The current study aimed to investigate the levels of heavy metals [cadmium (Cd), zinc (Zn), arsenic (As), lead (Pb), and mercury (Hg)] in local rice varieties named Jamila (JM), Santana (STN), Kwandala (KW), and Sipi (SP) collected from Danbatta town of Kano State, Northwestern Nigeria. The samples of local rice varieties were digested using HNO3 and HCl as digestion acids in a ratio of 2:1 (v/v). The digested samples were later analyzed for heavy metals using atomic absorption spectrophotometer. Moreover, the health risk assessment of heavy metals by the consumption of local rice varieties among local children and adults was also estimated based on estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR). The concentrations of Cd, Zn, and Pb dry weight basis observed in the range of 0.002- 0.06, 0.02-20.0, and 1.16-14.2mg/kg, respectively. Hg was detected only in SP rice variety with a concentration of 0.022 mg/kg. Whereas, As was detected in STN (0.086 mg/kg), KW (0.006 mg/kg), and SP (0.028 mg/kg). The resulting data showed that Cd, Zn, Hg, and As were within the maximum permissible limits set by regulatory bodies. The EDI values ranged from 1.21E-5 - 1.21E-1 and 5.0E-6 – 5.0E-2 for children (24 kg body weight) and adults (70 kg body weight), respectively. The data of the non-carcinogenic risk assessment indicated that the THQ values of Cd, Hg, and As were less than the maximum permissible limit of 1.00 for both children and adults. The HI data showed the potentially high possible health risk of the heavy metals by the consumption of the studied local rice varieties, with Pb being the major contributor. Similarly, resulting data of TCR for Cd and Pb showed high cancer risk upon the consumption of the studied local rice varieties over a long time.

In this study, phthalonitrile derivative was prepared by a nucleophilic substitution reaction of 3-nitrophthalonitrile in the presence of K2CO3 as a base in a non-aqueous organic solvent. Cyclotetramerization of phthalonitrile in the presence of metal salt, Ni(II)) gave peripherally substituted metal phthalocyanine complexes. The structure of the synthesized compounds was characterized by different analytical tools such as 1H NMR, UV-Vis, and FT-IR spectrophotometry and cyclic voltammetry. The disappearance of the C≡N stretching vibration from the IR spectra of phthalonitrile was observed at 2230 cm−1. The FTIR vibration results for C=O, C=C and C-O were 1712cm-1, 1615 cm-1 and 1276 cm-1 respectively. Solubility of metal phthalocyanine complexes was found to be very low in common laboratory solvents such as tetrahydrofuran (THF) and dimethylformamide (DMF). The electronic spectrum of NiPc in dimethylformamide (DMF) showed intense Q absorption at 690 nm. UV-Vis spectra of phthalocyanines showed electronic spectra with two strong absorption bands, Q and B bands. The Q band was found in 600–750 nm and B at 300–400 nm for both. The thermal stability of the phthalocyanine derivative was checked by T.G.A and the degradation was observed to start at 309 oC, which showed that the complex could withstand relatively high temperature. It could therefore be concluded that the metal phthalocyanine prepared in this study showed suitably high thermal stability and can be used for various applications

Dietary exposure to toxic metals has been identified as a risk to human health due to large amounts of these metals disposed of in the environment either as industrial waste or other sources due to human activities. In this study, three species of fishes (Tilapia zilli, Clarias lazera and Barbus lagoensis) were obtained, air-dried, milled and digested. The digested samples were analyzed for cadmium, chromium, lead and mercury using atomic absorption spectrophotometer (AAS). The results of the analysis showed that the concentration of cadmium in Tilapia zilli (0.0088mg/kg) and Barbus lagoensis (0.5134mg/kg) were higher than the maximum permissible level (0.003mg/kg) of cadmium in food and water. Similarly, chromium concentration in Barbus lagoensis (0.069mg/kg) was higher than the permissible level (0.05mg/kg). Also, concentrations of lead in Clarias lazera (0.019mg/kg) and Barbus lagoensis (0.0739mg/kg) were above the maximum permissible level (0.01mg/kg) in food and water as recommended by the standard organization of Nigeria. The findings also revealed that mercury concentration in Tilapia zilli (0.0058mg/kg) was high and above the maximum permissible level (0.001mg/kg) stated in SON regulations. This study confirms the increased danger of consuming fish that is contaminated with these heavy metals, and if it is allowed to continue, long-term exposure may lead to kidney failure and other diseases associated with these heavy metals. Proper monitoring and enforcement by regulatory agencies are required.

Cobalt phthalocyanine was synthesized from 3-nitrophthalonitrile using phthalamide as a precursor. Nitration in position 3 of the phthalamide led to the formation of 3-nitrophthalamide; then dehydration bythionyl chloride in N, N-dimethylformamide led to the formation of 3- nitrophthalonitrile. Phthalonitrile derivative was prepared by a nucleophilic substitution reaction of 3 nitrophthalonitrile in the presence of K2CO3 as a base in a non aqueous organic solvent. Cyclotetramerization of phthalonitrilein in the presence of metal acetate, (Co(Ac)2.4H2O) gave peripherally substituted metal phthalocyanine complexes. The structure of the synthesized compounds was characterized by different analytical tools such as UV-Vis, FT-IR spectrophotometry and cyclic voltammetry The disappearance of the C≡N stretching vibration from the IR spectra of phthalonitrile wasobserved at 2230 cm−1. The FT-IR vibration results for cobalt phthalocyanine was found to be 1709cm-1, 1611 cm-1 and 1275 cm-1 for C=O, C=C and C-O respectively. Solubility of metal phthalocyanine complexes was found to be very low in common laboratory solvents such as tetrahydrofuran (THF) and dimethylformamide (DMF). The electronic spectrum of CoPc in dimethylformamide (DMF) showed intense Q absorption at 677 nm. UV-Vis spectra of phthalocyanines showed electronic spectra with two strong absorption bands, Q and B bands. The Q band was found in 600–750 nm and B at 300 400 nm for both. The thermal stability of the phthalocyanine derivative was checked by T.G.A and the degradation was observed to start at 300oC, which showed that the complex could withstand fairly high temperature. It could therefore be concluded that the metal phthalocyanine prepared in this study showed fairly high thermal stability and can be used for various applications such as dye.