diff --git a/SalesforceApiClient.cs b/SalesforceApiClient.cs
index f306042..4afffd6 100644
--- a/SalesforceApiClient.cs
+++ b/SalesforceApiClient.cs
@@ -18,11 +18,9 @@ namespace Salesforce.NET
     public class SalesforceApiClient
     {
         private const string ContextKey = "SalesforceApiContext";
+        private const string ApiVersion = "51.0";
 
         private readonly Task initializationTask;
-        private readonly string batchProcessingConnectionString;
-
-        const string apiVersion = "51.0";
 
         private SalesforceContext SalesforceContext
         {
@@ -524,7 +522,7 @@ namespace Salesforce.NET
         {
             await AssertInitializedAsync();
 
-            return UrlUtility.Combine(SalesforceContext.InstanceUrl, $"services/data/v{apiVersion}/{relativeApiUrl}");
+            return UrlUtility.Combine(SalesforceContext.InstanceUrl, $"services/data/v{ApiVersion}/{relativeApiUrl}");
         }
 
         private string GetObjectName<T>()
@@ -625,4 +623,4 @@ namespace Salesforce.NET
 
         #endregion
     }
-}
+}
\ No newline at end of file