diff --git a/app/Http/Controllers/PdfController.php b/app/Http/Controllers/PdfController.php
index 5f29047..c1615b8 100644
--- a/app/Http/Controllers/PdfController.php
+++ b/app/Http/Controllers/PdfController.php
@@ -71,6 +71,17 @@ class PdfController extends Controller
             ], 400);
         }
 
+        $grExists = GRMaster::where('plant_id', $plantId)
+            ->where('gr_number', $data['gr_number'])
+            ->first();
+
+        if (!$grExists) {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => "GR Number {$data['gr_number']} not found for plant {$data['plant_code']}!"
+            ], 404);
+        }
+
         $scannedBy = $data['scanned_by'] ?? null;
 
         if ($scannedBy == '' || $scannedBy == null) {
@@ -146,6 +157,45 @@ class PdfController extends Controller
             ], 400);
         }
 
+        $missingSerialsByItem = [];
+
+        foreach ($data['item_codes'] as $item) {
+            $itemCode = $item['item_code'];
+            $serialNumbers = $item['serial_numbers'];
+
+            // Get the item id
+            $itemObj = Item::where('plant_id', $plantId)
+                ->where('code', $itemCode)
+                ->first();
+
+            if (!$itemObj) {
+                continue;
+            }
+
+            $itemId = $itemObj->id;
+
+            $foundSerials = GRMaster::where('plant_id', $plantId)
+                ->where('gr_number', $data['gr_number'])
+                ->where('item_id', $itemId)
+                ->whereIn('serial_number', $serialNumbers)
+                ->pluck('serial_number')
+                ->toArray();
+
+            $missingSerials = array_diff($serialNumbers, $foundSerials);
+
+            if (count($missingSerials) > 0) {
+                $missingSerialsByItem[$itemCode] = array_values($missingSerials);
+            }
+        }
+
+        if (count($missingSerialsByItem) > 0) {
+            return response()->json([
+                'status_code' => 'ERROR',
+                'status_description' => 'Some serial numbers not found in DB for given plant, GR number, and item!',
+                'missing_serials' => $missingSerialsByItem
+            ], 400);
+        }
+
         // foreach ($data['item_codes'] as $item)
         // {
         //     $itemCode = $item['item_code'];