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Spectrophotometric determination of strychnine and methylatropine by extraction with tetrabromophenolphthalein ethyl ester
SHORT COMMlJNICATIONS
222
R&sum&-On a rdahst des stparatlons analytiques nettes et soa2-, so,zet S,0a2de l’ordre du mIcrogramme mmce ascendante sur de la cellulose mlcrocrlstalhne avec le lM-a&tone (30. 20 : 2) comme systbme solvant. Les esptces colonm6trie annulaire
Tahrru.
Vol 20. pp 222-224
rapldes de quantltts d’lons SL-. par chromatographle en couche mtlange n-propanol-ammomaque sipartes ont itC ditermmees par
Pergamon Press. 1973 Prmted I” Great Bnlaln
SPECTROPHOTOMETRIC DETERMINATION OF STRYCHNINE AND METHYLATROPINE BY EXTRACTION WITH TETRABROMOPHENOLPHTHALEIN ETHYL ESTER (Received 5 Aprrl 1972. Accepted 15 May 1972)
Green6 or Bromophenol Blue’ * have been Some acid dyes,‘,’ such as Bromothymol Blue, ‘-’ Bromocresol used for the spectrophotometraz determination of ammes, alkaloids or quaternary ammomum salts These dyes are dlbaslc acids, and have serious drawbacks because of their extreme sensltlvlty to change m acidity; an indeterminate number of 1 1 and 1 2 Ion-pairs are formed with resultant poor reproduclblhty and extreme pHdependence. Tetrabromophenolphthalem ethyl ester (TBPE), which has Just one acidic group, IS able to form only a 1 1 Ion-pair complex, which 1s reproducibly extracted Various ammes, alkaloids and quaternary dmmomum salts have been extracted with TBPE at pH 7 5 mto 1,2-drchloroethane. The colour of the extracts fall into three categories: (I) blue (iomc form of TBPE) which 1s extracted m the presence of many quaternary ammomum salts and alkaloids such as spartem, (II) red which IS developed m the presence of alkaloids such as strychnme, physostigmme, qumldme and homatropme, a weak red colour 1s given by ammes such as a-naphthylamme and trlethanolamme; (in) yellow (molecular form of TBPE) wtnch IS the same colour as the reagent blank even m the presence of amhne, dlmethylamme, N,N’-dlmethylformamlde, ethylenedlammetetraacetic acid, or mtrllotriacetlc acid. If the extraction IS performed from acidic solution, the colours of the extracts are all yellow even m cases (I) and (II). This paper deals with the determmatlon of methylatropme and strychnine as representatives of the quaternary ammomum salts and the alkaloids, and as widely used medlcmes (parasympatholytlcs etc) Hexamtrodlphenylamme has been used as a spectrophotometrlc reagent for alkaloids or quaternary methods have also been investigated “-‘4 ammomum salts,’ ‘O and tltrlmetrlc
EXPERIMENTAL
Reagents Tetrabromophenolphthaleln ethyl ester (TBPE) pocassxm salt (m w 700 I) Welghed amounts were dissolved m ethyl alcohol. Standard strychnrne and methylarropme solutions. Weighed amounts of strychnine sulphate (dried at 105’) or N-methylatropme bromide (dned at 105’) were dissolved m water and diluted to known volume. Buffer solutrons, pH 8 and pH 9.5. Appropriate volumes of 04M potassium dlhydrogen phosphate, 0 06M sodium borate and 3M sodium hydroxide were mlxed All the chemicals were of reagent grade. and demmerahzed water was used Procedures Sfrychnme. Transfer 2-10 ml of strychnme solutron (20 x IO-‘M), 2 ml of TBPE solution (4 x lo-‘M), and 5 ml of buffer solution (pH 8) into a 100-ml separatmg funnel, dilute to 25 ml with water and shake the After separation of the two layers, run off the extract solution for 2 mm with 10 ml of 1,2-dlchloroethane. mto a glass tube through a filter paper to remove any droplets of water Measure the absorbance of the extract at 560 nm, using a reagent blank or water ds a reference Methyhtroprne Transfer 2-10 ml of standard methylatropme solution (1 0 x IO-‘M), 2 ml of TBPE solution (2 x IO-‘M). and 5 ml of buffer solution (pH 9.5) into a IOO-ml separatmg-funnel Treat the mixture In the same manner as described for strychnme Measure the absorbance at 615 nm.
SHORT COMMUNlCATlONS
RESULTS AND Absorptron
223
DtSCUSSlON
spectra
In the absence of methylatropme or strychnme a yellow compound IS extracted mto dtchloroethane, whtlst m then presence a blue (& 615 nm) or red (i.,,, 560 nm) one IS formed The change m colour may be attrtbuted to the formation of an ton-pan or addttton compound between the TBPE and the quaternary ammonmm catron or the alkalotd Eflct of
wrzables
Methylarropme or strychmne was extracted wtth TBPE from a sertes of aqueous soluttons buffered at various pH values The absorbance of the extract was constant when the pH of the aqueous phase lay wtthm the range 9 O-10 5 for methylatropme and 7.0-9.0 for strychmne Extreme pH-dependence was observed for the determmatlon of qumme or thlamme with Bromophenol Blue’ or Bromothymol Blue.’ hmilarly, constant absorbance many pH range could not be obtamed when Bromophenol Blue or Bromocresol Green was used as extractant for methylatropme or strychmne pH
It IS found that the concentratton of TPBE should be mamtamed at more than Reagent concentration 20-fold molar excess over methylatropme or 40-fold molar excess over strychnine to obtain a maxtmum and constant extraction Excess (2-10 ml) of the buffer solutron used m the procedure had no mfluence on the absorbance of the extracts. When the amount of the buffer solutron was less than 2 ml. separatron of the two layers was poor Solrentfor exrraccron The behavtour of vartous solvents m the extractton was studted Solvents were found to fall mto the followmg categorres (I) Those whrch enhance the extractton, e g., 1,2-dtchloroethane, chloroform (ri) Those whtch do not extract the coloured complex even m the presence of quaternary ammonmm salts or alkalords, e.g. carbon tetrachlonde, cyclohexane, n-hexane, toluene, monochlorobenzene fur) Those wtth which the blue TBPE IS extractable even without quaternary ammonium salts or alkalotds. ey., butyl acetate. ether, ethyl acetate. rsopentyl alcohol, mtrobenzene, methyl tsobutyl ketone Of these. 1.2-dtchloroethane was found to be most suttable for the extractton of the methylatropme or strychnme complexes Oriter tiarrableP Full colour development tooh about 1 mm of shakmg Contmued shaking up to 5 mm produced no further change m absorbance. The colour mtenstty of the dtchloroethane extracts remams constant for 1 hr Fluctuattons m room temperature (14 -22”) were wtthout measurable effect on the absorbance A hnear relatlonshlp was obzerved between the absorbance of the extract and the Cahbratton and precwon concentration of methylatropme (8.0 x lo-‘40 x 10V6M, molar absorptlvlty 190 x 10’ I~mole-‘~cm-l at 615 nm) or strychnine (1.6 x 10e6-8.0 x 10w6M, molar absorpttvtty 8.0 x lo4 l.mole-‘cm-’ at 560 nm) m the unttal aqueous phase The reproduc~bllIty was estimated from the results for ten sample soluttons, each wtth a final methylatropme concentratton of 4.0 x 10e6M The mean absorbance was 0 761, standard devtatton @008 Compostrron
of the coloured
species
Contmuous vartattons plots (TBPE + methylatropme = 8 x 10e6MM,i, = 590, 615 and 630 nm; TBPE + strychnme = 5 x 10-5M. j. = 540. 560 and 600 nm) have a maxrmum at 05 mole-fractton of TBPE. mdtcatmg a 1 I TBPE-methyIatroptne or TBPE-strychnine ratto In order to mvestt8ate the state of the coloured spectes m drchloroethane, the electrical conductrvtty of the extracts was measured The results obtamed shows that the TBPE-methylatropme spectes IS m the tomzed state and the TBPE-strychnme spectes IS m the molecular state m dtchloroethane The extracted specres therefore. may be formulated as StrychnmeH(TBPE) and [Methylatropme]+[TBPE]Etfecr of
foretgn
sl(bstance.~ and anafysts
of pracrzcal
sampies
Potassmm nitrate. ammomum sulphate, magnesmm chlottde, calcrum chlorrde, acetates. citrates. sahcylates, glucose. lactose. o-cresol. phenol and amlme do not mterfere m the determmatron of methylatropme or strychnine when present at the level of 2 x 10e3M Alkalotds interfere. The method was apphed to a strychnme mJectron obtained from a drugstore The result was 2 57 x lo-“M strychnme by the proposed method. and 2 48 x 10e3M by the tttrlmetrrc method r4 The proposed method has proved apphcable to the deter~nat~on of many quatemary ammonium salts and alkaloids such as spartem. qumme. physosttgmme, homatropme, and atropme *MASAHIRO TSUBOUCHI *TADAO SAKAI
mtorl L ,111ers1t\ 7iotrorr.Jnpm
~T~SHIKAZU WATAKE ~KAZUHITO KANAZAU’A ~MASAYA TANAKA
224
SHORT
COMMUNWATIONS
REFERENCES 1 M. E. Auerbach, Anal. Chem, 1943. 15, 492. 2. P B. Marshall and E. W Rogero, Blochem, J , 1945, 39, 258 3. V D Gupta and D E Cadwallader, J Pharm. SCL, 1968, 57, 112 4 G Schdl, Acra Pharm. Sueclca, 1964, 1, 101, Chem. Abstr , 1965. 63, 1657 5. Idem, Ibtd, 1965, 2, 13, Chem Abstr, 1965.63. 8125 6 H M N. H. Irving and J. J. Markham. Anal. Chm. Acta, 1967, 39, 7 7 M. Tatsuzawa, S. Nakayama and A. Okawara, Bunsekl Kagaku, 1970. 19. 761. 8 L. D Metcalfe, Anal Chem., 1960, 32, 70 9 G Schill and B Damelsson, Anal Chrm. Acfa. 1959, 21. 248 10. Idem, IbId., 1959, 21. 341 11 K. K. Kundu and M. N. Das, Anal. Chem., 1959, 31, 1358 12. K. Howorka and M. HBdicke, Pharm. Zentralhalle, 1959,98, 538 13. The Japanese Pharmacopeta, VII-l, Part II, p. 210, Nankodo, 1965 14 lbrd., p 647
Summary-A new apphcatlon of monoactdic dyes IS reported for the determmatlon of strychnme and methylatropme The method IS based on solvent extraction mto 1,2-dichloroethane of the Ion-pir or addltlon compound formed between tetrabromophenolphthalem ethyl ester and quaternary ammomum salts or alkaloids. The absorbance of the extracts 1s linearly dependent on the concentration of strychnme or methylatropine mitlally present m the aqueous solution Zusammmfassung-Es wlrd uber eme neue Anwendung van Farbstoffen mit emer sauren Funktion zur Bestimmung von Strychnm und Methylatropm benchtet. Die Methode beruht auf der Extraktlon des Ionenpaars oder der Additionsverbmdung aus Tetrabromphenolphthalelngthylester und quartaren Ammomumsalzen oder Alkaloiden m 1,2-Dichlodthan. Die Extmktion der Extrakte hangt hnear von der Konzentration von ursprunghch m der wal3rigen Losung vorhegendem Strychnm oder Methylatropm ab. R&sum&On rapporte une nouvelle apphcatlon d’un colorant monoaclde au dosage de la strychnine et de la mbthylatropme La methode est basic sur I’extractlon par solvant en 1,2-dichlor&thane de la paIre d’ions ou de compost d’addition form6 entre l’ester Bthyhque de la tttrabromoph&nolphtaltlne et les d’ammomums quaternalres ou les alcaloldes 11 y a relation linhlre entre l’absorptlon et la concentratton en strychnine ou en mCthylatropme mltialement prbsente dans la solution aqueuse
Tolunru. Vol 20. pp 224-227 Pergamon Press 1973 Prmted m Great Bratam
STUDY
OF Cu(II)-HYDRAZINE-6-METHYLPICOLINALDEHYDE SYSTEM: A NEW “IN SITU” REACTION (Recewed
23 February
1972. Accepted
5 July
1972)
The analytlcal apphcatlons of 6-methylplcolmaldehyde acme (6-Me-PAA) and hydrazone (6-Me-PAH) as photometric selective reagents for copper(I) have been reported. ’ * This paper reports primary and secondary “m wu” reactlons between (I) copper(I1) and 6-Me-PA and hydrazme. and (II) copper(I)-6-Me-PAA with hydrazme or hydroxylamme. These “m S~CU ” colour developments sometimes have practical advantages ’ 6 EXPERIMENTAL
Reuyents &Me-PA, 6-Me-PAA and 6-Me-PAH. Aqueous or ethanohc solutions of 6-Me-PA, hydrazme hydrate. hydroxylamme hydrochloride, 6-Me-PAA, and 6-Me-PAH were used. The synthesis of the latter reagents has been described previously ’ * Bugler FolutlonA Acetlc acid-so&urn acetate and boric acid-sodium hydroxide mixtures were used as appropriate. All the reagents used were analytical grade
222
R&sum&-On a rdahst des stparatlons analytiques nettes et soa2-, so,zet S,0a2de l’ordre du mIcrogramme mmce ascendante sur de la cellulose mlcrocrlstalhne avec le lM-a&tone (30. 20 : 2) comme systbme solvant. Les esptces colonm6trie annulaire
Tahrru.
Vol 20. pp 222-224
rapldes de quantltts d’lons SL-. par chromatographle en couche mtlange n-propanol-ammomaque sipartes ont itC ditermmees par
Pergamon Press. 1973 Prmted I” Great Bnlaln
SPECTROPHOTOMETRIC DETERMINATION OF STRYCHNINE AND METHYLATROPINE BY EXTRACTION WITH TETRABROMOPHENOLPHTHALEIN ETHYL ESTER (Received 5 Aprrl 1972. Accepted 15 May 1972)
Green6 or Bromophenol Blue’ * have been Some acid dyes,‘,’ such as Bromothymol Blue, ‘-’ Bromocresol used for the spectrophotometraz determination of ammes, alkaloids or quaternary ammomum salts These dyes are dlbaslc acids, and have serious drawbacks because of their extreme sensltlvlty to change m acidity; an indeterminate number of 1 1 and 1 2 Ion-pairs are formed with resultant poor reproduclblhty and extreme pHdependence. Tetrabromophenolphthalem ethyl ester (TBPE), which has Just one acidic group, IS able to form only a 1 1 Ion-pair complex, which 1s reproducibly extracted Various ammes, alkaloids and quaternary dmmomum salts have been extracted with TBPE at pH 7 5 mto 1,2-drchloroethane. The colour of the extracts fall into three categories: (I) blue (iomc form of TBPE) which 1s extracted m the presence of many quaternary ammomum salts and alkaloids such as spartem, (II) red which IS developed m the presence of alkaloids such as strychnme, physostigmme, qumldme and homatropme, a weak red colour 1s given by ammes such as a-naphthylamme and trlethanolamme; (in) yellow (molecular form of TBPE) wtnch IS the same colour as the reagent blank even m the presence of amhne, dlmethylamme, N,N’-dlmethylformamlde, ethylenedlammetetraacetic acid, or mtrllotriacetlc acid. If the extraction IS performed from acidic solution, the colours of the extracts are all yellow even m cases (I) and (II). This paper deals with the determmatlon of methylatropme and strychnine as representatives of the quaternary ammomum salts and the alkaloids, and as widely used medlcmes (parasympatholytlcs etc) Hexamtrodlphenylamme has been used as a spectrophotometrlc reagent for alkaloids or quaternary methods have also been investigated “-‘4 ammomum salts,’ ‘O and tltrlmetrlc
EXPERIMENTAL
Reagents Tetrabromophenolphthaleln ethyl ester (TBPE) pocassxm salt (m w 700 I) Welghed amounts were dissolved m ethyl alcohol. Standard strychnrne and methylarropme solutions. Weighed amounts of strychnine sulphate (dried at 105’) or N-methylatropme bromide (dned at 105’) were dissolved m water and diluted to known volume. Buffer solutrons, pH 8 and pH 9.5. Appropriate volumes of 04M potassium dlhydrogen phosphate, 0 06M sodium borate and 3M sodium hydroxide were mlxed All the chemicals were of reagent grade. and demmerahzed water was used Procedures Sfrychnme. Transfer 2-10 ml of strychnme solutron (20 x IO-‘M), 2 ml of TBPE solution (4 x lo-‘M), and 5 ml of buffer solution (pH 8) into a 100-ml separatmg funnel, dilute to 25 ml with water and shake the After separation of the two layers, run off the extract solution for 2 mm with 10 ml of 1,2-dlchloroethane. mto a glass tube through a filter paper to remove any droplets of water Measure the absorbance of the extract at 560 nm, using a reagent blank or water ds a reference Methyhtroprne Transfer 2-10 ml of standard methylatropme solution (1 0 x IO-‘M), 2 ml of TBPE solution (2 x IO-‘M). and 5 ml of buffer solution (pH 9.5) into a IOO-ml separatmg-funnel Treat the mixture In the same manner as described for strychnme Measure the absorbance at 615 nm.
SHORT COMMUNlCATlONS
RESULTS AND Absorptron
223
DtSCUSSlON
spectra
In the absence of methylatropme or strychnme a yellow compound IS extracted mto dtchloroethane, whtlst m then presence a blue (& 615 nm) or red (i.,,, 560 nm) one IS formed The change m colour may be attrtbuted to the formation of an ton-pan or addttton compound between the TBPE and the quaternary ammonmm catron or the alkalotd Eflct of
wrzables
Methylarropme or strychmne was extracted wtth TBPE from a sertes of aqueous soluttons buffered at various pH values The absorbance of the extract was constant when the pH of the aqueous phase lay wtthm the range 9 O-10 5 for methylatropme and 7.0-9.0 for strychmne Extreme pH-dependence was observed for the determmatlon of qumme or thlamme with Bromophenol Blue’ or Bromothymol Blue.’ hmilarly, constant absorbance many pH range could not be obtamed when Bromophenol Blue or Bromocresol Green was used as extractant for methylatropme or strychmne pH
It IS found that the concentratton of TPBE should be mamtamed at more than Reagent concentration 20-fold molar excess over methylatropme or 40-fold molar excess over strychnine to obtain a maxtmum and constant extraction Excess (2-10 ml) of the buffer solutron used m the procedure had no mfluence on the absorbance of the extracts. When the amount of the buffer solutron was less than 2 ml. separatron of the two layers was poor Solrentfor exrraccron The behavtour of vartous solvents m the extractton was studted Solvents were found to fall mto the followmg categorres (I) Those whrch enhance the extractton, e g., 1,2-dtchloroethane, chloroform (ri) Those whtch do not extract the coloured complex even m the presence of quaternary ammonmm salts or alkalords, e.g. carbon tetrachlonde, cyclohexane, n-hexane, toluene, monochlorobenzene fur) Those wtth which the blue TBPE IS extractable even without quaternary ammonium salts or alkalotds. ey., butyl acetate. ether, ethyl acetate. rsopentyl alcohol, mtrobenzene, methyl tsobutyl ketone Of these. 1.2-dtchloroethane was found to be most suttable for the extractton of the methylatropme or strychnme complexes Oriter tiarrableP Full colour development tooh about 1 mm of shakmg Contmued shaking up to 5 mm produced no further change m absorbance. The colour mtenstty of the dtchloroethane extracts remams constant for 1 hr Fluctuattons m room temperature (14 -22”) were wtthout measurable effect on the absorbance A hnear relatlonshlp was obzerved between the absorbance of the extract and the Cahbratton and precwon concentration of methylatropme (8.0 x lo-‘40 x 10V6M, molar absorptlvlty 190 x 10’ I~mole-‘~cm-l at 615 nm) or strychnine (1.6 x 10e6-8.0 x 10w6M, molar absorpttvtty 8.0 x lo4 l.mole-‘cm-’ at 560 nm) m the unttal aqueous phase The reproduc~bllIty was estimated from the results for ten sample soluttons, each wtth a final methylatropme concentratton of 4.0 x 10e6M The mean absorbance was 0 761, standard devtatton @008 Compostrron
of the coloured
species
Contmuous vartattons plots (TBPE + methylatropme = 8 x 10e6MM,i, = 590, 615 and 630 nm; TBPE + strychnme = 5 x 10-5M. j. = 540. 560 and 600 nm) have a maxrmum at 05 mole-fractton of TBPE. mdtcatmg a 1 I TBPE-methyIatroptne or TBPE-strychnine ratto In order to mvestt8ate the state of the coloured spectes m drchloroethane, the electrical conductrvtty of the extracts was measured The results obtamed shows that the TBPE-methylatropme spectes IS m the tomzed state and the TBPE-strychnme spectes IS m the molecular state m dtchloroethane The extracted specres therefore. may be formulated as StrychnmeH(TBPE) and [Methylatropme]+[TBPE]Etfecr of
foretgn
sl(bstance.~ and anafysts
of pracrzcal
sampies
Potassmm nitrate. ammomum sulphate, magnesmm chlottde, calcrum chlorrde, acetates. citrates. sahcylates, glucose. lactose. o-cresol. phenol and amlme do not mterfere m the determmatron of methylatropme or strychnine when present at the level of 2 x 10e3M Alkalotds interfere. The method was apphed to a strychnme mJectron obtained from a drugstore The result was 2 57 x lo-“M strychnme by the proposed method. and 2 48 x 10e3M by the tttrlmetrrc method r4 The proposed method has proved apphcable to the deter~nat~on of many quatemary ammonium salts and alkaloids such as spartem. qumme. physosttgmme, homatropme, and atropme *MASAHIRO TSUBOUCHI *TADAO SAKAI
mtorl L ,111ers1t\ 7iotrorr.Jnpm
~T~SHIKAZU WATAKE ~KAZUHITO KANAZAU’A ~MASAYA TANAKA
224
SHORT
COMMUNWATIONS
REFERENCES 1 M. E. Auerbach, Anal. Chem, 1943. 15, 492. 2. P B. Marshall and E. W Rogero, Blochem, J , 1945, 39, 258 3. V D Gupta and D E Cadwallader, J Pharm. SCL, 1968, 57, 112 4 G Schdl, Acra Pharm. Sueclca, 1964, 1, 101, Chem. Abstr , 1965. 63, 1657 5. Idem, Ibtd, 1965, 2, 13, Chem Abstr, 1965.63. 8125 6 H M N. H. Irving and J. J. Markham. Anal. Chm. Acta, 1967, 39, 7 7 M. Tatsuzawa, S. Nakayama and A. Okawara, Bunsekl Kagaku, 1970. 19. 761. 8 L. D Metcalfe, Anal Chem., 1960, 32, 70 9 G Schill and B Damelsson, Anal Chrm. Acfa. 1959, 21. 248 10. Idem, IbId., 1959, 21. 341 11 K. K. Kundu and M. N. Das, Anal. Chem., 1959, 31, 1358 12. K. Howorka and M. HBdicke, Pharm. Zentralhalle, 1959,98, 538 13. The Japanese Pharmacopeta, VII-l, Part II, p. 210, Nankodo, 1965 14 lbrd., p 647
Summary-A new apphcatlon of monoactdic dyes IS reported for the determmatlon of strychnme and methylatropme The method IS based on solvent extraction mto 1,2-dichloroethane of the Ion-pir or addltlon compound formed between tetrabromophenolphthalem ethyl ester and quaternary ammomum salts or alkaloids. The absorbance of the extracts 1s linearly dependent on the concentration of strychnme or methylatropine mitlally present m the aqueous solution Zusammmfassung-Es wlrd uber eme neue Anwendung van Farbstoffen mit emer sauren Funktion zur Bestimmung von Strychnm und Methylatropm benchtet. Die Methode beruht auf der Extraktlon des Ionenpaars oder der Additionsverbmdung aus Tetrabromphenolphthalelngthylester und quartaren Ammomumsalzen oder Alkaloiden m 1,2-Dichlodthan. Die Extmktion der Extrakte hangt hnear von der Konzentration von ursprunghch m der wal3rigen Losung vorhegendem Strychnm oder Methylatropm ab. R&sum&On rapporte une nouvelle apphcatlon d’un colorant monoaclde au dosage de la strychnine et de la mbthylatropme La methode est basic sur I’extractlon par solvant en 1,2-dichlor&thane de la paIre d’ions ou de compost d’addition form6 entre l’ester Bthyhque de la tttrabromoph&nolphtaltlne et les d’ammomums quaternalres ou les alcaloldes 11 y a relation linhlre entre l’absorptlon et la concentratton en strychnine ou en mCthylatropme mltialement prbsente dans la solution aqueuse
Tolunru. Vol 20. pp 224-227 Pergamon Press 1973 Prmted m Great Bratam
STUDY
OF Cu(II)-HYDRAZINE-6-METHYLPICOLINALDEHYDE SYSTEM: A NEW “IN SITU” REACTION (Recewed
23 February
1972. Accepted
5 July
1972)
The analytlcal apphcatlons of 6-methylplcolmaldehyde acme (6-Me-PAA) and hydrazone (6-Me-PAH) as photometric selective reagents for copper(I) have been reported. ’ * This paper reports primary and secondary “m wu” reactlons between (I) copper(I1) and 6-Me-PA and hydrazme. and (II) copper(I)-6-Me-PAA with hydrazme or hydroxylamme. These “m S~CU ” colour developments sometimes have practical advantages ’ 6 EXPERIMENTAL
Reuyents &Me-PA, 6-Me-PAA and 6-Me-PAH. Aqueous or ethanohc solutions of 6-Me-PA, hydrazme hydrate. hydroxylamme hydrochloride, 6-Me-PAA, and 6-Me-PAH were used. The synthesis of the latter reagents has been described previously ’ * Bugler FolutlonA Acetlc acid-so&urn acetate and boric acid-sodium hydroxide mixtures were used as appropriate. All the reagents used were analytical grade