The chromatographic analysis was performed under ambient conditions with the Waters HPLC system employing a reversed phase Waters BDS Hypersil C18 column (100 x 4.6 mm, particle size of 5 μm) and a Waters scanning fluorescence detector (Model 474) with excitation and emission wavelengths of 230 and 295 nm, respectively. Mixture of phosphate buffer: acetonitrile (65:35, v/v; pH 10.2) at a flow rate of 1.0 mL/min was used as the mobile phase. Letrozole peaks were detected at a retention time of around 2.6 min. Three sets of calibration plots were constructed for method validation. Linearity was evaluated at 10 standards covering the concentration range of 5–5000 ng/mL and the lower limit of detection was 5 ng/ml. The intra and inter-assay precision for letrozole varied from 0.7–3.9% RSD for the above-mentioned range.
Model 474
Manufactured by Waters Corporation
Sourced in United States
The Model 474 is a laboratory instrument designed for the analysis of samples. It features precise measurements and a compact design to support various research and testing applications.
Automatically generated - may contain errors
Lab products found in correlation
Model 515, by Waters Corporation (2 mentions)
Waters 474, by Waters Corporation (2 mentions)
Model 717, by Waters Corporation (2 mentions)
Bds hypersil c18 column, by Waters Corporation (1 mentions)
Hplc system, by Waters Corporation (1 mentions)
Zorbax rx sil column, by Agilent Technologies (1 mentions)
Alliance 2695 separation module, by Waters Corporation (1 mentions)
Wako kit, by Fujifilm (1 mentions)
5 protocols using model 474
1
Sensitive Letrozole Quantification
2
Plasma Antioxidant Extraction and Analysis
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The plasma biochemical parameters were analyzed via colorimetric enzymatic assays with commercial kits; fasting glucose, triglycerides (TGs), and total cholesterol (TC) were assessed with Biosystems kits (Biosystems, Barcelona, Spain); and a Wako kit was used for free cholesterol (FC) (Wako Chemicals, Richmond, VA, USA). Cholesteryl esters (CEs) were calculated by subtracting the free cholesterol from the total cholesterol.
For plasma antioxidant extraction, one volume of plasma was first deproteinized with one volume of ethanol, and then, tocopherols and retinoids were extracted twice with two volumes of hexane, as previously described [15 (link)]. Tocopherols and retinoids were simultaneously separated using normal-phase HPLC with a Zorbax RX-SIL column (25 cm × 4.6 mm i.d.; 5 μm particle size; Agilent Technologies, Madrid, Spain) installed on a 2695 Alliance separation module (Waters, Barcelona, Spain) coupled with a fluorescence detector (model 474, Waters), as described previously [16 (link)].
For plasma antioxidant extraction, one volume of plasma was first deproteinized with one volume of ethanol, and then, tocopherols and retinoids were extracted twice with two volumes of hexane, as previously described [15 (link)]. Tocopherols and retinoids were simultaneously separated using normal-phase HPLC with a Zorbax RX-SIL column (25 cm × 4.6 mm i.d.; 5 μm particle size; Agilent Technologies, Madrid, Spain) installed on a 2695 Alliance separation module (Waters, Barcelona, Spain) coupled with a fluorescence detector (model 474, Waters), as described previously [16 (link)].
3
HPLC Analysis of Aflatoxin M1 in Milk
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HPLC (Alliance 2690 Separation Module System, Waters, Milford, MA) equipped with a fluorescence detector (Model 474, Waters) was used to separate and detect AFM1. A C18 reversephase column (Capsell PAK 4.6 mm ¥ 250 nm, 5 mm, Shisheido, Tokyo, Japan) was used to separate AFM1 and was maintained at 30°C in a column chamber. The mobile phase consisted of acetonitrile and water (25:75, v/v), and was pumped at a flow rate of 0.8 mL/min. AFM1 was detected at an excitation and emission wavelength of 365 and 450 nm, respectively. The R2 value of the linear regression for the AFM1 calibration curve was >0.999. Twenty microliter of the raw milk sample reconstituted in the mobile phase was injected into the system.
4
Amino Acid Analysis in Fish Samples
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Following the method previously described by Bosch et al. (2006) , the amino acid contents of the fish carcasses, diets and faeces were determined using a Waters HPLC system (Waters 474, Waters, Milford, MA, USA) consisting of two pumps (Model 515, Waters), an auto sampler (Model 717, Waters), a fluorescence detector (Model 474, Waters) and a temperature control module. Aminobutyric acid was added as an internal standard before hydrolysation. Amino acids were derivatised with AQC (6-aminoquinolyl-N-hydroxysuccinimidyl carbamate). Methionine and cysteine were determined separately as methionine sulphone and cysteic acid after oxidation with performic acid. Amino acids were separated with a C-17 reverse-phase column Waters Acc. Tag (150 mm x 3.9 mm) and then converted to methionine and cysteine.
Digestible amino acids were determined by faeces analysis: ADCAA
Digestible amino acids were determined by faeces analysis: ADCAA
5
Amino Acid Analysis of Aquatic Diets
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Amino acids of raw materials, experimental diets, fish (five per tank) and faeces were analysed prior to diet formulation through a Waters HPLC system (Waters 474, Waters, Milford, MA, USA) consisting of two pumps (Model 515, Waters), an auto sampler (Model 717, Waters), a fluorescence detector (Model 474, Waters) and a temperature control module, following the method described by Bosch et al. (2006) . Aminobutyric acid was added as an internal standard pattern before hydrolysation. The amino acids were derivatised with AQC (6aminoquinolyl-N-hydroxysuccinimidyl carbamate). Methionine and cysteine were determined separately as methionine sulphone and cysteic acid after oxidation with performic acid. Amino acids were separated with a C-18 reverse-phase column Waters Acc. Tag (150 mm × 3.9 mm) and then transformed to methionine and cysteine. Essential and non-essential amino acid content of different ingredients are shown in Supplemental material (S1). The amino acid content of fish is shown in Supplemental material (S2). Retention efficiencies of ingested amino acid (AAIRE) were calculated for each experimental group.
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