internal standard

1,2-Distearoyl-sn-glycerol is an internal standard for the isolation and characterization of molecular species of 1,2-diacyl-sn-glycerol (DAG).

Enflurane (Efrane), a volatile anaesthetic, is a potent inhibitor of high conductance Ca2+-activated K+ channels of Chara australis. Enflurane is an internal standard in monitoring halogenated volatile anaesthetics by headspace gas chromatography-mass spectrometry. It allows rapid adjustments of anesthesia depth with little change in pulse or respiratory rate.

5-Methyl-2-Hexanol is a non-crystallizable secondary alcohol used as an internal standard for ultrasonic-assisted extraction of aroma compounds from grape brandies and aqueous-alcoholic wood extracts.

1,5,5-Trimethylhydantoin (TMH) serves as a non-isotopic internal standard (IS).

2-Hydroxy-6-methoxybenzoic acid (6-Methoxysalicylic acid) may be employed as internal standard for the determination of acetylsalicylic acid (aspirin, ASA) and its major metabolite, salicylic acid (SA),and exhibits significant analgesic effects

2-Ethylbutyric acid is an internal standard that can be used in calibration methods for VFA analytical standards for feces.

Candesartan-D4 is the deuterated form of Candesartan (TMSM-3481). It is an orally active Angiotensin II AT1 receptor blocker and PPAR-γ agonist with long-lasting antihypertensive effects, used as an internal standard in PK studies.

Doxepin-D3 hydrochloride is a deuterium-labeled, stable isotope-labeled analogue of doxepin hydrochloride, primarily used as an internal standard for quantitative analysis. Doxepin hydrochloride (T1540) is a tricyclic antidepressant (TCA) and uesd for treating depression, anxiety, and insomnia.

Fexofenadine-D6 is the deuterium substituent of Fexofenadine (T21390) and can be used as an internal standard for the determination of non-sofenadine concentrations in human plasma.

Antitumor agent-163 (Compound 3) serves as a photosensitizer in molecular-targeted photodynamic therapy (MT-PDT) aimed at carbonic anhydrase IX (CAIX). Under illumination at 540 nm, Antitumor agent-163 inactivates CAIX protein through singlet oxygen generation without affecting internal standard proteins such as α-tubulin, β-actin, and proliferating cell nuclear antigen (PCNA). It induces cell membrane damage and reduces cell viability with IC50 values of 0.2 μM for A549 and 0.05 μM for U87MG. Furthermore, Antitumor agent-163 demonstrates antitumor activity in mouse models.

Iobenguane-d4 is a deuterium-labeled, quadruple-labeled isotopic internal standard of iodinated benzylguanidine (MIBG). Iobenguane-d4 can be used for the accurate quantitative detection of iodinated benzylguanidine in biological samples (plasma, tissue, urine).

N,N-Dimethyl psychosine is a derivative of Psychosine. It can be utilized as an internal standard compound for the quantification of Psychosine in lipid extracts subjected to alkaline treatment.

PhIP-D3 is a deuterated internal standard for PhIP (T16525).

1-Palmitoyl-2-hydroxy-sn-glycero-3-PE is a naturally occurring lysophospholipid and endogenous metabolite used in biochemical experiments and drug synthesis research.

(±)-5,7-Dimethyltocol is a form of tocopherol. It has similar antioxidant activity to α-tocol, but lower activity than γ-tocol, in antioxidant assays using menhaden oil or squalene as substrates. It also increases microviscosity of rat liver liposomes containing phosphatidylcholine (PC) by 70.6% when used at a molar ratio of 0.2 to PC. (±)-Dimethyltocol has been used as an internal standard for the quantification of 5,7-tocol, α- and γ-tocopherol, and α- and γ-tocopheryl quinone by HPLC.

13C15-Nivalenol is intended for use as an internal standard for the quantification of nivalenol by GC- or LC-MS. Nivalenol (T13797) is a trichothecene mycotoxin that has been found inFusarium.1It is lethal to mice (LD50= 6.9 mg/kg).2Nivalenol (5, 10, and 15 mg/kg) also induces thymic, splenic, and Peyer's patch cell apoptosis in mice.3

3-Acetyldeoxy Nivalenol-13C17 is intended for use as an internal standard for the quantification of 3-Acetyldeoxy Nivalenol (T13493) by GC- or LC-MS. 3-Acetyldeoxy Nivalenol is a mycotoxin that has been found in F. graminearum.

4-deoxy Nivalenol-13C15 is intended for use as an internal standard for the quantification of 4-deoxy nivalenol by GC- or LC-MS. 4-deoxy Nivalenol (T15097) is a trichothecene mycotoxin that has been found inFusarium.1It binds to eukaryotic ribosomes and inhibits protein synthesis in mice when administered at doses ranging from 5 to 25 mg/kg. 4-deoxy Nivalenol (T15097) (0.1 and 0.2 mg/kg) induces emesis in pigs and decreases feed consumption in pigs when administered at a dose of 40 ppb in the diet.2It induces lethality in mice (LD50= 46-78 mg/kg).34-deoxy Nivalenol has been found inF. graminearum-infected cereal grains such as wheat, barley, and corn.

Guanfacine-13C,15N3 is intended for us as an internal standard for the quantification of guanfacine by GC- or LC-MS. Guanfacine (T22824) is an α2-adrenergic receptor (α2-AR) agonist with Kivalues of 93, 1,380, and 3,890 nM for α2A-, α2B-, and α2C-ARs, respectively, in a radioligand binding assay.1It has EC50values of 52, 288, and 602 nM for α2A-, α2B-, and α2C-ARs, respectively, for stimulated [35S]GTPγS binding. It also binds to imidazoline receptor 1 (Ki= 19 nM in a radioligand binding assay).2Guanfacine (0.3-5 mg/kg) binds to adrenergic receptors in the central nervous system and lowers blood pressure in hypertensive rats in a dose-dependent manner.3It also improves spatial working memory deficits induced by hypobaric hypoxia in rats.4Formulations containing guanfacine are used in the treatment of high blood pressure and attention deficit hyperactivity disorder (ADHD).

D-Fructose-13C6 can be used as an internal standard for the quantification of D-Fructose (TMSM-0907) by GC- or LC-MS.

2-deoxy-D-Glucose-13C is intended for use as an internal standard for the quantification of 2-deoxy-D-glucose by GC- or LC-MS. 2-deoxy-D-Glucose (T6742) is a glucose antimetabolite and an inhibitor of glycolysis. It inhibits hexokinase, the enzyme that converts glucose to glucose-6-phosphate, as well as phosphoglucose isomerase, the enzyme that converts glucose-6-phosphate to fructose-6-phosphate.

Oleic Acid-13C is intended for use as an internal standard for the quantification of oleic acid by GC- or LC-MS. Oleic Acid (T2O2668) is a monounsaturated fatty acid and a major component of membrane phospholipids that has been found in human plasma, cell membranes, and adipose tissue.1,2 It contributes approximately 17% of the total fatty acids esterified to phosphatidylcholine, the major phospholipid class in porcine platelets.1 Oleic acid inhibits collagen-stimulated platelet aggregation by approximately 90% when used at a concentration of 10 μg/ml. It also inhibits fMLF-induced neutrophil aggregation and degranulation by 55 and 68%, respectively, when used at a concentration of 5 μM, similar to arachidonic acid .3 Oleic acid (60 μM) induces release of intracellular calcium in human platelets.4

Lauric Acid-13C is intended for use as an internal standard for the quantification of Lauric Acid (TMSM-1441) by GC- or LC-MS. Lauric acid is a medium-chain saturated fatty acid. It has been found at high levels in coconut oil.1Lauric acid induces the activation of NF-κB and the expression of COX-2, inducible nitric oxide synthase (iNOS), and IL-1α in RAW 264.7 cells when used at a concentration of 25 μM.2

Octanoic Acid-13C is intended for use as an internal standard for the quantification of Octanoic Acid (T3946) by GC- or LC-MS. Octanoic acid is a medium-chain saturated fatty acid. It has been found in Teleme cheeses made from goat, ovine, or bovine milk.1 Octanoic acid is active against the bacteria S. mutans, S. gordonii, F. nucleatum, and P. gingivalis (IC80s = <125, <125, 1,403, and 2,294 μM, respectively).2 Levels of octanoic acid are increased in the plasma of patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, an inborn error of fatty acid metabolism characterized by hypoketotic hypoglycemia, medium-chain dicarboxylic aciduria, and intolerance to fasting.3,4