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I-Melamine sisingcolisi sokutya esaziwayo esinokubakho kwiindidi ezithile zokutya ngengozi nangenjongo. Injongo yolu phononongo yayikukuqinisekisa ukufunyanwa kunye nokulinganiswa kwe-melamine kwifomyula yosana kunye nomgubo wobisi. Iisampulu zokutya ezingama-40 ezithengiswayo, kuquka ifomula yosana kunye nomgubo wobisi, ezivela kwimimandla eyahlukeneyo yase-Iran zahlalutywa. Umxholo we-melamine oqikelelweyo weesampulu wamiselwa kusetyenziswa inkqubo ye-chromatography-ultraviolet (HPLC-UV) esebenza kakuhle. I-calibration curve (R2 = 0.9925) yakhiwe ukuze kufunyanwe i-melamine kuluhlu lwe-0.1–1.2 μg mL−1. Imida yokulinganiswa kunye nokufunyanwa yayiyi-1 μg mL−1 kunye ne-3 μg mL−1, ngokwahlukeneyo. I-Melamine yavavanywa kwifomyula yosana kunye nomgubo wobisi kwaye iziphumo zabonisa ukuba amanqanaba e-melamine kwisampulu yefomyula yosana kunye nomgubo wobisi yayiyi-0.001–0.095 mg kg−1 kunye ne-0.001–0.004 mg kg−1, ngokwahlukeneyo. Ezi xabiso zihambelana nomthetho we-EU kunye neCodex Alimentarius. Kubalulekile ukuqaphela ukuba ukusetyenziswa kwezi mveliso zobisi ezinomthamo omncinci we-melamine akubeki mngcipheko mkhulu kwimpilo yabathengi. Oku kukwaxhaswa ziziphumo zovavanyo lomngcipheko.
I-Melamine yikhompawundi yendalo enefomula yemolekyuli i-C3H6N6, ephuma kwi-cyanamide. Inonyibiliko oluphantsi kakhulu emanzini kwaye imalunga ne-66% ye-nitrogen. I-Melamine yikhompawundi esetyenziswa kakhulu kwimizi-mveliso enoluhlu olubanzi lokusetyenziswa ngokusemthethweni kwimveliso yeplastiki, izichumisi, kunye nezixhobo zokucubungula ukutya (kubandakanya ukupakishwa kokutya kunye nezixhobo zasekhitshini)1,2. I-Melamine ikwasetyenziswa njengomthwali wamayeza okunyanga izifo. Umlinganiselo ophezulu we-nitrogen kwi-melamine unokukhokelela ekusetyenzisweni gwenxa kwekhompawundi kwaye udlulisele iipropati zeemolekyuli zeproteni kwizithako zokutya3,4. Ke ngoko, ukongeza i-melamine kwimveliso yokutya, kuquka iimveliso zobisi, kwandisa umxholo we-nitrogen. Ke ngoko, kwagqitywa ngempazamo ukuba umxholo weproteni yobisi wawuphezulu kunokuba wawunjalo ngokwenene.
Kwigram nganye yemelamine eyongeziweyo, umxholo weproteni yokutya uya kwanda nge-0.4%. Nangona kunjalo, imelamine iyanyibilika kakhulu emanzini kwaye inokubangela umonakalo omkhulu. Ukongeza i-1.3 grams yemelamine kwiimveliso zolwelo ezifana nobisi kunokunyusa umxholo weproteni yobisi nge-30% 5,6. Nangona imelamine yongezwa kwizilwanyana nakwiindawo zokutya zabantu ukuze kwandiswe umxholo weproteni7, iCodex Alimentarius Commission (CAC) kunye namagunya kazwelonke abazange bayivume imelamine njengesongezelelo sokutya kwaye bayidwelise njengeyingozi ukuba iginyiwe, iphefumlwe, okanye ifunxwe lusu. Ngo-2012, i-World Health Organisation's (WHO) International Agency for Research on Cancer yadwelisa imelamine njenge-Class 2B carcinogen kuba inokuba yingozi kwimpilo yabantu8. Ukuvezwa ixesha elide kwimelamine kunokubangela umhlaza okanye umonakalo wezintso2. Imelamine ekutyeni inokudibana ne-cyanuric acid ukwenza iikristale ezimthubi ezinganyibilikiyo emanzini ezinokubangela umonakalo kwizintso nakwizicubu zesinyi, kunye nomhlaza womchamo kunye nokunciphisa ubunzima9,10. Ingabangela ityhefu yokutya ngokukhawuleza, kwaye xa iphezulu, ibulale, ngakumbi kwiintsana nabantwana abancinci.11 I-World Health Organisation (WHO) ikwamisele i-tolerable daily intake (TDI) ye-melamine ebantwini kwi-0.2 mg/kg ubunzima bomzimba ngosuku ngokusekelwe kwizikhokelo ze-CAC.12 I-US Food and Drug Administration (US FDA) imisele inqanaba eliphezulu le-residue ye-melamine kwi-1 mg/kg kwifomula yeentsana kunye ne-2.5 mg/kg kwezinye ukutya.2,7 NgoSeptemba 2008, kwaxelwa ukuba abavelisi abaninzi befomula yeentsana zasekhaya bongeze i-melamine kumgubo wobisi ukuze bandise umxholo weproteni kwiimveliso zabo, nto leyo ebangele ityhefu yomgubo wobisi kwaye yabangela isiganeko sobuthi be-melamine kuzwelonke esagulisa abantwana abangaphezu kwama-294,000 kwaye sangenisa abantu abangaphezu kwama-50,000 esibhedlele.13
Ukuncancisa akusoloko kusenzeka ngenxa yezinto ezahlukeneyo ezifana nobunzima bobomi basezidolophini, ukugula komama okanye umntwana, okukhokelela ekusetyenzisweni kwefomyula yosana ukondla iintsana. Ngenxa yoko, kuye kwasekwa iifektri zokuvelisa ifomula yosana esondele kangangoko kubisi lwebele ngokwendlela oluyilwe ngayo14. Ifomyula yosana ethengiswa kwimarike idla ngokwenziwa ngobisi lwenkomo kwaye idla ngokwenziwa ngomxube okhethekileyo wamafutha, iiproteni, iicarbohydrate, iivithamini, iiminerali kunye nezinye izinto ezidityanisiweyo. Ukuze ibe kufutshane nobisi lwebele, umxholo weproteni kunye namafutha efomyula uyahluka, kwaye kuxhomekeke kuhlobo lobisi, ziqiniswa ngezinto ezidityaniswe neevithamini kunye neeminerali ezifana nesinyithi15. Ekubeni iintsana ziliqela elinovakalelo kwaye kukho umngcipheko wokutyhefeka, ukhuseleko lokusetyenziswa komgubo wobisi lubaluleke kakhulu kwimpilo. Emva kwetyala letyhefu ye-melamine phakathi kweentsana zaseTshayina, amazwe kwihlabathi liphela aye anikela ingqalelo kulo mba, kwaye uvakalelo lwale ndawo nalo luye lwanda. Ke ngoko, kubaluleke kakhulu ukomeleza ulawulo lokuveliswa kwefomyula yosana ukuze kukhuselwe impilo yeentsana. Kukho iindlela ezahlukeneyo zokufumanisa i-melamine ekutyeni, kuquka i-high-performance liquid chromatography (HPLC), i-electrophoresis, indlela yokuva, i-spectrophotometry kunye ne-antigen-antibody enzyme-linked immunosorbent assay16. Ngo-2007, i-US Food and Drug Administration (FDA) yaphuhlisa yaza yapapasha indlela ye-HPLC yokumisela i-melamine kunye ne-cyanuric acid ekutyeni, eyona ndlela isebenzayo yokumisela umxholo we-melamine17.
Uxinaniso lweMelamine kwifomula yeentsana olulinganiswe kusetyenziswa indlela entsha ye-infrared spectroscopy luqala kwi-0.33 ukuya kwi-0.96 milligrams ngekhilogram (mg kg-1). 18 Uphononongo eSri Lanka lufumanise amanqanaba e-melamine kumgubo wobisi olupheleleyo ukusuka kwi-0.39 ukuya kwi-0.84 mg kg-1. Ukongeza, iisampulu zefomula yeentsana ezingenisiweyo zazinamanqanaba aphezulu e-melamine, kwi-0.96 kunye ne-0.94 mg/kg, ngokwahlukeneyo. La manqanaba angaphantsi komda wolawulo (1 mg/kg), kodwa inkqubo yokubeka esweni iyafuneka ukuze kukhuseleke abathengi. 19
Izifundo ezininzi zihlolisise amanqanaba e-melamine kwiifomyula zeentsana zase-Iran. Malunga ne-65% yeesampuli ziqulethe i-melamine, ngomyinge we-0.73 mg/kg kunye nobuninzi be-3.63 mg/kg. Olunye uphando lubike ukuba inqanaba le-melamine kwifomyula yeentsana laliqala kwi-0.35 ukuya kwi-3.40 μg/kg, ngomyinge we-1.38 μg/kg. Ngokubanzi, ubukho kunye nenqanaba le-melamine kwiifomyula zeentsana zase-Iran ziye zavavanywa kwizifundo ezahlukeneyo, ezinye iisampuli ezine-melamine zidlula umda ophezulu obekwe ziigunya zolawulo (2.5 mg/kg/feed).
Ukuqwalasela ukusetyenziswa okukhulu komgubo wobisi ngokuthe ngqo nangokungathanga ngqo kwishishini lokutya kunye nokubaluleka okukhethekileyo komgubo wobisi lweentsana ekondleni abantwana, olu phononongo lujolise ekuqinisekiseni indlela yokufumanisa i-melamine kumgubo wobisi kunye nefomyula yosana. Enyanisweni, injongo yokuqala yolu phononongo yayikukuphuhlisa indlela ekhawulezayo, elula nechanekileyo yokulinganisa yokufumanisa ukungcoliswa kwe-melamine kwifomyula yosana kunye nomgubo wobisi kusetyenziswa i-chromatography yolwelo olusebenza kakuhle (HPLC) kunye nokufumanisa i-ultraviolet (UV); Okwesibini, injongo yolu phononongo yayikukufumanisa umxholo we-melamine kwifomyula yosana kunye nomgubo wobisi othengiswa kwimarike yase-Iran.
Izixhobo ezisetyenziselwa uhlalutyo lwe-melamine ziyahluka ngokuxhomekeke kwindawo yokuvelisa ukutya. Indlela yohlalutyo lwe-HPLC-UV enobuntununtunu nethembekileyo isetyenzisiwe ukulinganisa iintsalela ze-melamine kubisi nakwifomyula yosana. Iimveliso zobisi ziqulethe iiproteni ezahlukeneyo kunye namafutha anokuphazamisana nokulinganiswa kwe-melamine. Ke ngoko, njengoko kuphawuliwe nguSun et al. 22, icebo elifanelekileyo nelisebenzayo lokucoca liyimfuneko ngaphambi kohlalutyo lwezixhobo. Kolu phononongo, sisebenzise izihluzi zesirinji ezilahlwayo. Kolu phononongo, sisebenzise ikholamu ye-C18 ukwahlula i-melamine kwifomyula yosana kunye nomgubo wobisi. Umfanekiso 1 ubonisa i-chromatogram yokufumanisa i-melamine. Ukongeza, ukubuyiswa kweesampuli eziqulethe i-melamine eyi-0.1–1.2 mg/kg kususela kwi-95% ukuya kwi-109%, i-regression equation yayiyi-y = 1.2487x − 0.005 (r = 0.9925), kwaye amaxabiso e-relative standard deviation (RSD) asusela kwi-0.8 ukuya kwi-2%. Idatha ekhoyo ibonisa ukuba le ndlela ithembekile kuluhlu loxinzelelo olufundweyo (Itheyibhile 1). Umda wokufumanisa izixhobo (i-LOD) kunye nomda wokulinganisa (i-LOQ) we-melamine yayiyi-1 μg mL−1 kunye ne-3 μg mL−1, ngokulandelelana. Ukongeza, i-UV spectrum ye-melamine ibonise ibhendi yokufunxa kwi-242 nm. Indlela yokufumanisa inobuthathaka, inokuthenjwa kwaye ichanekile. Le ndlela ingasetyenziselwa ukumisela rhoqo inqanaba le-melamine.
Iziphumo ezifanayo ziye zapapashwa ngababhali abaliqela. Indlela ye-high-performance liquid chromatography-photodiode array (HPLC) yaphuhliswa ukuze kuhlalutywe i-melamine kwiimveliso zobisi. Imida ephantsi yokulinganisa yayiyi-340 μg kg−1 yomgubo wobisi kunye ne-280 μg kg−1 yomgubo wosana kwi-240 nm. UFilazzi et al. (2012) baxele ukuba i-melamine ayizange ifunyanwe kwifomula yosana yi-HPLC. Nangona kunjalo, i-8% yeesampulu zomgubo wobisi zazine-melamine kwinqanaba le-0.505–0.86 mg/kg. UTittlemiet et al.23 benze uphando olufanayo kwaye bafumanisa ukuba umxholo we-melamine kwifomula yosana (inombolo yesampulu: 72) yi-high-performance liquid chromatography-mass spectrometry/MS (HPLC-MS/MS) umalunga ne-0.0431–0.346 mg kg−1. Kuphononongo olwenziwe nguVenkatasamy et al. (2010), indlela ye-green chemistry (engena-acetonitrile) kunye ne-reversed-phase high-performance liquid chromatography (RP-HPLC) zisetyenzisiwe ukuqikelela i-melamine kwifomyula yosana kunye nobisi. Uluhlu loxinzelelo lwesampulu lwaluqala kwi-1.0 ukuya kwi-80 g/mL kwaye impendulo yayi-linear (r > 0.999). Le ndlela ibonise ukubuyiselwa kwe-97.2–101.2 kuluhlu loxinzelelo lwe-5–40 g/mL kwaye ukuphinda kuvele kwakungaphantsi kwe-1.0% yokuphambuka okuqhelekileyo. Ngaphezu koko, i-LOD ebonweyo kunye ne-LOQ yayiyi-0.1 g mL−1 kunye ne-0.2 g mL−124, ngokulandelelana. ULutter et al. (2011) bafumanise ungcoliseko lwe-melamine kubisi lwenkomo kunye nefomyula yosana esekwe kubisi besebenzisa i-HPLC-UV. Uxinzelelo lwe-Melamine lwaluqala kwi-< 0.2 ukuya kwi-2.52 mg kg−1. Uluhlu olune-linear dynamic lwendlela ye-HPLC-UV yayiyi-0.05 ukuya kwi-2.5 mg kg−1 yobisi lwenkomo, i-0.13 ukuya kwi-6.25 mg kg−1 yefomyula yosana ene-protein mass fraction ye-<15%, kunye ne-0.25 ukuya kwi-12.5 mg kg−1 yefomyula yosana ene-protein mass fraction ye-15%. Iziphumo ze-LOD (kunye ne-LOQ) zaziyi-0.03 mg kg−1 (0.09 mg kg−1) yobisi lwenkomo, i-0.06 mg kg−1 (0.18 mg kg−1) yefomyula yosana <15% yeproteni, kunye ne-0.12 mg kg−1 (0.36 mg kg−1) yefomyula yosana eyi-15% yeproteni, kunye ne-0.12 mg kg−1 (0.36 mg kg−1) yefomyula yosana eyi-15% yeproteni, kunye nomlinganiselo wesignali-kwingxolo we-3 kunye ne-1025 ye-LOD kunye ne-LOQ, ngokwahlukeneyo. UDiebes et al. (2012) baphande amanqanaba e-melamine kwisampulu yefomyula yosana kunye ne-milk powder besebenzisa i-HPLC/DMD. Kwifomyula yosana, amanqanaba aphantsi naphezulu yayingama-9.49 mg kg−1 kunye nama-258 mg kg−1, ngokulandelelana. Umda wokufunyanwa (LOD) yayiyi-0.05 mg kg−1.
UJavaid nabanye baxele ukuba iintsalela zemelamine kwifomula yosana zazikuluhlu lwe-0.002–2 mg kg−1 yiFourier transform infrared spectroscopy (FT-MIR) (LOD = 1 mg kg−1; LOQ = 3.5 mg kg−1). URezai nabanye 27 bacebise indlela ye-HPLC-DDA (λ = 220 nm) yokuqikelela i-melamine kwaye bafumene i-LOQ ye-0.08 μg mL−1 yomgubo wobisi, owawuphantsi kunenqanaba elifunyenwe kolu phononongo. USun nabanye baphuhlise i-RP-HPLC-DAD yokufumanisa i-melamine kubisi olumanzi nge-solid phase extraction (SPE). Bafumene i-LOD kunye ne-LOQ ye-18 kunye ne-60 μg kg−128, ngokulandelanayo, ebuthathaka ngakumbi kunophando lwangoku. UMontesano nabanye . iqinisekisile ukusebenza kakuhle kwendlela ye-HPLC-DMD yokuvavanya umxholo we-melamine kwizongezo zeproteni ezinomda wokulinganisa we-0.05–3 mg/kg, eyayingenabungozi kangako kunendlela esetyenzisiweyo kolu phononongo29.
Ngokungathandabuzekiyo, iilabhoratri zohlalutyo zidlala indima ebalulekileyo ekukhuseleni okusingqongileyo ngokubeka iliso kungcoliseko kwiisampuli ezahlukeneyo. Nangona kunjalo, ukusetyenziswa kwenani elikhulu lee-reagents kunye nezinyibilikisi ngexesha lohlalutyo kunokubangela ukwakheka kweentsalela eziyingozi. Ke ngoko, i-green analytical chemistry (GAC) yaphuhliswa ngo-2000 ukunciphisa okanye ukuphelisa iziphumo ezimbi zeenkqubo zohlalutyo kubasebenzi nakwindalo esingqongileyo26. Iindlela zemveli zokufumanisa i-melamine kubandakanya i-chromatography, i-electrophoresis, i-capillary electrophoresis, kunye ne-enzyme-linked immunosorbent assay (ELISA) zisetyenzisiwe ukuchonga i-melamine. Nangona kunjalo, phakathi kweendlela ezininzi zokufumanisa, ii-electrochemical sensors zitsale ingqalelo enkulu ngenxa yobuntununtunu bazo obuhle, ukukhetha, ixesha lokuhlalutya ngokukhawuleza, kunye neempawu ezisebenziseka lula30,31. I-nanotechnology eluhlaza isebenzisa iindlela zebhayoloji ukwenza izinto ze-nanomaterials, ezinokunciphisa ukuveliswa kwenkunkuma enobungozi kunye nokusetyenziswa kwamandla, ngaloo ndlela zikhuthaza ukuphunyezwa kweendlela ezizinzileyo. Ii-nanocomposites, umzekelo, ezenziwe ngezinto ezinobuhlobo nokusingqongileyo, zingasetyenziswa kwii-biosensors ukufumanisa izinto ezifana ne-melamine32,33,34.
Olu phononongo lubonisa ukuba i-solid-phase microextraction (SPME) isetyenziswa ngokufanelekileyo ngenxa yokusebenza kwayo kakuhle kwamandla kunye nozinzo xa kuthelekiswa neendlela zemveli zokukhupha. Ubungane nokusingqongileyo kunye nokusebenza kakuhle kwamandla kwe-SPME kwenza ukuba ibe yindlela engcono kakhulu kuneendlela zemveli zokukhupha kwikhemistri yohlalutyo kwaye ibonelela ngendlela ezinzileyo nefanelekileyo yokulungiselela isampuli35.
Ngowama-2013, uWu nabanye baphuhlise i-biosensor ye-plasmon resonance (mini-SPR) ebukhali kakhulu nekhethayo esisebenzisa ukudibana phakathi kwe-melamine kunye ne-anti-melamine antibodies ukufumanisa ngokukhawuleza i-melamine kwifomyula yosana kusetyenziswa i-immunoassay. I-biosensor ye-SPR edityaniswe ne-immunoassay (esebenzisa i-albumin ye-bovine serum ye-melamine) yiteknoloji elula ukuyisebenzisa nengabizi kakhulu enomlinganiselo wokufumanisa we-0.02 μg mL-136 kuphela.
UNasiri no-Abbasian basebenzise i-sensor ephathekayo enamandla aphezulu kunye ne-graphene oxide-chitosan composites (GOCS) ukufumanisa i-melamine kwiisampulu zorhwebo37. Le ndlela ibonise ukukhetha okuphezulu kakhulu, ukuchaneka, kunye nokuphendula. I-sensor ye-GOCS ibonise uvakalelo oluphawulekayo (239.1 μM−1), uluhlu oluthe ngqo lwe-0.01 ukuya kwi-200 μM, i-affinity constant ye-1.73 × 104, kunye ne-LOD ukuya kuthi ga kwi-10 nM. Ngaphezu koko, uphando olwenziwe nguChandrasekhar et al. ngo-2024 lwamkele indlela enobuhlobo nokusingqongileyo kwaye engabizi kakhulu. Basebenzise i-papaya peel extract njenge-arhente yokunciphisa ukwenza i-zinc oxide nanoparticles (ZnO-NPs) ngendlela enobuhlobo nokusingqongileyo. Emva koko, indlela ekhethekileyo ye-micro-Raman spectroscopy yaphuhliswa ukuze kuchongwe i-melamine kwifomyula yosana. Ii-ZnO-NPs ezifunyenwe kwinkunkuma yezolimo zibonakalise amandla njengesixhobo esibalulekileyo sokuxilonga kunye netekhnoloji ethembekileyo, engabizi kakhulu yokujonga nokubona i-melamine38.
U-Alizadeh et al. (2024) basebenzise iqonga le-fluorescence le-metal-organic framework (MOF) elinobuthathaka kakhulu ukumisela i-melamine kumgubo wobisi. Uluhlu olunemigca kunye nomda wokufumanisa ophantsi we-sensor, ochongiweyo kusetyenziswa i-3σ/S, yayingama-40 ukuya kuma-396.45 nM (elilingana ne-25 μg kg−1 ukuya kwi-0.25 mg kg−1) kunye ne-40 nM (elilingana ne-25 μg kg−1), ngokwahlukeneyo. Olu luhlu lungaphantsi kakhulu kwamanqanaba aphezulu e-residue (MRLs) amiselwe ukuchongwa kwe-melamine kwifomyula yosana (1 mg kg−1) kunye nezinye iisampulu zokutya/zokutya (2.5 mg kg−1). I-Fluorescent sensor (terbium (Tb)@NH2-MIL-253(Al)MOF) ibonise ukuchaneka okuphezulu kunye nokukwazi ukulinganisa okuchanekileyo kune-HPLC39 ekufumaneni i-melamine kumgubo wobisi. Ii-biosensors kunye ne-nanocomposites kwi-green chemistry aziphuculi kuphela amandla okufumanisa kodwa zinciphisa neengozi zokusingqongileyo ngokuhambelana nemigaqo yophuhliso oluzinzileyo.
Imigaqo yekhemistri eluhlaza isetyenzisiwe kwiindlela ezahlukeneyo zokufumanisa i-melamine. Enye indlela kukuphuhlisa indlela ye-green dispersive solid-phase microextraction esebenzisa i-polymer yendalo ye-polar β-cyclodextrin edityaniswe ne-citric acid ukuze kukhutshwe i-melamine 40 ngokufanelekileyo kwiisampuli ezifana nefomyula yosana kunye namanzi ashushu. Enye indlela isebenzisa i-Mannich reaction yokufumanisa i-melamine kwiisampuli zobisi. Le ndlela ayibizi kakhulu, inobuhlobo nokusingqongileyo, kwaye ichanekile kakhulu ngoluhlu oluyi-linear lwe-0.1–2.5 ppm kunye nomda wokufumanisa ophantsi 41. Ngaphezu koko, indlela engabizi kakhulu nenobuhlobo nokusingqongileyo yokufumanisa ubungakanani be-melamine kubisi olumanzi kunye nefomyula yosana yaphuhliswa kusetyenziswa i-Fourier transform infrared transmission spectroscopy echanekileyo kakhulu kunye nemida yokufumanisa ye-1 ppm kunye ne-3.5 ppm, ngokulandelanayo 42. Ezi ndlela zibonisa ukusetyenziswa kwemigaqo yekhemistri eluhlaza kuphuhliso lweendlela ezisebenzayo nezizinzileyo zokufumanisa i-melamine.
Izifundo ezininzi ziye zacebisa iindlela ezintsha zokufumanisa i-melamine, ezinje ngokusetyenziswa kwe-solid-phase extraction kunye ne-high-performance liquid chromatography (HPLC)43, kunye ne-fast high-performance liquid chromatography (HPLC), engadingi zixhobo zokulungisa ezintsonkothileyo okanye ii-ion-pair reagents, ngaloo ndlela kunciphisa ubungakanani benkunkuma yeekhemikhali44. Ezi ndlela aziboneleli nje kuphela ngeziphumo ezichanekileyo zokumisela i-melamine kwiimveliso zobisi, kodwa zikwahambelana nemigaqo ye-green chemistry, zinciphisa ukusetyenziswa kweekhemikhali ezinobungozi kwaye zinciphise impembelelo iyonke kwindalo esingqongileyo yenkqubo yohlalutyo.
Iisampulu ezingamashumi amane zeempawu ezahlukeneyo zivavanyiwe kathathu, kwaye iziphumo ziboniswe kwiTheyibhile 2. Amanqanaba eMelamine kwisampulu yefomyula yosana kunye neyomgubo wobisi aqala kwi-0.001 ukuya kwi-0.004 mg/kg kwaye ukusuka kwi-0.001 ukuya kwi-0.095 mg/kg, ngokwahlukeneyo. Akukho tshintsho lubalulekileyo lubonwe phakathi kwamaqela amathathu eminyaka yefomyula yosana. Ukongeza, i-melamine ifunyenwe kwi-80% yomgubo wobisi, kodwa i-65% yefomyula yosana yayingcoliswe yi-melamine.
Umxholo we-melamine kumgubo wobisi lwemizi-mveliso wawuphezulu kunakwifomyula yosana, kwaye umahluko wawubalulekile (p<0.05) (Umfanekiso 2).
Iziphumo ezifunyenweyo bezingaphantsi kwemida ebekwe yi-FDA (ngaphantsi kwe-1 kunye ne-2.5 mg/kg). Ukongeza, iziphumo zihambelana nemida ebekwe yi-CAC (2010) kunye ne-EU45,46, oko kukuthi umda ophezulu ovumelekileyo yi-1 mg kg-1 kwifomyula yosana kunye ne-2.5 mg kg-1 kwiimveliso zobisi.
Ngokutsho kophando olwenziwe ngo-2023 nguGhanati et al.47, umxholo we-melamine kwiintlobo ezahlukeneyo zobisi olupakishiweyo e-Iran wawuphakathi kwe-50.7 ukuya kwi-790 μg kg−1. Iziphumo zabo zazingaphantsi komda ovumelekileyo we-FDA. Iziphumo zethu ziphantsi kunezo zikaShoder et al.48 kunye noRima et al.49. UShoder et al. (2010) bafumanise ukuba amanqanaba e-melamine kumgubo wobisi (n=49) amiselwe yi-ELISA aphakathi kwe-0.5 ukuya kwi-5.5 mg/kg. URima et al. bahlalutye iintsalela ze-melamine kumgubo wobisi nge-fluorescence spectrophotometry baza bafumanisa ukuba umxholo we-melamine kumgubo wobisi wawuphakathi kwe-0.72–5.76 mg/kg. Uphononongo lwenziwe eKhanada ngo-2011 ukujonga amanqanaba e-melamine kwifomyula yosana (n=94) kusetyenziswa i-chromatography yolwelo (LC/MS). Amanqanaba e-Melamine afunyenwe engaphantsi komda owamkelekileyo (umgangatho wokuqala: 0.5 mg kg−1). Akunakwenzeka ukuba amanqanaba e-melamine akhohlisayo afunyenweyo ayeyindlela esetyenziselwa ukwandisa umxholo weproteni. Nangona kunjalo, oku akunakuchazwa ngokusebenzisa izichumisi, ukufuduselwa komxholo wesikhongozeli, okanye izinto ezifanayo. Ngaphezu koko, umthombo we-melamine kumgubo wobisi ongeniswe eKhanada awuzange utyhilwe50.
UHassani nabanye balinganise umxholo we-melamine kumgubo wobisi kunye nobisi oluyilwelo kwimarike yase-Iran ngo-2013 baza bafumana iziphumo ezifanayo. Iziphumo zibonise ukuba ngaphandle kohlobo olunye lomgubo wobisi kunye nobisi oluyilwelo, zonke ezinye iisampulu zazingcoliswe yi-melamine, ngamanqanaba aqala kwi-1.50 ukuya kwi-30.32 μg g−1 kumgubo wobisi kunye ne-0.11 ukuya kwi-1.48 μg ml−1 kubisi. Okuphawulekayo kukuba, i-cyanuric acid ayizange ifunyanwe nakweyiphi na iisampulu, nto leyo eyanciphisa amathuba okuba ityhefu ye-melamine ifumaneke kubathengi. Izifundo zangaphambili zihlolisise uxinano lwe-melamine kwiimveliso zetshokholethi eziqulethe umgubo wobisi. Malunga ne-94% yeesampulu ezingenisiweyo kunye ne-77% yeesampulu zase-Iran zaziqulethe i-melamine. Amanqanaba e-Melamine kwiisampulu ezingenisiweyo ayeqala kwi-0.032 ukuya kwi-2.692 mg/kg, ngelixa lawo akwiisampulu zase-Iran ayeqala kwi-0.013 ukuya kwi-2.600 mg/kg. Lilonke, i-melamine ifunyenwe kwi-85% yeesampuli, kodwa luphawu olunye kuphela olwalunamanqanaba angaphezu komda ovumelekileyo.44 UTittlemier nabanye baxele amanqanaba e-melamine kumgubo wobisi ukusuka kwi-0.00528 ukuya kwi-0.0122 mg/kg.
Itheyibhile 3 ishwankathela iziphumo zovavanyo lomngcipheko kumaqela amathathu eminyaka. Umngcipheko wawungaphantsi ko-1 kuwo onke amaqela eminyaka. Ngoko ke, akukho mngcipheko kwimpilo ongengowomhlaza ovela kwi-melamine kwifomyula yosana.
Amanqanaba aphantsi ongcoliseko kwiimveliso zobisi anokubangelwa kungcoliseko olungenziwanga ngabom ngexesha lokulungiselela, ngelixa amanqanaba aphezulu anokubangelwa kukongeza ngabom. Ngaphezu koko, umngcipheko jikelele kwimpilo yabantu ngokutya iimveliso zobisi ezinamazinga aphantsi e-melamine uthathwa njengophantsi. Kungagqitywa kwelokuba ukutya iimveliso ezinamanqanaba aphantsi kangaka e-melamine akubeki mngcipheko kwimpilo yabathengi52.
Ukuqwalasela ukubaluleka kolawulo lokhuseleko lokutya kwishishini lobisi, ingakumbi ngokubhekiselele ekukhuseleni impilo yoluntu, kubaluleke kakhulu ukuphuhlisa nokuqinisekisa indlela yokuvavanya nokuthelekisa amanqanaba e-melamine kunye neentsalela kumgubo wobisi kunye nefomula yosana. Indlela elula nechanekileyo ye-HPLC-UV spectrophotometric yaphuhliswa ukuze kumiselwe i-melamine kwifomula yosana kunye nomgubo wobisi. Le ndlela yaqinisekiswa ukuqinisekisa ukuthembeka kwayo kunye nokuchaneka kwayo. Imida yokufumanisa kunye nokulinganisa yale ndlela ibonakaliswe ukuba inobuthathaka ngokwaneleyo ukulinganisa amanqanaba e-melamine kwifomula yosana kunye nomgubo wobisi. Ngokwedatha yethu, i-melamine ifunyenwe kwiisampulu ezininzi zase-Iran. Onke amanqanaba e-melamine afunyenweyo ayengaphantsi kwemida ephezulu evumelekileyo ebekwe yi-CAC, ebonisa ukuba ukusetyenziswa kwezi ntlobo zeemveliso zobisi akubeki mngcipheko kwimpilo yabantu.
Zonke ii-reagents zeekhemikhali ezisetyenzisiweyo bezingodidi lohlalutyo: i-melamine (2,4,6-triamino-1,3,5-triazine) i-99% ecocekileyo (iSigma-Aldrich, eSt. Louis, MO); i-acetonitrile ye-HPLC (iMerck, eDarmstadt, eJamani); amanzi acocekileyo kakhulu (iMillipore, eMorfheim, eFransi). Izihluzi zesirinji ezilahlwayo (iChromafil Xtra PVDF-45/25, ubungakanani bepore yi-0.45 μm, ububanzi bemembrane yi-25 mm) (iMacherey-Nagel, eDüren, eJamani).
Kusetyenziswe ibhafu ye-ultrasonic (e-Elma, eJamani), i-centrifuge (eBeckman Coulter, eKrefeld, eJamani) kunye ne-HPLC (e-KNAUER, eJamani) ukulungiselela iisampulu.
Kusetyenziswe i-chromatograph yolwelo esebenza kakuhle kakhulu (KNAUER, eJamani) exhotyiswe nge-UV detector. Iimeko zohlalutyo lwe-HPLC bezimi ngolu hlobo lulandelayo: inkqubo ye-UHPLC Ultimate exhotyiswe ngekholamu yohlalutyo ye-ODS-3 C18 (4.6 mm × 250 mm, ubungakanani be-particle 5 μm) (MZ, eJamani) yasetyenziswa. I-HPLC eluent (isigaba esiphathwayo) yayingumxube we-TFA/methanol (450:50 mL) enesantya sokuhamba se-1 mL min-1. Ububanzi bobude bokubona babuyi-242 nm. Umthamo wenaliti yayiyi-100 μL, ubushushu bentambo babuyi-20 °C. Ekubeni ixesha lokugcina ichiza lide (imizuzu eli-15), inaliti elandelayo kufuneka yenziwe emva kwemizuzu engama-25. I-Melamine ichongiwe ngokuthelekisa ixesha lokugcina kunye nencopho ye-UV spectrum yemigangatho ye-melamine.
Isisombululo esiqhelekileyo se-melamine (10 μg/mL) salungiswa kusetyenziswa amanzi saza sagcinwa efrijini (4 °C) kude nokukhanya. Nciphisa isisombululo sesitokhwe ngesigaba esihambayo kwaye ulungiselele izisombululo ezisemgangathweni ezisebenzayo. Isisombululo ngasinye esiqhelekileyo safakwa kwi-HPLC izihlandlo ezisi-7. I-calibration equation 10 yabalwa ngohlalutyo lokubuyela umva lwendawo yencochoyi emiselweyo kunye noxinzelelo olumiselweyo.
Umgubo wobisi lwenkomo ofumaneka kurhwebo (iisampulu ezingama-20) kunye neesampulu zeentlobo ezahlukeneyo zefomyula yobisi lwenkomo olusekelwe kubisi lwenkomo (iisampulu ezingama-20) zithengwe kwiivenkile ezinkulu nakwiikhemesti zase-Iran ukuze kondliwe iintsana zamaqela ahlukeneyo eminyaka (iinyanga ezi-0–6, iinyanga ezi-6–12, kunye neenyanga ezingaphezu kwe-12) kwaye zigcinwe kubushushu obusefrijini (4 °C) de kube luhlalutyo. Emva koko, i-1 ± 0.01 g yomgubo wobisi ohomogenized yalinganiswa yaza yaxutywa ne-acetonitrile:water (50:50, v/v; 5 mL). Umxube wavuselelwa umzuzu o-1, emva koko wafakwa kwi-ultrasonic bath imizuzu engama-30, waza ekugqibeleni washukunyiswa umzuzu o-1. Umxube emva koko waxutywa kwi-centrifuge kwi-9000 × g imizuzu eli-10 kubushushu begumbi kwaye i-supernatant yahluzwa kwi-2 ml autosampler vial kusetyenziswa isihluzo sesirinji esingu-0.45 μm. I-filtrate (250 μl) emva koko yaxutywa namanzi (750 μl) yaza yafakwa kwinkqubo ye-HPLC10,42.
Ukuqinisekisa le ndlela, simisele ukubuyisa, ukuchaneka, umda wokufumanisa (i-LOD), umda wokulinganisa (i-LOQ), kunye nokuchaneka phantsi kweemeko ezifanelekileyo. I-LOD ichazwe njengomxholo wesampulu onokuphakama okuphezulu okuphindwe kathathu kwinqanaba lesandi elisisiseko. Kwelinye icala, umxholo wesampulu onokuphakama okuphezulu okuphindwe kalishumi kunomlinganiselo wesignali-kwingxolo uchazwe njenge-LOQ.
Impendulo yesixhobo imiselwe kusetyenziswa i-calibration curve equlathe amanqaku edatha asixhenxe. Kusetyenziswe umxholo we-melamine owahlukileyo (0, 0.2, 0.3, 0.5, 0.8, 1 kunye no-1.2). Ulungelelwano lwenkqubo yokubala i-melamine lumiselwe. Ukongeza, amanqanaba ahlukeneyo e-melamine ongezelelweyo kwiisampulu ezingenanto. I-calibration curve yakhiwe ngokufaka rhoqo i-0.1–1.2 μg mL−1 yesisombululo se-melamine esiqhelekileyo kwifomyula yosana kunye neesampuli zobisi oluyimpuphu kwaye i-R2 yayo = 0.9925. Ukuchaneka kuhlolwe ngokuphindaphindeka kunye nokuphindaphinda kwenkqubo kwaye kufezekiswe ngokufaka iisampulu kwiintsuku zokuqala nezithathu ezilandelayo (nge-triplicate). Ukuphindaphindeka kwendlela kuhlolwe ngokubala i-RSD % kwiingqinisiso ezintathu ezahlukeneyo ze-melamine eyongeziweyo. Izifundo zokubuyisela zenziwe ukuze kuchongwe ukuchaneka. Umlinganiselo wokubuyela kwimeko yesiqhelo ngendlela yokukhupha ubalwa kumanqanaba amathathu oxinzelelo lwe-melamine (0.1, 1.2, 2) kwiisampulu zefomyula yosana kunye nobisi olomileyo9,11,15.
Umlinganiselo oqikelelweyo wokutya okutyayo (i-EDI) umiselwe kusetyenziswa le fomyula ilandelayo: i-EDI = i-Ci × i-Cc/BW.
Apho iCi ingumlinganiselo ophakathi wemelamine, iCc ngumlinganiselo wobisi olusetyenziswayo kwaye iBW ngumlinganiselo wobunzima babantwana.
Uhlalutyo lwedatha lwenziwe kusetyenziswa i-SPSS 24. Ukuhambelana kwavavanywa kusetyenziswa uvavanyo lweKolmogorov-Smirnov; yonke idatha yayiluvavanyo olungelulo olwe-parametric (p = 0). Ke ngoko, uvavanyo lweKruskal-Wallis kunye novavanyo lweMann-Whitney zisetyenzisiwe ukufumanisa umahluko obalulekileyo phakathi kwamaqela.
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