&lt;title&gt;Linearity and effective optical pathlength of liquid waveguide capillary cells&lt;/title&gt;

Belz, Mathias; Dress, Peter; Sukhitskiy, Aleksandr; Liu, Suyi

doi:10.1117/12.371300

“…The spectral range of the Cary-50 is 190-1,100 nm, the spectral resolution is 0.15 nm, and the detection range is 0.0005-3 absorbance units (AU). The effective optical pathlength of the LWCC-2 capillary cell was determined to be 0.4837 m with a holmium wavelength calibration standard (Sigma-Aldrich) following the procedure of Belz et al (1999). The standard, 15% weight/ volume in perchloric acid arrived in a sealed glass ampule, was diluted 100-fold with deionized water (Milli-Q, Millipore), and was stored in an amber glass bottle at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Variation in colloidal chromophoric dissolved organic matter in the Damariscotta Estuary, Maine

Floge

¹

,

Wells

²

2007

Limnology & Oceanography

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The relationship between chromophoric dissolved organic matter (CDOM), colloidal DOM (.1 kDa), and phytoplankton biomass in marine waters of the Damariscotta estuary, Maine, was studied using flow field-flow fractionation (flow FFF). The goal was to determine whether temporal variability in CDOM in this region is due in part to rapid cycling of marine colloids. CDOM absorption of filtered (0.2 mm) seawater correlated positively with colloidal absorbance (r 2 5 0.772, p 5 0.021). We observed changes in colloidal size spectra and CDOM optical properties associated with phytoplankton biomass. In particular, a significant positive correlation was found between the ,18 kDa colloidal fraction and chlorophyll a (Chl a) (r 2 5 0.819, p 5 0.013). While we did not find significant relationships between Chl a and either CDOM absorption or the spectral slope of filtered seawater (r 2 and p values of 0.079, 0.590 and 0.111, 0.519, respectively), we did observe patterns of higher CDOM absorption and spectral slopes following periods of increased phytoplankton biomass. The spectral slope of colloidal material often was significantly lower than that of filtered seawater and normally varied significantly with colloidal size. These findings show that colloidal processes can contribute to CDOM optical signatures in coastal waters.

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“…At wavelengths <350 nm, the difference between the two spectra increased to a maximum of 0.08 m -1 at 240 nm, with a corresponding standard deviation of 0.13 m -1 . The holmium standard was used to determine the effective optical pathlengths of the type I and type II waveguides using the method of Belz et al (1999). This procedure calibrates the pathlength at a single wavelength (536 nm).…”

Section: Assessmentmentioning

confidence: 99%

“…One method of increasing spectroscopic sensitivity is to increase the sample cell pathlength via custom long-path cells (Bricaud et al 1981;Peacock et al 1994) or capillary optical waveguide cuvettes (D'Sa et al 1999;Belz et al 1999;Dallas and Dasgupta 2004). Long-pathlength liquid core waveguides (LCW), introduced commercially by World Precision Instruments in 1997, can be used for high-sensitivity UV-visible absorbance measurements of CDOM.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2009

Limnology & Ocean Methods

0

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In the past decade, technological advances in optical sensors have facilitated an increased understanding of the relationship between optical characteristics and biogeochemistry of our oceans. In particular, long-pathlength liquid core waveguide cells (LCWs) are being used to "map" chromophoric dissolved organic matter (CDOM), as a biogeochemical tracer, in various coastal and open ocean regions. At present, two LCW cell types are used in the study of marine CDOM, and concerns about discrepancies in data collected with the different cell types and problems with baseline offsets have arisen. We conducted a direct comparison of absorption coefficient spectra of a dissolved spectrophotometric standard, molecular weight standard (MWS), and dilution series of natural seawater obtained in type I and type II LCWs to assess data agreement and potential colloidmediated biases. Although no statistical difference was observed for the dissolved standard, we found the type I to have a slight bias toward higher absorption coefficient values for MWS 14-150 kDa (within 95% confidence interval) and natural seawater. Seawater CDOM spectral slopes differed significantly between type I and type II LCWs, with a maximum difference in slope of 0.0006 nm -1 . Fastidious elimination of microbubbles from the capillary cells greatly reduced baseline offsets and markedly improved CDOM spectral slope precision.

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“…Light is confined within the liquid core by total internal reflection at or near the cell wall when the refractive index (n) of the liquid is higher than the refractive index of the cell wall or covering ( Fig. 1) (Belz et al 1999;D'Sa et al 1999;Byrne and Kaltenbacher 2001). There are two types of liquid core waveguides (types I and II), which differ solely in the composition of cell wall material.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, Green and Blough (1994) found that the absorption coefficient spectra of CDOM isolated via solid-phase C 18 extraction differed greatly from that found in the original water sample. One method of increasing spectroscopic sensitivity is to increase the sample cell pathlength via custom long-path cells (Bricaud et al 1981;Peacock et al 1994) or capillary optical waveguide cuvettes (D'Sa et al 1999;Belz et al 1999;Dallas and Dasgupta 2004). Long-pathlength liquid core waveguides (LCW), introduced commercially by World Precision Instruments in 1997, can be used for high-sensitivity UV-visible absorbance measurements of CDOM.…”

Section: Introductionmentioning

confidence: 99%

Analytical intercomparison between type I and type II long‐pathlength liquid core waveguides for the measurement of chromophoric dissolved organic matter

Floge

¹

,

Hardy

²

,

Boss

³

et al. 2009

Limnology & Ocean Methods

View full text Add to dashboard Cite

In the past decade, technological advances in optical sensors have facilitated an increased understanding of the relationship between optical characteristics and biogeochemistry of our oceans. In particular, long-pathlength liquid core waveguide cells (LCWs) are being used to "map" chromophoric dissolved organic matter (CDOM), as a biogeochemical tracer, in various coastal and open ocean regions. At present, two LCW cell types are used in the study of marine CDOM, and concerns about discrepancies in data collected with the different cell types and problems with baseline offsets have arisen. We conducted a direct comparison of absorption coefficient spectra of a dissolved spectrophotometric standard, molecular weight standard (MWS), and dilution series of natural seawater obtained in type I and type II LCWs to assess data agreement and potential colloidmediated biases. Although no statistical difference was observed for the dissolved standard, we found the type I to have a slight bias toward higher absorption coefficient values for MWS 14-150 kDa (within 95% confidence interval) and natural seawater. Seawater CDOM spectral slopes differed significantly between type I and type II LCWs, with a maximum difference in slope of 0.0006 nm -1 . Fastidious elimination of microbubbles from the capillary cells greatly reduced baseline offsets and markedly improved CDOM spectral slope precision.

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<title>Linearity and effective optical pathlength of liquid waveguide capillary cells</title>

Cited by 27 publications

References 1 publication

Variation in colloidal chromophoric dissolved organic matter in the Damariscotta Estuary, Maine

Variation in colloidal chromophoric dissolved organic matter in the Damariscotta Estuary, Maine

Untitled

Analytical intercomparison between type I and type II long‐pathlength liquid core waveguides for the measurement of chromophoric dissolved organic matter

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