1-Methylcyclopropene Impurities. GC method. CIPAC Collaborative Trial according to CIPAC Information Sheet Number 282

Transcription

1 1-Methylylopropene Impuritie GC method CIPAC Collaborative Trial aording to CIPAC Information Sheet Number 282 D. Verona AgroFreh, In. 727 Norritown Road Spring Houe, Pa United State April 2009 Page 1 of 7

2 1-Methylylopropene Impuritie OUTLINE OF METHOD 1-hloro-2-methylpropene () and 3-hloro-2-methylpropene () are impuritie in the ative ingredient 1-methylylopropene (1-MCP). 1-MCP i a ga at room temperature and i tabilized for ommerial ue by enapulation in SmartFreh 3.3% Tehnology. 1-MCP, and are releaed for analyi by diolving a formulation ample in water in an airtight ontainer. The ontainer headpae i ampled and analyzed by apillary ga hromatography with flame ionization detetion and external tandard alibration. and ontent i reported a perent relative to 1-MCP onentration whih i determined by a eparate method [1]. REAGENTS Water purified to remove trae of heavy metal 1-hloro-2-methylpropene () purity 98.0% minimum 3-hloro-2-methylpropene () purity 98.0% minimum and Stok olution. Meaure the (10 ul) into a 10 µl yringe, injet the into a 1 liter gla bottle equipped with a VICI ga tight valve. Repeat thi proedure to introdue into the ame bottle. Shake the bottle vigorouly on a mehanial haker for at leat 60 minute. Calulate the onentration (mg/ml) of the ( ) and ( ) (Note 1). and Calibration olution. Meaure the tok olution (200 ul) into a 250 µl ga tight yringe, injet the ontent of the yringe into a 250 ml gla bottle equipped with a VICI ga tight valve. Shake the bottle vigorouly on a mehanial haker for at leat 60 minute. Calulate the onentration (mg/ml) of ( ) and ( ) baed on volumetri dilution of the tok olution. Prepare dupliate alibration olution (olution C A and C B ) (Note 1). APPARATUS Ga hromatograph equipped with plit/plitle inlet and a flame ionization detetor Capillary olumn DB-624: 30 m x 0.25 mm (i.d.) and 1.4 µm film thikne (Agilent, In.) Eletroni integrator or data ytem Analytial balane with 0.1 mg enitivity Mehanial haker rotary or reiproating type Mininert ga tight valve with 24 mm ap ize for 250 ml bottle; with 1/8 inh NPT thread for 1 L bottle (Preeiion Sampling, In.) Page 2 of 7

3 Ga tight gla yringe 0.25 ml and 0.50 ml, equipped with ~5 m ide port needle (Note 2) Liquid yringe 10 µl Gla or plati yringe to meaure 3 ml, equipped with a 22 to 25 gauge needle Gla bottle 250 ml (nominal) Boton Round, 24 mm threaded nek; 1 liter (nominal) gla Media/olution bottle with polypropylene plug eal ap and pouring ring (Note 3) PROCEDURE (a) Ga hromatographi ondition (typial): Column DB m length x 0.25 mm i.d. x 1.4 µm film thikne (Note 4) Injetion ytem Injetor mode pilt injetion Injetor inert 4 mm i.d., traight through gla (no gla wool) (Note 5) Injetion volume 0.50 ml Split flow 20 ml/min Detetor flame ionization Temperature Injetion port 75 C Detetor 185 C Oven program temp 1 40 C, hold 0 min, ramp rate 25 C/min temp C, hold 0 min Ga flow rate Carrier: Helium 2 ml/min; approximately 40 m/e ( run at ontant flow) Detetor: Air 400 ml/min Hydrogen 45 ml/min Nitrogen (make up) arrier flow + make up flow = 30 ml/min Retention time 2.6 min to 2.8 min 2.7 min to 2.9 min (b) Sytem equilibration. Injet 0.5 ml aliquot of the alibration olution C A until the repone fator obtained for two oneutive injetion differ by le than 5%. Then injet 0.5 ml aliquot of alibration olution C B. The repone fator for olution C B hould not deviate by more than 5% from that of olution C A, otherwie prepare new alibration olution (Note 6). If the peak retention time are not within the lited time window, adjut the arrier flow rate aordingly. Page 3 of 7

4 () Linearity hek. Chek the linearity of the method by injeting 0.50 ml aliquot of olution with and onentration of 0.5, 1 and 2 time that of the alibration olution before onduting analye. (d) Sample preparation. Prepare ample olution in dupliate (olution S A and S B ). Weigh (to the nearet 0.1 mg) 90 mg to 110 mg (w mg) of SmartFreh 3.3% Tehnology into a 250 ml gla bottle. Cap the bottle with a ga tight valve immediately. Injet water (3 ml) through the valve into the bottle. Cloe the valve. Plae the bottle on a mehanial haker and mix vigorouly for a minimum of 60 minute (Note 7). (e) Determination. Injet in dupliate 0.50 ml aliquot from the headpae of eah ample olution braketing them by injetion of the alibration olution a follow: alibration olution C A, ample olution S A, ample olution S A, alibration olution C B, ample olution S B, ample olution S B, alibration olution C A, and o on. Meaure the relevant peak area. (e) Calulation. Calulate the onentration (mg/ml) of and in the tok olution. d V P d V P = = V V b b = onentration of the tok olution (mg/ml) = onentration of the tok olution (mg/ml) d = denity (mg/ml) d = denity of (mg/ml) P = purity of expreed a a deimal fration P = purity of expreed a a deimal fration V = volume of the tandard material (ml) V = volume of the tandard material (ml) V b = volume of the tok olution preparation bottle (ml) Calulate the onentration of and in the alibration olution. V V b V V V = = Vb = onentration of the in the alibration olution (mg/ml) = onentration of the in the alibration olution (mg/ml) = volume of the tok olution aliquot diluted (ml) = volume of the alibration tandard preparation bottle (ml) b Page 4 of 7

5 Calulate the repone fator for and. f = f = i H i H fi = individual repone fator fi = individual repone fator = onentration of the in the alibration olution (mg/ml) = onentration of the in the alibration olution (mg/ml) H = peak area of in the alibration olution H = peak area of in the alibration olution Calulate the mean value of eah pair of repone fator braketing the two injetion of a ample and ue thi value for alulating the and ontent of the braketed ample injetion. ontent = f H HS w w 1000 g/kg f H HS 1000 w ontent = g/kg w f = mean repone fator f = mean repone fator H w = peak area of in the ample preparation H w = peak area of in the ample preparation HS = volume of the headpae in the ample preparation bottle (ml) (= bottle volume water volume) w = ma of ample taken (mg) and peifiation are baed on the perent relative onentration veru 1-MCP. 1-MCP ontent mut be determined by a eparate method [1] ontent g/kg % Relative ontent = MCP ontent g/kg ontent g/kg % Relative ontent = MCP ontent g/kg REFERENCES [1] Methylylopropene, GC Method Page 5 of 7

6 Note 1 Segregate the yringe ued to prepare the CMP alibration olution; do not ue for injetion of ample preparation. Note 2 Side port needle are required; tandard taper needle will partially plug and aue irreproduible injetion volume. Note 3 Aurately meaure the total volume of eah type of bottle uing water i.e. vendor volume peifiation are approximate and uually do not inlude the volume in the nek of the bottle. The plati ap of the media bottle mut be taped to make a hole with thread to aommodate a ga tight valve with a male 1/8 inh NPT thread. Note 4 DB-624 i manufatured by J&W and ditributed by Agilent. It i a proprietary phae; the performane of imilar phae from other upplier i unertain. Condition the olumn before ue at 225 C following the manufature intrution. Note 5 An inert with an internal volume of approximately 1 ml i neeary to ompletely ontain the large ample volume injeted. Note 6 Peak area will vary with injetion peed. During tandard and ample injetion depre the yringe plunger with a ontant and onitent peed. Fat injetion peed an be reprodued mot eaily. Note 7 Inure that all of the ample powder drop onto the bottom of the bottle and that none adhere to the iide wall. The ample mut be in ontat with the water during mixing. Writ ation haker are not reommended. Stati harge on the gla bottle an ompromie weighing auray and preiion, if tati i a problem weigh the ample onto a piee of weighing paper and tranfer into the bottle. Page 6 of 7

7 Repreentative Chromatogram SmartFreh 3.3 % Tehnology FID1 A, Front Signal ( \2008DEC D) Norm MCP min Page 7 of 7