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I-Melamine iyinto engcolile yokudla eyaziwayo engaba khona ezigabeni ezithile zokudla kokubili ngengozi nangenhloso. Inhloso yalolu cwaningo kwakuwukuqinisekisa ukutholwa nokulinganiswa kwe-melamine kufomula yezingane kanye nempuphu yobisi. Kwahlaziywa amasampula okudla angu-40 atholakala kwezentengiselwano, okuhlanganisa ifomula yezingane kanye nempuphu yobisi, avela ezifundeni ezahlukene zase-Iran. Okuqukethwe kwe-melamine okulinganiselwe kwamasampula kwanqunywa kusetshenziswa uhlelo lwe-chromatography-ultraviolet (HPLC-UV) olusebenza kahle kakhulu. Ijika lokulinganisa (R2 = 0.9925) lakhiwa ukuze kutholakale i-melamine ebangeni eliphakathi kuka-0.1–1.2 μg mL−1. Imikhawulo yokulinganisa nokuthola yayingu-1 μg mL−1 kanye no-3 μg mL−1, ngokulandelana. I-Melamine yahlolwa kufomula yezingane kanye nempuphu yobisi futhi imiphumela yabonisa ukuthi amazinga e-melamine kumasampula efomula yezingane kanye nempuphu yobisi ayengu-0.001–0.095 mg kg−1 kanye no-0.001–0.004 mg kg−1, ngokulandelana. Lezi zindinganiso zihambisana nomthetho we-EU kanye ne-Codex Alimentarius. Kubalulekile ukuqaphela ukuthi ukusetshenziswa kwale mikhiqizo yobisi enokuqukethwe okuncishisiwe kwe-melamine akubeki ingozi enkulu empilweni yabathengi. Lokhu kusekelwa futhi yimiphumela yokuhlolwa kwengozi.
I-Melamine iyinhlanganisela yezinto eziphilayo enefomula yama-molecule i-C3H6N6, etholakala ku-cyanamide. Inomswakama ophansi kakhulu emanzini futhi cishe ingu-66% we-nitrogen. I-Melamine iyinhlanganisela yezimboni esetshenziswa kabanzi enezinhlobo eziningi zokusetshenziswa okusemthethweni ekukhiqizeni amapulasitiki, umanyolo, kanye nemishini yokucubungula ukudla (kufaka phakathi ukupakishwa kokudla kanye nempahla yasekhishini)1,2. I-Melamine isetshenziswa futhi njengesithwali semithi yokwelapha izifo. Ingxenye ephezulu ye-nitrogen ku-melamine ingaholela ekusetshenzisweni kabi kwenhlanganisela futhi inikeze izakhiwo zama-molecule eprotheni ezithakweni zokudla3,4. Ngakho-ke, ukufaka i-melamine emikhiqizweni yokudla, kufaka phakathi imikhiqizo yobisi, kwandisa okuqukethwe kwe-nitrogen. Ngakho-ke, kwaphethwa ngephutha ukuthi okuqukethwe kweprotheni yobisi kwakuphakeme kunalokho okwakuyikho ngempela.
Kuwo wonke amagremu e-melamine angeziwe, okuqukethwe kwamaprotheni ekudleni kuzokwanda ngo-0.4%. Kodwa-ke, i-melamine incibilika kakhulu emanzini futhi ingabangela umonakalo omkhulu. Ukwengeza amagremu angu-1.3 e-melamine emikhiqizweni ewuketshezi njengobisi kungandisa okuqukethwe kwamaprotheni obisi ngo-30%5,6. Nakuba i-melamine ingezwa ekudleni kwezilwane ngisho nakubantu ukuze kwandiswe okuqukethwe kwamaprotheni7, i-Codex Alimentarius Commission (CAC) kanye neziphathimandla zikazwelonke azizange zivume i-melamine njengesithako sokudla futhi ziyibeke ohlwini njengeyingozi uma igwinywa, ihogelwa, noma imuncwa ngesikhumba. Ngo-2012, i-World Health Organization (WHO) International Agency for Research on Cancer yabala i-melamine njenge-Class 2B carcinogen ngoba ingaba yingozi empilweni yabantu8. Ukuchayeka isikhathi eside ku-melamine kungabangela umdlavuza noma umonakalo wezinso2. I-Melamine ekudleni ingahlangana ne-cyanuric acid ukuze kwakheke amakristalu aphuzi angancibiliki emanzini angabangela umonakalo ezicutshini zezinso nezesinye, kanye nomdlavuza womgudu womchamo kanye nokwehla kwesisindo9,10. Kungabangela ubuthi obuyingozi ekudleni, futhi uma kugxilwe kakhulu, ukufa, ikakhulukazi ezinsaneni nasezinganeni ezincane.11 I-World Health Organization (WHO) iphinde yabeka isilinganiso sokudla kwansuku zonke (TDI) se-melamine kubantu ku-0.2 mg/kg isisindo somzimba ngosuku ngokusekelwe eziqondisweni ze-CAC.12 I-US Food and Drug Administration (US FDA) ibeke izinga eliphezulu lokusala kwe-melamine ku-1 mg/kg kufomula yezinsana kanye no-2.5 ​​mg/kg kokunye ukudla.2,7 NgoSepthemba 2008, kwabikwa ukuthi abakhiqizi abaningana befomula yezinsana zasekhaya babengeze i-melamine ku-milk powder ukwandisa okuqukethwe kwamaprotheni emikhiqizweni yabo, okwaholela ekufakweni kobuthi be-milk powder futhi kwabangela isigameko sobuthi be-melamine ezweni lonke esagulisa izingane ezingaphezu kuka-294,000 futhi sangenisa esibhedlela izingane ezingaphezu kuka-50,000.13
Ukuncelisa ibele akwenzeki njalo ngenxa yezici ezahlukahlukene njengobunzima bempilo yasemadolobheni, ukugula kukamama noma ingane, okuholela ekusetshenzisweni kwefomula yezingane ukondla izinsana. Ngenxa yalokho, kuye kwasungulwa amafektri okukhiqiza ifomula yezingane eseduze ngangokunokwenzeka nobisi lwebele ngokwesakhiwo14. Ifomula yezingane ezithengiswa emakethe ivame ukwenziwa ngobisi lwenkomo futhi ivame ukwenziwa ngengxube ekhethekile yamafutha, amaprotheni, ama-carbohydrate, amavithamini, amaminerali nezinye izinto ezihlanganisiwe. Ukuze isondele kubisi lwebele, okuqukethwe kwamaprotheni namafutha efomula kuyahlukahluka, futhi kuye ngohlobo lobisi, kuqiniswa ngezinto ezihlanganisiwe ezifana namavithamini namaminerali njengensimbi15. Njengoba izinsana ziyiqembu elibucayi futhi kunengozi yokungenwa ubuthi, ukuphepha kokusetshenziswa kobisi oluyimpuphu kubaluleke kakhulu empilweni. Ngemuva kwecala lobuthi be-melamine phakathi kwezinsana zaseShayina, amazwe emhlabeni wonke aqaphele kakhulu le nkinga, futhi ukuzwela kwale ndawo nakho kuye kwanda. Ngakho-ke, kubaluleke kakhulu ukuqinisa ukulawulwa kokukhiqizwa kwefomula yezingane ukuze kuvikelwe impilo yezinsana. Kunezindlela ezahlukahlukene zokuthola i-melamine ekudleni, okuhlanganisa i-high-performance liquid chromatography (HPLC), i-electrophoresis, indlela yokuzwa, i-spectrophotometry kanye ne-antigen-antibody enzyme-linked immunosorbent assay16. Ngo-2007, i-US Food and Drug Administration (FDA) yasungula futhi yashicilela indlela ye-HPLC yokunquma i-melamine kanye ne-cyanuric acid ekudleni, okuyindlela ephumelela kakhulu yokunquma okuqukethwe kwe-melamine17.
Ukuhlushwa kwe-melamine kufomula yezinsana okulinganiswe kusetshenziswa indlela entsha ye-infrared spectroscopy kwakusukela kuma-milligram angu-0.33 kuya ku-0.96 ngekhilogramu (mg kg-1). 18 Ucwaningo eSri Lanka luthole amazinga e-melamine ku-powder yobisi oluphelele ukusuka ku-0.39 kuya ku-0.84 mg kg-1. Ngaphezu kwalokho, amasampula efomula yezinsana angenisiwe aqukethe amazinga aphezulu e-melamine, ku-0.96 kanye no-0.94 mg/kg, ngokulandelana. Lawa mazinga angaphansi komkhawulo wokulawula (1 mg/kg), kodwa kudingeka uhlelo lokuqapha ukuphepha kwabathengi. 19
Izifundo eziningana zihlole amazinga e-melamine kuma-formula ezinsana zase-Iran. Cishe amasampula angu-65% aqukethe i-melamine, ngesilinganiso esingu-0.73 mg/kg kanye nomkhawulo ophezulu ongu-3.63 mg/kg. Olunye ucwaningo lubike ukuthi izinga le-melamine ku-formula yezinsana lalisukela ku-0.35 kuya ku-3.40 μg/kg, ngesilinganiso esingu-1.38 μg/kg. Sekukonke, ukuba khona kanye nezinga le-melamine kuma-formula ezinsana zase-Iran kuye kwahlolwa ezifundweni ezahlukene, kanti amanye amasampula aqukethe i-melamine adlula umkhawulo omkhulu obekwe yiziphathimandla ezilawulayo (2.5 mg/kg/feed).
Uma sicabangela ukusetshenziswa okukhulu kobisi oluyimpuphu oluqondile nolungaqondile embonini yokudla kanye nokubaluleka okukhethekile kobisi oluyimpuphu oluncane ekondleni izingane, lolu cwaningo luhlose ukuqinisekisa indlela yokuthola i-melamine kubisi oluyimpuphu kanye nefomula yosana. Eqinisweni, inhloso yokuqala yalolu cwaningo kwakuwukuthuthukisa indlela esheshayo, elula futhi enembile yokuthola ukuxutshwa kwe-melamine kufomula yosana kanye ne-powder yobisi kusetshenziswa i-chromatography yoketshezi esebenza kahle kakhulu (i-HPLC) kanye nokutholwa kwe-ultraviolet (UV); Okwesibili, inhloso yalolu cwaningo kwakuwukuthola okuqukethwe kwe-melamine kufomula yosana kanye ne-powder yobisi ethengiswa emakethe yase-Iran.
Izinsimbi ezisetshenziselwa ukuhlaziya i-melamine ziyahlukahluka kuye ngendawo yokukhiqiza ukudla. Indlela yokuhlaziya i-HPLC-UV ebucayi nethembekile yasetshenziswa ukukala izinsalela ze-melamine kubisi kanye nefomula yezingane. Imikhiqizo yobisi iqukethe amaprotheni namafutha ahlukahlukene angaphazamisa ukulinganiswa kwe-melamine. Ngakho-ke, njengoba kuphawuliwe nguSun et al. 22, isu lokuhlanza elifanele nelisebenzayo liyadingeka ngaphambi kokuhlaziywa kwezinsimbi. Kulolu cwaningo, sisebenzise izihlungi zesirinji ezilahlwayo. Kulolu cwaningo, sisebenzise ikholomu ye-C18 ukuhlukanisa i-melamine kufomula yezingane kanye nempuphu yobisi. Isibalo 1 sibonisa i-chromatogram yokuthola i-melamine. Ngaphezu kwalokho, ukubuyiswa kwamasampula aqukethe i-melamine engu-0.1–1.2 mg/kg kwaqala ku-95% kuya ku-109%, i-regression equation yayingu-y = 1.2487x - 0.005 (r = 0.9925), kanye namanani okuphambuka okujwayelekile (RSD) asukela ku-0.8 kuya ku-2%. Idatha etholakalayo ikhombisa ukuthi le ndlela ithembekile ebangeni lokuhlushwa elifundwe (Ithebula 1). Umkhawulo wokutholwa kwezinsimbi (i-LOD) kanye nomkhawulo wokulinganiswa (i-LOQ) we-melamine kwakuyi-1 μg mL−1 kanye ne-3 μg mL−1, ngokulandelana. Ngaphezu kwalokho, i-UV spectrum ye-melamine ibonise ibhendi yokumunca ku-242 nm. Indlela yokuthola iyazwela, ithembekile futhi inembile. Le ndlela ingasetshenziswa ekunqumeni njalo izinga le-melamine.
Imiphumela efanayo ishicilelwe ngababhali abaningana. Indlela ye-high-performance liquid chromatography-photodiode array (HPLC) yasungulwa ukuze kuhlaziywe i-melamine emikhiqizweni yobisi. Imikhawulo ephansi yokulinganisa yayiyi-340 μg kg−1 yempuphu yobisi kanye ne-280 μg kg−1 yefomula yosana ku-240 nm. UFilazzi et al. (2012) babike ukuthi i-melamine ayizange itholakale kwifomula yosana yi-HPLC. Kodwa-ke, amasampula angu-8% empuphu yobisi aqukethe i-melamine ezingeni lika-0.505–0.86 mg/kg. UTittlemiet et al.23 benze ucwaningo olufanayo futhi bathola okuqukethwe kwe-melamine kwifomula yosana (inombolo yesampula: 72) nge-high-performance liquid chromatography-mass spectrometry/MS (HPLC-MS/MS) ukuthi cishe ibe ngu-0.0431–0.346 mg kg−1. Esifundweni esenziwe nguVenkatasamy et al. (2010), indlela ye-green chemistry (ngaphandle kwe-acetonitrile) kanye ne-reversed-phase high-performance liquid chromatography (RP-HPLC) yasetshenziswa ukulinganisa i-melamine kufomula yezingane kanye nobisi. Uhla lokuhlushwa kwesampula lwalusukela ku-1.0 kuya ku-80 g/mL kanti impendulo yayiqondile (r > 0.999). Le ndlela ibonise ukubuyiselwa okungu-97.2–101.2 ngaphezu kohla lokuhlushwa okungu-5–40 g/mL kanti ukuphindaphindeka kwakungaphansi kuka-1.0% ukuphambuka okujwayelekile okuhlobene. Ngaphezu kwalokho, i-LOD ebonwe kanye ne-LOQ kwakungu-0.1 g mL−1 kanye no-0.2 g mL−124, ngokulandelana. ULutter et al. (2011) bathole ukungcoliswa kwe-melamine kubisi lwenkomo kanye nefomula yezingane esekelwe ubisi besebenzisa i-HPLC-UV. Ukuhlushwa kwe-Melamine kwaqala ku-< 0.2 kuya ku-2.52 mg kg−1. Ububanzi obuguquguqukayo obuqondile bendlela ye-HPLC-UV babungu-0.05 kuya ku-2.5 mg kg−1 yobisi lwenkomo, u-0.13 kuya ku-6.25 mg kg−1 wefomula yosana enengxenye yesisindo samaprotheni engu-<15%, kanye no-0.25 kuya ku-12.5 mg kg−1 wefomula yosana enengxenye yesisindo samaprotheni engu-15%. Imiphumela ye-LOD (ne-LOQ) yayingu-0.03 mg kg−1 (0.09 mg kg−1) yobisi lwenkomo, u-0.06 mg kg−1 (0.18 mg kg−1) wefomula yosana engu-<15% protein, kanye no-0.12 mg kg−1 (0.36 mg kg−1) wefomula yosana engu-15% protein, enesilinganiso sesignali-kuya-kumsindo esingu-3 kanye no-1025 se-LOD kanye ne-LOQ, ngokulandelana. UDiebes et al. (2012) bahlole amazinga e-melamine kumasampula efomula yosana kanye nempuphu yobisi besebenzisa i-HPLC/DMD. Kufomula yosana, amazinga aphansi kakhulu naphezulu kakhulu ayengu-9.49 mg kg−1 kanye no-258 mg kg−1, ngokulandelana. Umkhawulo wokutholwa (i-LOD) wawungu-0.05 mg kg−1.
UJavaid nabanye babike ukuthi izinsalela ze-melamine kufomula yezinsana zaziphakathi kuka-0.002–2 mg kg−1 yi-Fourier transform infrared spectroscopy (FT-MIR) (LOD = 1 mg kg−1; LOQ = 3.5 mg kg−1). URezai nabanye 27 baphakamise indlela ye-HPLC-DDA (λ = 220 nm) yokulinganisa i-melamine futhi bathola i-LOQ engu-0.08 μg mL−1 yempuphu yobisi, eyayiphansi kunezinga elitholwe kulolu cwaningo. USun nabanye benzise i-RP-HPLC-DAD yokuthola i-melamine ebisini oluwuketshezi ngokukhipha i-solid phase (SPE). Bathole i-LOD kanye ne-LOQ engu-18 kanye no-60 μg kg−128, ngokulandelana, okuzwela kakhulu kunocwaningo lwamanje. UMontesano nabanye . kuqinisekisile ukusebenza kahle kwendlela ye-HPLC-DMD yokuhlola okuqukethwe kwe-melamine ezithasiselweni zamaprotheni ngomkhawulo wokulinganisa ongu-0.05–3 mg/kg, okwakungazweli kakhulu kunendlela esetshenziswe kulolu cwaningo29.
Akungabazeki ukuthi amalabhorethri okuhlaziya adlala indima ebalulekile ekuvikeleni imvelo ngokuqapha ukungcola kumasampula ahlukahlukene. Kodwa-ke, ukusetshenziswa kwenani elikhulu lama-reagents kanye nezinyibilikisi ngesikhathi sokuhlaziya kungabangela ukwakheka kwezinsalela eziyingozi. Ngakho-ke, i-green analytical chemistry (GAC) yasungulwa ngo-2000 ukunciphisa noma ukuqeda imiphumela emibi yezinqubo zokuhlaziya kubasebenzi kanye nemvelo26. Izindlela zokuthola i-melamine zendabuko ezifaka phakathi i-chromatography, i-electrophoresis, i-capillary electrophoresis, kanye ne-enzyme-linked immunosorbent assay (ELISA) zisetshenziswe ukuhlonza i-melamine. Kodwa-ke, phakathi kwezindlela eziningi zokuthola, izinzwa ze-electrochemical zidonsele ukunaka okukhulu ngenxa yokuzwela kwazo okuhle kakhulu, ukukhetha, isikhathi sokuhlaziya okusheshayo, kanye nezici ezisebenziseka kalula30,31. I-nanotechnology eluhlaza isebenzisa izindlela zebhayoloji ukuhlanganisa izinto ezincane, ezinganciphisa ukukhiqizwa kwemfucuza eyingozi kanye nokusetshenziswa kwamandla, ngaleyo ndlela zikhuthaze ukusetshenziswa kwemikhuba eqhubekayo. Ama-nanocomposites, isibonelo, enziwe ngezinto ezinobungani nemvelo, angasetshenziswa kuma-biosensors ukuthola izinto ezifana ne-melamine32,33,34.
Ucwaningo lubonisa ukuthi i-solid-phase microextraction (SPME) isetshenziswa ngempumelelo ngenxa yokusebenza kahle kwamandla okuphezulu kanye nokusimama kwayo uma kuqhathaniswa nezindlela zokukhipha zendabuko. Ubungane bemvelo kanye nokusebenza kahle kwamandla kwe-SPME kwenza kube yindlela enhle kakhulu kunezindlela zokukhipha zendabuko kumakhemikhali okuhlaziya futhi kuhlinzeka ngendlela eqhubekayo nephumelelayo yokulungiselela isampula35.
Ngo-2013, uWu nabanye bakhe i-biosensor ye-plasmon resonance (mini-SPR) ezwela kakhulu futhi ekhethayo esebenzisa ukuhlangana phakathi kwe-melamine nama-anti-melamine antibodies ukuthola ngokushesha i-melamine kufomula yosana kusetshenziswa i-immunoassay. I-biosensor ye-SPR ehlanganiswe ne-immunoassay (kusetshenziswa i-albumin ye-bovine serum ye-melamine) ubuchwepheshe obulula ukubusebenzisa futhi obungabizi kakhulu obunomkhawulo wokuthola ongu-0.02 μg mL-136 kuphela.
UNasiri no-Abbasian basebenzise inzwa ephathekayo enamandla amakhulu ngokuhlanganiswa nama-graphene oxide-chitosan composites (GOCS) ukuthola i-melamine kumasampula ezentengiselwano37. Le ndlela ibonise ukukhetha okuphezulu kakhulu, ukunemba, kanye nokuphendula. Inzwa ye-GOCS ibonise ukuzwela okuphawulekayo (239.1 μM−1), ububanzi obuqondile obungu-0.01 kuya ku-200 μM, i-affinity constant engu-1.73 × 104, kanye ne-LOD efinyelela ku-10 nM. Ngaphezu kwalokho, ucwaningo olwenziwe nguChandrasekhar et al. ngo-2024 lwamukele indlela enobungani nemvelo futhi engabizi kakhulu. Basebenzise i-papaya peel extract njenge-ejenti yokunciphisa ukwenziwa kwe-zinc oxide nanoparticles (ZnO-NPs) ngendlela enobungani nemvelo. Ngemva kwalokho, kwasungulwa indlela ehlukile ye-micro-Raman spectroscopy yokunquma i-melamine kufomula yezingane. Ama-ZnO-NP atholakala emfucumfucwini yezolimo abonise amandla njengethuluzi lokuxilonga eliwusizo kanye nobuchwepheshe obuthembekile, obungabizi kakhulu bokuqapha nokuthola i-melamine38.
U-Alizadeh et al. (2024) basebenzise ipulatifomu ye-fluorescence ye-metal-organic framework (MOF) ebucayi kakhulu ukunquma i-melamine ku-milk powder. Ububanzi obuqondile kanye nomkhawulo ophansi wokuthola we-sensor, onqunywe kusetshenziswa i-3σ/S, kwakungu-40 kuya ku-396.45 nM (okulingana no-25 μg kg−1 kuya ku-0.25 mg kg−1) kanye no-40 nM (okulingana no-25 μg kg−1), ngokulandelana. Lolu bubanzi lungaphansi kakhulu kwamazinga aphezulu okusala (ama-MRL) abekwe ukuhlonza i-melamine kufomula yezinsana (1 mg kg−1) kanye namanye amasampula okudla/okudla (2.5 mg kg−1). I-Fluorescent sensor (terbium (Tb)@NH2-MIL-253(Al)MOF) ibonise ukunemba okuphezulu kanye nekhono lokulinganisa elinembile kune-HPLC39 ekutholeni i-melamine ku-milk powder. Ama-biosensors nama-nanocomposites ku-green chemistry awagcini nje ngokuthuthukisa amakhono okuthola kodwa futhi anciphisa izingozi zemvelo ngokuhambisana nezimiso zentuthuko esimeme.
Izimiso ze-green chemistry zisetshenziswe ezindleleni ezahlukene zokunquma i-melamine. Enye indlela ukuthuthukiswa kwendlela ye-green dispersive solid-phase microextraction esebenzisa i-polymer yemvelo ye-polar β-cyclodextrin exhunywe ne-citric acid ukuze kukhishwe i-melamine 40 ngempumelelo kumasampula afana nefomula yezinsana namanzi ashisayo. Enye indlela isebenzisa i-Mannich reaction yokunquma i-melamine kumasampula obisi. Le ndlela ayibizi, inobungani nemvelo, futhi inembe kakhulu ngebanga eliqondile elingu-0.1–2.5 ppm kanye nomkhawulo ophansi wokuthola 41. Ngaphezu kwalokho, indlela engabizi kakhulu nenobungani nemvelo yokunquma inani le-melamine kubisi oluwuketshezi kanye nefomula yezinsana yathuthukiswa kusetshenziswa i-Fourier transform infrared transmission spectroscopy enokunemba okuphezulu kanye nemikhawulo yokuthola engu-1 ppm kanye no-3.5 ppm, ngokulandelana 42. Lezi zindlela zibonisa ukusetshenziswa kwezimiso ze-green chemistry ekuthuthukiseni izindlela eziphumelelayo nezisimeme zokunquma i-melamine.
Izifundo eziningana ziphakamise izindlela ezintsha zokuthola i-melamine, njengokusetshenziswa kokukhipha i-solid-phase kanye ne-high-performance liquid chromatography (HPLC)43, kanye ne-fast high-performance liquid chromatography (HPLC), engadingi ukwelashwa okuyinkimbinkimbi noma ama-ion-pair reagents, ngaleyo ndlela kuncishiswe inani lemfucuza yamakhemikhali44. Lezi zindlela azigcini nje ngokuhlinzeka ngemiphumela enembile yokunqunywa kwe-melamine emikhiqizweni yobisi, kodwa futhi zihambisana nezimiso ze-green chemistry, zinciphisa ukusetshenziswa kwamakhemikhali ayingozi futhi zinciphise umthelela jikelele wemvelo wenqubo yokuhlaziya.
Amasampula angamashumi amane emikhiqizo ehlukene ahlolwe kathathu, futhi imiphumela ivezwe kuThebula 2. Amazinga e-Melamine kumasampula efomula yosana kanye nempuphu yobisi ayesukela ku-0.001 kuya ku-0.004 mg/kg kanye nasukela ku-0.001 kuya ku-0.095 mg/kg, ngokulandelana. Azikho izinguquko ezibalulekile ezibonwe phakathi kwamaqembu amathathu eminyaka efomula yosana. Ngaphezu kwalokho, i-melamine itholakale ku-80% wempuphu yobisi, kodwa ama-65% empuphu yosana ayengcoliswe yi-melamine.
Okuqukethwe kwe-melamine ku-powder yobisi lwezimboni kwakuphakeme kunokwefomula yosana, futhi umehluko wawubalulekile (p<0.05) (Isithombe 2).
Imiphumela etholakele yayingaphansi kwemingcele ebekwe yi-FDA (ngaphansi kuka-1 no-2.5 ​​mg/kg). Ngaphezu kwalokho, imiphumela ihambisana nemingcele ebekwe yi-CAC (2010) kanye ne-EU45,46, okungukuthi umkhawulo ophezulu ovunyelwe ngu-1 mg kg-1 wefomula yezingane kanye no-2.5 ​​mg kg-1 wemikhiqizo yobisi.
Ngokusho kocwaningo lwango-2023 olwenziwa nguGhanati et al.47, okuqukethwe kwe-melamine ezinhlotsheni ezahlukene zobisi olupakishiwe e-Iran kwaqala ku-50.7 kuya ku-790 μg kg−1. Imiphumela yabo yayingaphansi komkhawulo ovunyelwe yi-FDA. Imiphumela yethu iphansi kunaleyo kaShoder et al.48 noRima et al.49. UShoder et al. (2010) bathole ukuthi amazinga e-melamine ku-milk powder (n=49) anqunywe yi-ELISA aqala ku-0.5 kuya ku-5.5 mg/kg. URima et al. bahlaziye izinsalela ze-melamine ku-milk powder nge-fluorescence spectrophotometry futhi bathola ukuthi okuqukethwe kwe-melamine ku-milk powder kwakungu-0.72–5.76 mg/kg. Ucwaningo lwenziwa eCanada ngo-2011 ukuze kuqashwe amazinga e-melamine ku-milk formula (n=94) kusetshenziswa i-liquid chromatography (LC/MS). Amazinga e-Melamine atholakale engaphansi komkhawulo owamukelekayo (izinga lokuqala: 0.5 mg kg−1). Akunakwenzeka ukuthi amazinga e-melamine akhohlisayo atholakele ayeyindlela esetshenziswa ukwandisa okuqukethwe kwamaprotheni. Kodwa-ke, lokhu akunakuchazwa ngokusebenzisa umanyolo, ukuthutha okuqukethwe kwesitsha, noma izinto ezifanayo. Ngaphezu kwalokho, umthombo we-melamine ku-milk powder ongeniswe eCanada awuzange udalulwe50.
UHassani nabanye balinganise okuqukethwe yi-melamine ku-milk powder kanye nobisi oluwuketshezi emakethe yase-Iran ngo-2013 futhi bathola imiphumela efanayo. Imiphumela ibonise ukuthi ngaphandle kohlobo olulodwa lwe-milk powder kanye nobisi oluwuketshezi, wonke amanye amasampula ayengcoliswe yi-melamine, ngamazinga asukela ku-1.50 kuya ku-30.32 μg g−1 ku-milk powder kanye no-0.11 kuya ku-1.48 μg ml−1 kubisi. Okuphawulekayo ukuthi i-cyanuric acid ayizange itholakale kunoma yimaphi amasampula, okunciphisa amathuba okuba nobuthi be-melamine kubathengi. 51 Izifundo zangaphambilini zihlole ukugcwala kwe-melamine emikhiqizweni yetshokolethi equkethe i-milk powder. Cishe ama-94% amasampula angenisiwe kanye nama-77% amasampula ase-Iran aqukethe i-melamine. Amazinga e-Melamine kumasampula angenisiwe asukela ku-0.032 kuya ku-2.692 mg/kg, kanti lawo kumasampula ase-Iran asukela ku-0.013 kuya ku-2.600 mg/kg. Sekukonke, i-melamine itholakale kumasampula angu-85%, kodwa uhlobo olulodwa kuphela oluthile olwalunamazinga angaphezu komkhawulo ovunyelwe.44 UTittlemier nabanye babike amazinga e-melamine ku-milk powder asukela ku-0.00528 kuya ku-0.0122 mg/kg.
Ithebula 3 lifingqa imiphumela yokuhlola ubungozi yamaqembu amathathu eminyaka. Ingozi yayingaphansi kweyodwa kuwo wonke amaqembu eminyaka. Ngakho-ke, ayikho ingozi yempilo engeyona ebangela umdlavuza evela ku-melamine kufomula yezingane.
Amazinga aphansi okungcola emikhiqizweni yobisi angase abangelwe ukungcola okungahlosiwe ngesikhathi sokulungiselela, kanti amazinga aphezulu angase abangelwe ukwengezwa ngamabomu. Ngaphezu kwalokho, ingozi iyonke empilweni yabantu ngokudla imikhiqizo yobisi enamazinga aphansi e-melamine ibhekwa njengephansi. Kungaphethwa ngokuthi ukudla imikhiqizo equkethe amazinga aphansi kangaka e-melamine akubeki bungozi empilweni yabathengi52.
Uma sibheka ukubaluleka kokuphathwa kokuphepha kokudla embonini yobisi, ikakhulukazi maqondana nokuvikela impilo yomphakathi, kubaluleke kakhulu ukuthuthukisa nokuqinisekisa indlela yokuhlola nokuqhathanisa amazinga e-melamine kanye nezinsalela ku-milk powder kanye nefomula yezingane. Indlela elula nenembile ye-HPLC-UV spectrophotometric yasungulwa ukuze kunqunywe i-melamine ku-milk powder kanye ne-milk powder. Le ndlela yaqinisekiswa ukuqinisekisa ukuthembeka kwayo kanye nokunemba kwayo. Imikhawulo yokuthola kanye nokulinganisa indlela iboniswe ukuthi inozwela ngokwanele ukukala amazinga e-melamine ku-milk powder yezingane kanye ne-milk powder. Ngokusho kwedatha yethu, i-melamine yatholakala kumasampula amaningi ase-Iran. Wonke amazinga e-melamine atholakele ayengaphansi kwemingcele ephezulu evunyelwe ebekwe yi-CAC, okubonisa ukuthi ukusetshenziswa kwalezi zinhlobo zemikhiqizo yobisi akubeki ingozi empilweni yabantu.
Zonke izinto ezisetshenziswayo zamakhemikhali zazisezingeni lokuhlaziya: i-melamine (2,4,6-triamino-1,3,5-triazine) emsulwa engu-99% (i-Sigma-Aldrich, eSt. Louis, MO); i-acetonitrile yezinga le-HPLC (i-Merck, eDarmstadt, eJalimane); amanzi amsulwa kakhulu (i-Millipore, eMorfheim, eFrance). Izihlungi zesirinji ezilahlwayo (i-Chromafil Xtra PVDF-45/25, usayizi wembobo ongu-0.45 μm, ububanzi be-membrane obungu-25 mm) (i-Macherey-Nagel, eDüren, eJalimane).
Kusetshenziswe i-ultrasonic bath (Elma, Germany), i-centrifuge (Beckman Coulter, Krefeld, Germany) kanye ne-HPLC (KNAUER, Germany) ukulungiselela amasampula.
Kwasetshenziswa i-chromatograph yoketshezi esebenza kahle kakhulu (KNAUER, eJalimane) ehlonyiswe nge-UV detector. Izimo zokuhlaziywa kwe-HPLC zazimi kanje: kwasetshenziswa uhlelo lwe-UHPLC Ultimate oluhlonyiswe ngekholomu yokuhlaziya ye-ODS-3 C18 (4.6 mm × 250 mm, usayizi wezinhlayiya 5 μm) (MZ, eJalimane). I-HPLC eluent (isigaba esiphathwayo) yayiyingxube ye-TFA/methanol (450:50 mL) enesilinganiso sokugeleza esingu-1 mL min-1. Ububanzi bobude bokubona babungu-242 nm. Umthamo womjovo wawungu-100 μL, izinga lokushisa lekholomu lalingu-20 °C. Njengoba isikhathi sokugcinwa komuthi side (imizuzu eyi-15), umjovo olandelayo kufanele wenziwe ngemva kwemizuzu engama-25. I-Melamine yatholakala ngokuqhathanisa isikhathi sokugcinwa kanye nenani eliphakeme le-UV spectrum yezindinganiso ze-melamine.
Isixazululo esijwayelekile se-melamine (10 μg/mL) salungiswa kusetshenziswa amanzi futhi sagcinwa esiqandisini (4 °C) kude nokukhanya. Nciphisa isisombululo sesitoko nesigaba esihambayo bese ulungisa izixazululo ezijwayelekile ezisebenzayo. Isixazululo ngasinye esijwayelekile safakwa ku-HPLC izikhathi ezingu-7. I-calibration equation 10 yabalwa ngokuhlaziywa kokuhlehla kwendawo ephakeme enqunyiwe kanye nokuhlushwa okunqunyiwe.
Impuphu yobisi lwenkomo etholakala ezitolo (amasampula angu-20) kanye namasampula ezinhlobo ezahlukene zefomula yobisi lwenkomo (amasampula angu-20) athengwe ezitolo ezinkulu nasemakhemisi endawo e-Iran ukuze kondliwe izinsana zamaqembu ahlukene eminyaka (izinyanga ezingu-0-6, izinyanga ezingu-6-12, kanye nezinyanga ezingaphezu kwe-12) futhi agcinwa ekushiseni okuqandisiwe (4 °C) kuze kube yilapho kuhlaziywa. Ngemuva kwalokho, i-1 ± 0.01 g yempuphu yobisi ehlanganisiwe yalinganiswa futhi yaxutshwa ne-acetonitrile:water (50:50, v/v; 5 mL). Ingxube yavuselelwa umzuzu ongu-1, yabe isifakwa emanzini okugeza nge-ultrasonic imizuzu engu-30, yabe isinyakaziswa umzuzu ongu-1. Ingxube yabe isifakwa ku-centrifuge ku-9000 × g imizuzu eyi-10 ekushiseni kwegumbi kanti i-supernatant yahlungwa ibe yi-2 ml autosampler vial kusetshenziswa isihlungi sesirinji esingu-0.45 μm. I-filtrate (250 μl) yabe isixutshwa namanzi (750 μl) yabe isifakwa ohlelweni lwe-HPLC10,42.
Ukuze siqinisekise indlela, sinqume ukubuyisa, ukunemba, umkhawulo wokuthola (i-LOD), umkhawulo wokulinganisa (i-LOQ), kanye nokunemba ngaphansi kwezimo ezifanele. I-LOD ichazwe njengokuqukethwe kwesampula okunokuphakama okuphezulu okuphindwe kathathu kunezinga lomsindo oyisisekelo. Ngakolunye uhlangothi, okuqukethwe kwesampula okunokuphakama okuphezulu okuphindwe kayishumi kunesilinganiso sesignali-kuya-kumsindo kuchazwe njenge-LOQ.
Impendulo yedivayisi inqunywe kusetshenziswa ijika lokulinganisa eliqukethe amaphuzu edatha ayisikhombisa. Okuqukethwe kwe-melamine okuhlukene kusetshenziswe (0, 0.2, 0.3, 0.5, 0.8, 1 kanye no-1.2). Ukulingana kwenqubo yokubala i-melamine kunqunywe. Ngaphezu kwalokho, amazinga amaningana ahlukene e-melamine angeziwe kumasampula angenalutho. Ijika lokulinganisa lakhiwa ngokujova njalo i-0.1–1.2 μg mL−1 yesisombululo se-melamine esijwayelekile kumasampula efomula yosana kanye nobisi oluyimpuphu kanye ne-R2 yayo = 0.9925. Ukunemba kuhlolwe ngokuphindaphindeka kanye nokuphindaphindeka kwenqubo futhi kwafezwa ngokujova amasampula ezinsukwini zokuqala nezintathu ezalandela (ngokuphindwe kathathu). Ukuphindaphindeka kwendlela kuhlolwe ngokubala i-RSD % yamazinga amathathu ahlukene e-melamine eyengeziwe. Izifundo zokubuyisela emuva zenziwe ukuze kutholakale ukunemba. Izinga lokululama ngendlela yokukhipha libalwe emazingeni amathathu okuhlushwa kwe-melamine (0.1, 1.2, 2) kumasampula efomula yosana kanye nobisi olomile9,11,15.
Ukudla okulinganiselwe kwansuku zonke (i-EDI) kunqunywe kusetshenziswa ifomula elandelayo: I-EDI = Ci × Cc/BW.
Lapho i-Ci ingumthamo we-melamine ojwayelekile, i-Cc ingukusetshenziswa kobisi kanti i-BW iyisisindo esimaphakathi sezingane.
Ukuhlaziywa kwedatha kwenziwe kusetshenziswa i-SPSS 24. Ukufaneleka kwahlolwa kusetshenziswa isivivinyo saseKolmogorov-Smirnov; yonke idatha yayiwukuhlolwa okungezona okwe-parametric (p = 0). Ngakho-ke, isivivinyo saseKruskal-Wallis kanye nesivivinyo saseMann-Whitney kwasetshenziswa ukuthola umehluko omkhulu phakathi kwamaqembu.
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