| Lacidipine | Cardiovascular | LC/MS/MS | 20-5000 pg/mL | Human EDTA Plasma |
| Lamivudine | Infectious Disease | LC/MS/MS | 10-5000 ng/mL | Human EDTA Plasma |
| Lamotrigine | Central Nervous System Agents | LC/MS | 50-10000 ng/mL | Human EDTA Plasma |
| Lansoprazole | Gastrointestinal | LC/MS/MS | 2.5-2000 ng/mL | Human EDTA K3 Plasma |
| Lansoprazole | Gastrointestinal | LC/MS/MS | 2-2000 ng/mL | Human EDTA Plasma |
| Lapatinib | TBD | LC/MS/MS | 100-10000 ng/mL | Human EDTA Plasma |
| L-Citrulline | Cardiovascular | LC/MS/MS | 150-10000 ng/mL | Human EDTA Plasma |
| L-Citrulline | Cardiovascular | LC/MS/MS | 150-10,000 ng/mL | Human EDTA Plasma |
| L-Citrulline | Cardiovascular | LC/MS/MS | 500-20,000 ng/mL | Rat EDTA Plasma |
| L-Citrulline | Cardiovascular | LC/MS/MS | 500 - 20000 ng/mL | Rat EDTA Plasma |
| Leflunomide metabolite (A77 1726) | Immunology | LC/MS/MS | 40-16000 ng/ml | Human EDTA K3 plasma |
| Lercanidipine | Cardiovascular | LC/MS/MS | 25-10000 pg/mL | Human EDTA Plasma |
| Letrozole | Oncology | LC/MS/MS | 0.50-200 ng/mL | Human K3 EDTA Plasma |
| Leukotriene B4 | Miscellaneous | LC/MS/MS | 0.5-250 ng/mL | Rat EDTA Plasma |
| Leukotriene B4 | Miscellaneous | LC/MS/MS | 25-12500 pg/mL | Human EDTA Plasma |
| Leukotriene B4 | Miscellaneous | LC/MS/MS | 25-12500 pg/mL | Human Urine |
| Leuprolide | Oncology OR Endocrinology | LC/MS/MS | TBD | Human EDTA Plasma |
| Levetiracetam | Central Nervous System Agents | LC /MS/MS | 100-40000 ng/mL | Human EDTA Plasma |
| Levodopa | Central Nervous System Agents | LC/MS/MS | 10-6000 ng/mL | Human EDTA Plasma |
| Levofloxacin | Infectious Disease | HPLC/FLR | 100-50000 ng/mL | Human Serum/Sputum Homogenate |
| Levofloxacin | Infectious Disease | HPLC/FLR | 200-100000 ng/mL | Human Urine |
| Levomethadone; Dextromethadone | Miscellaneous | LC/MS/MS | 0.5-100 ng/mL | Human Lithium Heparinized Plasma |
| Levonorgestrel | Endocrinology | LC/MS/MS | 125-25000 pg/mL | Human EDTA Plasma |
| Levothyroxine (T4) | Endocrinology | RIA | 10-250 ng/mL | Human Serum |
| Lidocaine | Pain | LC/MS/MS | 1-250 ng/mL | Human EDTA K3 Plasma |
| Linezolid | Infectious Disease | LC/MS/MS | 100-20000 ng/mL | Human EDTA Plasma |
| Liothyronine | Endocrinology | RIA | 0.5-25 ng/mL | Human Serum |
| Lisinopril | Cardiovascular | LC/MS/MS | 0.5-50 ng/mL | Human EDTA Plasma |
| Loperamide | Gastointestinal | LC/MS/MS | 50-5000 pg/mL | Human EDTA Plasma |
| Loperamide | Gastointestinal | LC/MS/MS | 25-2500 pg/mL | Human EDTA Plasma |
| Loratadine; Descarboethoxy Loratadine | Respiratory | LC/MS/MS | 20-20000 pg/mL | Human EDTA Plasma |
| Lorazepam | Central Nervous System Agents | LC/MS/MS | 1-75 ng/mL | Human EDTA K3 Plasma |
| Lorazepam | Central Nervous System Agents | LC/MS/MS | 0.1-30 ng/mL | Human EDTA K3 Plasma |
| Lorazepam | Central Nervous System Agents | LC/MS/MS | 0.5-100 ng/mL | Human Heparinized Plasma |
| Losartan | Cardiovascular | LC/MS/MS | 2-800 ng/mL | Human EDTA K3 Plasma |
| Losartan | Cardiovascular | LC/MS/MS | 2-500 ng/mL | Human Plasma |
| Losartan; Losartan Carboxy Acid | Cardiovascular | LC/MS/MS | 2-800 ng/mL | Human Lithium Heparinized Plasma |
| Losartan; Losartan Carboxy Acid | Cardiovascular | LC/MS/MS | 2-800 ng/mL | Human EDTA Plasma |
| Losartan; Losartan Carboxy Acid | Cardiovascular | LC/MS/MS | 1-2000 ng/mL | Human EDTA Plasma |
| Lovastatin | Cardiovascular | LC/MS/MS | 200-10000 pg/mL | Human EDTA Plasma |
| Lovastatin Hydroxy acid | Cardiovascular | LC/MS/MS | 200-10000 pg/mL | Human EDTA Plasma |
| Luteinizing Hormone (LH) | Endocrinology | RIA | 3-200 mIU/mL | Human Serum |