, designed with minimum deadspace, and able to withstand the high pressures developed when injecting a sample, without leakage. Taper needle fittings shall not be used. The plunger tip shall be made from PTFE with an internal O-ring to prevent loosening of the seal caus
27、ed by cold flow of the PTFE. Needles shall be non-coring and of side port type 2) . 4.10 Gas liquid chromatograph, fitted with a flame ionization detector, chart recorder and/or integrator, air circulating oven and column as specified in 4.11 and capable of maintaining the required conditions. 4.11
28、Gas chromatograph column that will give good resolution of the solvents to be monitored. NOTE 1Under general circumstances, a column giving good resolution, using a suitable gas flow, of a 12-component solution(3.2) is satisfactory (see Figure 2). A suitable column is2m 2 mm internal diameter stainl
29、ess steel or 2 m 4 mm internal diameter stainless steel or glass, filled with 15 % di-isodecyl phthalate + 3 % polyethylene glycol, relative molecular mass 380 to 420 on a white flux calcined non-acid-washed diatomaceous earth 80 to 100 mesh 2) . This column should be operated isothermally with inje
30、ction port and detector temperatures of 150 C. The recommended oven temperature is 80 C. Other temperatures within the range 70 C to 100 C may be used if necessary, by agreement between laboratories. Other columns may be used under appropriate conditions to confirm solvent identities and to monitor
31、other solvents of similar volatility. Before use a new column should be conditioned at 100 C, with the carrier gas passing, for 24 h or until a stable base line is achieved. The column should never be heated above 125 C. NOTE 2Nitrogen flows which have been found to give good resolution, as shown in
32、 Figure 2, are 27 ml/min for a 2 mm internal diameter column and 50 ml/min for a 4 mm internal diameter column. Helium may also be used as a carrier gas. 4.12 Pipette, for preparation of the calibration solution, or 1 ml or 2 ml syringe, of glass or glass/PTFE. 5 Selection and preservation of test s
33、amples 5.1 When testing printed material, choose an area of print representative of the complete design. Where more than one person or laboratory are involved, this area shall be closely defined, preferably by exchange of samples. 5.2 Fully wrap test samples in aluminium foil at all times to prevent
34、 loss of solvent. Fold samples from a converting machine and wrap in foil immediately, before transfer to the laboratory. Similarly, wrap reels for test. NOTEA refrigerator or deep freeze should be used for storage periods of more than a few hours. 6 Procedure without internal standard 6.1 Calibrati
35、on 6.1.1 Take three clean vials. Pour a small quantity of calibration solution into a small beaker. Hold a14l micropipette firmly with tweezers and lower it into the calibration solution until its lower end is just beneath the surface of the liquid. Hold the micropipette in this position for several
36、 seconds until it has completely filled with liquid. Remove the micropipette from the liquid, touch it against the side of the beaker to remove any liquid on the outside. of the micropipette, and drop it into one of the vials. Immediately seal the vial with a butyl rubber seal and aluminium cap usin
37、g the crimping tool. Repeat the process for the other two vials. Discard the surplus calibration solution. Do not, at any stage, touch a micropipette with fingers. 2) For information on the availability of suitable apparatus, apply to Enquiry Section (London), British Standards Institution, enclosin
38、g a stamped addressed envelope for reply. Figure 1 125 ml (nominal) vialBS6455:1984 BSI 08-1999 3 6.1.2 lncubate the sealed vial in the oven at 120 C for 20 0.25 min. 6.1.3 Place the gas syringe in the other oven at 60 C at least 10 min before required. 6.1.4 Wearing suitable eye protection and a gl
39、ove, withdraw the vial from the oven, insert the gas syringe through the septum cap and suck just over0.5 ml of the head-space gas from the vial into the syringe with a single stroke. Do not “pump” the plunger. Withdraw the syringe needle and expel gas from the syringe until it contains exactly 0.5
40、ml. Inject this gas into the gas chromatograph. NOTEThis operation should be done as quickly as possible and should not take longer than 10 s. 6.1.5 Record the chromatogram, choosing the attenuation setting to avoid changes as far as possible. 6.1.6 Repeat the procedure in 6.1.2 to 6.1.5 for the rem
41、aining vials. 6.1.7 Initially, carry out three replicate calibrations. Follow these with regular calibrations, at least daily. Replicate calibrations shall agree within 5%. Figure 2 Typical chromatogram produced by a 12-component calibration solutionBS6455:1984 4 BSI 08-1999 6.1.8 Remove the syringe
42、 plunger after each test and clean the barrel under vacuum. NOTEIt is suggested that the top of the syringe barrel be held against a rubber bung pierced with a tube attached to a source of vacuum (see Figure 3). 6.2 Analysis of samples 6.2.1 Unwrap the sample. If it has been kept in a refrigerator o
43、r deep freeze, allow to warm up to room temperature before unwrapping, so as to avoid condensation on the surfaces of the sample. With rolled stock, take the sample from an inner area by removing not less than twelve turns from the outside of the reel. Accurately cut a test piece of total area 0.01
44、m 2 . This may be one piece 100 mm 100 mm, or two pieces100 mm 50 mm, whichever is more suitable for the specific design. Roll the test piece to produce a small diameter tube and fold in half. 6.2.2 Without delay, transfer the test piece(s) fold first to an incubation vial and immediately seal the v
45、ial with a butyl rubber seal and aluminium cap using the crimping tool. Cut replicate test pieces now if required and seal in vials. Rewrap the sample. 6.2.3 Incubate the vial in the oven at 120 C for20 0.25 min. 6.2.4 Place the gas syringe in the other oven at 60 C at least 10 min before required.
46、6.2.5 Remove the vial from the oven. Withdraw a headspace sample using the warm gas syringe and inject 0.5 ml into the chromatograph, as described in6.1.4. 6.2.6 Record the chromatogram, choosing the attenuation setting to avoid changes as far as possible. 6.2.7 After each injection, clean the syrin
47、ge as described in 6.1.8. 6.2.8 After use, wash and dry vials thoroughly to remove all traces of solvent and moisture before storage in a solvent-free area. Discard used septa. Figure 3 Typical syringe cleaning apparatusBS6455:1984 BSI 08-1999 5 7 Procedure with internal standard 7.1 Calibration 7.1
48、.1 Take three clean vials. Pour small quantities of the calibration solution and the internal standard into separate small beakers. Fill one 1 4l micropipette with the internal standard as described in 6.1.1. Drop it into a vial, place the seal in position but do not crimp on the cap. Fill a second1
49、 4l micropipette with the calibration solution as described in 6.1.1, drop it into the vial and immediately seal the vial with a butyl rubber seal and aluminium cap using the crimping tool. Repeat the process for the other two vials. Discard the surplus calibration solution and internal standard. 7.1.2 Incubate the sealed vial in the oven at 120 C for 20 0.25 min. 7.1.3 Place the gas syringe in the other oven at 60 C at least 10 min before required. 7.1.4 Wearing suitable eye protection and a glove, withdraw the
