diff --git a/components/CertificateMinter.js b/components/CertificateMinter.js
index 5db8afa..8bf1285 100644
--- a/components/CertificateMinter.js
+++ b/components/CertificateMinter.js
@@ -4,7 +4,7 @@ import { ethers } from 'ethers';
 import { abi, NFT_CONTRACT_ADDRESS } from "../constants/index";
 
 const CertificateMinter = () => {
-  const [recipient, setRecipient] = useState('');
+  const [certificateId, setCertificateId] = useState('');
   const [userName, setUserName] = useState('');
   const [surName, setSurName] = useState('');
   const [email, setEmail] = useState('');
@@ -18,14 +18,19 @@ const CertificateMinter = () => {
         const signer = provider.getSigner();
         const certificateContract = new ethers.Contract(NFT_CONTRACT_ADDRESS, abi, signer);
 
-        await certificateContract.mintCertificate(recipient, userName, surName, email, companyName);
+        await certificateContract.mintCertificate(certificateId, userName, surName, email, companyName);
         alert('Certificate minted successfully!');
       } else {
         alert('Please connect your wallet');
       }
     } catch (error) {
       console.error('Error minting certificate:', error);
-      alert('Error minting certificate. Please check the console for details.');
+
+      if (error.code === 4001) {
+        alert('Certificate already issued');
+      } else {
+        alert('Error minting certificate. Please check the console for details.');
+      }
     }
   };
 
@@ -33,28 +38,28 @@ const CertificateMinter = () => {
     <div>
       <h2>Certificate Minter</h2>
       <label>
-        Recipient Address:
-        <input type="text" value={recipient} onChange={(e) => setRecipient(e.target.value)} style={{ color: 'black' }} />
+        Certificate ID:
+        <input type="text" value={certificateId} onChange={(e) => setCertificateId(e.target.value)} style={{ color: 'black' }} />
       </label>
       <br />
       <label>
         Name:
-        <input type="text" value={userName} onChange={(e) => setUserName(e.target.value)} style={{ color: 'black' }}/>
+        <input type="text" value={userName} onChange={(e) => setUserName(e.target.value)} style={{ color: 'black' }} />
       </label>
       <br />
       <label>
         Surname:
-        <input type="text" value={surName} onChange={(e) => setSurName(e.target.value)} style={{ color: 'black' }}/>
+        <input type="text" value={surName} onChange={(e) => setSurName(e.target.value)} style={{ color: 'black' }} />
       </label>
       <br />
       <label>
         Email:
-        <input type="text" value={email} onChange={(e) => setEmail(e.target.value)} style={{ color: 'black' }}/>
+        <input type="text" value={email} onChange={(e) => setEmail(e.target.value)} style={{ color: 'black' }} />
       </label>
       <br />
       <label>
         Company Name:
-        <input type="text" value={companyName} onChange={(e) => setCompanyName(e.target.value)} style={{ color: 'black' }}/>
+        <input type="text" value={companyName} onChange={(e) => setCompanyName(e.target.value)} style={{ color: 'black' }} />
       </label>
       <br />
       <button onClick={mintCertificate}>Mint Certificate</button>
diff --git a/constants/index.js b/constants/index.js
index a426048..d72f84a 100644
--- a/constants/index.js
+++ b/constants/index.js
@@ -1,22 +1,4 @@
 export const abi = [
-	{
-		"inputs": [
-			{
-				"internalType": "address",
-				"name": "to",
-				"type": "address"
-			},
-			{
-				"internalType": "uint256",
-				"name": "tokenId",
-				"type": "uint256"
-			}
-		],
-		"name": "approve",
-		"outputs": [],
-		"stateMutability": "nonpayable",
-		"type": "function"
-	},
 	{
 		"inputs": [],
 		"stateMutability": "nonpayable",
@@ -125,39 +107,6 @@ export const abi = [
 		"name": "ERC721NonexistentToken",
 		"type": "error"
 	},
-	{
-		"inputs": [
-			{
-				"internalType": "address",
-				"name": "recipient",
-				"type": "address"
-			},
-			{
-				"internalType": "string",
-				"name": "userName",
-				"type": "string"
-			},
-			{
-				"internalType": "string",
-				"name": "surName",
-				"type": "string"
-			},
-			{
-				"internalType": "string",
-				"name": "email",
-				"type": "string"
-			},
-			{
-				"internalType": "string",
-				"name": "companyName",
-				"type": "string"
-			}
-		],
-		"name": "mintCertificate",
-		"outputs": [],
-		"stateMutability": "nonpayable",
-		"type": "function"
-	},
 	{
 		"inputs": [
 			{
@@ -249,82 +198,6 @@ export const abi = [
 		"name": "OwnershipTransferred",
 		"type": "event"
 	},
-	{
-		"inputs": [],
-		"name": "renounceOwnership",
-		"outputs": [],
-		"stateMutability": "nonpayable",
-		"type": "function"
-	},
-	{
-		"inputs": [
-			{
-				"internalType": "address",
-				"name": "from",
-				"type": "address"
-			},
-			{
-				"internalType": "address",
-				"name": "to",
-				"type": "address"
-			},
-			{
-				"internalType": "uint256",
-				"name": "tokenId",
-				"type": "uint256"
-			}
-		],
-		"name": "safeTransferFrom",
-		"outputs": [],
-		"stateMutability": "nonpayable",
-		"type": "function"
-	},
-	{
-		"inputs": [
-			{
-				"internalType": "address",
-				"name": "from",
-				"type": "address"
-			},
-			{
-				"internalType": "address",
-				"name": "to",
-				"type": "address"
-			},
-			{
-				"internalType": "uint256",
-				"name": "tokenId",
-				"type": "uint256"
-			},
-			{
-				"internalType": "bytes",
-				"name": "data",
-				"type": "bytes"
-			}
-		],
-		"name": "safeTransferFrom",
-		"outputs": [],
-		"stateMutability": "nonpayable",
-		"type": "function"
-	},
-	{
-		"inputs": [
-			{
-				"internalType": "address",
-				"name": "operator",
-				"type": "address"
-			},
-			{
-				"internalType": "bool",
-				"name": "approved",
-				"type": "bool"
-			}
-		],
-		"name": "setApprovalForAll",
-		"outputs": [],
-		"stateMutability": "nonpayable",
-		"type": "function"
-	},
 	{
 		"anonymous": false,
 		"inputs": [
@@ -352,11 +225,6 @@ export const abi = [
 	},
 	{
 		"inputs": [
-			{
-				"internalType": "address",
-				"name": "from",
-				"type": "address"
-			},
 			{
 				"internalType": "address",
 				"name": "to",
@@ -368,20 +236,7 @@ export const abi = [
 				"type": "uint256"
 			}
 		],
-		"name": "transferFrom",
-		"outputs": [],
-		"stateMutability": "nonpayable",
-		"type": "function"
-	},
-	{
-		"inputs": [
-			{
-				"internalType": "address",
-				"name": "newOwner",
-				"type": "address"
-			}
-		],
-		"name": "transferOwnership",
+		"name": "approve",
 		"outputs": [],
 		"stateMutability": "nonpayable",
 		"type": "function"
@@ -482,6 +337,39 @@ export const abi = [
 		"stateMutability": "view",
 		"type": "function"
 	},
+	{
+		"inputs": [
+			{
+				"internalType": "uint256",
+				"name": "certificateId",
+				"type": "uint256"
+			},
+			{
+				"internalType": "string",
+				"name": "userName",
+				"type": "string"
+			},
+			{
+				"internalType": "string",
+				"name": "surName",
+				"type": "string"
+			},
+			{
+				"internalType": "string",
+				"name": "email",
+				"type": "string"
+			},
+			{
+				"internalType": "string",
+				"name": "companyName",
+				"type": "string"
+			}
+		],
+		"name": "mintCertificate",
+		"outputs": [],
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
 	{
 		"inputs": [],
 		"name": "name",
@@ -540,6 +428,82 @@ export const abi = [
 		"stateMutability": "view",
 		"type": "function"
 	},
+	{
+		"inputs": [],
+		"name": "renounceOwnership",
+		"outputs": [],
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
+	{
+		"inputs": [
+			{
+				"internalType": "address",
+				"name": "from",
+				"type": "address"
+			},
+			{
+				"internalType": "address",
+				"name": "to",
+				"type": "address"
+			},
+			{
+				"internalType": "uint256",
+				"name": "tokenId",
+				"type": "uint256"
+			}
+		],
+		"name": "safeTransferFrom",
+		"outputs": [],
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
+	{
+		"inputs": [
+			{
+				"internalType": "address",
+				"name": "from",
+				"type": "address"
+			},
+			{
+				"internalType": "address",
+				"name": "to",
+				"type": "address"
+			},
+			{
+				"internalType": "uint256",
+				"name": "tokenId",
+				"type": "uint256"
+			},
+			{
+				"internalType": "bytes",
+				"name": "data",
+				"type": "bytes"
+			}
+		],
+		"name": "safeTransferFrom",
+		"outputs": [],
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
+	{
+		"inputs": [
+			{
+				"internalType": "address",
+				"name": "operator",
+				"type": "address"
+			},
+			{
+				"internalType": "bool",
+				"name": "approved",
+				"type": "bool"
+			}
+		],
+		"name": "setApprovalForAll",
+		"outputs": [],
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
 	{
 		"inputs": [
 			{
@@ -590,8 +554,44 @@ export const abi = [
 		],
 		"stateMutability": "view",
 		"type": "function"
+	},
+	{
+		"inputs": [
+			{
+				"internalType": "address",
+				"name": "from",
+				"type": "address"
+			},
+			{
+				"internalType": "address",
+				"name": "to",
+				"type": "address"
+			},
+			{
+				"internalType": "uint256",
+				"name": "tokenId",
+				"type": "uint256"
+			}
+		],
+		"name": "transferFrom",
+		"outputs": [],
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
+	{
+		"inputs": [
+			{
+				"internalType": "address",
+				"name": "newOwner",
+				"type": "address"
+			}
+		],
+		"name": "transferOwnership",
+		"outputs": [],
+		"stateMutability": "nonpayable",
+		"type": "function"
 	}
 ];
 
 export const NFT_CONTRACT_ADDRESS =
-	"0x402F88e39B21390Ff962fb4bF1EE05f335E7dA3c";
+	"0xe7Bf32841a34C053aBcE967E0bE787F4164536d9";
diff --git a/nftCert.sol b/nftCert.sol
index 72c8090..283d88b 100644
--- a/nftCert.sol
+++ b/nftCert.sol
@@ -10,6 +10,9 @@ contract Certificate is ERC721, Ownable {
     // Mapping to store additional information for each certificate
     mapping(uint256 => CertificateInfo) private certificateInfoMapping;
 
+    // Mapping to check if a certificate with a given name and wallet address has been issued
+    mapping(string => mapping(address => bool)) private issuedCertificates;
+
     struct CertificateInfo {
         string userName;
         string surName;
@@ -20,18 +23,25 @@ contract Certificate is ERC721, Ownable {
     constructor() ERC721("Certificate", "CERT") Ownable(msg.sender) {}
 
     function mintCertificate(
-        address recipient,
+        uint256 certificateId,
         string memory userName,
         string memory surName,
         string memory email,
         string memory companyName
-    ) external onlyOwner {
-        uint256 tokenId = nextCertificateId;
-        _safeMint(recipient, tokenId);
-        nextCertificateId++;
+    ) external {
+        // Check if the certificate with the given ID has already been issued
+        require(!issuedCertificates[userName][msg.sender], "Certificate already issued");
+
+        _safeMint(msg.sender, certificateId);
 
         // Store additional information using a mapping
-        _storeCertificateInfo(tokenId, userName, surName, email, companyName);
+        _storeCertificateInfo(certificateId, userName, surName, email, companyName);
+
+        // Mark the certificate as issued
+        issuedCertificates[userName][msg.sender] = true;
+
+        // Update the nextCertificateId only if the mint is successful
+        nextCertificateId = certificateId + 1;
     }
 
     function _storeCertificateInfo(