Zinc is frequently present at trace

Zinc is frequently present at trace level in cadmium and their compounds . However, the spectrophotometric determination of this element in these matrices is troublesome because many of the chromogenic reagents proposed also react with cadmium.
Numerous methods have been published for such determination. However, they are not simple and usually require extensive and laborious steps for the separation of zinc from cadmium, using procedures which involve: liquid – liquid extraction [1 – 6] of zinc or cadmium, ion ex- change [7,8], and precipitation [9].
This paper proposes a method for the separation and determination of zinc in cadmium matrices based on solid-phase extraction (SPE) of zinc in the form of thiocyanate complexes by the polyurethane foam (PU foam).
The PU foam has been used as a solid sorbent on a wide variety of inorganic and organic compounds from different media. It was first proposed by Bowen [10] in 1970. Braun [11–13] and Palagyi [14] have described reviews about the use of PU foam in procedures of separation and preconcentration.
The use of PU foam for zinc extraction has been proposed by several authors [15–18]. The extraction mechanism of the zinc by the PU foam in the form of thiocyanate complexes has been studied by Moody et al. [15]. Maloney et al. [16] have proposed a procedure for simultaneous extraction of zinc, cobalt(II), iron(III) and cadmium(II) from thiocyanate medium by PU foam. Nickel is not extracted. Braun and Abbas [17] have proved that zinc, mercury and indium are extracted quantitatively by PU foam in the form of thiocyanates complexes. Hamza et al. [18] have used PU foam treated with dithizone for the extraction of zinc and bis- muth.
Zinc(II) reacts instantaneously with 4-(2- pyridylazo)-resorcinol (PAR) [19,20] in the range of pH from 9.0 to 10.0, forming a com- plex with maximum absorption at 496 nm and molar absorptivity of 8.30×104 l mol− 1 cm− 1. Cadmium(II) also reacts with PAR, forming a
complex with absorption maximum at 510 nm
and molar absorptivity of 8.12 × 104 l cm−1.
mol − 1

Results (Thai) 1:

Zinc is frequently present at trace level in cadmium and their compounds . However, the spectrophotometric determination of this element in these matrices is troublesome because many of the chromogenic reagents proposed also react with cadmium.Numerous methods have been published for such determination. However, they are not simple and usually require extensive and laborious steps for the separation of zinc from cadmium, using procedures which involve: liquid – liquid extraction [1 – 6] of zinc or cadmium, ion ex- change [7,8], and precipitation [9].This paper proposes a method for the separation and determination of zinc in cadmium matrices based on solid-phase extraction (SPE) of zinc in the form of thiocyanate complexes by the polyurethane foam (PU foam).The PU foam has been used as a solid sorbent on a wide variety of inorganic and organic compounds from different media. It was first proposed by Bowen [10] in 1970. Braun [11–13] and Palagyi [14] have described reviews about the use of PU foam in procedures of separation and preconcentration.การใช้โฟม PU สำหรับสกัดสังกะสีได้รับการเสนอชื่อ โดยผู้เขียนหลาย [15-18] กลไกการสกัดสังกะสีโดยโฟม PU ในรูปแบบของคอมเพล็กซ์ thiocyanate ได้ถูกศึกษาโดยมู้ดดี้ et al. [15] Maloney et al. [16] ได้เสนอขั้นตอนสำหรับพร้อมสกัดสังกะสี cobalt(II), iron(III) และ cadmium(II) จาก thiocyanate ปานกลาง โดย PU โฟม ไม่มีสกัดนิกเกิล Braun และระเบิด [17] ได้พิสูจน์ว่า สังกะสี ปรอท และอินเดียมที่สกัด quantitatively โดย PU โฟมในรูปแบบของคอมเพล็กซ์ thiocyanates Al. ร้อยเอ็ดฮัมซะฮ์ [18] ได้ใช้โฟม PU รับ dithizone การสกัดสังกะสีและ bis muthZinc(II) ปฏิกิริยากับ 4-(2-pyridylazo)-resorcinol (หุ้น) [19,20] ในช่วงของ pH จาก 9.0 10.0 ขึ้นรูปเพล็กซ์ com มีการดูดซึมสูงสุดที่ 496 nm และสบ absorptivity ของ 8.30 × 104 l mol− 1 cm− 1 instantaneously Cadmium(II) ยังทำปฏิกิริยากับพาร์ ขึ้นรูปแบบด้วยการดูดซึมสูงสุดที่ 510 nmและสบ absorptivity ของ 8.12 × 104 l cm−1โมล− 1

Results (Thai) 3:

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