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  • Determination of urinary levels of leukotriene B(4) using ad highly specific and sensitive methodology based on automatic MEPS combined with UHPLC-PDA analysis.

Determination of urinary levels of leukotriene B(4) using ad highly specific and sensitive methodology based on automatic MEPS combined with UHPLC-PDA analysis.

Talanta (2015-10-11)
Rosa Perestrelo, Catarina L Silva, José S Câmara
ABSTRACT

Leukotriene B4 (LTB4) is a potent mediator of inflammation and plays a key function in the pathophysiology of chronic asthma. Detectable urinary levels of LTB4, arises from the activation of leukotriene pathways. In this study an ultra-fast, selective and sensitive analytical method based on semi-automatic microextraction by packed sorbents (MEPS) technique, using a new digitally controlled syringe (eVol®) combined with ultra-high pressure liquid chromatography (UHPLC), is proposed for the measurement of urinary LTB4 (U-LTB4) levels in a group of asthmatic patients (APs) and healthy controls (CTRL). Important parameters affecting MEPS performance, namely sorbent type, number of extraction cycles (extract-discard) and elution volume, were evaluated. The optimal experimental conditions among those investigated for the quantification of U-LTB4 in urine samples were as follows: porous graphitic carbon sorbent (PGC), 10 extractions cycle (10×250 μL of sample) and LTB4 elution with 100 μL of acetonitrile. The UHPLC optimum conditions resulted in a mobile phase consisting of 95% (v/v) of acid aqueous solution (v/v), and acetonitrile 5% (v/v); flow rate of 500 µL/min, and a column temperature of 37±0.1 °C. Under optimized conditions the proposed method exhibit good selectivity and sensitivity LOD (0.37 ng/mL) and LOQ (1.22 ng/mL). The recovery ranging from 86.4 to 101.1% for LTB4, with relative standard deviations (% RSD) no larger than 5%. In addition, the method also afforded good results in terms of linearity (r(2)>0.995) within the established concentration range, with a residual deviation for each calibration point below 6%, and intra- and inter-day repeatability in urine samples with RSD values lower than 4 and 5%, respectively. The application of the method to urine samples revealed a tendency towards the increased urinary LTB4 levels in APs (5.42±0.17 ng/mL) when compared to those of CTRL group (from ND to 1.9 ng/mL). Urinary measurement of LTB4 may be an interesting and non-invasive option to assess control of asthma.

MATERIALS
Product Number
Brand
Product Description

Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 85 μm (CAR/PDMS), needle size 24 ga, for use with manual holder, StableFlex fiber
Supelco
SPME Portable Field Sampler, coating CAR/PDMS
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 85 μm (CAR/PDMS), needle size 23 ga, StableFlex, for use with autosampler
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 23 ga, StableFlex, for use with manual holder or autosampler, fiber L 2 cm
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 23 ga, StableFlex, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 7 μm (PDMS), needle size 23 ga, for use with autosampler
Supelco
SPME fiber assembly polyacrylate (PA), df 85 μm (PA), for use with autosampler, needle size 24 ga
Supelco
SPME fiber assembly polyacrylate (PA), df 85 μm (PA), for use with manual holder, needle size 24 ga
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 24 ga, StableFlex, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 100 μm (PDMS), for use with autosampler, needle size 23 ga
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), needle size 23 ga, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 30 μm (PDMS), needle size 24 ga, for use with autosampler
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), needle size 23 ga, for use with manual holder
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 24 ga, for use with manual holder
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 24 ga, StableFlex
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 7 μm (PDMS), needle size 24 ga, for use with manual holder
Supelco
SPME Portable Field Sampler, coating PDMS
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 100 μm (PDMS), needle size 24 ga, for use with manual holder
Supelco
SPME fiber assembly polyacrylate (PA), df 85 μm (PA), for use with autosampler, needle size 23 ga
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 85 μm (CAR/PDMS), needle size 24 ga, StableFlex, for use with autosampler
Supelco
SPME Sampling Stand, for use with 15 mL vials
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 100 μm (PDMS), for use with manual holder, needle size 23 ga
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), needle size 24 ga, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 30 μm (PDMS), needle size 24 ga, for use with manual holder
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 7 μm (PDMS), needle size 24 ga, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 100 μm (PDMS), for use with autosampler, needle size 24 ga
Supelco
SPME Sampling Stand, for use with 4 mL vials
Supelco
SPME Portable Field Sampler, coating PDMS/DVB
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), for use with manual holder, needle size 24 ga
Supelco
SPME-OC Fiber Assembly, Polydimethylsiloxane/Divinylbenzene (PDMS/DVB), df 75 μm (Coating thickness includes 65 μm coating + 10 μm OC (overcoating)), needle size 23 ga, pkg of 3 ea, fiber L 1 cm