 const substances = [
 
  {
    "item": "Lime juice",
    "ph_lower": 2.0,
    "ph_upper": 2.35,
    "category": "Food/Beverage",
    "note": "Similar to lemon but often slightly more acidic; great for testing strong acid colors on pH paper; pH can vary slightly with variety (e.g., Key limes lower)",
    "image": "/substances/lime_juice.jpg"
  },

  {
    "item": "Cola / soda pop",
    "ph_lower": 2.5,
    "ph_upper": 3.5,
    "category": "Beverage",
    "note": "Phosphoric + carbonic acid combo gives low pH; carbonation can affect strip reading slightly — test fresh-opened for best accuracy",
    "image": "/substances/cola.jpg"
  },
 
  {
    "item": "Grapes (most varieties)",
    "ph_lower": 2.8,
    "ph_upper": 3.3,
    "category": "Food",
    "note": "Tartaric and malic acids drive low pH; Concord grapes often more acidic — juice or fresh for calibration",
    "image": "/substances/grapes.jpg"
  },
  {
    "item": "Strawberries",
    "ph_lower": 3.0,
    "ph_upper": 3.9,
    "category": "Food",
    "note": "Citric and malic acids give bright tartness; ripeness affects pH (riper = slightly higher) — vibrant color helps with visual strip matching",
    "image": "/substances/strawberries.jpg"
  },
  {
    "item": "Raspberries",
    "ph_lower": 3.2,
    "ph_upper": 3.7,
    "category": "Food",
    "note": "Citric acid dominant for sharp flavor; similar to strawberries but often a bit less variable — good berry reference",
    "image": "/substances/raspberries.jpg"
  },

  {
    "item": "Apples (eating/fresh)",
    "ph_lower": 3.3,
    "ph_upper": 4.0,
    "category": "Food",
    "note": "Malic acid gives tartness (Granny Smith lower, sweeter varieties higher) — common household item for easy testing",
    "image": "/substances/apple.jpg"
  },

  {
    "item": "Ketchup",
    "ph_lower": 3.89,
    "ph_upper": 3.92,
    "category": "Condiment",
    "note": "Tomatoes + vinegar/acids for tight range; very stable — useful narrow-range reference near 4.0",
    "image": "/substances/ketchup.jpg"
  },

];