UPLC-MS/MS method for determination of retinol and α-tocopherol in serum using a simple sample pretreatment and UniSpray as ionization technique to reduce matrix effects

AbstractBackgroundOur goal was to develop a simple, rapid and precise ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the determination of retinol and α-tocopherol in serum. Currently published LC-MS/MS methods either require complex extraction procedures (liquid-liquid or solid-phase) or do not meet desirable specifications for imprecision in serum (coefficient of variation [CV] <6.8% and 6.9%, respectively).MethodsSample preparation consisted of a simple protein precipitation with ethanol and acetonitrile. Stable isotope-labeled internal standards (IS) and a homemade calibration curve were used for quantification. The analysis was performed using an Acquity I-class Xevo TQ XS LC-MS/MS. Chromatographic runtime was 6.0 min using a reversed phase gradient elution. UniSpray (US) as an ionization technique was compared to electrospray ionization (ESI). Analytical validation included matrix effect, recovery and trueness compared to National Institute of Standards and Technology (NIST) standards and United Kingdom National External Quality Assessment Service (UK NEQAS) samples.ResultsIntra- and inter-run CVs were <4.9% for retinol and <1.7% for α-tocopherol, both complying with desirable specifications for imprecision. Bias compared to NIST standards was <3.1% for both compounds. The method was linear over the entire tested range. The lower limit of quantification (LLOQ) with US was lower than with ESI for both retinol (0.022 vs. 0.043 mg/L) and α-tocopherol (0.22 vs. 0.87 mg/L). Matrix effects were not significant (<15%) for retinol. However, for α-tocopherol matrix effects of on average 54.0% were noted using ESI, but not with US.ConclusionsWe developed a fast, precise and accurate UPLC-MS/MS method for the determination of retinol and α-tocopherol in human serum using a single-step sample pretreatment. Ionization using US eliminated the matrix effects for α-tocopherol.

Download Full-text

Determination of Tranquilizers in Swine Urine by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

Molecules ◽

10.3390/molecules23123215 ◽

2018 ◽

Vol 23 (12) ◽

pp. 3215 ◽

Cited By ~ 1

Author(s):

Yingyu Wang ◽

Xiaowei Li ◽

Yuebin Ke ◽

Chengfei Wang ◽

Yuan Zhang ◽

...

Keyword(s):

High Performance ◽

Solid Phase ◽

Multiple Reaction Monitoring ◽

Gradient Elution ◽

Reversed Phase ◽

Single Step ◽

Swine Urine ◽

Relative Standard ◽

Positive Mode

A rapid, reliable, and sensitive method was developed for the determination of ten tranquilizers in swine urine. Sample preparation was based on solid-phase extraction, which combined isolation of the compounds and sample cleanup in a single step. Separation was performed on a reversed phase C18 column by gradient elution with a chromatographic run time of seven minutes, consisting of 0.1% formic acid in water and acetonitrile as the mobile phase. Multiple reaction monitoring in positive mode was applied for data acquisition. Matrix-matched calibration was used for quantification and good linearity was obtained with coefficients of determination higher than 0.99. The average recoveries of fortified samples at concentrations between 0.05 and 10 µg/L ranged from 85% to 106% with interday relative standard deviations of less than 13% in all cases. The limits of detection and limits of quantification obtained for tranquilizers in the urine were in the ranges of 0.03–0.1 µg/L and 0.05–0.25 µg/L, respectively. The applicability of the proposed method was demonstrated by analyzing real samples; diazepam was detected at concentrations between 0.3 and 0.6 μg/L.

Download Full-text

Multiresidue Determination of Eleven Quinolones in Milk by Liquid Chromatography with Fluorescence Detection

Journal of AOAC International ◽

10.1093/jaoac/88.6.1688 ◽

2005 ◽

Vol 88 (6) ◽

pp. 1688-1694 ◽

Cited By ~ 14

Author(s):

Guixiang Yang ◽

Baoyin Lin ◽

Zhenling Zeng ◽

Zhangliu Chen ◽

Xianhui Huang

Keyword(s):

Fluorescence Detection ◽

Solid Phase ◽

Gradient Elution ◽

Reversed Phase ◽

Phase Gradient ◽

Liquid Chromatographic Method ◽

Relative Standard ◽

Multiresidue Determination ◽

Liquid Chromatographic

Abstract A liquid chromatographic method with fluorescence detection was developed for simultaneous determination of norfloxacin, ofloxacin, ciprofloxacin, pefloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine in milk. The samples were extracted with 10% trichloroacetic acid/acetonitrile (9 + 1, v/v) and cleaned by Strata-X reversed-phase solid-phase extraction cartridges. The 11 quinolones were separated on a reversed-phase C18 column (Hypersil BDS-C18) with mobile phase gradient elution and detected with fluorescence by means of a wavelength program. The recoveries for milk fortified with the 11 quinolones at 3 levels were 69–88%, with acceptable relative standard deviations of <9% (intraday) and <14% (interday). The limits of detection were 23 μg/L for enrofloxacin, and 1–9 μg/L for the other 10 quinolones.

Download Full-text

LC–MS-MS Method for the Determination of Antidepressants and Benzodiazepines in Meconium

Journal of Analytical Toxicology ◽

10.1093/jat/bkaa012 ◽

2020 ◽

Vol 44 (6) ◽

pp. 580-588

Author(s):

A López-Rabuñal ◽

E Lendoiro ◽

M Concheiro ◽

M López-Rivadulla ◽

A Cruz ◽

...

Keyword(s):

Extraction Efficiency ◽

Solid Phase ◽

Gradient Methods ◽

Reversed Phase ◽

Process Efficiency ◽

Limit Of Quantification ◽

Mode 2 ◽

Positive Mode ◽

Compound Method

Abstract An LC–MS-MS method for the determination of 14 benzodiazepines (BZDs) (alprazolam, α-hydroxyalprazolam, clonazepam, bromazepam, diazepam, nordiazepam, lorazepam, lormetazepam, oxazepam, flunitrazepam, 7-aminoflunitrazepam, triazolam, midazolam and zolpidem) and 15 antidepressants (ADs) (amitriptyline, nortriptyline, imipramine, desipramine, clomipramine, norclomipramine, fluoxetine, norfluoxetine, sertraline, norsertraline, paroxetine, venlafaxine, desmethylvenlafaxine, citalopram and desmethylcitalopram) in meconium was developed and validated. Meconium samples (0.25 ± 0.02 g) were homogenized in methanol and subjected to mixed-mode cation exchange solid-phase extraction. Chromatographic separation was performed in reversed phase, with a gradient of 0.1% formic acid in 2 mM ammonium formate and acetonitrile. Two different chromatographic gradient methods were employed, one for the separation of ADs and another for BZDs. Analytes were monitored by tandem mass spectrometry employing electrospray positive mode in MRM mode (2 transitions per compound). Method validation included: linearity [n = 5, limit of quantification (LOQ) to 400 ng/g], limits of detection (n = 6, 1–20 ng/g), LOQ (n = 9, 5–20 ng/g), selectivity (no endogenous or exogenous interferences), accuracy (n = 15, 90.6–111.5%), imprecision (n = 15, 0–14.6%), matrix effect (n = 10, −73 to 194.9%), extraction efficiency (n = 6, 35.9–91.2%), process efficiency (n = 6, 20.1–188.2%), stability 72 h in the autosampler (n = 3, −8.5 to 9%) and freeze/thaw stability (n = 3, −1.2 to −47%). The method was applied to four meconium specimens, which were analyzed with and without hydrolysis (enzymatic and alkaline). The authentic meconium samples tested positive for alprazolam, α-hydroxyalprazolam, clonazepam, diazepam, nordiazepam, fluoxetine, norfluoxetine, clomipramine and norclomipramine. Therefore, the present LC–MS-MS method allows a high throughput determination of the most common BZDs and ADs in meconium, which could be useful in clinical and forensic settings.

Download Full-text

Determination of Flumorph Residues in Vegetables, Soil, and Natural Water by Solid-Phase Extraction Cleanup and High-Performance Liquid Chromatography with UV Detection

Journal of AOAC International ◽

10.1093/jaoac/91.6.1459 ◽

2008 ◽

Vol 91 (6) ◽

pp. 1459-1466 ◽

Cited By ~ 7

Author(s):

Ji-Ye Hu ◽

Yu-Chao Zhang ◽

Hai Yan

Keyword(s):

Solid Phase Extraction ◽

Natural Water ◽

High Performance ◽

Solid Phase ◽

Residue Analysis ◽

Reversed Phase ◽

Uv Detection ◽

Phase Extraction ◽

Limit Of Quantification

Abstract A method for high-performance liquid chromatographic (HPLC) determination of flumorph residues in cucumber, tomato, soil, and natural water was developed and validated. Primary secondary amine or octadecylsilyl (C18) solid-phase extraction cartridges were used for sample preparation. Reversed-phase HPLC with UV detection was used for separation and quantification of the pesticide. The combined cleanup and chromatographic method steps were sensitive and reliable for simultaneous determination of residues of the 2 isomers of flumorph in the studied samples. This method is characterized by recovery >97.9, coefficient of variation <6.2, and limit of quantification of 0.01 mg/kg, in agreement with directives for method validation in residue analysis. Flumorph residues in the samples were further confirmed by HPLC/mass spectrometry. The proposed method is fast, easy to perform, and could be used for monitoring of pesticide residues.

Download Full-text

Determination of Amoxicillin in Trout by Liquid Chromatography with UV Detection after Derivatization

Journal of AOAC International ◽

10.1093/jaoac/82.6.1345 ◽

1999 ◽

Vol 82 (6) ◽

pp. 1345-1352 ◽

Cited By ~ 9

Author(s):

Lambert K Sørensen ◽

Heļga Hansen ◽

Lena Snor

Keyword(s):

Solid Phase Extraction ◽

Muscle Tissue ◽

Solid Phase ◽

Reversed Phase ◽

Uv Detection ◽

Phase Extraction ◽

Phase Gradient ◽

Repeatability Standard Deviation ◽

Liquid Chromatographic

Abstract A liquid chromatographic (LC) method based on solid-phase extraction was developed for determination of amoxicillin in muscle tissue of rainbow trout. The compound was extracted in an aqueous solution by precipitation of organic material with a mixture of sulfuric acid and sodium tungstate. The extract was processed by solid-phase extraction on an end-capped phenyl sorbent, and concentrated on a divinylbenzene-co-ΛN-vinylpyrrolidone polymeric sorbent. The extract was derivatized and analyzed by reversed-phase gradient LC on a C18 column with UV detection at 323 nm. The method detection limit was 2.9 μg/kg. Mean recovery in muscle was 80.5% (range 10-200 μg/kg). The method was applied to fillets from trout offered feed containing amoxicillin in an aquaculture pilot plant. Amoxicillin was detected in muscle tissue shortly after administration but not 3 weeks later. The relative repeatability standard deviation for incurred residues in muscle tissue was 6.4% (range 11-143 μg/kg).

Download Full-text

Determination of retinol, alpha-tocopherol, and beta-carotene in serum by liquid chromatography with absorbance and electrochemical detection.

Clinical Chemistry ◽

10.1093/clinchem/33.9.1585 ◽

1987 ◽

Vol 33 (9) ◽

pp. 1585-1592 ◽

Cited By ~ 54

Author(s):

W A MacCrehan ◽

E Schönberger

Keyword(s):

Electrochemical Detection ◽

Chromatographic Separation ◽

Protein Denaturation ◽

Internal Standard ◽

Beta Carotene ◽

Gradient Elution ◽

Reversed Phase ◽

Alpha Tocopherol ◽

Phase Gradient

Abstract We describe a method for the determination of retinol, alpha-tocopherol, and beta-carotene in serum, using a liquid-chromatographic separation with wavelength-programmed ultraviolet/visible absorbance and amperometric electrochemical detection with a glassy carbon electrode. After protein denaturation and addition of an internal standard, tocol, 250-microL samples are twice extracted with hexane. The reversed-phase, gradient-elution chromatographic separation provides baseline resolution of: the all-trans isomer of retinol from the cis isomers, alpha- from gamma-tocopherol, and all-trans-beta-carotene from alpha-carotene and from cis-beta-carotene isomers. The linearity of response and the detection limits for the two detectors for the three analytes are measured. A comparison of the values obtained for serum extracts shows good agreement between the absorbance and electrochemical detectors.

Download Full-text

Determination of Mesalamine Related Impurities from Drug Product by Reversed Phase Validated UPLC Method

E-Journal of Chemistry ◽

10.1155/2011/382137 ◽

2011 ◽

Vol 8 (1) ◽

pp. 131-148 ◽

Cited By ~ 2

Author(s):

Trivedi Rakshit Kanubhai ◽

Patel Mukesh C ◽

Kharkar Amit R

Keyword(s):

Degradation Products ◽

Drug Product ◽

Gradient Elution ◽

Reversed Phase ◽

Forced Degradation ◽

Limit Of Quantification ◽

Release Formulation ◽

Delayed Release ◽

Related Substances

In the present study gradient reversed-phase UPLC method was developed for simultaneous determination and separation of impurities and degradation products from drug product. The chromatographic separation was performed on acquity UPLC BEH C18 column (50 mm×2.1 mm, 1.7 µm) using gradient elution. Other UPLC parameters which were optimised are flow rate, 0.7 mL/min; detection wavelength, 220 nm; column oven temperature, 40°C and injection volume 7 µL. Stability indicating capability was established by forced degradation experiments and separation of known degradation products. The method was validated as per International Conference on Harmonization (ICH) guideline. For all impurities and mesalamine, LOQ (limit of quantification) value was found precise with RSD (related standard daviation) of less than 2.0%. In essence, the present study provides an improved low detection limit and lower run time for evaluation of pharmaceutical quality of mesalamine delayed-release formulation. Moreover, the developed method was successfully applied for quantification of impurities and degradation products in mesalamine delayed-release formulation. The same method can also be used for determination of related substances from mesalamine drug substance.

Download Full-text

Simultaneous determination of 11 preservatives in cosmetics and pharmaceuticals by matrix solid-phase dispersion coupled with gas chromatography

Acta Chromatographica ◽

10.1556/1326.2019.00700 ◽

2020 ◽

Vol 32 (3) ◽

pp. 203-209

Author(s):

Yun-feng Liu ◽

Jia-ling Zhang ◽

Xue-fei Nie ◽

Ping Zhang ◽

Xiao-qing Yan ◽

...

Keyword(s):

Gas Chromatography ◽

Simultaneous Determination ◽

Matrix Effects ◽

Solid Phase ◽

Correlation Coefficients ◽

Sample Pretreatment ◽

Matrix Solid Phase Dispersion ◽

Phase Dispersion ◽

Flame Ionization

A convenient method was developed for simultaneous determination of 11 preservatives in cosmetics and pharmaceuticals. Matrix solid-phase dispersion had been optimized as the sample pretreatment technology, using Florisil as a dispersant, anhydrous sodium sulfate as a dehydrant, formic acid as an additive, and n-hexane and ethyl acetate as eluents successively, and followed by gas chromatography–flame ionization detection on a TR-5 capillary column. Experimental results showed that 11 preservatives were baseline separated within 22 min. Good linearities were observed in the concentration range of 0.53–250 μg/mL for all analytes, and there were also minor differences. All correlation coefficients (r) were more than 0.995. The average recoveries at 3 levels of spiked samples ranged from 80% to 124% with 0.9–12% intra-day RSD and 1.8–12% inter-day RSD. The limits of detection were less than 0.18 μg/mL for all analytes. Besides, there was no obvious matrix effect on the analytes. The conclusion was that the developed method was simple, cheap, accurate, precise, and environment-friendly, in addition to existing little matrix effects. It could be recommended to determine 11 preservatives individually or in any their combinations to not only in liquid and gel cosmetics but also in liquid medicine and ointment.

Download Full-text

An analytical procedure for the determination of different therapeutic drugs in surface waters

Water Science & Technology ◽

10.2166/wst.2009.339 ◽

2009 ◽

Vol 60 (2) ◽

pp. 449-458 ◽

Cited By ~ 2

Author(s):

Irena Baranowska ◽

Bartosz Kowalski

Keyword(s):

Analytical Procedure ◽

Solid Phase ◽

Beta Blockers ◽

Gradient Elution ◽

Reversed Phase ◽

Therapeutic Drugs ◽

Array Detectors ◽

Oasis Hlb ◽

Spe Method

An analytical procedure for the determination of 10 drugs belonging to three different therapeutic groups was analysed. Several compounds were investigated which comprise of beta-blockers: sotalol (SOT), metoprolol (MET), propranolol (PRO), carvedilol (CAR); corticosteroids: prednisolone (PRE), dexamethasone (DEX); analgesic, non-steroidal anti-inflammatory (NSAID): paracetamol (PAR), metamizole (MTZ), aspirin (ASP) and ketoprofen (KET). Reversed-phase liquid chromatography with gradient elution, fluorescence (FL) and diode array detectors (DAD) was applied for the selective investigation of the drugs. Three solvents were used as the mobile phase: methanol, 0.05% trifluoroacetic acid (TFA) in water and acetonitrile. The solid phase extraction (SPE) method using the Oasis HLB column was proposed for the preconcentration step. The recovery level for most of the drugs was above 80%. The low values of limits of detection (LOD) for PAR, SOT, MTZ, MET, SAL, PRO, PRE, CAR, DEX and KET were achieved: 106 ng L−1, 1,048 ng L−1, 2.48 ng L−1, 2.17 ng L−1, 16.5 ng L−1, 1.10 ng L−1, 160 ng L−1, 6.62 ng L−1, 76.5 ng L−1 and 45.2 ng L−1, respectively. The suggested method was used for the determination of drugs in spiked surface water.

Download Full-text

Determination of Benzoylurea Insecticides in Apples and Pears by Solid-Phase Extraction Cleanup and Liquid Chromatography with UV Detection

Journal of AOAC International ◽

10.1093/jaoac/82.1.213 ◽

1999 ◽

Vol 82 (1) ◽

pp. 213-216 ◽

Cited By ~ 7

Author(s):

Nicholas G Tsiropoulos ◽

Pipina G Aplada-Sarlis ◽

George E Miliadis

Keyword(s):

Solid Phase Extraction ◽

Solid Phase ◽

Gradient Elution ◽

Reversed Phase ◽

Phase Extraction ◽

Relative Standard ◽

Benzoylurea Insecticides ◽

Preliminary Extraction ◽

Liquid Chromatographic

Abstract A liquid chromatographic (LC) method was developed and statistically validated for simultaneous determination of 5 benzoylurea insecticides (di-flubenzuron, triflumuron, teflubenzuron, flufenoxuron, and lufenuron) in apples and pears. It involves preliminary extraction with ethyl acetate–sodium sulfate and cleanup on silica solid-phase extraction cartridges using dichloromethane–2-propanol (9 + 1) as eluant. The eluate is dried under nitrogen and redissolved in methanol. Benzoylurea insecticides are determined by reversed-phase LC with gradient elution at 42°C and UV diode array detection. Recoveries from samples fortified with the 5 insecticides at 0.02–0.5 mg/kg ranged from 83 to 102% for apples and from 75 to 99% for pears. Relative standard deviations were 0–12%. Limits of detection were 0.01 mg/kg for apples and 0.02 mg/kg for pears.

Download Full-text