Isopropanol lc ms grade

The analytical standard of PALBO was provided by Toronto Research Chemicals (Toronto, Canada, product N. P139900, lot N. 1-ZPK-125-1), RIBO hydrochloride (product N. M15373, lot N. 12195) and LETRO (product N. L6545, lot N. 0000028530) were supplied by Merck-Sigma Aldrich. Stable isotopically labeled internal standards D₆-RIBO (product N. C4503, lot N. PO-ALS-18-007-B1), D₈-PALBO (product N. C5108, lot N. SA-ALS-15-120-P1) and ¹³C₂,¹⁵N₂-LETRO (product N. C595, lot N. JA-ALS-18-104-P3) were synthesized by Alsachim (Illkirch Graffenstaden, France). LC-MS grade isopropanol was supplied by Merck-Sigma Aldrich while LC-MS grade methanol was purchased from Carlo-Erba (Milano, Italy). “Type 1” ultrapure water was produced at our department by a Milli-Q^® IQ 7000 system (Merck). Drug-free plasma/K-EDTA from healthy volunteers to prepare daily standard calibration curves and quality control samples (QCs) was provided by the transfusion unit of our institution.

LC-MS-grade water, methanol
(MeOH), and acetonitrile
were purchased from Altmann Analytik GmbH & Co. KG, Germany. LC-MS-grade
isopropanol, the herbicide isoproturon (analytical standard), the
benzodiazepines diazepam (analytical standard) and midazolam (analytical
standard), and the drug ketamine (analytical standard) were purchased
from Sigma-Aldrich Chemie GmbH, Germany. The test solutions were prepared
at a concentration of 1 μg/L to 8 mg/L. As a sample solvent
for the extraction matrix, LC-MS-grade water and MeOH, mulled wine
(“Heißer Hirsch”, Acht Grad plus GmbH, Germany),
tap water (Hannover, Germany), stream water (Mühlenbach, Neukloster,
Germany), spring water (Rosenborn, Harsefeld, Germany), and river
water (Leine, Hannover, Germany) are used.

Ultrapure water was obtained by purifying demineralized water in a Direct-Q 3 UV-R system (Merck, Millipore, Darmstadt, Germany). LC-MS-grade acetonitrile, methanol, ammonium formate, and HPLC-grade chloroform were purchased from Carl Roth GmbH and Co. KG (Karlsruhe, Germany). LC-MS-grade isopropanol was from Merck KgaA (Darmstadt, Germany). LC-MS tuning mix and hexamethoxyphosphazine, used as tuning standards, as well as hexakis(1H,1H,3H-tetrafluoropropoxy)phosphazine, and purine, used as lock masses, were purchased from Agilent Technologies (City of Santa Clara, CA, USA). Acetic acid, ethanol, sodium carbonate, disodium hydrogen phosphate, sodium chloride, potassium chloride, and potassium dihydrogen phosphate (all analytical-grade) were from Carl Roth GmbH and Co. KG (Karlsruhe, Germany). 2,2’-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), fluorescein, and trolox (all analytical-grade) were from Sigma-Aldrich Chemie GmbH (Deisenhofen, Germany). 2,2’-Azobis(2-methylpropionamidine) dihydrochloride (AAPH), potassium peroxodisulphate, and gallic acid (both of analytical-grade) were purchased from Fisher Scientific GmbH (Schwerte, Germany). Folin-Ciocalteu phenol reagent (analytical-grade) was obtained from Merck KgaA (Darmstadt, Germany). Acetone (analytical-grade) was obtained from VWR International LLC (Fontenay-sous-Bois, France).